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At the end of the month, I’m going to sit on the panel for a breakout session of the Connecticut Concrete Promotion Council’s annual Forum in Hartford. The title of the session is “Dispelling the Myths of ICF Construction.” Before I do this, I’d like to initiate a discussion of just what those myths (or truths) might be.
So, what prevents you from using ICFs? Or, why do you use ICFs? What concerns do you have? What solutions have you found?
Thanks,
Andy
Replies
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Andy, I have been working with a couple for a good while trying to get started on a 5000 foot custom house using ICF's. We have been having permit problems(not with the ICF's, permit folks like them), it is a waterfront lot, critical areas, etc. I have done a lot of research in the last 6 months and have seen a number of homes going up. I am very impressed and look forward to working with these. I was very hesitant at first, figuring that they would be cost prohibitive, but my numbers look to be only about $8K more for a house this size over traditional woodframe. There are a number of experienced subs in area that help take a lot of guess work out of the equation and save me from getting killed with the learning curve! Sounds good in theory anyway!! I'll let you know how it works out. I hope to have a permit in the next 3-4 weeks.
Kimball
*Andy, I have tried to keep an open mind on this subject, but my practical experience tells me I'd rather stick with a regular poured foundation. My concerns with ICF's are: Expense, Time required to construct a basement using this method, Exterior waterproofing problems, Trouble keeping the forms straight, Brick ledge problems, Need for an expensive concrete pumper etc. etc. I just don't see any practical reason to use them.
*Andy, after reading the article in the latest JLC I can guarantee I'll never use them. Regular poured for me.icf article
*Great, that's the sort of response I'm looking for. Keep 'em coming.Andy
*I was also leery about using ICF's in the ground. We found a system which uses conventional steel forms for a poured foundation, with a 2 1/2" thick sheet of foam on the inside, with plastic webs like the ICF's. This eliminates the insulation and framing in the basement. Cost is about break even. It also eliminates problems with ICF's in the ground(foam puncture, insects, etc.) They put a foam block-out at upper level to form a ledge for your ledger board. It's actually quite simple and not nearly as time consuming as cutting individual pockets. The main and second floors will be ICF(exterior walls). You can actually stack ICF's on a block foundation as well. I've always been a traditional wood frame guy, so this is new to me too. But like I said, I have done a lot of research and the owners are dead set to try this. I'll let you know how it turns out. Email me if you want the details and name of the foundation system. [email protected] I know there are those who frown upon using brand names!! Also, deck ledgers must be installed at this time, bolted through hollow core and tied to rebar before pour. All foundation penetrations need to be well thought out ahead of time too. If you miss one, you need to core-drill later!
*Andy - are you going to write this your self?I have been thinking about using ICFs for my future home. The main reasons being that I will only be building two or three foundations and I had to go to the expense of building forms that will result in messed up plywood that I won't really want to use for something else. There appears to be no place within 100 miles that would possibly rent forms. My questions: How do the "matrix" type ICFs compare with the solid wall type? Are they actually as strong, do they really save enough concrete to be worthwhile? I have always vibrated concrete (slightly, of course) in standard forms. I have read that you shouldn't do this with ICFs. How does one assure that the concrete gets into all the nooks and crannies without using a vibrator and what is the risk of seperating the mix? How much of a problem is there with bugs actually tunneling in the styrofoam? Does the borax treatment take care of this? What other environmentally treatments are available.What are the best products to cover the ICFs when they are below surface level? How good is Rastra and how does it compare to regular ICFs? Just how much more difficult to work with and how dusty to cut is Rastra? How does the insulating qualities of these ICFs compare with the all poly ones? Are there other products on the market that provide an ICF that is more substantial than the standard poly ones? What is the best way to tie the rebar in the slab or footing into the ICFs. The JCL article mentioned drilling holes to stick the rebar in. I would think it would be easier and faster to leave the rebar partly in and partly out of the footing like with a standard wall. Of course, if one used the matrix type ICF, one would have to measure the rebar-in-footing spacing carefully to avoid coming up in the solid part of the ICF.And verify the various parameters such as the proper gravel size and type, slump mix, etc. Of course, we will expect a "Consumer Guide" rating of all of the ICFs on the market as to utility, durability, cost, etc., and the designation of a "best buy" product...
*I've used them several times with no problems and like their advantages. I've heard concerns expressed about providing a home for carpenter ants etc. but haven't seen it. I would like more hard evidence on that point.I do vibrate.I leave rebar standing about three feet vertical from the footing to tie to and tie the horizontals to it. Low expansion spray foan helps to tie the foam down, fill bottom gaps, and make minor repairs.Be sure to brace well and pump slow.
*Andy, I have worked with several brands for basement walls, foundations and full house structures. These brands are Diamond Snap, Glacier -Lite and Cempo/Rastra. Like everything, there are advantages and disadvantages and probably no one right answer to their use. Here are some of my observations: They are more expensive than poured concrete or concrete block wall. However, after pricing one full basement that was specified to be insulated inside and out with 2" of HDPS, I found that the cost difference was a wash for that job. It actually saved me some overall time and I was able to set the blocks myself. No crew, no heavy foundation forms to tote around. The actuall pour took 2hours with a pump truck and several people helping. The bracing was actually quite minimal for 8 foot walls and 30x20 foot perimeter.Been using alot of Cempo or Rastra blocks the last couple of years. Full walls, sometimes 2-storys. The advantage is in theory, one can plaster the inside right onto the polystyrene/cement form and do the same outside with stucco. In theory. But with plaster on the inside one has a potential for several different substrate to plaster, wood for door and window jambs, maybe a rim or rafter plate, not to mention electrical/plumbing chases. These all will react differently with plaster, especially intregal coloured. One could sheetrock over the walls using adhesive but that may incur added expense. ( One trick that I find works well for anchors for wall hangings is to add a bit of steel wool to the anchor fastener before screwing into the wall. It helps the ICF hold better)I use a low expanding adhesive polyurthane glue to bond the blocks together and to the footings. On the Diamond, the blocks were 12" which required more horizontal rebar than code-required 16". The Glacier-Lite was 16" and both use a plastic web that holds the vertical and horizontal bar nicely for tieing. The Cempo/Rastra are bigger blocks, 32"x 48" which requirer punching rebar through for 16" centers. Not too difficult though.This is getting long-winded, sorry.Problems. Waterproofing the foundation is difficult. I find the best solution is to use a fabric covering which waterproofs and protects the block from backfilling. Run it over the footings as much leakage can occur at the joint between footings and wall. Good drainage is a must.Pour mix is essential as well as a pump truck. I think the last mix was a 7sack with pea-gravel (3/8minus) with maybe a six or seven slump. This pumps well into the chambers and flows well to reduce voids in the wall. It is difficult to vibrate thouroughly especially with high walls, rebar and a 6" chamber. The highest I will pour at one time is eight feet though I will do it in 3 or four passes to avoid blowing out the blocks. One advantage the ICF do have is a better cure, especially in winter.I use an electric chainsaw to cut chases after the pour for electrical and whatever. Use a Simpson strap and foam adhesive to fill in after, the strap to serve as a nail deflector.I question the efficiency of the ICFs at least in a heating climate. At best one has R-14 on the inside (2"polystyrene) and then 6-8" of concrete before another R-14. As the house size grows, so does the concrete mass. It will take awhile and abit of energy to heat that mass and keep it warm with colder outside temps. I had some of my concerns answered in an article in the ENVIRONMENTAL BUILDING NEWS (http//.buildinggreen.com) a while back addressing this same issue. Their conclusion was that the ICF principle works better in a cooling climate than a heating climate. My own evidence seems to bear that out as well. Sort of rambling my apologyswalk gooddavid
*Casey, I already wrote that article, in issue 128. That's why I've been invited to participate in the Connecticut Concrete Promotion Council's forum. I like ICFs - used them for my own basement - so I'm sure that most of people's concerns can be addressed. That said, ICFs are not always appropriate, either. I posted to get a better feel for what people perceive as the downside of ICFs, so that I don't get completely blindsided in a public forum.As well as I'm able to, I'll try to answer your questions in order. If by "matrix" you mean the grid-type ICFs that shape the concrete like a breakfast waffle, no, they probably aren't as strong as ICFs that form straight-sided walls. However, the real question is, "Are they strong enough?" You bet. Your design may require engineering in some locales with grid ICFs though. Are they more cost effective? I don't know, and that's something you'll have to analyze based on location.Some ICF manufacturers say that you can vibrate. Eco-Block comes to mind. To ensure good concrete flow, you use a smaller aggregate, perhaps more sand in a mix that's accordingly beefed up with more Portland, or you add a plasitcizer to the mix. Then, you rod the pour and beat the forms with hammers and wood blocks.I don't know what the best waterproofing membrane is. I used an incredibly sticky 60 mil. thick membrane whose manufacturer I forget.There's Rastra and one other cement composite block whose name escapes me. You'd have to read the manufacturers's literature and compare the R-values.You've nailed the rebar dilemma. I'd set the first course and then drill. You can find much greater ICF expertise on http://www.ICFweb.com/ Andy
*Andy - if you are casting about for projects to take care of the too much time on your hands, how about doing the definitive article on insulation? (roof ventilation might be even more fun...) I would certainly appreciate a scientifically grounded article on the advantages and problems with various insulating strategies, particularly with an eye toward fire resistance. Many at breaktime favor cellulose over fiberglas, but I still read reports that cellulose can breakdown over time if exposed to wet conditions. Some other areas of concern is what are the best ways to provide maximum fire resistance with various insulation, particularly the foam insulations. Some info on the best means of providing thermal breaks when working with light gauge steel framing would also be good.Most of the FH articles tend to be anecdotal. This is great for techniques and ideas, but on occasion I would appreciate something more research based. On insulation, perhaps a staff writer could work with staff scientists at NREL, Lawrence Berkeley Lab, Rocky Mountain Institute, and others to come up with a good compilation of current research findings.I would volunteer to do it, but I think my inability to talk to sources over the telephone would severely hamper my ability to do a decent job. An article on the current state of energy efficiency in housing would be a good follow-on to the insulation article. OK, and then when you finish that, how about an article comparison testing all of the various makes of windows that have been mentioned in Breaktime threads. When you finish these, I will have few more...
*David- I would appreciate a bit more discussion of comparing working with the Rastra type product and regular ICFs - does Rastra hold up better to abuse. Is the dust from cutting the forms a real problem? What is the cost of the poly/concrete forms relative to the all poly type.David or Andy:If one were to use all poly grid type ICF construction for basement walls, what is the best way to tie a partition wall to the outer grid wall? There have been a couple of discussion threads on the best ways to install electrical wiring in poly ICFs. With Rastra or similar construction do you just route out channels in the ICFs and run Romex in the channel; if so, do you really go into the ICF 1.25" or do you use some type of protective plate over the wiring to allow a shallower groove?Andy - about the bugs - are they as much of a problem with the poly ICFs as they are with my computer code?
*I don't know much about wiring in ICFs, nor do I know much about partition walls. Bugs are a worry, particularly in the south. I believe that Reward Wall Systems offers borate treated ICFs that should address this concern. However, borates are water soluable, which leaves you with the same concern as you have with cellulose. As far as cellulose goes, my response is that insulation shouldn't get wet. If it does, you have a different problem. Also, I've thrown FG on a scrap fire. It may not be flammable, but it sure does burn! At least the facing and/or the binders did, and there was no recognizable FG in the ash pile. It's possible that the glass melted Even without the borates, I'd risk the cellulose. Imagine trying to light a bundle of newspaper or a pile of sawdust. Neither burns very well because they don't get air. Andy
*Andy, I'm a complete fan of ICF construction, but I don't see it as the solution to every building problem. I've had people put plans in front of me which had things like exterior walls over a room below and ask if I could build that in concrete (Sure, but it's easier with wood) or walls of windows with 8" between window openings (Again, easier with wood) or curved walls (do I have to say it?) ICF's should be assembled by carpenters, preferably by the carpenters who will be completing the house because that will encourage care in leveling and squaring thing up. And they can be, too. The reason I poured my first one was that it put control of the foundation in my hands, the way it hadn't been in many years.I don't think it should be left to foundation people to whom a half inch here or there means nothing. ICF constrtuction is not a job for amateurs, either. It looks simple enough and is, really, but you don't have to make much of a mistake with concrete for it to cost you a lot of money. As for concerns about the products, well, we're all learning as we go along. There's just not enough of a body of knowledge and experience yet to avoid trouble all the time. An example - something that would never have occurred to me beforehand - did you know that copper pipes embedded in foam can, hell, will, squeak against the foam as they expand and contract? There's tricks to ICF construction just as there are to all other materials and we'll learn them just as we have with wood or anything else - by making mistakes. (Remember the carpenter's first law: Build first for your enemy, Second for your friend, and Last for yourself.) I sure wish I lived in one. The first thing people who do live in them tell you about is how quiet it is inside. Then they start boasting about their heat bills. (ZZZZZZZZ) After 10 years, they'll be boasting about what they haven't spent on repairs. (ZZZZZZZ)While their neighbours in their wood frame, T-brace, foam for sheathing houses are watching their tract palaces tumble down about their ears. Ron
*I was sure i wanted foam blocks for my recent foundation until i found out:Insulation: i saw the R-figures you posted in your article, Andy, but they seem to be under dispute as being quite inflated by the manufacturers over real-world performance, especially if the block absorbs moisture. Still, with the energy savings, you could probably afford to have borate sprayed around the foundation every year!Pheromones: the off-gassing of the foam may mimic termite love-breath, and so attract them. And those new gals from Formosa seem to be settling down to raising babies rather quickly!Borate: i read a study where borate-treated foam was placed next to wood in dirt, and while the termites preferred the wood, the study might have been more to the point if it had put the foam between the termites and the wood, to see if the termites wouldn't go through the foam to get to the wood. Also, even though termites don't eat foam, it provides a cozy nesting area for them.I went with AWW--no blowouts, no learning curve, no bugs, lots of stuff to nail to, places to run wires and pipe, insulation bays. Oh, and it doesn't crack!
*CaseyR, I'll try to answer your questions with my experience. I don't find the dust a problem when cutting. A good 8pt handsaw for small cuts, larger or more numerous I use an electric chainsaw. Since most of the cutting is outside dust is easily managed. I still wear a good dust mask. Dust becomes more of an issue once the blocks are up and the structure closed in. There is some potential shaving of the walls to flatten the surface and then the issue of cutting in wiring chases. A guage block is used for depth control on the chain saw and the cut is maybe 1-1/2" wide. A good dust mask and following clean up minimizes the problem. As with all tools, daily cleaning of accumulated dirt and dust helps prolong their life. As far as cost comparison between different blocks, I have no fiqures. Several considerations though, the primary being that because of their size (32x72x12inchs) and their portland component, Rastra or Cempo blocks are heavy. Stacking a wall of any heigth requires a crane or extended boom machinery that can increase the cost. With the poly-grid style blocks, I could stack and tie maybe 35 blocks a day. It is about 30- with the Rastra, but you are laying maybe 2-300% more wall area but with the added expense of a boom and operator. These numbers are hyperthetical as the dimensions of your wall will determine actual completion. Tieing rebar is the time consuming activity. I don't bother with tieing every piece in the middle bar of the rastra since it is a pain to get in there.Durability seems to favour the rastra. The straight HDPS blocks can snap easily if mis-handled. It is not to troublsome as the urethane glue does a pretty good job of rebuilding the break. A piece of plywood and brace is a good insurance though for the pour.Interior partition walls, window and door jambs and floor rims, I layout before I pour and set anchor bolts into the pour cavity. The door and window openings I make large enough for a double jamb all around. That way the anchor bolts are covered and I have a bit of shim room between the jambs to insure plumb, level and square. The patition wall studs I take down after the pour and label to be reused when the walls are framed, holes already drilled and fitted.I covered my experience with electrical abit in my earlier post. I have been platering right to the rastra (one advantage maybe of the rastra) so even with a shallow box, I need all of 2" for depth. Metal boxes are used and anchored to the concrete core with tapcons. The romex is run thru the routrd channels. I use 16d nails stuck into the foam to hold the wire and then use expanding foam to fill the channels back in. An old serrated bread knife does a slick job of cutting the cured excess. I use simpson straps as a nail plate, set into the foam and then foamed over. The urethane foam and the rastra foam are pretty similar as far as substrate for the plaster.hope this is helpfulwalk gooddavid
*I am still undesided as to the true effectiveness of the ICF in wall construction in regards to heating. I have no doubt and have experienced the advantages of the walls in regards to summer cooling. It works great. But heating is a different situation.R-value of the blocks, I think is greatly over-rated. The effective R-value in terms of heating would at best be R-14 if one is generous and gives the poly form R-7/inch. But then you have a considerable mass of concrete, a heat sink which must be warmed to decrease the delta-T of the outside world. Once warmed it needs to keep absorbing heat to offset the loss through again at best R-14 exterior insulation. The colder it is outside or the greater the difference in delta-T outside vs inside temperature, the more heat one needs to maintain the inside temperature.I have experienced the thermal mass effect in log homes, but no one considers them to be necessarily energy efficient. Unless there are other considerations such as fire (as in forest fire) or maybe insect pests (no experience there), I would rather put my money in a stick-framed double-wall and 7" of dense pack cellulose. I think it is a more efficient structure, as quiet as ICF, maybe not quite as bomb-proof, but less-expensive to build.Any thoughts?walk gooddavid
*Learning more about ICFs is a good thing. When more people truly learn about them their objections and fears simply dissolve. When more people learn enough to use more of them then we will be on our way to using less energy to heat and cool our homes, and we won't be replacing each home every 60 years or so. My wife's brother lives in Austria in a home the neighbors refer to as the new house because it is only 350 years old. Not insulated, but it isn't wood. Learn even more! Take a look at how http://www.Reddi-Form.com builds curved walls fast and pours them 14' high in one shot with little to no bracing. With most icfs, brick ledges, angles, and more are far easier than with wood or with the old non-insulated concrete walls. 35 years of building houses and some of us old dogs can actually learn new tricks if we realize there is a real reward for learning.
*The insulated concrete forms would have cost me $1540 for my house for "R14, if one is generous", not including spray foam, corner blocks, etc. I can get R-19 FG for less than $300. When i worked it out before, concrete for walls would have cost almost the same as the wood, a wash.
*Andy,I was so impressed by your article and your house that I recommended clients to seriously consider ICF's for their upcoming project, and will be installing an EPS system in late May/early June. It should work out well because their son is going to be working on the house with me, and wants to learn construction, so he'll learn it from the ground down, then up, so to speak! (We're going to dig the hole too).One thing I'm not sure of is how much benefit the insulation will be for this because they are going with a full walkout basement on the east side (longest) and may have an access door, a set of french doors, and a window or two on that wall to lose lots of heat from.But I'm looking forward to the installation-I've been curious about this for years, and now I can find out experimentally. And I agree with one of the above posters, that if we set these walls to my standards as a carpenter, the foundation should be a better form than what we typically get around here. The house I framed last fall was off by 1 1/2" in a 50 foot run...but that's the worst I've seen.Mainly-if you install ICF's and can get paid for doing the installation, and it provides interesting work, why not? For me, it seems like a good way to spend a week in May.Now, gotta get that tape back to you!MD
*A little education on "R-value". R-value relates to a material's ability to resist the transfer (or flow) of heat. Thermal mass relates to a material's ability to store heat. This thermal mass reduces the peak temperature difference (the driver in heat transfer). The larger the temperature swings from day to night, the more significant thermal mass becomes. Since wood frame homes have very little mass and more substantial possibility for cavity insulation, R-value figures have served that market very well.ICF manufacturer's are locked into the public's familiarity with R-value. They struggle with how to market the effectiveness of this style construction. Hence, they market an "equivalent" R-value. Because of the thermal dynamics, this will apply only to a certain climate. On a true measure of R-value, the claims appear highly exaggerated. This marketing approach offers a really great opportunity for competition to put questions into someone interested in building with ICFsOne certain claim ICF's have is long term insulation stability. Just as a styrofoam coffee cup does not get soggy, the ICF does not absorb water to degrade its insulation value. Once covered (protected from ultra violet radiation), it does not degrade. Also, because of its rigidity, it stays in place.I have performed energy consumption calculations comparing structures with only changing the wall construction. In each case, ICFs use significantly less energy (20 to 40%). The resulting ICF homes closely follow the energy consumption calculations. I also have had similar agreement when performing energy consumption calculations for non-ICF structures (so I assume I am doing something correct).Hope this helps on the A/C-Heating issue...Jerry Harber, P.E.
*SG, my prejudices are going to show here, but I'd be very surprised if most "R-19" FG walls perform even close to R-19. There's a big difference between lab numbers and real world performance. You are probably able to properly detail FG bats to achieve good performance, but I've never seen them installed properly by a subcontractor. Most people simply don't get that you can't simply stuff batts into a cavity and hope to achieve the nominal performance.Please note that, in my article, I qualified the ICF industry's "effective R-40" claims. My own basement has 5-in. of foam surrounding the concrete. Realisticly, that's R-4 per inch, or R-20, with no air infiltration. And since I did my own foundation, it was level, square and straight.Andy
*Thanks Scott. It takes a kindred spirit to be impressed by an unfinished house! You've got one of my tapes? I must trust you, 'cause I don't remember that.Andy
*FYI,Reward does not offer a borate treated form. Polysteel has licensed the technology from AFM and has incorporated PerForm-Guard in all of its forms that are manufactured in its Gainesville Florida plant. Per-Form Guard is the only code approved (SBCCI)for installing foam below grade in areas of heavy termite infestation.The Per-Form Guard is added during the bead expansion process and is throughout the form and is not simply a topical treatment.For information on wiring installation check out http://www.polysteel.comDave WatsonSales ManagerAmerican Polysteel800-977-3676
*Had my own home constructed using all ICF construction all the way up to the roofline. If I had it to do over again, I'd use traditional construction methods. I didn't construct the walls myself - I sub'ed the work out to a Reward Wall distributor. A number of the walls were as much as an inch and a half out of plumb, some had bulges and one wall has a 2" bow in it that extends for 30'. Definitely ended up costing a lot more than anticipated, with the other trades charging more to fix, compensate for and hide the shoddy wall installation.
*Dave, I looked on the Polysteel site and didn't find the electrical installation information. Was it in the Installation Handbook section that was "under construction" or did I not look in the right place. I did appreciate the safety information section.
*Electrical and plumbing lines fit easily and in accordance with code requirements by simply cutting a channel into the foam and placing the wiring or piping into the wall. For plumbing lines larger than 1-1/2" O.D., you may need to set them in place prior to placing concrete.The best tool to use is a hot knife (about $100.00). It's the same tool used for EIFS.Billy
*People who know the facts about ICFs understand that, if built properly, there is not a higher quality building envelope. The negative myths about ICFs mainly have to do with termites, fire, difficulty in installation, and high cost. The simple answer is, YES, these are factors you do have to consider when building with ICFs. The specifics, however, depends on too many variables. Do more research (I suggest you take sometime to visit http://www.ICFweb.com) before embracing or dismissing this much maligned technology.Rick
*Thanks for the correction, Dave.
*I'm not impressed with FG, either, even properly detailed, but i threw it in for a cost comparison. I'm currently deciding between icynene and DP cells--the stachy thing makes me nervous.
*ICF construction and its negatives or drawbacks.Many people believe that there are drawbacks to ICF contstuction. No. Every negative I have read on this board seems a bit unfounded. If there is a negative, I would honestly say that it is the lack of educated, expierienced and knowledgeble contractors. I will address these one at a time as best I can.***remember that what I am comparing here is one of our expierienced crews, to one of you concrete or framing crews with top expierience and knowledge.Issues: 1. "Expense:"Contractors with several years expierience in the ICF industry are compeating dollar for dollar with wood and concrete construction primarily in the colder Northern areas of North America generally the uppermost states boardering Canada. As well, many manufacturers are redesigning the blocks to be more user freindly in that the steel requirements are lowering, the concrete in some systems is designed for 20Mpa instead of 25 Mpa (about $20.00 more per cubic meter), and the ancillary product manufacturers are starting to catch up and with the added competion, all the numbers are going down. As well the expierience of several years of ICF for a crew is now the norm, not the exception. If you look closely at the cost comparitives, you will see that over seven years the gap is closing very quickly. Maybe not even yet in the more southern areas, but up here, due to the design restrictions, they are already on par. Expensive engineering is being replaced with code acceptance of all the products and methods used in ICF construction as the testing and approvals have really started to take off, and standards have been set.Now lets add in an all ICF house, and tie in Clear span OWSJ concrete composite floors, now we are talking savings, no need to fight with ledger boards, its faster, easier, simpler stronger, and safer. Most of all, you save up to 10% per floor in labour and materials. In this scope, ICF construction is cheaper, not more expensive.2. "Time required to construct a basement using this method:" Many people base opinions on older type or generation 1 blocks, we are now able to buy 2nd generation blocks which increase the speed of construction by reducing or eliminating bracing, wire tying, taping and strapping requirements as well as better designs for ease and speed of block handling and placement. As well, there are newer and better ancillary products and construction techniques, which again cuts the time and cost down considerably. In the end, One Basement a day (1500 square feet) is currently being completed by one of our crews, which includes the pour. Now take a closer look at the remainder, Insulation and studding for basement walls....complete, exterior Platon waterproofing, completed in one hour, exterior above grade parging, one coat completion in two hours. ICF's save time, they do not add time.And when you include the OWSJ composite concrete floor system, The crew in question completes the entire basement, complete with first floor assembly, ready to backfill in two days for a 1500 square foot L or T shaped building.3. "Exterior waterproofing problems:" Again the products are now in place which prevent this from ever being a problem. Often the installed costs are down to 25 cents a square foot, as opposed to the current standard, and is installed quickly, providing the protection from lumber and rock punctures. Best of all, it gets applied by the same crew doing the basement, no waiting for another crew to come in and spray a coating. One final note on this, the foam is a cusion to the actions of frost jacking of stones into the wall assembly. Absorbing the point load of any rocks against the foundation, the foam acts as a cusion, wereas a concrete or block wall is so rigid, it is incapable of movement without cracking the damproofing and allowing water to enter. Best of all, you can backfill with sand, silty sand anything but straight clay. How much will you charge for importing sand???4. "Trouble keeping the forms straight." Not to an expierienced crew, remember that as the years go by, more and more people and research is being completed. As you would select a quality framer to ensure square, level, Plumb and true, you sould be doing the same with your ICF guy. How many wood frame buildings are perfect, or concrete foundations poured properly. The big difference here is that the ICF has to be done right the first time. The framing carpenters can tear it apart again, or build to suit the foundation.5. "Brick ledge problems:" I agree totally, thats why we use a thicker ICF wall from the foundation up to ensure that this is not a problem, the same as the block and concrete guys.6. "Need for an expensive concrete pumper etc." Yes you need the concrete pumper, but again the overall cost would still include this, ergo, the costs would or should still be about the same. Quick note, how are the concrete former pouring here???7. "I have always vibrated concrete (slightly, of course) in standard forms. I have read that you shouldn't do this with ICFs." The 2nd generation blocks all take internal vibrators, this is not an issue anymore.8."How much of a problem is there with bugs actually tunneling in the styrofoam?" NONE, this should not even be an issue, deal with it in an identical manner as wood frame dwellings. Cost and labour are the same. There are also no confirmed reports of carpenter ants or termite infestations, as well, many manufacturers are include an insect repellant in thier eps products to eliminate the risk.9. " What are the best products to cover the ICFs when they are below surface level? Sheet poly protective membranes such as dimple membranes and/or stuccos and parging, some use a peel and stick waterproofing.10. "And verify the various parameters such as the proper gravel size and type, slump mix, etc." If you are vibrating the mix should be a standard for any 6" form. High slumps and pea gravel are considerations taken into accound only in situations such as high concentrations of reinforcement or chase and opening congestion. If vibrating, the standard 20mpa, 3/4 stone and no slump inducers, simply a 4" slump (which is a standard for most concrete used in residential) will do fine in many of the newer 2nd generation forms.11."I leave rebar standing about three feet vertical from the footing to tie to and tie the horizontals to it" Why... If you pour a wall with a key way, or you pour a wall with shear bar, its the same. The advantage to concrete over ICF is that the concrete walls resists the earth pressure by pushing against the slab and the floorbos. Easy enough, simply omit the foam in 3" holes at the slab elevation every 12" or so, and the problem is solved. Many systems now do not require any tying of rebar, again they tend to be the second generation systems. This is another, not an issue.12. "I question the efficiency of the ICFs at least in a heating climate." simply put, effective r-value for wood frame insulated to R-22 in North Bay, Ontario=R 17.4, 6" ICF wall equates to R 34.7 Energy bills on caparative structures in area proove a 40 to 70 percent energy savings.I could probably ramble on for hours on this. The fact isIN THE END THE COST IS LESS IF YOU BUILD A TOTAL CONCRETE HOME TO CONSRUCT AND OPERATE.I would like to have people note a couple of rather significant points here.1. North america is the only place in the world where wood framing is the standard of construction, concrete is by far, more the international standard of construction.2. Wood frame homes do not often make it past two generatons of a family, they just simply do not last.3. Concrete homes have very few components to them. Much unlike a wood frame which is rickety and haphasardly connected with wood and nails and joints that rotate, wood that rots.4. Heating and comfort savings on the equipment costs, and long term energy costs. No contest here, I love warm living, and again, when you combine the concrete buiding concept to develope thermal mass and integrate radiant technology, the costs are often less for construction, with a fairly significant reduction in construction time.To name a few. But hey, if you want to see it and read it, go to http://www.arit.com and investigate. I think you will find all the information your heart desires on that site in respect to concrete technologies and ICF's. The site is tailored to the consumer.
*Billy, I run the Simpson strap over my wiring chace for some added protection. I usually run them only on chases above 42". Since I plaster and not hang drywall, I like the added security in case of a misguided picture hanger. Also, I can only consistently get 1-1/2" depthfor the wire, which in my mind is too close, though it does pass code.walk gooddavid
*Mark, I have not built as many structures using ICFs as your company, but I have built a few, three in the last 3 years. Generally 3000-8000sqft two storys, all but the gables are block. We use CEMPO block and at first RASTRA. Since we do not build duplicate homes, my estimates for cost differences are just that, estimates. I find ICFs run about 10% more for the cost of the job. But that is so dependent on plans and details.I am a carpenter and a builder with wood so I confess to certyain prejudices to such. I agree that many houses that are built today and in the past will not last many generations. However I think so much of that today, is due to material choices and in shoddy workmanship. There are many examples of wood structures in Europe that date 300 years or more. In this country I have rennovated a number of houses built in the 1800's that have been structurally sound. My current house is over 90 years old and shows no signs of decay.The ability to reconstruct and reuse building material is a plus in my mind and I do not think it is as feasible building with concrete.Despite your enthusiasm for such building, I still have my doubts. One which I voiced earlier which you picked up on was my questioning their efficiency in heating climates. I do and I have seen no conclusive evidence to the contrary. The same has do do with manufactorer's claim of R-value. To the best of my knowledge there is no standard for "mass-enhanced R-value" only for steady-state R-values. And yet many ICF manufacturers use the enhanced value to inflate their claims. You claim your 6" ICF wall gives you R-34.7 yet your web-site claim is for 5" of EPS @ R-25. Are you adding more insulation? One source of independent information I have found so far was reported in the ENVIRONMENTAL BUILDING NEWS V.7, No. 4-- April 1998. (www.greenbuilding.com/features/tm/thermal.html) It's conclusion was "Thus, high-mass walls are most beneficial in moderate climates that have high diurnal temperature swings around the desired indoor setpoint." It further concludes "In northern climates when the temperature during a 24-hour period in winter is always well below the indoor temperature, the mass effect offers almost no benefit and the enhance mass R-value is nearly identical to the steady-state R-value."Your energy savings are computed how? In reading HUD's Report... INSULATING CONCRETE FORMS: COMPARATIVE THERMAL PERFORMANCES prepared by NAHB Research December 1999, there are some interesting highlights. They built 3 identical houses and monitered temps One was LITE-FORM ICFs, one was REDDI-FORM ICF and the third was conventional wood framing. Their conclusions for winter energy use were that the ICFs enjoyed a 20% energy savings. But when one considers that the traditional wood framed house was 2x4 construction with fiberglass batts framed over a block foundation with only inside EPS. I would expect more of a difference. If there ever was a skewed test, this is one. How does ICFs compare to a proper double-framed wall system with 7" of DPcells. The dimensions most surely are more even. Even 4" of EPS will do better than R-11 fiberglass batts. If the conclusions of the EBN report are correct, then we are comparing two different R-value walls, 4' of EPS at say R-20 vs 2x4 batts at R-11. I cannot buy it.I am interested in learning more as I do build with them. It is what people seem to be sold on. But until I have more definitive evidence to the energy efficiency, I would rather stick with a properly insulated, and constructed wood house.walk gooddavid
*Some other thoughts I have concerning ICFs so I will start a different post.One I briefly entered into is remodel/rennovatipon. Many of us are strictly remodelers. How does it work with ICFs? My next concern is for me more important. Today the buzz-word in building is "green". We hear how OSB and engineered wood products are green. We are told that polyurethane foam or ESP is environmentally responsible. And some claims are made for ICFs to the same.Are they really all that good.? To determine that there are many issues to consider, but not only in the final home. Energy consumption in the house is important, but how about during manufacturing? Manufacturing results in tremendous energy consumption for both cement and EPS, not to mention the toxicity of some of the waste products. What of the remains of the building after it's life expentency is over or if there is some reason for it to be reduced to "landfill" before it's time?I think we need to consider these issues as well when we build.walk gooddavid
*To the best of my knowledge there is no standard for "mass-enhanced R-value" only for steady-state R-values. R-value calculations are used to avoid the cost of physical testing by using developed formula's and algorithms for estimating the R-value of a wall (thank you Pieter).What I have quoted is the "effective" r-value of two wall assemblies which were physically tested using the "gaurded hot box", which is the most accurate means of testing. In cold climates, the savings are more significant, due to the combined savings from lowered air infiltration, Thermal Mass effect (as we are building the entire structure of concrete including interior components), and lowered thermal transmition due to non conductive components. Lets take this one item at a time.Calculated R-values although an R-11 fiberglass bat in wood fram, with 1/2" plywood and 1/2" gypsum board has an R value of 13.6 at the center of the wall cavity, if the 2x4 wood framing is taken into account, the "clear" wall R value is 10.6 If we take into account other misc items not included in the clear wall value (includes corners, wall/roof and floor connectino, window headers, sills, jambs etc.), the the calculated r-value of the assembly is 9.6. ICF's do not have this restriction.Convection.When the batts are improperly installed leaving cavities, or settlement over time occures, convection occures. in 1993 the National Research Council of Canada study "measured thermal resistance of frame walls with defects in the installation of mineral fiver insulation" 3/4" gaps in the four corners of the cavity only, caused a reduction of 30 to 40% of the entire insulations R-value. (lord knows why they opted to study this).Thermal MassAlthough more pronounced when the delta temperature flows from a positive to a negative difference between the interior and the exterior of the building envelope, In cold climates, heat flow reversals within mass walls occure in the spring, summer and fall. However, with the inclusion of interior concrete structure, the overall storage capability is increased, and by utilizing gains during operating hours, although the shifts are slight, the overall BTU storage and transfers remain about the same.Infiltraion. Majorly underated in the North. Rather than elaborate on too much detail of the small things, the contributing factors to added infiltration and exfiltration are:Stack effect-big deal in cold climates, with the higher BTU requirements the building is always applying pressure to the envelope.Vapour Pressure-with the added problems association with high humidity levels and relative humidity problems associated with higher delta Temperatures between the indoor and outdoor enviornments, the heavier indoor air often pushes itself out, effectively pumping heat through the small holes. One thing about humidity, it is always trying to even itself out, therfor the higher humidities are trying to move to the lower humidity areas. One good example is the frost build up around the cracks in doors. on cold days.A final Note:CTL engineering completed the report "Analysis to determine thermal mass performance of a typical 9 in. ICFA form wall". The conclusion was that although the wall was calculated in both U and R values that the overall thermal performace varies with climate. The wall had 2"eps, 5" concrete and 2" eps, and was compared to an equivilant wood framed wall assembly (r-17.5). The resulting comparison detailed what many believe to be the standard for comparison for ICF construction. (By the way, the warmer the climate, the higher the equivilant r-value of the low mass ICF wall system.) For example. I live in North Bay, Ontario. Here this type of low mass wall performs to R-24.8 with a U factor of 0.0403. But hey, if I lived in Daytona Beach, Florida (huh, I wish), The thermal performance woud equate to over R-50 with a U factor of less than 0.020.Why do ICF's perform so well up here... They reduce the secondary losses of conduction and infiltration, and inconsistencies in construction, as well as providing (to some degree) thermal mass effect, however moreso, they provide an even insulated wallsystem which does not decay at the rate of standard construction systems. Remember wet batts have very little R-value, and condensation at dewpoints will reduce this value, and destroy a building within a few years. Yes homes in the south are lasting far more favorably, however, they do not have to endure the rigours of Northern Climates.Mark Ross
*to mad dog,Have fun with it. foam foundations do cost a little more but I live in an isolated area so it's almost impossible to get a concrete sub out here and those willing to come in this labor market are from the bottom of the barrel (eyeball square and level- you know what I mean) so these forms let me set forms to my standards of acuracy on my scedule without a big investment in forms - it's a job cost.
*Mark, In reading your last post, we are not that different in our opinions only in our approach to the matter of ICFs. I agree with most everything you say with some considerations.Your last post seems to agree with the contention that the colder the climate ( a heating climate) there is a decrease in the enhanced R-value of the ICF wall. I do not know if the studys being done at OAKridge are completed, but one concern was how many climate models needed to be studied to provide data for standards. How well do ICF low-mass walls stand to temps ranging from 40below to a high of 20 below, lasting for 2-3 weeks?My main considerations are the premise that ICFs are more energy efficient then a steady-state no-mass wall. I understand why the ICF industry wants to compare it to "standard" industry wood construction, it can't help but make them look good. Standard construction especially with batts are terribly inefficient. But by your own calcs and those done by HUD, a standard ICF wall has a third more or better R-value than the standard wood frame. That I repeat is hardly an equitable or valid comparison. I would hope to see less energy consumption in an ICF construction.There are many ways to reduce and even eliminate air infiltration in wood construction, that do not appreciably raise the cost of the construction, or decrease permiabilty of exterior envelope. How does ICF construction compare to a 2x8 wall with DPcells? The R-values are more comparable as is the wall thickness. How does construction cost compare in the efficiency mix? How does the total manufactoring process factor into the energy mix?Other conderations have to do with design, floor area vs mass volumne. How do the variables in design affect energy efficiency?I think back to Andy's original posting. It was two parts as I read it; the technical considerations when using ICFs and another question, should we or when should we use ICFs. There are definite situtions wetre ICFs perform well and would be my first choice. But there are situations and conditions that I would not consider ICFs.walk gooddavid
*Ron,You may have saved me just in time! I need to run some copper pipes from an ICF basement to the rest of the house for heat and domestic hot/cold water. I had planned to run them in channels and then foam over. Sounds like that may not be the best plan. What do you suggest?TIA,Jerry
*Andy,#1 Cost of materials: I can beat the thermal proficiency of ICFs - whole wall construction including air infiltration - by $3 to $5 per living square foot based on average home using wood frame construction.#2 Local ICF availability: Limited local supply. One company quoted me a great price on blocks - then added the shipping - nearly doubled the price.#3 Locally trained installers: What if I want sub out "the framing" - no one local has a clue.#4 Sidewall shingling: OK, you can fir out a wall for horizontal siding (clap, fiber cement, vinyl) or apply EIFS top coat but you can't apply a local favourite: white or red cedar. Unless of course you want to sheathe the entire exterior - big expense of labor and material.#5 Local concrete supplier mixes. Only one local company has an ICF mix that can pump through a 2 or 3" hose. The usual pump mix (almost like a slab mix) only pumps easily through a 6" pipe which is a little too big and messy for ICFs. The one local mix is plasticized and creamy but at $25 per yard premium ---- That drives the cost up even more.No trouble discussing ICF possiblities with custom clients; most have heard of ICFs and have a good impression of them. But when they get the price.... They see their dreams of the whirlpool, granite countertops and stamped driveway fade. Then they cutback on ICFs.....
*Jerry, My experience is too limited to give you a suggestion that I know will wiork. I would probably try to run the piping in interior partitions. If that's impossible, then how about plastic pipe? Maybe copper doesn't squeak if it's loose in a groove or fastened in only one or two spots. I'd like to know, myself. Anybody?
*Mike, Re number 4, how about skip sheathing on the walls or using shingle panels? I have never used panels, but surely a strip of 1 x 3 for every shingle course wouldn't break the bank.
*Well I have no choice as to where it will be run; maybe I'll make the groove on the large side the stuff it with fiberglass. Or should I fill with dense pack cells :-)Jerry
*Mark- One consideration not yet pointed out in these postings in favour of the R-value of ICF is the conduction of heat/cold from the ground through the footings up through the walls and into the structure. This does, of course decrease with the distance from the footing. BTW - Your postings are well- stated and your points are valid. Andy- I am currently planning to build a modest 3-level ICF home on the north shore of Lake Erie and aside from the difficulty of finding a contractor/builder familiar with ICF (many haven't even heard of it!) I'm encountering rejection/ hostilities toward ICF from the local (small-town) municipal building department during my pre-construction scouting. In my personal examination of ICF vs. conventional houses which I have visited it would appear that ICF has suffered in reputation mainly as a result of the rampant epidemic of incompetence which seems to have permeated the building trades.(I am now donning my Nomex suit :) ) Poor workmanship which has become all too frequently the accepted norm in conventional construction is much more evident and pronouced in ICF construction, in particular when a mediocre tradesman with, say 20 years' experience in conventional building is now asked to do something "differently" (read "competently"). Cut corners in a conventional house and it is usually easily covered up- missing insulation won't show. Cut corners with ICF and the results can ,and have been, disastrous (blowouts etc.) ; and are VERY evident. The learning curve for ICF building is said to start flattening at about 5 houses. I believe that ICF will gain widespread acceptance among homeowners and builders as experience is gained by skilled construction teams. But they need to take that plunge into unfamiliar territory first. In short - I think ICF is getting a "bum rap" because of poor workmanship. In my humble opinion - a competently-constructed ICF house simply makes a superior house. Period. Regards - Brian
*I think you're right about the competence of builders in ICF's, I spent a couple of days at ahome show recebtly trying to sell my services as an ICF builder and talked to quite a lot of people who are already living in them. They are either very happy or very unhappy with their houses. One man told me he heated his 6400 sf house for $2000 last year (I spent near $1000 to heat 1300sf). A woman told me about her house, which leaks at every joint, straight walls are a fantasy and the house is visibly crooked. These are both built with the same block.
*What about this take on the reputation of ICF as an alternative building material:First, the manufacturer's allow the widespread dissemination of information that may have started out correct, but by the time it gets half way around the country, there are people making statements that have grown from modest claims to massively overblown "wish it to be true, sounds like it should be true, so therefore, I will state it like I know it to be true, so the next guy will say it is true".Second, the manufacturers and agents propagate the problems of misinformation and poor installation by recruiting many installers that unfortunately couldn't make it as a framing sub or concrete sub. They recruit these clowns that couldn't square a doghouse. They lure them in with dreams of "it's easy, you can make money"....but they don't bother to check references or give them a litmus test of sorts...This is akin to taking your car to the shop for a transmission rebuild....do you think the guy has never done it before? or do you expect that guy to have been truly "certified"? The term "certified" within the ICF industry may mean that the guy had the money to attend a glorified sales training class...therefore he/she is "certified". I would contend that it is easier to become a certified dealer or distributor of an ICF product than it is to build with it....which ought to come first? ICF combines more than framing and concrete, it combines with that, general building experience that neither sub has ever encountered (and sure as hell isn't going to learn in a two day training class)...if the sub was a concrete contractor, he doesn't know how high a window should be over a garden tub let alone over the kitchen counter, if the sub was a framer, hell, he doesn't know what a 6" slump concrete really looks like, it's a guess. How high off the floor does the dryer vent need to be? Next ICF job you go to, ask the guy that is installing what a 3-4-5 triangle is.....you will probably get a blank stare...If that happens, don't even bother to mention "Pythagorean theorem". Last year we happened upon a couple guys installing ICF walls for a home, we watched them square corners with a speed square...That's a certified installer. (I guess that's more accurate than a PLS-5 to some). The blocks all work, they will perform for the install, they will offer a better home, but they are brain dead. The other part of the big puzzle that gets left out when ICF goes in is the failure to complete the envelope of the house with energy efficient products. ICF is an upgraded product, it doesn't fit for every house, but just like dishwashers, pretty soon it will become a standard part of many homes. The cost is relative, sometimes it costs a lot more, sometimes the payback in energy savings alone is less than two years....just depends. Superior Energy Wise in Dallas will for a couple hundred bucks analyze the home and predict energy usage for both ICF and wood frame construction and offer a warranty for the savings....many times in the south, the savings equals the extra cost in less than 3 years...after that, the homeowner gets a true savings every month. In 3 years from now, that $$ amount will be substantial.
*Ron,I haven't crossed the bridge yet, but both ideas may work. I've never used the shingle panels because I like to vary the shingle exposure so a course matches the top and bottom of windows and doors if possible - makes for a clean look. I don't think the panels are adjustable.mike
*Certainly, a new standard has to be accepted for plumb and straight with ICF walls. I have looked at a number different homes built with several brands of ICF and noticed "pillowing" between the spreaders on all of them. I am a contractor and used ICF's on my own home and had no end of trouble keeping the walls straight and plumb. I also used a product that had quality problems and had 7 blowouts inspite of the fact that we poured in 4' then 16" lifts. Each blowout caused a wow in the wall that has driven me nuts ever since. Could chalk it all up to the learning curve or just bad luck. Also, attaching siding and sheetrock is very time consuming at least as far as my contractor sensibilities are concerned. My local PUD energy advisor has serious doubts as to the added energy efficency of the ICF product that I used over that of a framed wall. One other personal comment seems in order. The sellers and manufacturers, and even installers, could just as easily sell cars or religion or any product for that matter. Hopefully we will see more building industry information and less from the sellers and manufacturers. I will use these products for all of the good reasons the builders suggest, but I will have to adjust what I concider to be fine home building.
*Thanks everyone for your input. My panel time went fairly well, although the audience wasn't really what I'd hoped. They were all concrete producers hoping to learn that ICF construction would help them to sell more concrete.I did get to hang out with some ICF and PCA people, so it wasn't a total bust. One of the guys I was presenting with was Jeff Preble, an ICF producer and contractor whom I've known for a couple of years. He again brought home the idea that education about using ICFs is critical, and that the type of block we use is only one component. Concrete, pumping and careful construction all play equally important roles.Andy Engel
*
At the end of the month, I'm going to sit on the panel for a breakout session of the Connecticut Concrete Promotion Council's annual Forum in Hartford. The title of the session is "Dispelling the Myths of ICF Construction." Before I do this, I'd like to initiate a discussion of just what those myths (or truths) might be.
So, what prevents you from using ICFs? Or, why do you use ICFs? What concerns do you have? What solutions have you found?
Thanks,
Andy