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Basement insulation (exterior) covering

Posted by sfallen2002 (My Page) on
Fri, May 1, 09 at 22:42

What's the recommended way to protect an exterior insulated basement?

I'm about to put in some footing drains, and I want to add some insulation to the exterior. I believe I'm going to have to clean the wall off, then waterproof, then insulate, then..? I'd like to use something that is low/no maintenance. Only thing I have seen is some kind of stucco cement board at Menards.

Is this stuff attached with adhesive..?

There's about 8-13 inches between the ground level and the bottom of the siding. I;m pretty sure that means I need flashing to go over the insulation and protective materials - right..?

Never done this before, would be nice to get a project done right the first time!


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RE: Basement insulation (exterior) covering

This is no small project and there are a variety of ways to tackle it, which vary depending on the conditions around your home and the area of the continent you're in.

Most typically, first comes waterproofing, sprayed or applied barrier. Then the insulation, most often EPS (expanded polystyrene) or XPS (extruded polystyrene) boards mechanically attached. You need no further protection for these boards below grade, as long as you backfill with care. That means no large rocks, frozen chunks of hard clay, tree stumps etc.

For the insulation to be effective, the above grade section of the basement should also be insulated. That's the section that accounts for 30% of heat loss from a basement. And, yes, you have to protect that portion with flashing and some protective materials.

If you are in the US South, foam insulation must be used with caution as some types are banned locally and frowned on elsewhere, as subterranean termites can tunnel through the foam and into the wooden superstructure without being detected.

Here is a link that might be useful: Basement Insulation Systems


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RE: Basement insulation (exterior) covering

Thanks for the link. Yeah, I understand it's not a job for the timid but.. had a serious problem with the floods, water infiltrating through the floor, and as far as I can tell, the only reason it did that is because there was no place else for the water to go. Soil is a very dense clay - once it's waterlogged, that's it - no drainage to speak of except natural grade. works pretty well normally, but it's time to fix the caved in cistern.. etc.

Sounds like there's no great consensus for finishing the above grade part of exterior insulation. Leaning toward cement parge/stucco.

Mechanical fasteners - meaning one bolts the XPS to the wall..? Guess I have mroe reading to do.

Thanks again!


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RE: Basement insulation (exterior) covering

Mechanical fasteners are not required on the exterior, but unless you're working with a new wall, you're not likely to get it perfectly clean enough to ensure the best setting. Just use concrete screws (Tapcons, e.g.) and washers.

Also, be sure to cover the weepers with a minimum of 18" of coarse gravel, then geotextile, then free-flowing fill. That could be sand or recycled material. Don't backfill with the native clay.


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