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MarineMom 05-01-2012 03:09 PM

How to Insulate Crawl Space
I really need some help. I bought a cottage built in 1900 and really need to add some insulation! I'm starting with the crawl space and am unsure of what to use. The house sits on an incline and there is maybe 3' of clearance on the high side. So...that being said I'm not sure fiberglass insulation between the joist would be suitable. I was looking at Reflectix and was hoping this may work (installed in the R17 manner according to their website). Is this actual "insulation" or would I just be installing a draft barrier?? (Which I do need as the house was quite drafty over the winter)

jaydevries 05-01-2012 05:13 PM

depends on crawl space if it is vented or sealed crawlspace

MarineMom 05-01-2012 08:11 PM

The house is on pillars. It has been nicely "pinned" with trim. I'm not sure if that allows enough air flow to qualify. It is not vented.

jaydevries 05-01-2012 08:51 PM

what state are you in

HANKNJAKE 05-01-2012 10:08 PM

Have you thought about spray foam insulation? This gives you an excellent insulation and helps seal out the moisture. It is easily applied and can get into hard to reach areas. Call a local insulator and ask him for advice.

MarineMom 05-01-2012 10:33 PM

I'm in southern Ohio. I have considered spray foam, however I wasn't able to find anyone near this area with experience using the product. All the research I have done Online said it's not recommend for DIY. I'm open to all options

jaydevries 05-01-2012 11:05 PM

ok so do you live on the river i am near columbus :thumbup:
1 are there plumbing supply lines in crawl space?
2 when you say pinned with trim does that mean around crawlspace it is sealed all the way to ground?
3 is it dirt floor and does it have a plastic barrier on ground or on floor joists

also here is a diy closed cell foam link

casey2u 05-01-2012 11:38 PM

I sorta like spray foam, but I don't like the DIY "kits" which come up to 600 board feet per kit, typically. It's a long story involving the technical details of pro foam installed with a heated hose and (expensive) foam proportioner, vs. the refrigerant-driven approaches like Tiger Foam, Dow FrothPak, Handi-Foam, etc. (my problem has to do with the GWP of the propellants, if you're interested).

Anyway: it can be quite hard to get a foam applier to install a tiny job (or even return your phone calls!). If you simultaneously want them to spray your attic you might sweeten the deal, but it's the most expensive insulation in any case.

Reflectix is fine, as long as you don't believe basically anything they say about it. The EPA, I think it was, tested such insulations under slabs (where the manufacturer DOES recommend them: radiant barrier under a slab, ha ha!) and found they amounted to an R2 or so, as I recall. They would be a fine draft barrier but for the challenge of installing them tightly. You haven't described your perimeter crawlspace wall, you could make it a partially-conditioned crawlspace (insulated the side walls, vapor barrier on the floor, toss in a dehumidifier, and bob's your uncle): that has a lot of advantages.

Combinations of foam board and small spray foam cans used thoughtfully (propellant: isobutane GWP 1.0 vs. 1200+ on FrothPak) can make for a tight install. In any case it's probably worth putting a vapor barrier down on the ground, to reduce moisture in your "dank" crawlspace: even in crawlspaces with "adequate" ventilation, natural ventilation relies on wind and other air movement -- it's a bad (if common and legal) design.


MarineMom 05-02-2012 10:27 PM

Wow! So much information! Let me start by thanking you.
I don't live in Athens near the river, but its a short commute. And same weather patterns...all 4 seasons.
I'm not sure what the building codes were, if any, when the house was built. It is a small cottage at 1080 sq ft. Actually 1 of 3 company row houses. So yes I have found it difficult to get a contractor to respond. And there are very few left locally which is why I would really like a dig option.
I will be installing 6 mill plastic. The under pinning wrap does go all around the perimeter and does go completely to the ground. Yes, there is plumbing under there also. The crawl space walls are not currently insulated. I have saw that method in my tootle research but wondered if it would be enough R value. Is this something that is standard? Also, I'm not sure what type of dehumidifier goes under a house. Any links on it?

Gary in WA 05-02-2012 11:45 PM

"Any links on it?"------ this will get you started;

Up to code, an air supply for the furnace if under there, an exhaust:

If you go closed crawl (insulating walls), check for radon and termites;

If no vinyl flooring above, this is optimal;


MarineMom 05-03-2012 08:55 PM

I love this site!!! So much information. I'm crawling under my house again this weekend for another good look. I couldn't be happier with all the options you have pointed me too. I may be the only female excited about insulation. :thumbup:

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