People always say that Hell is “below”, I just never realized it was right below the floorboards. 

We all know how many holes can be drilled through the sills and in the field for wiring and piping runs, without (traditionally) even a feeble effort made to seal them….  The house pictured below must have had a couple of hundred (including abandoned holes or "misfires" with nothing even going through them).  The big cutout around the shower drain in this house sure helps this home’s bathtub cool off extra fast.

The sub-floor was subsequently done in closed-cell spray foam.  All seemed well until I followed behind the foam installer to verify that he provided the contracted thickness (and he had a heads-up ahead of time that I’d be checking). The nail in the third photo is two inches long (the contracted foam thickness) and touching the subfloor. While much of the floor has the expected two inches (and some more than that), it is not hard to find areas with less.  Hard to estimate the weighted-average thickness….

Any opinions out there on a reasonable/acceptable degree of variance in thickness for spray-foam applications on subfloors? 

Incidentally, conditioned crawlspace wasn't pursued because no one in this rural area could be found who has done one before, heavy soil moisture much of the year, and the local heating contractors have a hard time doing even conventional work correctly.

(oh, and the ducts are laying on the ground while waiting for the foam contractor to come back and review the issues…..)

 

Yet more evidence that Kermit was Right.

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Hi Evan, don't I love the real world.

One consideration involving the average insulation thickness is that the pluses don't match the minuses when it comes to counting btus.  For example, with a 2" requirement an area that is only 1" thick will double the heat loss in that area.  Where another area of similar size that is 3" thick will only reduce the heat loss (over 2") by 33%.  So, when you are trying to estimate the average depth applied, you will also need to weight the areas of plus and minus to account for the difference in heat loss.  Since even a average depth would be a wild guess, I would go for my minimum depth with little or no exception.

Bud

Thx, and agreed.  Same goes for mpg, which most consumer's don't quite grasp....

Per the SPFA guidelines and almost any contract document I have seen - if 2" is listed as the minimum thickness, anything under that is a deficiency

The only exception from the SPFA is if it is only specified as an air-barrier & then you would have to see what the manufacturers minimums are

Now if they just agreed to 1 lift of the material (depends on brand but that generally equates to 1 1/2 to 2" thick) - then 1/4" difference is deemed excellent, 1/2 is good 3/4 is fair & 1 is poor

Simply based off that bottom photo, no matter which one of the three above applies - it is a poor job that needs to be corrected. I would also make sure you check any little high spots to make sure it isn't blistered and also think about a few core samples to make sure it has good adhesion, etc... As a general rule we try to do the inspection while the installer is still on site to confirm everything is fine before they pack up there tools - it is generally best for both parties.

Thanks much, Sean. 

I'm not familiar with the jargon "1 lift".  Can you let me know what that refers to?

Murphy's Law had it that I was not in the area when the install happened.

 

 

Generally OC foam is sprayed in 1 shot or lift ~ CC foam due to the exothermic reaction generally gets sprayed in multiple lifts or one risks having the foam not meet specs or catching on fire

Depending on the manufacturer & the applicator a CC lift can be as thin as 1/2" but generally it runs around an inch to two - but in general most go for an 1.5 to 2 inch thick

I'm wondering how it ended up. Are you happy with the job? I'm considering taking foam to my own house in similar situation. It's much more expensive than the locally acceptable fiberglass batts, but it would solve multiple problems if done right. (big if?) When you went down to inspect soon after the job, did you borrow their protective gear?

Jill in Santa Fe NM

It's done.  Short story.  I'm happy.  Major comfort increase. Bathtub stays warm way longer now.... (sorry shower fans, we have little girls who just insist on baths.)  Time will tell about energy. Boots had crappy foil bubble-wrap insulation and are now nicely foamed as well.  I've heard people complaining about shrinkage.  No sign of that whatsoever.

Long story.  It took me more than two months to get them back and they fixed the problem (I actually ended up with a thicker application than was required -- 3" and more in many spots).  However, the ducts had to be lowered while they did the work and so those sat on the ground until the corrections were made. The foam people did end up overly compressing the ducts in some spots (where they couldn't be lowered) --- gotta love it: one insulation contractor compromising the work of another.  They were not willing to reinstall the ducts ("We don't do ducts").  I knew that in advance, and reluctantly agreed.  Couldn't get return calls from HVAC contractors, so reinstalled myself, which was a blessing in disguise as I was able to correct multiple sins of the original installers.  By properly stretching and rerouting in a few places, I was able to eliminate many feet of material and reduce static losses (see  photo: original installation front, improved back).

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Thanks. That's encouraging. Somewhat unfortunate, but you're right on about inspecting the work.

Also I concur about the importance of comfort. The crawlspace might not be the most important place in the house for energy loss, but it has the "creepy factor". Good to get that under control....

I'm not sure what climate region you are in but if it's anything like Wisconsin, you might need to take precautions so your pipes don't freeze unless you have some heat loss from the main floor, ductwork, and/or equipment in the crawlspace.

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