Styrofoam wall board???

I have a question because I personally have never ran across this before. In the garage the exterior walls were build then covered with a styrofoam board (not the standard rigid foam board like DOW etc…). There are several areas where it is damaged and the vinyl siding is exposed. It just falls apart when you touch it. (See Pictures)

What is your opinion of this?

I would say if its deteriorating then it will be a matter of time until the siding becomes loose also. It could cause siding issues if it hasent already. What a fun repair that will be, especialy if its the whole house. It could be from the heat. I would think the application should be sufficent, but I can’t tell you why its rotting.

Your right, some of the siding is loose. Probably from objects falling into it from inside the garage. I would hate to see if someone tried to prop up their bicycle on this wall, it would fall right through :shock:.

This is framed in a technique to give a thermally better wall by covering most of the studding with insulation rather than wood sheathing thus creating a thermal break. Notice that there is panel sheathing at the corners to give the structural rigidity needed by codes.

They neglected to finish the inside walls and protect the foam!!

I have built a lot of houses but have never seen white styrofoam used for sub sheathing. It looks like the type of styrofoam used in basement remodels which has a poor bonding trait. In other words it falls apart when touched. Just a guess.

This is the standard method for manufactured homes. They only use sheathing on the corners, and styrofoam everywhere else. The busted foam is probably from interior damage. It is ok for a garage if you add insulation to the cavity and an interior wall finish of some kind.

You can break into these types of homes with a pocket knife!

Don’t worry, Joe! The crooks still go for the windows and doors…it’s quicker.

In the mid-to-late 1980’s, I was hired by a housing co-op to inspect a couple of duplexes they were were having built using this style of energy efficient construction. This was in a fairly “rough” part of town…never heard of them being broken into with a “sharp utility knife”.