Patching and Plastering - Protecting exterior pink board
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berkshirebear
04-30-09, 11:22 AM
Default Protecting Foam Insulation
The basement of this house has leaked, at the floor/wall joint for 35 years. It's a poured basement, full height, sitting on a poured floor. The contractor who did it, did nothing to key the walls to the floor, did an improper backfill and outside drainage job, The soil here is tight clay. Fortunately we are on a hillside and the downhill side is open for any water that misses the floor drains to just flow out. That's background.
Late last fall I had a contractor dig out the whole foundation, clean, tar, inject the crack, put a new drain system in and properly backfill it. While he was at it, we added 2" pink foam board to the outside. The foam board that is exposed above the soil is my problem. It is bolted to the wall with Tapcon screws. The top edge was cut at a 45 degree angle and fit snugly up under the T1-11 sheathing. Exposure ranges from 2" to 4.5' as the ground slopes.
I need to protect the foam from oxidation, strong sunlight on two sides, and the abuse of lawn mowing, etc. A contractor (friend) suggests parging, but agrees that it's likely to just loosen and fall away because of the extremes of weather and temperature that will hit the south wall. We've also had the suggestion to buy cement board (Hardieboard) 1/2" and glue it with contractor's adhesive to the face of the foam. The bottom edge would be in ground contact, buried perhaps 3"; is it stable in that situation?
Any other suggestions are most welcome.
BTW, It's not clear which forum to post this in. If I've missed, please move it or tell me where to re-post it.
BerkshireBear
(Location: Berkshire Mts. very close to where NY, MA, & VT come together.)
The basement of this house has leaked, at the floor/wall joint for 35 years. It's a poured basement, full height, sitting on a poured floor. The contractor who did it, did nothing to key the walls to the floor, did an improper backfill and outside drainage job, The soil here is tight clay. Fortunately we are on a hillside and the downhill side is open for any water that misses the floor drains to just flow out. That's background.
Late last fall I had a contractor dig out the whole foundation, clean, tar, inject the crack, put a new drain system in and properly backfill it. While he was at it, we added 2" pink foam board to the outside. The foam board that is exposed above the soil is my problem. It is bolted to the wall with Tapcon screws. The top edge was cut at a 45 degree angle and fit snugly up under the T1-11 sheathing. Exposure ranges from 2" to 4.5' as the ground slopes.
I need to protect the foam from oxidation, strong sunlight on two sides, and the abuse of lawn mowing, etc. A contractor (friend) suggests parging, but agrees that it's likely to just loosen and fall away because of the extremes of weather and temperature that will hit the south wall. We've also had the suggestion to buy cement board (Hardieboard) 1/2" and glue it with contractor's adhesive to the face of the foam. The bottom edge would be in ground contact, buried perhaps 3"; is it stable in that situation?
Any other suggestions are most welcome.
BTW, It's not clear which forum to post this in. If I've missed, please move it or tell me where to re-post it.
BerkshireBear
(Location: Berkshire Mts. very close to where NY, MA, & VT come together.)
XSleeper
04-30-09, 04:47 PM
I've seen masons tack a fiberglass mesh over the foam and then parge/stucco with SureWall.
Bud9051
04-30-09, 05:43 PM
I have envisioned the rough fiber mess concrete backer board sealed to a framework of pressure treated wood so the insulation would be totally enclosed. Then a skim coat of fiber cement for a finish. Possibly some trim bent to fit the top. Haven't tried it yet, but when oil prices head north again people will be adding foam everywhere and we will need to establish ways to install and finish.
I've seen stucco over what you have, and it was falling off. I've seem carpenter ants go right through the foam into homes. Termites love an enclosed path, to travel from wood to moisture.
Good Luck
Bud
I've seen stucco over what you have, and it was falling off. I've seem carpenter ants go right through the foam into homes. Termites love an enclosed path, to travel from wood to moisture.
Good Luck
Bud
coops28
05-01-09, 06:16 AM
Maybe you could put tyvek or tar paper over it and carry the t1-11 down over it.
berkshirebear
05-03-09, 05:43 AM
I spent a day visiting all sorts of building supply places in the area. Several called manufacturers support lines for me. Lots of creative thinking but not much that would work. The only sheet material that is certified for ground contact would be PT plywood, but the stuff available is so squirrely that it would look like it had measles from the number of Tapcons it would take to hold it flat. The manufacturer of the sticky mesh said they don't sell it in the north. So it looks like I need to attach expanded wire mesh to the foam, then cover it with stucco. Both Quikcrete and Sackrete seem to have appropriate products for that.
Now I'm stuck with a different problem. The Tapcon drilling through the two inches of foam is doubly difficult. Hard to hold the drill in place when drilling blind. The foam wraps itself in the flutes of the bit and encourages it to walk on the concrete surface.. But even worse, the concrete is refusing to drill in about 1/2 of the spots. It's very hard or some of the aggregate they put into it might have been pure quartz or flint. Now I'm looking for a way to get those holes in without going poor on carbide drill bits.
Now I'm stuck with a different problem. The Tapcon drilling through the two inches of foam is doubly difficult. Hard to hold the drill in place when drilling blind. The foam wraps itself in the flutes of the bit and encourages it to walk on the concrete surface.. But even worse, the concrete is refusing to drill in about 1/2 of the spots. It's very hard or some of the aggregate they put into it might have been pure quartz or flint. Now I'm looking for a way to get those holes in without going poor on carbide drill bits.
tightcoat
05-04-09, 11:04 AM
Rent or borrow a hammer drill.
Hilti makes special devices for holding foam. it should also work for holding it with the mesh on top.
Look into an EIFS system for the finish. Some will work over extruded foam.
You might find a supplier to sell it to you but they shouldn't.
If you live in termite country be double sure to keep the house inspected and treated. You have created a thoroughfare for them to enter the structure undetected.
If I were doing this I would attach metal lath through the foam into the concrete and then stucco it with conventional three coat Portland cement plaster.
Yes, every fastener you put through the foam is a heat leak.
You still have created a termite haven.
Hilti makes special devices for holding foam. it should also work for holding it with the mesh on top.
Look into an EIFS system for the finish. Some will work over extruded foam.
You might find a supplier to sell it to you but they shouldn't.
If you live in termite country be double sure to keep the house inspected and treated. You have created a thoroughfare for them to enter the structure undetected.
If I were doing this I would attach metal lath through the foam into the concrete and then stucco it with conventional three coat Portland cement plaster.
Yes, every fastener you put through the foam is a heat leak.
You still have created a termite haven.