Building Structural Brackets for a Balcony Deck

Last year, Pariseault Builders handed me plans for a pair of structural brackets intended to support a 5-by-8-foot second-story balcony.

I coated the layers with waterproof West System 105 epoxy (the only adhesive used for this project), then stapled them together using 7/16-inch by 1 1/2-inch galvanized staples on 4-inch centers. Next, I glued a double layer of 1/4-inch poplar to the inner and outer curved surfaces; this conserved the more costly sapele, which would form only the outer 1/4-inch layer on the curves.

For the straight legs of the brackets, I cut 4x6 Parallams to length, then epoxied solid sapele blocks to the ends. This would simplify the veneering process because the finished ends would later be chamfered at 45 degrees.

On the opposite ends, I used a band saw to cut forks for a saddle joint of the horizontal members, and to cut reciprocal tongues on the vertical.

With the aid of a plywood routing template, I cut the sapele slightly oversized for the side panels for the curved braces. To guide alignment during glue-up, I added sacrificial shoulder cuts to the ends of the template; a few carefully placed brad nails held them in position for clamping. After the epoxy set, I trimmed the edges flush with the core, using a bearing-under router bit.

For ease of dry-bending, I had Dwyer plane the veneer lumber for the curve laminations to a 1/4-inch thickness. Using plenty of clamps, I epoxied the outer curves first. I also glued solid lumber to the ends of the braces to provide a weatherproof cap.

I then dressed the side and front faces of the posts and beams with 4/4 sapele, again routing the edges flush with the core before applying the adjacent overlapping pieces. I ran these pieces long on the tongued ends and short on the forked ends to provide an additional structural overlap at the corner joint.

Rather than using sapele for the unseen backs and tops of the brackets, I overlapped the sides by a generous 3/4 inch, and did the same with the solid end blocks, creating a recessed surround into which I would later epoxy 3/4-inch MDO plywood.

To help rout pockets in the posts and beams to receive the brace tenons, I made a plywood template that fit slightly loosely around the tenons. I then used a top-bearing straight bit to cut the pockets. The loose fit ensured struggle-free assembly, and the epoxy filled any gaps. (Proprietary thickeners change the consistency of epoxy from "maple syrup" to "peanut butter," or anywhere in between, so it will stay where you put it.)

The plan called for bolting the finished brackets through solid posts in the first-floor wall framing. To avoid bungs or other weather-vulnerable surface marring, I encapsulated the 1-by-12-inch galvanized machine bolts within the bracket verticals. During bracket assembly, I set one bolt at the top in a pocket cut into the saddle joint ...

... and passed another through the brace tenon at the bottom. I bedded all the tenons in thickened epoxy and screwed them from the back using 3 5/8-inch LedgerLok screws. For good measure, I also capped the bolts with a custom mix of sawdust and epoxy.

Now I could glue and clamp the finish faces to the inner curves, rout the edges flush, and fill the backs with glued-in MDO plywood. Ultimately, the engineered core material was completely encased in truly weatherproof material.

A final sanding to a 150-grit surface completed my part of the job. I made an extra set of MDO infills to serve as drilling guides for installation and slipped them over the bolts for delivery.

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