Free-Floating Slab-on-Grade Inspections (Garage, Basement)
Inspections for free-floating slabs-on-grade are performed after the gravel base and the vapor retarder have been installed. The slab inspection cannot be performed until after the under-slab plumbing and/or radon venting inspections have been performed by the local jurisdiction.
Our inspection will check that a minimum of 4 inches of gravel base has been installed and properly compacted and that the a 6-mil (minimum) vapor retarder has been placed over the gravel base. The grade stakes or chalk lines must indicate that the slab thickness will be a minimum of 3-1/2” thick. If a spread footing or thickened slab is being poured monolithically with the slab, we will verify that the proper reinforcing bars have been installed and are supported by metal chairs.
If framing is installed, the inspection must be performed prior to installing the subfloor sheathing. Our inspectors will verify that 1/2”-diameter anchor bolts have been installed at a maximum spacing of 6 feet on center. An anchor is required to be installed within 12 inches of each end of a sill plate section or length.
If alternate metal strap anchors are used, the anchors must be installed and spaced in accordance with the manufacturer’s recommendations for substitution of the code-required 1/2”-diameter anchor bolts. Recommendations may be provided for a retrofit anchor bolt system to bring the anchorage into compliance with the local building code requirements.
For crawl spaces, the CMU block pier construction will be checked for compliance with the local building code. If the pressure-treated sill plates have been installed, we will verify the anchor bolt placement for attachment of the sill plate to the top of the foundation wall. If the sill plates have not yet been installed, a separate “green plate” inspection will be required.
Inspections for foundation walls are performed after the concrete masonry unit (CMU) block walls have been laid or poured concrete walls have been formed. Our inspectors will check the vertical, and horizontal (when required), steel reinforcing bar installation, bar spacing, and wall thickness for compliance with the minimum building code requirements and the project design documents, when available.
In addition, we will document the anticipated elevation of the exterior grade, which will establish the unbalanced fill for the foundation walls. In addition to the above information, we also document the name of the concrete supplier, the concrete strength and any additives, as well as the weather conditions at the time of the site visit.
