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What is the best method for framing this uneven basement wall

What is the best method for framing this uneven basement wall


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Old 09-25-12, 08:46 PM
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What is the best method for framing this uneven basement wall

Hello everyone. Just bought a house and am already looking to turn the completely unfinished basement into a small work/shop area. I'm trying my hand for the first time at framing a wall and think I understand the basics.

One of the walls that I need to frame has a bunch of obstructions that I think make it a real pain to add a conventional top plate on the bottom of the floor joists.

I've attached a picture and hope that you guys can offer some suggestions as to how to deal mostly with the plumbing hanging below the joists and in close proximity to the wall. Because the AC duct extends all the way down this wall I am absolutely planning on installing a soffit around the AC vents so I'm not too concerned if the top of the framed wall actually meets the bottom of the floor joists (if that makes sense).

Additionally - should I pull the 2x4 frame away from the wall to completely cover the 4" PVC (it's sticking about 5" away from the wall) - or should I just use 2x6 top and bottom plates and then 2x4's mounted at the edge of the framing?

 
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Old 09-25-12, 09:31 PM
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Welcome! I'll try to give you a decent answer since this is your first question. LOL

It's a tough one.

I think I would opt to just use 2x6's for that whole wall (treated wood against the floor). Space them away from the wall 1/2" - 1" or so, since untreated wood should not contact concrete. Put the top plate a couple inches above the bottom of the ductwork. To hold the wall plumb, nail or screw treated 2x4's (14 1/2" long) to the wall between your studs right below the top plate. Nail another 2x4 on top of that if needed. Then plumb your wall and shoot each stud to the blocking. Do this to each stud bay. This creates a continuous fire stop behind the wall. Attach the sole plate to the floor. Notch your top plate tightly around the waste pipes since they should also be sealed with fire rated foam before you drywall. Any plumbing cleanouts must remain accessible so you may have to extend them to/through the surface of the new wall, or just plan to build a cabinet door in front of them.

Nail a ledger across the front of that wall near the top... bottom of the ledger should be at least 2" below the ductwork. Then build the front of your soffit- attach a top plate to the bottom of the joists in front of the ductwork, the bottom of that soffit face framing will be level with the bottom of your wall ledger. Then frame in the bottom of the soffit with 2x4's laid flat, assuming this is a very short length not much wider than the ductwork. This allows 1/2" of space between the framing and the duct. Do not place framing in contact with the duct or it will make noise. Also do not attach anything to the ductwork except for a register extension. (frame a box around the register extension so that the register will have something solid to screw to.)

I suppose you could use 2x4 walls and a 2x6 for the top plate, if you can angle some nails down through the top plate into your PT blocking that you have attached to the wall. IMO it would jsut be easier to frame and would be stronger and straighter if you just use 2x6 for the whole wall. Remember to use ACQ rated fasteners for any nailing that is in pressure treated wood.
 
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Old 09-25-12, 09:41 PM
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Thanks for the prompt reply XSleeper.

I have a few questions to help me clarify better about what you're describing.

1. Are you suggesting the whole framed portion of the wall be 2x6 including the studs? Or are you saying the top and bottom plate should be 2x6 and that I should nail 2x4 "rails" to the wall that the 2x4 studs will mount up against?

2. Am I even attaching the top plate to anything or just leaving it to float freely? Perhaps I don't really understand the concept of a firestop.
 
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Old 09-25-12, 09:51 PM
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Yes, I'd frame the whole wall with 2x6 studs. (sorry I edited and clarified that a couple minutes ago). If you used 2x6 as top and bottom plates and spaced them 1" away, then used 2x4 studs, the studs would end up being 3" away from the concrete, and you couldn't nail the wall to your blocking through the studs even if you doubled it up. You'd need 3 pc of blocking which is a little crazy.

And yes, the wall will just go up about 7 feet and end. The pressure treated blocking you install onto the wall will butt right up under your top plate... filling in the 1" gap behind the wall, and give you something to nail the wall to.

Fire stops are needed to prevent a fire from spreading quickly through a home. Imagine your wall is spaced 1" away from the wall, and a fire breaks out within the wall, behind the drywall... maybe due to an electrical short. With no fire stop, the fire would go straight up that 1" gap and up into your floor joists, and travel down the floor joists, spreading quickly. The blocking on the wall does two things. One, it gives you something to nail the wall to so that the top is secure and plumb. Two, it blocks the 1" gap behind the wall so that if there is a fire inside the wall, it would need to either burn through the top plate, or the fire stop in order to spread further, giving firefighters a few extra minutes to get to your home before it's completely burnt down.

Fire stops are hard to understand, as far as when and where they are needed, but usually the inspector (on new homes he comes through before any drywall is hung) is kind enough to point them out, maybe teach you a little something, and then you have to fix everything he's pointed out before he gives the go ahead to insulate and drywall.

I'm not real clear on the requirements for fire stops around ductwork inside a long soffit. I will see what I can find on that. Maybe someone else will chime in later tonight or tomorrow.

Edit: I think in all cases, the ceiling above/around the ductwork must be covered in drywall prior to framing the soffit. This closes the lid on the entire soffit. Batt insulation may be another option. (IRC 302.11.1)

See the following document for a couple illustrations. Page 5, fig 5, 6

Keep in mind that not ALL areas enforce these code requirements. If there is any doubt, check with your local building inspectors.
 

Last edited by XSleeper; 09-25-12 at 10:14 PM.
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Old 09-25-12, 10:48 PM
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the 2x4's (14-1/2" long) that you're recommending nailing to the wall and then hold the studs in place - are those placed vertical or horizontal?

I've seen some instances where people mounted there blocking vertically - but that doesn't really act as a "Firestop"...

You also mention in the 2nd answer "And yes, the wall will just go up about 7 feet and end. The pressure treated blocking you install onto the wall will butt right up under your top plate... filling in the 1" gap behind the wall, and give you something to nail the wall to."

Are you suggesting that I build the wall on the floor first (as opposed to constructing "in position")?
 
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Old 09-26-12, 05:23 AM
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Horizontal. The space between studs that are 16" on center is 14 1/2".

You "could" build the wall on the floor first, or at least parts of it. You'd then stand it up, align the front edge along a chalk line that you've snapped on the floor, then shoot/screw the sole plate to the floor. You'd then probably plumb each end of the wall you built and shoot/screw some of the horizontal blocking to the wall (directly under the top plate, which is also horizontal), then attach the wall to the blocking. Once the ends are plumb, you could probably install blocking in the middle next to ensure the center isn't bowed. Then complete the blocking by installing some horizontal blocking in every stud bay.

But you certainly don't HAVE to build the wall on the floor first. If you think it's easier to build it in place, go right ahead.
 
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Old 09-27-12, 09:57 AM
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FWIW I had a similarly challenging wall in my basement. I've not read the other posts in this thread, but what the contractor ended up doing was, since he had to soffit around the air vents anyway, he ended up connecting the front of the wall to the back of the soffit vent.

I'd try and encompass that sewer line in the wall to avoid losing too much wall space.
 
 

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