Builders who install rigid foam insulation need to know what type of fasteners to use for a variety of substrates. One challenging situation involves installing rigid foam or furring strips over concrete, as might happen when rigid foam is installed on the interior of a basement wall. But even builders who are familiar with fastening methods for concrete might wonder if the same techniques are appropriate for brick walls.
In this article, I’ll try to provide advice on the best mechanical fasteners for concrete, brick, or CMU (concrete masonry unit) walls. I’ll consider a variety of scenarios, including the attachment of furring strips directly to the wall, the attachment of rigid foam without furring strips, and the attachment of furring strips through a layer of rigid foam. I’ll also look at the best fasteners for OSB or plywood subfloor panels when the subfloor is installed over continuous rigid foam above a basement slab.
Types of fasteners
There are two basic types of fasteners for concrete and masonry:
- The first category of fasteners requires a predrilled hole. Examples of this type of fastener include concrete screws (for example, Tapcons), wedge anchors, hammer-set fasteners (for example, Red Head Hammer-Set Nail Drive Concrete Anchors), certain concrete nails (for example, Trufast Tru-Grip fluted concrete nails), and plastic fasteners for holding rigid foam to a concrete wall (for example, Styro Industries Tapit fasteners, Rodenhouse Plasti-Grip PMF fasteners, or Hilti IDP anchors).
- The second category of fasteners does not require a predrilled hole. Examples of this type of fastener include powder-actuated fasteners, fasteners driven by gas-actuated tools (that is, tools with an internal-combustion engine that uses disposable gas cartridges), and old-fashioned concrete nails.
Drilling a hole in concrete
If you’re using a fastener that requires a pre-drilled hole, you’ll need a hammer drill…
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