EcoRenovator - View Single Post - AC Insulates Under Floor of 120 Year Old Crawlspace

Snail · 09-27-14, 06:31 PM

Not Icelandic, although some of my ancestors do figure in the Orkneyinga Saga. What’s unlucky about being Icelandic anyway? The fact that their ancestors made it across the far North Atlantic in open boats seems astonishingly lucky to me!

Over 4 decades of house ownership, a few minor disasters like those I mention don’t seem too unusual surely? And the flooding atrocity as you put it was actually a bit of undeserved good luck, as it made me aware of the fact that the insulating film was risky and in fact had already exacerbated a poor exterior deck detail that was directing water into the perimeter joist at one point. (If I’m a klutz, you should see the DIY workmanship of some of the previous owners of houses I’ve bought – shudder!)

From the early 1970’s until at least the early 90’s, underfloor insulating using perforated film was a common new construction detail. It was laid over the floor joists with a 75 to 100mm drape between each joist, just before the floor was placed over it. The theoretical R-value is about 2.2 but real values were a little over 1.3. However it was extremely vulnerable to wind, even though it was only used for houses with continuous perimeter walls (with ventilation ports). Even if it wasn’t ripped out, measured values deteriorate to about R-0.8 over time. (R-values in SI units, multiply by 5.7 for US units).

As a general but related observation, it seems to me that virtually every technique for insulating houses appears to have major downside risks of encouraging condensation and trapping moisture. I'm hoping that a conditioned crawl-space may be less risky?

We seem to be avoiding colds at the risk of being poisoned by some deadly mould spore or having our houses, or at least our finances, collapsing as a result of structural failure! I exaggerate – but maybe not much? Perhaps we should just harden up. Now those guys in the sagas wouldn’t be having with this insulation for softies. If you are cold, just get some vigorous exercise hacking off a few heads!

09-27-14, 06:31 PM	#42
Snail Lurking Renovator Join Date: Jul 2011 Location: Palmerston North Posts: 20 Thanks: 3 Thanked 9 Times in 7 Posts	Perforated foil Not Icelandic, although some of my ancestors do figure in the Orkneyinga Saga. What’s unlucky about being Icelandic anyway? The fact that their ancestors made it across the far North Atlantic in open boats seems astonishingly lucky to me! Over 4 decades of house ownership, a few minor disasters like those I mention don’t seem too unusual surely? And the flooding atrocity as you put it was actually a bit of undeserved good luck, as it made me aware of the fact that the insulating film was risky and in fact had already exacerbated a poor exterior deck detail that was directing water into the perimeter joist at one point. (If I’m a klutz, you should see the DIY workmanship of some of the previous owners of houses I’ve bought – shudder!) From the early 1970’s until at least the early 90’s, underfloor insulating using perforated film was a common new construction detail. It was laid over the floor joists with a 75 to 100mm drape between each joist, just before the floor was placed over it. The theoretical R-value is about 2.2 but real values were a little over 1.3. However it was extremely vulnerable to wind, even though it was only used for houses with continuous perimeter walls (with ventilation ports). Even if it wasn’t ripped out, measured values deteriorate to about R-0.8 over time. (R-values in SI units, multiply by 5.7 for US units). As a general but related observation, it seems to me that virtually every technique for insulating houses appears to have major downside risks of encouraging condensation and trapping moisture. I'm hoping that a conditioned crawl-space may be less risky? We seem to be avoiding colds at the risk of being poisoned by some deadly mould spore or having our houses, or at least our finances, collapsing as a result of structural failure! I exaggerate – but maybe not much? Perhaps we should just harden up. Now those guys in the sagas wouldn’t be having with this insulation for softies. If you are cold, just get some vigorous exercise hacking off a few heads!