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Cut a joist in the wrong spot on a deck rebuild in Eugene | Carpenters - Vivisector

Cut a joist in the wrong spot on a deck rebuild in Eugene

Was replacing a rotted ledger board and marked the new joist locations with a chalk line. My saw kicked back on a knot and I cut the line a full inch off. Had to sister a new piece onto the side of the joist with construction adhesive and three inch screws to get the bearing back. Anyone ever have to fix a bad cut on a structural piece like that?

4 comments

4 Comments

bettyramirez7mo ago

Wait, they only used three inch screws for a sistered joist? That seems way too short to get any real grip into the good wood. I've always heard you need screws long enough to go deep into the original piece, like at least half the joist thickness again. That fix sounds like it's just hanging on by the glue.

the_oliver5mo ago

Bettyramirez hits the nail on the head, reminds me of when my buddy tried to fix a sagging porch with drywall screws and hope. That glue and three inch screw combo is just asking for a creaky floor in a year.

paul_ramirez7mo ago

A contractor friend told me a story about a similar fix that failed after a few years. The adhesive cracked from the wood flexing and the screws just sheared right off. He had to go back and bolt everything properly. Ross is right about the hinge effect, that thin line of screws creates a weak spot that bends. Bolting through both pieces spreads the load way better. It's a weekend killer to fix it now, but way better than redoing the whole deck later.

ross.christopher7mo ago

That sister joint with just adhesive and screws is gonna be the weak spot now. For something structural like a joist, you really need to bolt it. Through bolts with washers, or at least some structural screws rated for that. The adhesive can fail and those three inch screws don't have the shear strength. I'd go back and add some 1/2 inch bolts through both pieces. It's a pain but you don't want that hinge effect over time.