[RickT]

My house is being resided and I'm planning on building a deck next spring. I thought that as long as the old siding is coming off, now might be a good time to install a ledger board. My house sheathing is 1" foam board, not OSB. Should I install the ledger board over the foam board, or should I cut the foam board away to expose my sill plate, install pressure treated 2x? ledger board to the sill plate? I was thinking that the foam board would compress and would never allow a solid enough installation of the ledger board, but I wanted to ask you guys.
Thanks,
Rick

[Big Dave]

I would advise to cut the foam out and replace with osb. I've worked for people who nailed over the foam but like you said it just isn't as strong of a bond.

[AtlanticWBConst.]

Originally Posted by RickT

My house is being resided and I'm planning on building a deck next spring. I thought that as long as the old siding is coming off, now might be a good time to install a ledger board. My house sheathing is 1" foam board, not OSB. Should I install the ledger board over the foam board, or should I cut the foam board away to expose my sill plate, install pressure treated 2x? ledger board to the sill plate? I was thinking that the foam board would compress and would never allow a solid enough installation of the ledger board, but I wanted to ask you guys.
Thanks,
Rick

RickT...your intuition is absolutely, 100 % right..... about the foam...

Install your ledger board onto your sill plate....

However, what we do is to make sure that the areas is water and moisture tight:

a.) The area of the sill plate and wall sheathing is covered with a water and ice shield membrane.
b.) Install spacers between the ledger and the sill plate to allow water and moisture run-off.
c.) Install proper aluminim (or other proper material) ... capped & bent ....over the ledger board....away from your house...

[North Country]

Cut the foam away, then slide flashing up underneath the foam/bend so it comes out over the top of the ledger board, then install ledger to floor rim joist.

[RickT]

Thanks, guys. The foam board goes. Of course I'll be sure to properly flash the ledger board. Now I have another question. The aluminum sill of the patio door I just installed cantilevers aboaut 1 1/4" passed the foam board. Cutting the 1" foam will leave 2 1/4" of the aluminum sill cantilevered passed the rim joist. Installing 2x? pressured treated ledger will leave the aluminum sill cantilevered 3/4" passed the ledger board. Is that OK? I guess I'd like the first decking board to be flush with the aluminum sill rather than tucked under it or above it. I also don't want to leave 3/4" of the aluminum sill unsupported because I expect it will bend over time as it's stepped on. Should I install two pressure treated 2x to make essentially a 3" thick ledger board that fully supports the aluminum sill and stands proud of it by 3/4" instead of coming short of the edge by 3/4"? Also, I have a sample of the decking I plan to use, so I can determine what height to install the ledger so that the decking comes flush with the aluminum sill.
Thanks again,
Rick

[Darylh]

Deck surface is usally 2 inches below the finished floor of your house or at the very least your deck boards should tuck underneath you door cill.I know you don't like this but if the wind blows in a rain storm you could get leakage into the house.