Poured concrete foundations are a problem for some of us around here. The few ‘crete subs that do it are OK, sort of, but they tend to overbook themselves and then end up giving poor service, schedule-wise. It is sort of hit and miss on accuracy, too, depending on which of their leads runs the job.
I am seeing GCs taking control and buying ICF packages from ARXX, Logix, and others, then doing all the work themselves, subbing only the flatwork.
Have you any experience with this? How do your costs work out, material, labor, and overhead, versus subbing out a conventional formed-and-poured concrete foundation?
You of course need to net into the whole picture the costs saved in insulating the walls, and studding them out if there is any basement finish.
Replies
Stinger, the first cost I would factor in would be the time-cost of money.
A month delay on a big custom could easily equate to 5 or 10 k.
blue
I did my own ICF basement and hired a solo finisher to do the basement floor. By the time I factored in cost of the materials and my time, and the cost of insulation and labor, I think I paid more by doing it myself. If you're a good framing contractor with a decent knowledge of how concrete work is done (specifically the reinforcing and bracing required), I think ICF's will provide a decent cost savings overall.
Some things I learned:
Hey Stinger,
We poured our own basement walls. 9'h 10" thick. Lansing poured walls gave us a bid of 19K. We rented the forms for 3500 ( found out later another company would have been half that ). Total cost when we were
all done was 10K I think. Saved alot, but its alot of work. The foam
blocks are way too expensive. I think $2.85 sf. That doesnt include
the cost of concrete.
Hope this helps.
Rob Teed
Dream Builders
I've done just what you are talking about on secveral foundations for additions, and for my onw house. Here on the island, it is a hard thing to schedule ferry, crete crew, weather, pump, weather, readymix trucks, and weather, all on the same day. That males a poured foundation get expensive. unless a conctrete sub already has his forms and equipment on the island, he hesitates to make a commitment, 'cause once it is out here, he is locked into this job until fiinished with no fliopping back and forth between jobs acor4ding to weather etc.
so i do the samller addition pours myself mostly with AARX
an ICF system WILL cost more to do than poured, but you get more for it. Also, there is a compensating cost savings in less crete used, and the insulation is already done.
As blue pointed out, there will be a cost in waiting through a delay for the regular concrete crew. For me, the cost is more in schedule than in interest at the bank. I can't keep my subs waiting for me while the concrete crew daily calls and says, another day or wekk...
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While in Wyoming I worked for a GC that used ARXX for our own foundations and entire walls as well as selling the block retail. Prior to that I worked for two other GC on large summer homes and they both used ICFs and poured our own foundations.
The cost of block is the main disadvantage and you can minimize that in a few ways. If you start using "shallow frost protected foundations" it's possible to only use two rows of block. Of course, some areas only need two rows of block anyway, but in the colder climates the difference can be significant. You can also save block by planning the house in a way that allows easier cuts on the blocks. A simple foundation won't benefit much from this, but a large-complicated contraption that needs a lot of special reinforcement will and total cost savings can be 25% or more.
Shop around for your block since the margins are quite high and you might save 25% if someone has some extra block they need to peddle. Also find ways to cut down on the number of special purpose blocks that you use since these are a bit spendy for what you get. Instead of adjustable angle corners for that 30degree bump out, we would simply cust straight blocks that had damaged corners and do the extra bracing.
Our labor costs were relatively low since it didn't take our best people to lay block. A few laborers caught on quickly and after a few jobs, they could lay block for an entire house with very little supervision. Truth be told one of those laborers contributed more profitability per man than anyone else on the crew when they were doing foundations.
A cost that isn't usually considered but should be is the cost of failure. Many GCs get into ICFs only to fall short of what they were trying to accomplish. Some get caught with $10k in forms that aren't worth much and others just lose their shirt when 20 yards of concrete blow out of a poorly supported 8' wall.
We would sell block to anyone and if they hadn't used ARXX before we could rent out an experienced ARXX carpenter to show them how to get started and to check up on them occasionally. There are always problem areas that the uninitiated don't recognize and can cost a bunch when sections of walls are blowing out or separating. On pour day for full-height walls I would strongly recommend having an experienced crew run the show with your carpenters along to learn and help as needed. ICFs aren't rocket science, but they have unique problems must be taken into account.
Three types of bad things seem to happen. Probably the most common are the small blowouts that happen at corners, along the top few sections, and anywhere the continuity of full blocks are interrupted. Our crew always had a few small areas that needed to be reinforced during a pour--and that's a good day! The trick is identifying as many of these areas as possible and adjusting things accordingly. We've cleaned up after other GCs that have lost entire walls to poor bracing and that is expensive.
Second are probably the completely out of line walls since ICFs loaded with mud are about as straight as wet cardboard. Many new to ICFs fail to understand that bracing can push a mud filled wall quite well, but can't pull it back because of connector limitations. If you are doing a lot of short walls or any full-height you'll want a set of adjustable bracing. We would usually rent braces for $1k a week or so. Even with relatively good bracing and no blowouts it's easy to build things that cannot be made plumb once poured. Block settles about 1/16" per row with mud and it always surprised me how many people try to fight this with uneven bracing/patching and sometimes lose. The top layers of block will want to lift and separate without proper vertical reinforcement. Corners can't be vibrated and are typically the most vulnerable. Anywhere blocks are cut need to be reinforced. Vertical seams need a lot of attention.
Third are the problems caused by improper mud or placement. Smaller aggregate helps a great deal. Vibration is mandatory since the matrix of block webs and rebar resist mud quite well. I was hired to fix some problems with a newly constructed two-story log home. Among other things, the foundation ICFs were poured and not vibrated. The honeycomb was extensive and apparently not known to anyone else since the foam hid the damage, which was a very bad deal with the weight of two stories of logs above. This made for a legal battle between the contractor and an insurance company--the contractor lost.
Basically I think it's a great way to build and it's easy to train wood carpenters to do it well. In fact wood carpenters seem to pick it up faster than those experienced with concrete forms since the processes and problems are so different. If you are going to do it, do it well.
Best of luck, Don
Good points Don.
Something I would like to pick up from your statementes and go forward with -0 blowoutsI have never had anythjing close to a blowout. I think that is because I have worked with crete before and know where the hydraulic pressure is apt to be the worst, and that as a carpenter, I am able to see the structrural deficiences in the stack. So I can anticipate where blowouts are most likely to occour and take action to have them re-inforced well before the concrete trucks arrive.
So that is my point, think it through and anticipate blowouts rather than have a big crew running around like chickens being chased by a fox trying to fix the blowouts as they happen. It is less stressful that way.
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It might not pencil out dollarswise to form and pour your own foundations, but it's interesting and challenging work. And in my mind, it's part of "carpentry", which I set out to learn over 30 years ago. It's like drywall taping, roofing, insulating, hardwood floor sanding, cabinetmaking, hanging crown, etc - not something I'd want to do every day, but fine as a part of a larger project.
One of the great frustrations I've found as a "contractor", and seen in other contractors, is dealing with subs. I've even found myself carrying some of that frustration around and allowing it to creep into my dealings with people. So I try to do as much of my own work as I can, including form work.
Yes, the fewer mud leaks the better and as you know it's just a matter of anticipating and fixing before the pour, not during. Many of our projects go without any real problems, but we do push things--by design. (And probably run like chickens once in a while;-)
If I was 90% sure a small area will be OK, then there's probably no need to reinforce it. Having said that, all the little things do add up and having 100 areas that were 90% ok, means there were 10 that needed an extra reinforcement. If those 10 problems took 5 minutes each to fix, that's a savings of 450 minutes (7.5 hr) over what would be required to reinforce all small areas up front before the pour. $200 savings at very little risk.
While we often poured 10 vertical feet of block going from footer to truss anchor, the way we poured mud allowed problems to be fixed quickly and safely. Full bracing was used which also allowed us to plank and easily walk completely around the perimeter of the house. One person ran the pump hose in 2' lifts putting a lot of mud down quickly. Directly behind him was the guy vibrating. The other two would stand by to fix blocks that appeared to need a little help. The short lifts made leaking block joints easy to find and fix. For the majority of the pour the two "runners" would have very little to do, other than those 10 problem areas that we spoke of earlier. On the last lift, the two runners set the laser at truss height and would trowel the top level (foam never settles completely level). They would also insert truss anchors, plumb the walls, and concentrate on any remaining problems that might arise.
All in all 4 guys pouring 60 yards of mud and ending up with a structure ready for trusses 8 hours later with only 50 minutes of block repair along the way isn't half bad.
Yeah, I wasn't criticising you - just underlind that important point for others learning.
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Darn it, that did sound a little crabby didn't it? Ooops, sorry about that. :-)
no sweata. I like your posts - mostlyBTW, I backpacked the Middle Fork of the Salmon many moons ago. Stepson lives and builds in Sand Point now.
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Always done my own concrete work.
Paying myself $60/hr but not counting already depreciated machinery/forms, costs today work out to about $220 yard for 8 ft walls, $140 yard for flat work. Add in your form/machinery; costs. Does not include excavation. Small under 5 yard DIY jobs and bags/etc into 3 cuft mixer, not counting exercise/workout time<G>, works out to about $50 yard for either type work.
Regional differences sometimes blow me away. There is almost no such thing as an insulated basement with 9' walls around here... it's all 2-3' crawl space or even slab on grade. Some GCs do their own work, some use a concrete sub with varying results. There always seems to be a big shortage of good concrete crews, and either knowing one, or having your own, is worth big bucks. In your situation I would hope you have at least one ace concrete guy on your crew, or plan on becoming one.
ICFs seem to be getting good reviews, even great reviews depending on the system used. One guy here built a Poly Steel house... locally the subs call it the styrofoam house. Concrete is $150+ per yard for 6 sack pea gravel so I don't foresee a big boom.
Concrete is $150+ per yard for 6 sack pea gravel so I don't foresee a big boom
I've heard some gripes like "Well, ya' gotta put that (spread) footer in there, an' tha's another trip an' costs too much." I wind up having to point out that they need a footer for cmu too.
The "trick" of it I've found is, you have to balance the costs all the way across the work.
So, that using 60% fewer yards of concrete "pays" for a pump truck; not having to finish 1800, 1900, 2000 sf of concrete "saves" 6-7 man/days of concrete finishing labor (but adds some labor for the formwork, bracing, vibration, etc.)
Like everything else, it's a balancing act.Occupational hazard of my occupation not being around (sorry Bubba)
Stinger,
You have very precisely laid out the reasons I first started laying up ICF's 12 years ago.
A series of foundations I subbed out ended up screwed up one way or another.
On one especially bad little addition, we made a full size pattern of the outside of the wall. the first thing the foundation sub did was chop that up and throw the pieces aside. And then they poured exactly to the height I marked out but they inserted a piece of PT 2 x 4 in the outside of the pour - which meant I had to drop the siding line on the addition 1 1/2" below the siding on the rest of the house to cover that.
On another house with a lot of steps in the basement wall, one corner was out 4 1/2". The level of the top of the pour was like waves on the sea. And then we suspect the foundation sub of sneaking back after hours to steal some scaffold.
There were others, too. It seemed that whenever I subbed a foundation, the only thing I ever learned was to never deal with that particular SOB again. Now that I do the formwork myself with ICF, I learn something new from every mistake (because I try not to make the same mistake twice) and what I learn will make the next job easier.
Ron