I am replacing the “board and batton” siding on a house in San Jose, CA. The original siding is 1/2 inch exterior premium grade plywood installed on an inset in the foundation with 1×4 old growth redwood battons (house was built in 1962). I’m looking for recommendations on the best way to detail this installation of the new 1/2 inch siding.
The concrete foundation has a 1/2 inch inset x 2 inches deep. The original 1/2 ply siding set into this inset such that the outside face of the ply was essentially flush with the concrete foundation. Amazingly after 50 years there is very little damage on the bottom edge of the ply, with only two small areas that are rotted.
See picture attached.
So here is my question: what would be the best installation detail for the interface of the ply siding and the concrete foundation? Install as they did in 1962? Add a gap of say 3/16 inch between the bottom of the ply and the concrete? Add a metal “Z” flashing tucked behind the ply and overlapping the concrete?
Notes: I’m removing the siding primarily to install new windows which are taller to meet Egris, and taking advantage of the open wall to upgrade the wiring and add insulation. I plan on using Tyvek behind the new ply siding. I will reuse the wonderful old growth redwood battons. I’m installing Anderson windows per their instructions.
Appreciate any guidance on what is the best installation detail for the ply siding on this house.
Carl
Replies
Howdy
Normally, I say if it ain't brok, don't fix it.
Yours has worked for all this time with little problem, and if you shim it out, you could cause other troubles. For instance, that siding is likely a structural component of the all, preventing racking/shear, which would be important in sewismic zones.
Codes now require that wood in contact with Concrete be treated to prevent rot and insect incursion.
So you need to treat it with copper( CU Woodlife or other) or buy pressure treated, or separate it from contact. That shim space would separate it, but so would a flashing or tarpaper or something like vycor.
I would opt to do a metal flashing myself.
There is a peel and stick product like vycor that has a copper foil surface that might be the best choice.
You are in a dry cliumate where this might be of small importance if you are not subject to inspection