When a deck plan calls for skirtboards and the beam is a doubled rim joist, the skirtboards will be in contact with the face of the support posts. This means that the exposed top of the footings will project beyond the face of the skirt. You could deal with this by chiseling away the exposed concrete after pouring the footings, but that’s not necessary. Instead, cut a piece of rigid foam that fits the outside circle of the footing-form cylinder where the skirtboards will pass. Place the foam into the form before the pour, aligning it with the beam face and extending it about an inch below grade. After the concrete is cured and the cardboard form is peeled away, scrape the foam off the footing with an old putty knife or a flat-bar blade. When using this technique, it’s important that the anchor bolts be long enough to penetrate into the undammed portion of the footing. I always use 12-in. to 16-in. anchor bolts and wet-set them rather than risk drilling.
Mike Guertin, East Greenwich, RI
Edited and Illustrated by Charles Miller
From Fine Homebuilding #252