I recenty read an artical in fine homebuilding which stated that the best way to insulate a crawspace was to completly sill the ground with plastic and insulate the parameter of the crawspace instead of the traditional metod of stuffing insulation up in between the floor joist.
A few weeks later, I got a request from a client to check their house out and see if i could do anything about their mold problem and musty smell in the house.
They did not have any plastic vapor barrior, nor insulation at all under their house, so I recommended that we start by completley sealing the ground with 6 mil plastic. I have now installed the plastic covering 100% of the crawspace, using polyurathane caulk to glue the seams and glue the plastic to the sides of the parameter to make a completly airtight barrier between the ground and the crawspace / house.
This instantly got rid of the musty smell in the house for my client. Even in the craw space, if you close your eyes, you would think you were setting in a clean room.
My concern now is the several people have since told me that this is a bad idea to completly sill the ground under the house. The reason being that doing so will cause the house to dry out “to much” and cause warping in the framing, drywalls to crack, and doors, windows to stick.
The people I heard this from were not profesional contractors, but still, it’s got me woundering if I made a mistake in what I did. Does anyone have any input on this?
Replies
Not sure if I believe that one or not. I have been sealing up crawlspaces here for quite a while(10 yrs) and have not had any problems with them what so ever.
As an editor there, I had a little bit to do with several articles in FHB on this topic, and know a lot of the country's leading experts on the topic. To a degree, your friends have a point. If you do a good job sealing a crawlspace, the house will dry out. Wood will dry, and some miters and floorboards might open up. That's the downside.
The upside is that the potential for rot is reduced. The potential for allergy-causing mold and dust mites is reduced. The odd smell goes away. Odds are that if there was any condensation in the attic, sealing the crawl will make it stop. The house will probably cost less to heat.
I'd trade a few open miters for a healthier, better smelling, less-likely-to-rot and cheaper-to-heat-house. Once the humidity in the house stabilizes, fixing some open miters is a one time job.
Keep up the good work.
Andy
Arguing with a Breaktimer is like mud-wrestling a pig -- Sooner or later you find out the pig loves it.
Other people can talk about how to expand the destiny of mankind. I just want to talk about how to fix a motorcycle. I think that what I have to say has more lasting value. --Robert M. Pirsig
I'm with the others who say this is a crock. Just coffee shop talk from people with very little construction knowledge.
You could print out some of the stuff from buildingscience.com and show it to your clients. Maybe that would convince them.
A buddhist asks a hot dog vendor for his change, and the vendor replies "change comes from within"
I've probably inspected over 1500 houses with crawl spaces. I've never seen the problems you've been told about.
Sounds like you got a good start on the job.
Don't forget to also improve exterior water controls: good grading and good (10') downspout extensions.
You might also want to check the attic sheathing for rotted areas - a very damp crawl usually results in a lot of mold growth and sometimes rot on the bottom of the roof sheathing.
How high up the walls did you run the plastic?
And how much clearance is there between grade qand the bottom of the hosue framing?
If there isn't much external clearance (for moisture to evaporate from) and the plastic runs up the inside of the foundation, you can cause "rising damp" to get into the sill plate and rim joist and joists. It isn't likely, but I've sen it happen, as in the attached photo.
The key to forgiving others is to quit focusing on what they did to you, and start focusing on what God did for you. Max Lucado
Sojourners: Christians for Justice and Peace
Thanks for your reply. This is the first time I've used this chat room, or any chat room for that matter, and it looks like I've been missing out on a great way to get helpfull information.
I ran the plastic 12" up the parameter wall, and all columns. I think this is above the grade line all the way around the house, but I will double check for that next time I'm out there. I glued it all together with double beads of polyurathane caulk.
The next phase of this project, if they buy it, will be to install short 2x6 blocking around the parameter, at 16" oc, and stuff R19 insulation between them. I've gathered that I need to use non-faced insulation, as the paper would be a fire hazard if it was faced toward the inside of the crawspace, which is concrete block -brick veneer.
I've ask a few local insulation contractors if there was any better way to do this, but they all have the same reply, "insulate the parameter? never heard of doing that, we always just stick the mess up between the floor joist."
Where are you located?
In my area (NW Ohio) all new construction has fully insulated insulation on crawl space walls and blows conditioned air (almost everything is forced air here) into the crawl.
As someone noted, the buildingscience site has excellant info, as well.
And welcome to Breaktime.
As an aside, this is a 'discussion forum' (or 'forum') - a chat room uses "real time" message exchanges - messages tend to be short and, unless U R a tnagr, indecipherable {G} = "Grin"
In a chat room we'd both be logged on
I'd type a message and send it
You'd read it and respond
Yada yada
Kids love 'em, as do some adults - I don't, myself - they drive me crazy, but my daughters will have a bunch of open chats going at a time!
A list oif common abbreviations (for both chat rooms and forums) is at http://home.comcast.net/~bluebirdsong/vu/notebook/glossary.htmThe key to forgiving others is to quit focusing on what they did to you, and start focusing on what God did for you. Max Lucado
Sojourners: Christians for Justice and Peace
Bob, it sounds like you're saying to avoid running the plastic all the way to the sill? That seems like common sense... that some moisture trying to escape from behind the plastic would rise within the concrete and then dissipate to the inside and outside of the stemwall.
Along the same lines, there was mention a while ago about a heavy duty product for use as a VB in crawl spaces. Moistop or something along those lines... anyone know? I'm concerned because when I get around to lining my crawl, I know that future crawling I do during remodeling will damage 6 mil poly. I'd rather use something I can drag a toolbox around on.
Certainly on older construction - Andy Engel thinks it's OK on newer construction where the sill plate is well above grade; I don't like it there, myself, but not as much as I don't like it on older construction (especially because the sill plate isn't likely to be treated on older stuff.)
There are some products intended for "crawl traffic" but I don't know their names.
The key to forgiving others is to quit focusing on what they did to you, and start focusing on what God did for you. Max Lucado
Sojourners: Christians for Justice and Peace
I'd use Tu-Tuf, by Sto, over poly. Larry Janesksy's Basement Systems Co. uses a really thick vinyl type of product.
BTW, an approach I'd prefer is to plastic the floor and extend it to grade, as Bob suggests. Then, I'd insulate the perimeter with eps foam, which passes some moisture. Finally, run a dehumidifier in the space.
AndyArguing with a Breaktimer is like mud-wrestling a pig -- Sooner or later you find out the pig loves it.
Other people can talk about how to expand the destiny of mankind. I just want to talk about how to fix a motorcycle. I think that what I have to say has more lasting value. --Robert M. Pirsig
it will also stop termites by drying out the crawl space
BB
Do you have the form,osa termites in your area?
Are they also fond of damp/"soft" wood as are the subteranian termites?
The key to forgiving others is to quit focusing on what they did to you, and start focusing on what God did for you. Max Lucado
Sojourners: Christians for Justice and Peace
yes, they even have they own labor union.
Andy, that's my prescription when I need to seal up a space. Ideally, I open up at least 2 vents into the CS, and I get at a minimum a bathroom fan into the space, vented to the outside, preferably one with a boilt in humidistat.
After about 6 months, I like to get in and insulate the joist area with craft papered bats.
I've also learned that stopping the poly 3" short of the sill plate allows any moisture in there to wick up and get expelled by the fan.Quality repairs for your home.
Aaron the HandymanVancouver, Canada
I've used the Moistop product. Much toughr than plain old 6mil plastic when crawling or working on it. Has a sort of ripstop weave. Practically impossible to tear it! can poke small holes if you really try.
Matter of fact, I was moving a partial roll out back of the shop laast week that I forgot i had. After three years or so out in weather and sunlight, it was still just fine!
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I'm located in Raleigh, North Carolina.
I went into business for myself a coulple of years ago, advertising as a cabinetmaker. While waiting for the cabinet orders to come rolling in, I got lot's of request from people to do other stuf at their houses... painting, flooring, door and window replacement, and lot's of request for rotten wood repair. I quickly figured out that there are alot of houses out there that are falling apart, and shifted gears to a general home improvement business. Business has been good.
Every house I have been under around here is done the same way, insulation up between the floor joist, nothing on the parameter. Ocassionally, I'll see a few peices of plastic layed out sparaticaly under the house.
It's good to know there are some people out there trying to improve things, but I get the idea that alot of builders, at least in this area, are doing just enough to make a house sell, get their paycheck, and go home.
One of my most common calls I get, is where a deck has been attached to a house (some of these were built with the house, and as little as 3 years old), and the customer wants me to check out the rotten brick mold around the bottom of the door that leads out to the deck. On every one of these, it has turned out to be a rotted door frame, siding, studs, subfloor, floor joist, and header. $$$.
The main culprit seems to be the way decks are connected directly to the header of the house, and although they usually do have some flashing installed, it never extends up past the top of the deck surface, you know, where water runs back toward the house. It's as if the people building this thought as long as a little bit of flashing was stuck somewhere between the house and deck, it would somehow magically fight back water damage.
For the repair, I'll replace everything that rotted with treated wood, bring the deck 1 1/2" off the house for breathing room, install flashing in a common sense method that keeps water off of the house (4" above the deck surface, and 2" below the mud sill), and caulk the trim and everything else possible with polyurathane caulk, instead of the $.99 a tube cheap junk that I see all the painters around here using.
Guess I got off on a different subject there, but if you have any opinions on this too, I'm all ears.
st
You are not really off on another subject because preventing rot is a major part of fine homebuilding. You started out with moisture ingress from below and progessed here to moisture ingrees from decks.
I have a brother and a brother in law doing remo work in S Carolina. having visited there, I understand the difficulties you have with climate. But resst assurted that you will never run out of work, especially with your attitude towards doing it right.
And welcome to Breaktime. You WILL be back! Just like Arnold.
;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Bob:
You said: >> In my area (NW Ohio) all new construction has fully insulated insulation on crawl space walls and blows conditioned air (almost everything is forced air here) into the crawl. <<
That is not happening here in Raleigh NC. Someone may say that those dumb Southerners are slow to catch on, but I gotta wonder why the large national builders who build in both your and my area are not doing it here? Companies like Centex or Pulte. They are experts at saving 50 cents or a $, and it would seem obvious that not insulating the entire floor system would be less expensive, especially since most all builders here are putting down vapor barrier on the crawl floor anyway. Although you did preface your statement with "In may area", my point is that prescriptions for insulation and moisture control are highly geographic, and I am not so sure what is good for your area is good for my area. Different areas have different problems, such as mold, radon, and wood destroying insects of different types, these items being affected by environmental conditions such as average relative humidity levels, temperatures and soil types.
Just my opinion... Now I'm gonna get clobbered since I know you ae the master of debate ;-) Matt
I agree with your statement that building approaches vary with the regions of the country. We are building on a crawl-space foundation in Texas, about 75 miles north of Houston. I had always wanted to use the humidistat and vent but my cement contractor pointed out that , because our relative humidity is always so high, it would be better to try and combat the moisture in other ways.
We pre-treated for termites, used 6-ml poly and then decided to just pour the floor also. I was worried about the musty odors, radon and termites too. If we have managed to eliminate these, I think the extra money is worth it.
great topic. sounds like i need to get under my house with vb. it is 100 years old with a post and pier perimeter ( terrible drainage). the floor of the crawl space is lower than the surrounding yard. dirt is held back with horizontal board spaced 1/2" off the foundation siding. it is actually typical of houses in this area. where would one terminate the vb at the exterior 'walls'?
Edited 11/14/2004 12:07 am ET by paulg
paulg-
I couldn't open your file.
I'm curious to see if you were to run your pic thru Irfanview and making sure that the file is changed to a jpg, if it wouldn't simplify the process for the viewing.
http://forums.taunton.com/tp-breaktime/messages?msg=24441.1
thanks rez. it was not a pic but a drawing from a VERY cheap ($12.00-3d walkaround by abaracdata) cad program for my mac. i cant send any of the documents it produces by email either. it saves as a bin file and i cant figure out how to convert it. it is too late here in ca to get a pic but i will try tomorrow. i think that viewing program is for windows too. thanks. paul.
Search on Google fro a program called screenhunter. It is a free download. You can then capture whatever you see on your screen tosave as a GIF, JPG, or BTMP. Line drawings are best as GIF files, photos as JPEGs, and art as BTMPs but the BTMPs are large files to upload and download.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Bob, Regarding your photo: Done that way, the water is forced into the sill. IMO, it was done quick and dirty, so much easier to fasten to the wood than to the stemwalls. The place I bought my Tu-Tuf has a site that expressly forbids this practice. As a house inspector, you get to see all sorts of blunders, I bet.
I sealed the crawl under my house this fall, and ran the plastic (Tu-Tuf) up the stemwalls to about 3" below the sills, sealed to concrete with latex mastic and sheathing tape. The house is much drier and warmer than previous years, the smell is gone, and yes, a few doors have shifted lightly, but no big deal.
The biggest comfort difference may have to do with reduced infiltration. I closed over all but two of the foundation vents, and despite no additional air-sealing of the floor plane, there is a marked decrease in the chimney-effect draft we used to get when a top floor window was opened in winter. I am really glad I finally got around to doing this.
Before hitting on the soil-sealing/vent reduction program, I was thinking I'd have to spray polyurethane foam under the joists and subfloor to stop the draft, and never felt good about that approach, nevermind the high cost and likely refusal by foam guy to do the tight portions with only 14" clearance. Also, the furnace and duct runs are now in semi-conditioned space, so savings on losses there, too, as compared with the floor-plane solution.
Bill
Caulking the joints on the poly is fine, messy maybe, you might want to try the red tyvek tape on the lap joints. The tape also works good around posts, and venting/piping through the walls and so on.
David, does white tyvek tape do the same thing?
blueWarning! Be cautious when taking any framing advice from me. Although I have a lifetime of framing experience, all of it is considered bottom of the barrel by Gabe. I am not to be counted amongst the worst of the worst. If you want real framing information...don't listen to me..just ask Gabe!
I called it tyvek tape because that is where we use it the most, to seal the tyvek, but first thing on the job this AM I picked up a roll and it said TUCK tape. I should have said red tuck tape, I have never seen white tyvek tape but then I have never seen the source of the Ganges River either. Bets on what I see first.
I'm betting on the Tyvek....two milkbones...
blueWarning! Be cautious when taking any framing advice from me. Although I have a lifetime of framing experience, all of it is considered bottom of the barrel by Gabe. I am not to be counted amongst the worst of the worst. If you want real framing information...don't listen to me..just ask Gabe!
I will keep you posted.