I want to prep a basement floor for carpeting.The ceiling ht. is 7 ft. so i dont want to build up too much. Thinking of one layer of 1/2″ rigid foam (dow blue) and one layer of 1/2″ cdx plywood. Any other ideas?
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Foam board is not structural; you can't use it as a substrate for the subfloor without installing structural sleepers.
Is there a real need to insulate the floor before carpeting it? Most basement floors aren't that cold; the earth below them is a massive heat-sink that keeps the temperature of the floor slab fairly constant, winter and summer.
As long as there are no moisture issues, I find laying carpet directly on the slab--or over a carpet underlayment, if you want a little more cushion--to be perfectly fine.
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
If foam can handle being under the concrete and holding the entire slab, why can't it handle a man and a woman dancing on it?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Evenly dispersed static load vs. dynamic point loads.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
The plywood over it makes it a spread load. Works out fine. no point loads or bearing walls i=on it, of course.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Yah, well you gave me a chance to use some five-dollar words, did you expect me to keep quiet?
;o)
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
Just leave the ten dollar words alone. I can't afford to read them, let alone argue against them, LOL
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I should have mentioned this basement is a playroom for toddlers who frequently bounce their heads off the floor.FHB issue #169 "The Stay Dry, No Mold Finished Basement" cites the use of rigid foam insulation as key.1" foam, two layers of 1/2" plywood screwed to the concrete.I can't raise the floor 2" for headroom concerns but still like the idea of some protection from hardness and moisture.
foam underneathe won't make the surface any less hard. get carpet with 1/2" pad for head bouncers.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
What about the the moisture issue? ALL basement floors emit moisture.Separating the carpet from the concrete seems like a good idea to me
depends why you have a moisture issue.All do not have it, BTW.If it is just condensation the foam isolation temperature damper takes care of that.If it is leakage, you want the dricore or a sleeper system as well as find out why leaking and work to fix that.If it is moisture simply weeping through by VP, the slab should have been sealed and a VB under it when poured.To start testing why you have a moisture issue, take a piece of heavy plastic, or a garbage bag, and tape it down the floor with duct tape for a few days. moisture under it means it is coming up thru. MOisture on top of it with the underside staying dry means you have condensation.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
There's no leakage, just condensation from swampy summers on Long Island. The house is over fifty years old, well before any concerns of vapor proofing residential basements.
From past research it looks like there is no definite answer to controlling the slab moisture, which leads to moldy smell in the basement. Without a vapor barrier carpet and pad will make this problem worse because the pad and fibers hold moisture.
My plan for my basement is this: lay down 6 mil plastic sheet and seal the perimeter of the sheet to the floor with polyurethane caulk. Lay down underlayment for engineered flooring and use laminated flooring that has laminate on the underside as well. I plan to glue the joints as well even if they are locking joint to moisture proof the edges as best as possible. This way I hope to keep the moisture under the plastic and provide least amount of organic material to the mold. I have foam panel on the wall and joints sealed with spray foam. I used paperless sheetrock on the foundation walls. I am hoping these measures will limit the growth of mold. I found it is possible for some mold to grow in/around commercial tiles and glue so I plan not to use vinyl product. Good luck.
with glued down and glued joints, the EPS insulation bd IS a VB, but plastic first will make it impossible to glue the foam down, so you have everything floating. That would require the multiple plies with opposing seams and joints to tie things together. That is more work, more material, and greater elevation.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
<< I should have mentioned this basement is a playroom for toddlers who frequently bounce their heads off the floor. >>
oh it's for toddlers? forget it then...the foam will never handle that kind of weight. LOL.Justin Fink - FHB Editorial
Yes you can. The capacity of 2.5 lb density foam is higher than a lot of soils. It's in the range of 2500 psf.Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein (or maybe Mark Twain)
"Get off your dead #### and on your dying feet." Mom
"Everything not forbidden is compulsory." T.H. White, The Once and Future King
You should listen to Justin. Toddlers don't bend their knees when they run, so every footfall pounds the living bejaysus outta the floor system. There are special tables in the NBCC (subchapter 'T') just for those applications.
Seriously: Your figures are reassuring, but it's not the initial compressive resistance of foam board that worries me; it's how long the stuff will retain that resistance. I'm not sure we know that yet.
Me, I'm figuring I've got another 40-some years to go before I don't have to answer the phone, so I don't wanna build anything that won't last at least that long. I hate callbacks....
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
I'm no foam expert, but I think there are people who do "know" how long foam will retain its strength.Foam is used for SIP's, fill in highway construction (geofoam), shower pans, and myriad other applications. If the engineers are just guessing about the long term performance of foam, then we're all in trouble.
Jon Blakemore RappahannockINC.com Fredericksburg, VA
If the engineers are just guessing about the long term performance of foam, then we're all in trouble.
As well may be, but 'guessing' isn't the polite word. I think the correct term is 'rendering a professional opinion.'
As Andy points out, some builders have been using foam board buried under slabs for 20(+?) years; and that provides some hard info from which one can draw a conclusion:
Any other conclusion as to the performance of foam board under similar but not identical conditions is an opinion, not a historical fact.
The validity of any opinion will be tempered by the assumptions made by the person doing the opining. More importantly, those assumptions can range from conservative (and thus more likely to be valid) to 'self-servative' (as in the case of those made by the product's manufacturer, whose opinions should always be accepted with some reservations).
The gist of all my blather is not to assert that Andy's figures don't reflect the reality of those installations he knows about which have stood the test of time thus far--they obviously do--but to point out the difficulty of predicting the future on a grander scale.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
I understand where you're coming from, but it seems to me like you can make the judgment you're making about foam apply to myriad products.You like Schlüter products, right? Is there any 40 year old Ditra or Kerdi out there?How about Advantech? Maybe it turns to potato chips at year 26.I know how much you love joist hangers- have any of them been around for 50 years (wait, that's a bad example... <g>)I guess we all have to make the decision to use a material that's been in use for 200 years or try something new. If you want to stay away from foam, that's fine by me. I just don't see that it's that big of a risk. If it compresses 15%, you'll get a gap at your baseboard or your wall/ceiling GWB joint will crack.Now, if you will pardon me, I'm going to listen to an 8 track tape- you can't trust those compact discs you know... <g>
Jon Blakemore RappahannockINC.com Fredericksburg, VA
You are absolutely right.
As professionals, we all have to recommend choices for our clients to make as to materials and methods of work. I tend to be very conservative about those choices, but sometimes find myself handcuffed by the market because the older materials which have a 50+ year track record are no longer available. When was the last time you saw a lead shower pan, or heard of a tile-setter doing a full mud base instead of using CBU and thinset?
Do I like Kerdi and Ditra? Yes, and I use them frequently...and I hope to hell my trust in their products is not misplaced. But I won't know, will I, until some time off in the sweet by-and-by.
Would I use lead pans if I could get them (I can't)? Dunno; they were blown off the market by the membranes before I started building showers. CBU versus full mud? I ain't that good at mudding, since I've only done one or two jobs that way. Seems like the base material is the same (cement) so maybe not much to worry about; the weak point would be the screws attaching the CBU to the framing. Again, I don't know, but I hope I'm not wrong. So far, so good; 14 years and counting....
But those kinds of materials/method-of-work choices are in a different league to using (for instance) joist-hangers or putting foam into a structural system or using OSB-webbed 'truss-joists'. Tile (and a lot of other 'engineered' building materials) is trim. If the tile falls off the wall or the shower pan leaks, the house won't fall down.
However, if the OSB web in a TrusJoist starts to disintegrate after 30 years because the ozone produced by the oil-burner's blower motor degrades the glue holding it together, we no longer have just a trim problem.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
A few years back I dug up a styrofoam coffee cup that was about 4-feet in the ground. House was built in 1973, so the cup was in the ground for say 25 years. Could have drank from it. Now if that ain't scienterrific!
We've been building foundations on top of the stuff for at least 20 years, and probably more like 30. In 30 years, you and I are either going to be dead or too poor to bother suing.Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein (or maybe Mark Twain)
"Get off your dead #### and on your dying feet." Mom
"Everything not forbidden is compulsory." T.H. White, The Once and Future King
A couple of years ago I was on a job placing 2'x2'x2" granite pavers on pedestals over foam board. The foam was available in 20, 40, and 60 PSI ratings. These pavers weighed somewhere between 150 and 200 # per unit, and they did not visibly compress the 60 PSI foam, even after much foot traffic.
That would be fine if you glue it down using polyurethene faom glue. Enerfoam is what I use.
Other ways would be dricore or similar drainage plane, or a sleepre system
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I do think I'd switch to 3/4 T&G subfloor though or at least 5/8 T&G Advantech. Maintaining good alignment at butt seams will be a pain when gluing down otherwise.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
There are a few manufacturers of floating sub-floor systems. Basically 2x2-foot 'tiles' with a dimpled plastic bottom. The bottom is a vapor barrier that maintains an air space, allowing the floor to breath. The tiles are under an inch thick.
Think I saw them at Big Orange/Big Blue.
http://www.subflor.com/ADVANCE/home.asp
http://www.thrasherbasement.com/basement-waterproofing/basement-flooring.php
That is the dricore I mentioned
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
The Andy Engle who just joined this thread is the mojo dude who wrote the FHB article with this general idea demonstrated.
I thought introductions were in order.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
Dricore is a simple install;need to compare $ to plywood/osb and foam system. Andys method uses screws for fastening,tape for seams and no adhesive;simple enough. Still have joint alignment to deal with with single layer ply. T&G works but may negate cost factor.