Site-fabricated 2x4 blocking supports the lower band of fascia; a picture-frame decking border covers the gap created behind the top two courses of trim. Fascia dimensions vary depending on framing lumber sizes, but proportions of the tiers remain about the same.
One of my signature details is a three-course fascia. It adds to my bottom line, looks great, and most of all, helps to build my brand. When prospective clients see this detail on their neighbor's deck, all over my website, and (hopefully) throughout the Michigan communities where I build, they know who built the deck.
Layering the fascia offers a couple of advantages. It adds depth and gives an effect like crown molding to the deck rim, a big visual upgrade over standard single fascia. Also, it extends below the joists and beam, hiding all the framing material except for the support posts, whereas a single fascia board covers only the joists and leaves the beam exposed.
Preventing Rot
The key to a long-lasting fascia on a deck is to keep water out of the gap between the fascia and the framing. The best way to do this is to install a picture-frame border around the entire deck.
I cannot emphasis this point enough. When I see decks that were built without such a border, I usually find a significant amount of rot. Typically in those cases, the deck boards were cut flush with the joists, and the decking ends and the rim joist were then capped with fascia. Unfortunately, this practice creates a perfect place for water and debris to sit, eventually working the fascia loose from the rim board and encouraging the cut ends of wood decking to rot.
To support the picture frame where it runs parallel to the side joists, I frame decks with a second joist at the sides, spaced 3 5/8 inches away from the outer joist to allow the rail posts to drop right in. Then I add blocking between the two joists on 16-inch centers.
Once everything is installed, the top of the fascia will be flush with the top of the joists, and the board forming the picture frame will cover the joint between the fascia and the outer joist. To allow water to drain, I make sure the inside edge of the border decking doesn't extend over the inner joist.
Because the field decking and the picture-frame board are parallel at the rim joist, no additional framing is needed at that point.
Triple-Stacking the Fascia
After framing the deck, I install the posts, the decking, and the border. The border has to be wide enough to extend over three tiers of fascia (between 1 7/8 and 2 1/4 inches, depending on the material we're using), plus overhang about an inch beyond the fascia.
The stacked fascia will form a skirt that covers all the framing from the tops of the joists to the bottom of the beam, and blocking is required to carry this detail around the entire deck. Usually, we make the blocking by scabbing together two pieces of 2x4, one of which is long enough to extend past the other by the depth of the joists. We fasten this longer leg with screws to the back of the outer joist so that the shorter leg butts the bottom of the joist and is flush with the face.
Sometimes, the shape of the deck or the configuration of the framing makes it necessary to install an extra layer of horizontal blocking. When this happens, we increase the width of the picture-framed decking border to cover the additional thickness.
The total height of the three-tiered fascia varies depending on the depth of the beam and joists, but the proportions of the three pieces remain more or less the same. Typically, the middle and bottom courses are three- and four-times the width of the top course, respectively.
For the base course of fascia, we usually install a full piece of 1x12, flush with the elevation of the bottom of the beam, or with a small overhang. From a second 1x12, we rip an 8-inch-wide strip for the middle course, using scrap trim to fur out the top edge. We use the remaining 4-inch-wide piece for the top course, either full-width or ripped to a proportional dimension; again we use scrap trim or waste from the rips for furring.
Though it's a pretty simple detail, requiring only some blocking and about twice as much 12-inch fascia board as would be used for a single ply, the tiered fascia really sets my decks apart.
Bayn Wood owns Autumnwood Construction in Rochester, Mich.
