We recently learned that the block used on our home was out-of-spec. The majority of the corners were 1/4" to 3/8" taller than the straights. So instead of a uniform 16 inch height the corners blocks varied from 16.25" to 16.375". The end result is instead of tight horizontal seams between courses we have gaps up to 3/8 of an inch that are filled with spray foam or were left open. The use of out-of-spec material was kept secret from us and our engineer. It was know by the installer, GC, distributor and Fox Blocks. Additionally, we also discovered there are “post expansion” problems in our block/project. Can someone please explain to me what post expansion is and what sort of problems it could cause for my home?

The dirty little secret is that all blocks are not molded the same for each batch. When I sold BB the blocks were molded by CBIS in Mass and the blocks were some of the best molded I've used. I've never heard of post expansion. Eps will shrink after molding. BB used to place stickers on their blocks if they were less than 72 hrs old. From your pictures the blocks should have been rejected, not used when they are that far out of spec.

IS your concrete poured? Did the pour go OK, and were the walls trued up at the end of the pour? IT could be that the inconsistencies in your blocks were caused "post expansion"(foam didn't expand consistentely or shrunk back) and that is what they are refering to IRT your blocks. The gaps should be foamed to contain the concrete and maintan your insulation characteristics. Your engineer shouldn't really care as the forms are not really structural after the concrete cures, beyond containing the concrete and positioning the rebar to the designed locations... Because the ties are not resting directly on top of one another the wall may settle a little more in that area, but probably not very much, and the contractor ahould be aware and able to compensate for that.

Maybe it will help to look at it this way. Once the concrete cures, it is a re-enforced concrete wall(engineered to a structural design spec) with embeded ties and foam hanging off of it.

Inconsistent building materials happen. Your contractor should be able to deal with that and produce a finished product that is acceptable to you.