Having been tasked by SWMBO with putting a bench on our Trex deck, I’ve got a construction/design question. The bench itself will be made of redwood, but I’m unsure about the best way to attach it to the deck. I’m thinking about using hanger bolts screwed into the legs/back of the bench, set into holes drilled through the Trex deck, then bolted to an metal plate under the deck.
I was thinking about using 1/2″ x 6 (or perhaps 5/8″ x 6) hanger bolts — going about 3″ into the redwood legs, and leaving about an inch for the bolt once it’s through the Trex. Does this make sense? Will it be strong enough to hold the bench securely and safely?
Thanks,
-M.
Replies
Boy, you lost me on the hole bench scenario Mark.
If you are putting a bench on top of the Trex the only concern you should have is kick out on the legs. Gravity will take care of the rest.
We usually box frame our bench supports into the framing before we add the bench.I'd post pictures but I'm down in Oregon visiting my kids and on a dial up modem no less.
If your bench has a back rest I would not rely on bolts through the deck to support the torque of body weight to keep the bench upright.
Do you really need a backrest attached to the bench, or could you use the deck railing as a backrest?
Bob
"Rather be a hammer than a nail"
Bob, He's talking about hanger bolts, lag screw threads on one end and SAE threads on the other. I think what he's considering is drilling into the legs and running the hanger bolt lag screw end into the leg then drilling through the deck material to slip the threaded bolt through the deck. Sounds like overkill to me, and certainly no need for a metal plate.
I'd look at this as an option only if there were a chance the bench might be stolen. It would sure limit any future rearrangement of the "furniture" - you'd be left with those holes through the Trex. Something as simple as a stainless L bracket and some #8 wood screws might be a consideration.
Good luck. Greg.
You've interpreted my intentions exactly right. I'm worried about just depending upon gravity to hold the bench down because the back of the bench *is* the rail for this part of the deck, and the bench will be with it's back "feet" right a the edge of the deck. I'd hate to have a kid climb up on the back and have the whole thing tip over -- that's why I'm proposing to anchor the legs through the deck with the hanger bolts. If this was a wooden-surfaced deck I'd probably just toe-screw the feet to the deck, but I don't think that's feasible with Trex.
Upon reflection, I believe you're right about an anchor plate underneath the Trex being overkill -- a decent fender washer on the bolt should be plenty.
-M.