Prep a Walkout Wall for Cultured Stone
The walkout basement wall will be clad with Cultured Stone below the window sills. Here's how we prepped for installation.
The FHB House’s walkout basement wall will be clad with Boral’s Cultured Stone below the windows. The installation instructions limit how close the stones can be to grade or the patio slab. We could have just stopped the stone a few inches above grade, but that detail looks unusual — stone hovering with an airspace below — so we devised a detail to pad out the appearance of the foundation with a drip cap and small weep space.
We started by running 2-in. borate-treated EPS foam from the bottom of the window rough opening down to the footing and slab. We are using Roxul ComfortBoard IS over most of the exterior walls, but where the Cultured Stone is installed, we have to use rigid foam to handle the extra weight.
Along the bottom edge of the foam, we screwed two ground-contact-treated 2x6s with a 2×4 cap on the section resting on the footing, and two 2x4s set on top of the slab. The top of the lumber was beveled to shed water. Then a layer of 1×8 and 1×4 Boral TruExterior trim was screwed to the pressure-treated lumber. The TruExterior trim is rated for ground contact, so the final soil grade can be filled up to it.
An aluminum flashing caps over the layers. Finally, a strip of Cor-A-Vent SV-3 siding vent is attached with a 1/2-in. airspace to allow any water that leaks through mortar joints to weep out and air to flow behind the Cultured Stone.