I’m adding 1 1/2 formular foam to outside of 2×4 wall. Is there a ledger strip to protect the edge of the foam and also allow for 3/4 rainscreen ventilation?
It would be nice to have a product that would protect the edge of foam and then transition to insect screen for the rainscreen 3/4 inch. And then it would be great if it was available with a a vinyl siding start strip built in also! I may be asking for a lot, I know but is there such a product? Thanks, Dave Green
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Dave, where are you located? If you are in termite and carpenter ant territory, it is more important to protect the edge of the foam. I think you can use copper flashing over a ledger board to inhibit termites. Also if I were to redo my exterior foam I would tape the bottom of the foam with the aluminum tape.
I would also fill the gap of the rain screen and siding with either coravent or ridge vent mesh just to make sure no insects cannot squeeze into that gap.
Thanks Lucy, I'm in S.E. Michigan. I failed to mention that the foam will be extended past the block wall, so there will be nothing for the foam to 'rest' on. I saw in an earlier foam install article they used some aluminum flashing, I was just wondering if there was a product that would incorporate the foam and the rainscreen venting in one.
Dave,
We can get 1/2" or 3/4" rain screen flashings off the shelf at our lumberyards, but their metal shop will also make up U shaped bottom flashings out of perforated stock to cover any depth of foam and cavity. You install the flashing and then sit the foam and furring strips in the U, cover with siding and it is pest tight.
You might want them to punch perforations into the front three quarter inch of the bottom of that U shaped bottom flashing, Malcolm. That way the air can rise up through in front of that foam and any moisture that makes it way there can drain out. I had some custom soffit vent made at the local metal shop in eight foot lengths. I plan on making something similar to wrap the bottom of the EPS foam, and the firring strips, and mine will actually be more of a Z flashing as it will return under the OSB and extend down the masonry an inch or so. I intend to nail each piece to the strips and it will be stiff, being made from 29 gauge steel in any color they can make metal roofing. I intend to have the front bottom edge perforated for air flow.
Joe,
The stock we use is entirely perforated. Our code requires that the bottom of the cavity allow for ventilation and drainage. I don't think it makes any material difference that the perforations extend under the foam too.