Sway Braces for a Basement Studio

Hey guys, long time lurker, first time poster. I'm building my basement studio with double wall construction, new joists run on top of my walls between the existing joists. After taking all of the measures to avoid contact points with my existing structure, the city is now making me attach my rooms to the house in at least in a few places. Figured my best bet would be sway braces attaching my walls to the concrete foundation walls. Is anyone familiar with the following products? Thoughts? Iso-Brace: http://www.acoustiguard.com/Default.asp ... ations.pdf Kinetics Uni-Brace L: http://www.kineticsnoise.ca/arch/unibrace.html The airspace between my walls and the concrete foundation wall is 3", and these sway braces only span about 1-2", so I guess I would need to extend the sway braces using a 2x4. Curious to hear advice. PS - if I were to do it again, I'd probably use plywood instead of drywall for the first layer to make the structure rigid. However, I already hauled all the drywall in through the basement window before I finished building the walls, now there's no way to get more drywall or plywood in or out.

Figured my best bet would be sway braces attaching my walls to the concrete foundation walls.

In addition to talking to those places, also call Mason Industries and talk to the guys there, to see what they recommend.

I already hauled all the drywall in through the basement window before I finished building the walls, now there's no way to get more drywall or plywood in or out.

... unless you take out the drywall first, and store it elsewhere while you do it it right! Also, OSB is a good alternative to plywood: might be cheaper, too. - Stuart -

Soundman2020 wrote:

unless you take out the drywall first, and store it elsewhere while you do it it right! Also, OSB is a good alternative to plywood: might be cheaper, too. - Stuart -

Thanks Stuart. Unfortunately it's too late to get any 4x8 sheets of anything in or out. The only way was through a window, which is now blocked by a nearby wall. Is it possible that 2 layers of 5/8" drywall would make the structure rigid enough to not need sway braces? Or does it have to be a layer of OSB / plywood to not need sway braces? The framing seems fairly sturdy already and I'll be running my door jambs and window sills straight through my double walls, which will help a bit with rigidity as well. What do you think? S.J.

Is it possible that 2 layers of 5/8" drywall would make the structure rigid enough to not need sway braces?

I wouldn't count on drywall for structural integrity. It's fragile and brittle, and not much good in sheer. Also, if your municipality is saying that you need sway braces, then you need them! Regardless of what someone might tell you on the internet, those are the guys who make the rules, and they do it for a reason: your own safety. So I would go with their recommendations.

Or does it have to be a layer of OSB / plywood to not need sway braces?

OSB or ply will only help with sheer, which are forces along the surface of the wall itself, trying to collapse it sideways. OSB and play don't to much for the other forces acting on the wall, that are trying to topple it over. That's what you need sway braces for. Unfortunately, you don't have a lot of choice here. Talk to some of those manufacturers, take their suggestions to the inspector, and see which one(s) he will approve. - Stuart -

Thanks Stuart, I've been doing a lot of investigating trying to find a sway brace that will work for my scenario. Unfortunately it seems most sway braces, including the Mason Industries WIC, are designed for max 1 1/2" air spaces, while the space between my concrete foundation and my wood framed wall is actually 3". The advice I'm getting from these companies is to just scab on another piece of 2x4 to reduce my airspace. Wouldn't this defeat the purpose of making my airspace 3" in the first place? Also it seems like adding on a scrap of 2x4 would weaken the structural integrity of the sway brace system. Maybe I'm wrong? It sounds like the closest thing is the Mason Industries DNSB. It can make the span of 3", and I could attach the bolt end via an angle bracket attached to the side of my stud. Unfortunately, it's hella expensive @ $30/each + shipping. Any thoughts? Or do you suggest I bite the bullet on the DNSB. One nice thing about it, is it's preloaded, so the wall load can vary. Also, it has a 10Hz resonant frequency. Just a lot of $ for a sway brace. Attached is a picture of the purposed placement for the sway braces (all about 1' from the top of the wall). I'm thinking I shouldn't need to add sway braces between the two walls on the right of the drawing, due to my joists bridging the support from the opposing braced walls, plus the many common connection points. But, let me know what you think. Thanks, S.J.

"is to just scab on another piece of 2x4 to reduce my airspace" You meant to say increase, not reduce correct?

xSpace wrote:

You meant to say increase, not reduce correct?

The suppliers I've been talking to have told me if the sway brace isn't long enough to span the 3" gap, to add a piece of 2x4 to reduce the space from 3" to 1 1/2". Then, the sway brace will reach. To me, this seems like a makeshift solution in an effort to sell me their sway braces. Or maybe this is how it's done? For example, how do people normally attach a WIC sway brace? The WIC is 1 1/2". Surely, not everybody's airspace is exactly 1 1/2". But, I have been unable to find any instructions online explaining how to attach it. On a related note, there's 1 screw hole on either side of the WIC brace. How do you possibly get a drill or screwdriver behind the stud to attach it to both the concrete and the back side of the stud? The DNSB could work by attaching a metal L bracket to the side of the stud, and putting the bolt end through the L. I was just hoping for something a little less expensive ($30 / each + shipping). Or is that my best option? Thoughts?

The reduction of the brace span, I get it, to increase the span of the brace with added material. Engineer double talk as far as I am concerned :) I'll get back with you in the AM or in a few hours...whichever works out for me in this respect :)

If Mason says you can use blocking to extend the reach of the braces, then that's the way to go! There isn't really any tension or pressure on them anyway, if you mount them correctly ... except maybe in a major earthquake! :) Mounting holes: Follow the manufacturer's instructions. You might need to bolt them through the stud on one side, rather than screw them, for example. - Stuart -

Soundman2020 wrote:

There isn't really any tension or pressure on them anyway, if you mount them correctly ... except maybe in a major earthquake! :)

And this is where the issue of proper connections matters. What are the potential events in the geographical area, is the structure able to support a proposed load if one of these events takes place, will the connection stay put, will the exterior structure stay put and prevent the collapse of the interior construction or will it be a contributing factor? Lot of things to consider and do right the first time :)