Just began construction on our new home, about 50 miles south of Houston TX. One thing about the house that is very uncommon around here is it will have a closed/unvented crawl space above a full slab foundation. There’s a 3′ tall CMU perimeter stem wall that supports all of the exterior walls. The interior load bearing walls are supported by 3′ tall 2×6 pony walls. All floor joists are 11-7/8″ BC I-joists.

The subfloor is 1-1/8″ Advantech, and is 95% installed. Unfortunately, a lot of the subfloor was laid without leaving at least a 1/8″ gap between the 4′ edges. Many are butted together. All total, the subfloor has about 120 sheets of Advantech (some having the gap), so pulling them up and reinstalling would be a tough task. I’m not even sure it could be done without tearing up the subfloor and I-joists.

I’m looking for a reasonable solution to this. The builder suggested running a circular saw with a thin blade (with the blade depth set correctly) down the 4′ edges to create the gap. I’m okay with this it will achieve the desired result. Is this a good idea? Any reason not to do this (other than it should have been done correctly the first time)? If this will work, is it more important to cut all the way thru the Advantech subfloor, or to not cut into the I-joist at all? In other words, is it better err on the side of cutting a little less than 1-1/8″ or cutting a little more than 1-1/8″?

Thanks