How to tie new wall into parallel joists

[Brian Tymchak]

I've decided to wall in my basement shop, to keep dust from traveling, and so I can be a bit less fastidious about keeping the shop clean. The basement already has finished walls and textured ceiling. I need to add 2 short walls with both running parallel to the ceiling joists. I want to preserve the textured ceiling as much as possible to minimize repair work. I can cut the ceiling to fit the top cap but odds are that the top caps will land in the bay between ceiling joists. If the ceiling was open, it would be easy to add blocking between joists to tie the top caps into. But with just a ~4" openiing in the ceiling, I'm not sure how I can add that blocking. So, before I tear everything apart, I figured it would be a good idea to ask the more experienced here if there might be some techniques to tie in the walls that I'm not aware off.

Thanks.

[George Bokros]

It will be easier to shift the wall one way or the other to nail the top plate to the joist. It would only be a max of 8" one way or the other, no big change in either space.

[Brian Tymchak]

It will be easier to shift the wall one way or the other to nail the top plate to the joist. It would only be a max of 8" one way or the other, no big change in either space.

Hi George, I wish I could but unfortunately I can't do that. In both cases, I will be extending existing wall planes defined by the staircase.

Thanks.

[Paul F Franklin]

Since this is just a partition wall, just use a double thickness of 3/4 plywood as the top plate. Make it as wide as it needs to be to reach the nearest joist. There's really no need to cut into the existing ceiling. If it's close enough to a joist, you could also use a 2x8 or 2x10 as the top plate of the wall.

[Tom M King]

What material is the textured ceiling? I have some ideas, but need to know that.

[Jim Becker]

Since this is just a partition wall, just use a double thickness of 3/4 plywood as the top plate. Make it as wide as it needs to be to reach the nearest joist. There's really no need to cut into the existing ceiling. If it's close enough to a joist, you could also use a 2x8 or 2x10 as the top plate of the wall.

ALong this line, you can also use a normal top plate but put recess in the top of it that will accommodate strips of plywood that can extend over to a joist location that will permit you to put fasteners directly up into the joist. A little paint to match the ceiling color will make them somewhat disappear.

[Bill Dufour]

I would use Simpson A23 with screws to attach the top plate to the joists. As others said the top, top plate can be plywood or 2x6 or 2x8 to reach the joist.
Bil lD

[Brian Tymchak]

What material is the textured ceiling? I have some ideas, but need to know that.

Hi Tom, just a typical drywall ceiling with stipled compound. I had to fix a small section of the same type of ceiling in our kitchen following a leak in an upstairs shower drain. I want to avoid having to patch 20 ft if ceiling if I can.

[Brian Tymchak]

Since this is just a partition wall, just use a double thickness of 3/4 plywood as the top plate. Make it as wide as it needs to be to reach the nearest joist. There's really no need to cut into the existing ceiling. If it's close enough to a joist, you could also use a 2x8 or 2x10 as the top plate of the wall.

ALong this line, you can also use a normal top plate but put recess in the top of it that will accommodate strips of plywood that can extend over to a joist location that will permit you to put fasteners directly up into the joist. A little paint to match the ceiling color will make them somewhat disappear.

Ok, I see what you guys are saying. My goal is to install the walls such that they don't look like a retrofit, but if this is going to be overly complicated or impossible, then I'll likely be doing as you suggest.

Thanks!

[Brian Tymchak]

I would use Simpson A23 with screws to attach the top plate to the joists. As others said the top, top plate can be plywood or 2x6 or 2x8 to reach the joist.
Bil lD

Interesting. Never thought of an angle bracket. That's something I can think about tonight.

Thanks!

[Jim Becker]

It occurs to me after Bill's comment that what I previously recommended could also work with a strip of metal which would be even less visible once painted. I can appreciate your desire to make these walls look like they grew there naturally, but without buggering the ceiling to get blocking in, using an alternative way to tie into adjacent joists, despite the possibility of being noticable may be the best way to go. If you plan on loading these walls (shelving, etc.) then use more connections to make things stronger. But a good, tight fit with the top plate tied in will make for a reasonably strong wall setup.

[Bill Dufour]

I meant the metal up inside the ceiling screwed in with a right angle drill. I have also used a 2x2 screwed to a joist with a horizontal piece sitting on top or below. Have you looked at ceiling fan mounting boxes for ideas on how to tie things down with no access. Make you own with 2x lumber and a lag bolt or two
Wide cove molding will hide many a sin.

[Ron Selzer]

Hi George, I wish I could but unfortunately I can't do that. In both cases, I will be extending existing wall planes defined by the staircase.

Thanks.

So you have an anchor for one end and also possibly both ends.
To anchor the top in between the ends cut a section of ceiling out the width of the wall (3 1/2" stud+(1/2"x2drywall) =4 1/2") wide by 6" long then slide a piece of 2x4 up in place between the two floor joists, move this 2x4 over to the edge of the hole and shoot a drywall screw up into the ceiling to hold it in place. Then your new wall extension will cover the hole and screw thru the ceiling into the 2x4 between the floor joists holding it securely in place. Repeat how ever many times you feel is necessary to hold the wall securely in place. If both ends are secured to existing walls then one 2x4 every 4-6' in between would be plenty.
good luck
Ron

[Brian Tymchak]

So you have an anchor for one end and also possibly both ends.
To anchor the top in between the ends cut a section of ceiling out the width of the wall (3 1/2" stud+(1/2"x2drywall) =4 1/2") wide by 6" long then slide a piece of 2x4 up in place between the two floor joists, move this 2x4 over to the edge of the hole and shoot a drywall screw up into the ceiling to hold it in place. Then your new wall extension will cover the hole and screw thru the ceiling into the 2x4 between the floor joists holding it securely in place. Repeat how ever many times you feel is necessary to hold the wall securely in place. If both ends are secured to existing walls then one 2x4 every 4-6' in between would be plenty.
good luck
Ron

Hi Ron, both walls have an anchor on both ends.

So your suggestion is to use the ceiling itself to anchor the top of the wall. Interesting. I would not have thought that would be strong enough but your point of being anchored on 2 ends - maybe I'm be too worried about that. I didn't mention that there will be a door in each of these walls, not that that will add any load. And Jim did raise a good point about the load on the walls. I had not considered that. I'm thinking that load will very minimal, but that doesn't mean the next owner might not hang something heavy. Hmm, things to consider.

Thanks!

[Brian Tymchak]

I meant the metal up inside the ceiling screwed in with a right angle drill. I have also used a 2x2 screwed to a joist with a horizontal piece sitting on top or below. Have you looked at ceiling fan mounting boxes for ideas on how to tie things down with no access. Make you own with 2x lumber and a lag bolt or two
Wide cove molding will hide many a sin.

Thanks for the ideas Bill. Had not considered using a right angle drill, nor the notion of a fixture mount.

Has me thinking, assuming I can get screws into the joists thru a ~4" slot, about 2 L brackets made from 3/4" ply each screwed into opposite sides of joist bay, then tied together with another block of ply at the slot. This is kind of like the fixture mount.

Hmm, or maybe I can actually use fixture mounts with a block of wood instead of a fixture box, though that might get a little expensive.

Good stuff Bill! Thanks!