[adilj]

Hello,

I am a DIYer and first time poster here.
I am about to add a couple of non-load bearing interior walls to a large living room on the 2nd floor to carve out a bedroom.

I understood that I need to attach a top plate to the ceiling joists.
However, I noticed that my ceiling is not attached directly to the ceiling joists.
Instead there are 2x4s running under the ceiling joists and perpendicular to them. The ceiling drywall is attached to these 2x4s.

So my questions are:

1. Is there a name for these 2x4s" that sit under the joists....why would this have been done?
2. Can I attach my interior wall top plate to thse 2x4s or do I need to attach it to the joists itself?

Thanks.
-adil

 

[ront02769]

Hello,

I am a DIYer and first time poster here.
I am about to add a couple of non-load bearing interior walls to a large living room on the 2nd floor to carve out a bedroom.

I understood that I need to attach a top plate to the ceiling joists.
However, I noticed that my ceiling is not attached directly to the ceiling joists.
Instead there are 2x4s running under the ceiling joists and perpendicular to them. The ceiling drywall is attached to these 2x4s.

So my questions are:

1. Is there a name for these 2x4s" that sit under the joists....why would this have been done?
2. Can I attach my interior wall top plate to thse 2x4s or do I need to attach it to the joists itself?

Thanks.
-adil

Highly likely that they are one bye threes instead of two bye fours, called "firring strips", used to add stability to the ceiling jpists and to provide a wider surface on which to Screw the drywall to.

No worries about attaching the non-bearing wall to it. think about it, what forces will the wall experience? No downward pressure, just potential to move sidewards. So if you were to take a BIG hammer and try to hit one of those boards SIDEWARDS.....more likely you would break the hammer than move those things. So have at it. Ron

 

[joecaption]

Opening up a can of worms by adding a bedroom up there.
Going to need permits.
Windows need to be egress approved.
Stairway width, hand rails, run and rise, over head height come into question.
Zoning and heath dept. will need to sign off.
Arc fault circuit needs to be run.

 

[adilj]

Thanks for your replies.

I am not adding a room in the attic.
This is a finished second floor where there is a huge master hall/library attached to the master bedroom. Currently this master hall is largly unused and just has my computer table. I wanted to add partition walls and make a part of it into an office space/bedroom. I have pulled a permit and the only thing I require it for is the electrical.

Follow up question:
If I do attach the top plate to the joists, will 16d nails be long enough?
The top plate is 1 1/2", then there is drywall and furring strips (adding another 1 1/2") and then we get to the joists. If I miss the furring strips, the 16d nail will just be going through drywall and will probably be short of the joist, right?

-adil

 

[ront02769]

A 16p nail is 3 1/2" long. If you are running parallel to the firring, and not directly under a strip, that size would be way more than enough to hit the joist. Also, how many are you planning to put in? Remember that those fasteners are NOT DOING ANYTHING but keeping the top of the wall from moving sidewards. One nail/screw per jpist bay would be more than enough. Ron

 

[MushCreek]

1-1/2 (plate) + 1/2" (drywall) + 1-1/2" = 3-1/2". How is that nail going to reach the joist? If you can't hit a firring strip, use long screws. Don't drive them too hard or you'll warp the drywall over the air gap. If you can reach it from the attic, it would be better to put blocking where you fasten the top plate. Just shove some 2X in there. If you can line up with a firring strip, that will be plenty to nail to.

 

[ChuckF.]

Don't pound in nails if you can use screws because screws will be less likely to crack the sheetrock joints in the ceiling. Ditto on the bottom. Don't try to make the new wall too tight to the ceiling with wedge shims, just lay them in loosely and put a screw through them. You don't want to put any upward force on the ceiling because it's easy to upset the levelness of the ceiling and start cracking and popping of nails/screwholes that way. You also don't want to pull down on the ceiling.

On the floor don't try to set the wall on carpet. Solid hardwood floor ok, laminates or tile iffy. Down to floor plywood best.

You also should try to place the wall if/where it butts into another wall on a stud in the old wall, so you have something secure to screw to there.

 

[ront02769]

I believe that the op meant drywall PLUS firring strips add another inch and a half. But anyway, plate = 1 1/2", drywall = 1/2", standard firring = 3/4", getting us to 2 3/4" leaving 3/4" penetration into the jpist for a 16p nail.....but that said, my recommendation was to be sure to hit the firring strips. Ron

 

[MushCreek]

OP did say that firring strips were 2X4's. I used 2X4's in my house for firring, because they were cheaper and straighter than 1X's.

 

[ront02769]

Two bye less expensive than one bye? Must be a local thing. Around here a two bye four bye eight is about $2.50 at lowes. While for around $2.90 you get a 16' one bye firring strip (all we use). As to straightness, you snap a line, start at an end and work your way down, easy since the one bye bends so much easier. And I used the big box pricing because I just bought from there last week since that is wher local habitat has an account that we use for small jobs, e.g. Ten of these, ,six of those, box of deck screws, couple of outlet boxes and a new sink washer. Ron

 

[MT Stringer]

I didn't read all of the replies, but I do have my 2 cents to add.

Many years ago, I closed in a section across the rear of my garage to make a laundry room and a store room. I built the wall on the floor and then raised it as one unit. I had a little help doing that. In order for the wall to be raised to vertical, I built the wall a little short so the top plate wouldn't bind against the ceiling when it was raised. Then I used spacers (1x material) to fit in between the top plate and the existing drywall. Screwed and tatooed and it was a done deal.

If I remember correctly, I cut out the sheetrock and installed a couple of supports between the outside wall studs so I would have something to nail the wall stud to. Then covered it with a drywall patch.

Thirty years later, it is still intact! :smile:

 

[ront02769]

A good plan MT. Many people have zero idea about what is needed to hold a non-bearing wall up and in place. They assume that it prone to racking, twisting,, and all other manner of awful things...just as if it had the pressure of the structure on top being transmitted down. Whereas the pressure exerted on the top of the wall is zero...while the pressure on the bottom plate is just the weight of the wall itself. While I'm not saying that a nail at each end and every four feet or so top and bottom is all that is needed (although it probably is), it is clearly not a couple of 16p nails blasted into every bay. Ron

 

[adilj]

Thanks, everyone. I was careful to hit the firring strips and the wall is up. Now on to electrical and then drywall.

-adil