*
The floor joists in the old part of my houe are 2X8’s and the floor is 3 1/2″ lower than the floor in addition I’m currently building. I’d like to raise the old floor up to match the new floor. Whats the best technique to do this? I’m thinking of 2X4’s on edge with simpson/strong-tie repair plates on either side of the joist – say every 2′. Or, making a sandwich using plywood on either side of the joist.
Any good ideas?
Replies
*
How about laying 2x4's on edge, perpendicular to the current
joists, toenailing them to the joists, and attaching them to
the plate with a simpson or just toenailing there too. If
it's a longer than 16 foot run, you'll have to lap the
joints but assuming you'll be laying plywood, or at least
OSB, it's a pretty easy adjustment to make. If you're
laying hardwood, and by chance screwing through the face,
this would result in your plugs being offset, not the
greatest look but still doable. I did an elaborate job
recently with that setup, but it wasn't my idea. What
happened to the original f.f.
*
The first floor of the addition is the same level as
the original first floor. Because the new second floor floor joists are 12" , while the original are 2X8's, there is a descrepancy (I didn't want the ceiling in the addition to be 3 1/2" lower).
I'll be laying 3/4" T&G fir plywood with hardwood flooring on top.
I'm hoping to not have to lay the 2X4's perpendicular to the original flooring, if only because I didn't want to end up with a bunch of 16" X 16" squares in which to run ducts, pipes and the like.
Thanks!
Larry
*
The 16" x 16" squares are more of an advantage than a dis. Think 3 dimensionally. It allows you the option of running ducts and wires in EITHER direction, just pic a floor layer.
It maybe too late in the game for you (or you might of had other reasons), but why not raise the addition floor another 4" or so to create a step? I had to cross a similar bridge with my home plans. I didn't want to loose the ceiling height and in my case the new floor required 14" floor trusses (vs 8" joists). I choose to adjust the top of the new floor 7.5" higher (one step) than the old floor. Between the rooms and walls, there was a convienent location for the step. Some sections of the old floor were raised to match, most was not. Adds an interesting split level effect to the floor plan and didn't interfere with the stairs in the old section.
*I like Mad Dog's suggestion.If you decide against that, and put your 2x4s paralell to the joists (which I have done) I would use 3/4" cdx plywood gussets - say 16" long by 10" tall. I would nail a pair of them (one each side of the joist) at each end and probably every 2 feet or so. And nail the sox off of 'em. I have also firred ceilings down this way to accomodate new plumbing upstairs.
*If you decide to run them on top and parallel to the existing joists, I think Jim's gussets will be a lot quicker to install than using simpson type stuff, maybe safer too. I'd glue them too, may keep a few squeeks out with some construction adhesive. But blasting on plywood should go pretty fast rather than the metal stuff, and you won't be shooting sparks and nails all over, and it'll be stiffer too. Someone else might have a different recommendation about bridging this, but I'd skip it, (subject to code in some areas) especially with your concern for the hvac/plumbing access. With old joists, you're sure to have some out of level, so after you install the new ones on top, send strings perpendicular to them every 6-8 feet or so, and rather than trying to shim the low ones, take a hand planer and knock down the high ones if possible. If they are pretty good though with only a couple low ones, you could rip some 2x4 stock to suit rather than planing the majority. Don't plane the old joists, even if you think you got all the nails out. You didn't! This would also apply if you laid them crosswise, like in my first post.Let us know how it works out. Good
*Hey Mad Dog, if you ever want to relocate, I could use a good hand like you.
*JB,Awful good to hear that vote of confidence. I'd love to work out there. A bit wrapped up here right now, but I can see the future out there somewhere else, but would be honored to work with you.MD******
*
The floor joists in the old part of my houe are 2X8's and the floor is 3 1/2" lower than the floor in addition I'm currently building. I'd like to raise the old floor up to match the new floor. Whats the best technique to do this? I'm thinking of 2X4's on edge with simpson/strong-tie repair plates on either side of the joist - say every 2'. Or, making a sandwich using plywood on either side of the joist.
Any good ideas?