I have white oak hardwood floors on an old 1920s house.

My contractor is offering to do 2" of closed cell foam on the underside of my hardwood after he does the attic roof.

I have no other sub-floor other than these tongue/groove hardwoods, so closed cell would be applied directly to it.   It is pier and beam house with about 3 feet of crawl space - in Austin TX.

Is this safe?   Or is it dumb?

Possible pros: "Solidify" the floor, vapor barrier, bug barrier

Possible cons: damage floor?, solidifying could actually be bad,won't show plumbing leaks..

 

What's another good option?   Or is this the best?

 

Thx.

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My suggestion would be to test a small area where it wouldn't be noticed (like in a closet or something) and see what happens.

Safe - more than likely (see below)

Dumb - no

Other pro's - less air leakage, moisture intrusion, IAQ problems

Cons - foam leaking through gaps, possible problems if floor is not equalized (humidity)

 

I don't see the solidifying as an issue unless you have wild swings of humidity inside - nor do I see an issue with plumbing leaks - hopefully you will see it & clean up if it happens above the flooring, as for underneath - the chances are it wont happen where the flooring is, but under the insulation or closer to the bottom of the insulation

 

As it is a pier system, you may have to sheathe under the joists - see the AHJ

 

I'm looking at a similar project.

Contractor says prevailing environmental conditions (temperature/humidity) don't matter much when it comes to application.  Seems dubious.  What's the scoop?  I would think it's better to wait until late summer.....

Temp's & humidity do play a roll in the application process, equipment setup, etc... A lot of it depends on the brand chosen, knowledge of crew, equipment choices, etc... So for the most part the contractor is right, it doesn't matter to much as those are factors they are dealing with throughout the day

If it makes you feel better, I have a job that was sprayed when it was around 40 deg outside - no issues

Is it a matter that the floors won't allow more insulation, is there no space underneath your house, or are your house's floors sitting directly on dirt?

 

Because it would appear the R-rating of this procedure involves a value of 6.0 per inch meaning that your total gain in the floor's insulation value would be roughly R-12 which is inadequate.  The current Green Industry standard for floors is R-25 and while I'm sure some improvement is better than nothing but why not do it right the first time, I realize the house is old but I would expect contractors to be on top of this subject and I would further expect them not to recommend sub-standard procedures, even if the expense to do it right is greater, it's going to cost you more to have them come out again when it's not done right in the first place.

Then, your attic floor (meaning the ceiling of your house's living space) needs to be R-50 to R-70, your contractor's offer on under-insulating the floor leads me to believe he would also under-insulate the attic... However, is it that your contractor is low-balling or is it you who doesn't want to face the expense?

Look here, you have to know what it is you want from life but I can tell you with insulation, it is one of those things you want to face one time and be done with it, because if you half-ass it now you'll only have to look this problem in the face again not five years from now when the price of energy goes so high that you won't be able to afford not having it done, but with insulation it is a thing that once done it forever pays for itself by not only reducing your bills every month but also increasing your house's value.

Furthermore I believe the expense is currently still tax-deductible but don't quote me on that.

 

So it's either of hiring another contractor to do it right, or getting over yourself... And you can, if money is an issue, do only the attic and leave the floor for later or vice-versa, but it is my recommendation to do it right.

 

One more time.

Current Green Industry Standards for insulational R-values: 

Floors R-25, Attic (House ceiling) R-50

Texas is hot as hell.    The standard here for attic is R21, and nearly every contractor I've talked to (and that's many) say that getting the R21 with Closed Cell is going to make it ridiculous, putting me in the top 1%.

 

As for the floor of the house.    It is a 3 ft crawl space.    I mainly think I want a vapor barrier.    During the 3 semi-cold months in Texas, the floor does get somewhat cold, but I don't think it would take much to limit that - given the current floor, as mentioned, is solely the plank hardwood - in certain places you can see through it to the ground.   

 

I am thinking that for now I hold off on any insulation, and then as winter approaches, maybe go with some foam boards with insulation holding them in?

EPA's / DOE Home Performance with Energy Star protocol (the one intended for existing structures) sets the minimum at R-5 under floors. They do insist, however, on spray-foam insualtion. Makes sence to me, given foam's dual-purpose of air barrier and thermal barrier.

Hi Ryan.

 

Our company is in Texas and we coat attic roof decks and the underside of floors with our coating.  I do not have any picture to show you regarding the underside of wood floors.  I do, however, have a statement from government painter that sprayed our coating to the underside of a 34 foot mobile home.

 

The trailer had R-9 or R-11 insulation under the entire trailer and around the heater duct underneath.  They did before and after tests of the temperatures at different locations.  The before results are with the R- rated fiberglass in place.  That was then removed, the entire underside was sprayed with our coating and allowed to dry for three days.  Then they did the after test.

 

The application resulted in an 84% reduction in heater run time to bring the interior temp to 72-degrees and satisfy the thermostat.

 

www.ct-texas.com

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