[Greenbuilding] Crawlspace foam insulation -- how much?
Leslie Moyer
unschooler at lrec.org
Fri Jun 12 14:40:04 CDT 2015
And how would you propose we get rigid mineral fiber insulation into my
2'x2' crawl space entry? That's if I'm being generous....
On 6/12/15 2:17 PM, Alan Abrams wrote:
> Hi Leslie
>
> somehow I don't like the idea. I assume the insulation contractor is
> proposing to apply foam to the underside of the floor sheathing. If
> that is the case, there is the possibility of the exposed portion of
> the joists getting below dew point, and becoming saturated with
> condensed water vapor. IIRC, Joe Lstiburek has some really ugly photos
> of this condition.
>
> my preference (at a minimum) would be to seal and insulate the
> perimeter of the floor cavity with caulk and batts, and apply a smart
> membrane (like MemBrain) to the underside of the joists, carefully
> lapped and taped, and then some rigid mineral fiber insulation under
> that. Fire resistant, mold resistant, thermal bridge resistant, and
> semi permeable. The crawlspace can then behave or misbehave as it
> pleases, without impact on IAQ
>
> -aa
>
> Alan Abrams*
> */certified professional building designer, AIBD
> certified passive house consultant, PHIUS/
> /certified passive house builder, PHIUS//
> /cell 202-437-8583
> alan at abramsdesignbuild.com <mailto:alan at abramsdesignbuild.com>
> HELICON WORKS /Achitecture and Education/
> <http://www.heliconworks.com/index2.html>
>
> On Fri, Jun 12, 2015 at 2:55 PM, Leslie Moyer <unschooler at lrec.org
> <mailto:unschooler at lrec.org>> wrote:
>
> Yeah, well, I considered that option first and was ridiculed for
> that on this list several months ago. My crawl space is tight (for
> humans), but well-ventilated, so I'm going to go with this option
> as I think it is the most practical.
>
> --Leslie
>
> On 6/12/15 1:18 PM, Frank Tettemer wrote:
>> Hi Leslie,
>>
>> You may want to re-consider the idea of foaming the floor in a
>> crawl space. My concerns would be that the foam would act too
>> well as a vapour barrier, and you may have moisture/mildew
>> problems down the road in the crawl space. I AM in Canada, so
>> your geographic climate might create different problems than here.
>>
>> I always design any neccessary crawl spaces as a definite part of
>> the conditioned space of the home. That means insulating the
>> walls and the floor of the crawl space, and leaving the floor as
>> a vapour-open plane, as well as including the crawl space in the
>> heating design. This avoids condensation trouble, by keeping the
>> air warm and dry.
>>
>> Frank
>>
>> Frank Tettemer
>> Living Sol ~ Building and Design
>> www.livingsol.com <http://www.livingsol.com>
>> 613 756 3884
>>
>>
>> On 12/06/2015 2:02 PM, Leslie Moyer wrote:
>>> I am in NE Oklahoma. I'm in the process of getting estimates
>>> for crawlspace insulation in the floor joists--closed cell foam.
>>> My crawl space is dry now that we've fixed some plumbing
>>> problems, but I'm having some cupping issues with some wood
>>> flooring and part of the fiberglass batts that were originally
>>> in the house when we bought it were taken out over time for this
>>> and that. Anyway--closed cell foam seems to be the best solution.
>>>
>>> The first guy who came this morning wants to quote me 1.5" foam,
>>> though said he would quote 2" if that's what I really want,
>>> saying that would be enough for "Canada". I understand about
>>> the benefits of air sealing, but I was still thinking I would
>>> need more inches of foam according to what I've read on R-value
>>> & this area. Thoughts?
>>>
>>> --
>>> *Leslie Moyer*
>>>
>>>
>>>
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>>
>
>
> --
>
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