Hi guys. This is my first post, so bear with me. I am a home owner with some construction experience. Here’s my situation…
I have an 80 year old house with more that one broken floor joist in the basement. They are cracked at knots in the joists. Replacing or sistering full joists is not really an option because of plumbing and heating (steam) pipes. I read the “6 Ways to Stiffen a Bouncy Floor” article in the recent issue and though that I could use suggestion #3 Plywood strips as a suitable method of repair for my joists after jacking them up.
Here are my questions:
Should I put two layers of plywood on one side as the article suggests or should I sandwich the joist?
Will this work at all? If not are there any other suggestions, given my limited working space.
Replies
Here's a little bump for you - this will keep your question on the active screen until somebody who knows some thing comes along. Welcome to Breaktime!
in this situation, there are those on this forum with more experience than me, but this is what i read-
if the joists are breaking at the knots, then the lumber, and carpenters, were suspect to begin with, unless the wood and your house is very old, when roughsawn lumber was used-perhaps making it difficult to read the grain. I'd replace the joist as it may fail at another knot.
Expert since 10 am.
I have not seen that article, having let my subscription run out ( yes, guys, the renewal is in the mail now) but I don't even consider that suggestion acceptable for what you mention they recommend let alone a total repair of a broken joist.
The very fact it is broken at a knot tells me that it is undersized in the first place, so a band-aid approach won't gain you much.
But be that as it may, with full disclosure that I think this is domed to fail, the way to appraoch it is to use the thickest plywood you can ripped to the depth of the joists. Jack the joist to straight or slightly crowned up. Then use PL premium glue and nails to attaach the ply to both sides of the joist. wait a day for the glue to set before relieving the jack.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
Cracked? Or checked? Can you post some pics?
Try a bolted on steel strap across the knot - the example is a strap used to transfer load when 1/2 a double 2x10 had to be cut on a heating retrofit. Same bolt pattern both sides of the break.
View Image
I'll agree with Piffin, but add this:
You might try ordering lvl (laminated veneer lumber) instead of using regular plywood. If you use plywood, make sure that you have a good grade with many layers and no internal voids. You could also drill and bolt the patches on, as well as nailing them.
It would probably be good to do both the steel strap on the bottom of the joist and the ply on the sides.
Pif mentioned PL premium. I wanted to make sure that you realize that PL Premium is a specific product made by PL. I wasn't sure you'd know, thought redundancy would be better than missing out on using PL Premium.
I'm not sure from your post, but if you are trying to repair the joists en mass, if you can't get full lenght pieces in due to pipes and wires in the way, be sure to lap the patches so they don't end at the same places on either side of the same joist i.e. so the joints stagger.
Good luck, and welcome to Breaktime.
"Doubt is not a pleasant condition, but certainty is absurd."
~ Voltaire