Soffit Help

**Bob_99** · **02-02-07, 02:32 PM**

I've been putting off

treating some odd dimension wall/corner areas behind my listening area and my choices are wedges 12" by 24" (along the straight edges) or a soffit 10" high by 12" wide. I'm leaning toward the soffit and was wondering if anyone had thoughts on how build one. Should I wrap the fiberglass (703) and then mount it or should I mount the fiberglass and then wrap everything (including the support) in cloth (which would probably look better). If I wrap the fiberglass, should I glue the cloth to it? And lastly, I would really appreciate it if anyone had any thoughts about different types of supports

. I searched the web but mostly found soffit information for roofs

.

Thanks.

Bob

**bpape** · **02-02-07, 02:54 PM**

Just build a standard wall - but make it really short - like the 10". Hang it from the ceiling. Build another from 2x2 to extend from the wall to the one you just hung. Lay the fiberglass in the bottom part of the wall before putting it up in place in sections. Cover the outside in cloth and trim the edges.

I do this all the time with people I design rooms for. Works great.

Bryan

**Bob_99** · **02-02-07, 03:04 PM**

Bryan,

Thank you for the really quick response. I thought of something like that but was concerned about the gap between the cloth and the fiberglass but from what you said, I guess that's not a concern. Is that correct?

One more thought, do you glue the fabric to the wooden frame?

Thank you again.

Bob

**LewisCobb** · **02-03-07, 09:02 AM**

Quote:

Bob_99 wrote:

Bryan,

Thank you for the really quick response. I thought of something like that but was concerned about the gap between the cloth and the fiberglass but from what you said, I guess that's not a concern. Is that correct?

One more thought, do you glue the fabric to the wooden frame?

Thank you again.

Bob

Hi Bob - I have been designing my home theater for about a year now off and on - drawing, revising, re-drawing etc. I am currently at the point of trying to figure out the soffit myself and have been scouring all over the home theater forums as a result. Here's what I have learned -

- As Bryan pointed out, the skeleton is made up of 2 "ladders" - usually of 2x2 . I have a problem with this and am trying to figure out a better way as 2x2's have always ended up warping on me on other projects I have been involved with where I tried to do "decorative" work with construction lumber. So the jury's still out on the material for me. I have seen them built with 2x4's but it looks a bit on the extreme side for holding some fiberglass insulation - it is however another option for material.

Once you have the 2 "ladders" fastened up - or before as Bryan has pointed out - place the insulation in laying on the horzontal ladder. Some have filled the soffit - some have only had one layer and a little vertical layer against the inside of the vertical ladder. Usually those fellows are using rigid insulation and then in the "cavity" behind, they are filling with fluffy insulation to prevent resonances.

Now the covering - usually I have seen people wrap the framework - no glue - with acoustically transparent fabric and staple it. If you do a search on the forums where fellows are building home theaters you will find a number of photo - examples of this. There's all sorts of tricks to get a nice even seam and hide the staples. That's the area I have been researching at the moment and still can't get my head around it 100% - My soffit is going to have a decorative wood bullnose type edge and that, plus the fact I want to make the fabric coverings removable (like panels themselves) is causing me some head-scratching.

If I come up with some links for you I'll drop back and post 'em up.

Hope this helps a bit.

Lewis

PS - Perhaps a bit overkill if you are just building one simple soffit, but you might want to check out google's free Sketchup program - it's been a real help to me to try and visualize things as I plan my theater. A lot of fellows are using it for the this purpose.

**bpape** · **02-03-07, 09:26 AM**

No need to glue the cloth, just stretch from wall, around the corner, to the ceiling and staple. A small pc of quarter round will cover it and provide a nice finished look.

The gap is not a problem. If you want to make use of that space too, then just use a couple of L brackets and cut additional pcs to fit.

Bryan

**Bob_99** · **02-03-07, 02:42 PM**

Bryan and Lewis

Thank you both for the information

and I'm on my way to build some soffits. I can see that my first challenge is to find a piece of lumber that's not S shaped. I guess they don't grow straight trees anymore

.

Bob

**basementjack** · **02-03-07, 03:20 PM**

Hey Bob,

If you're at home depot, they have the building lumber, including 2x2s (Which Are NEVER straight!)
the next isle over they have differnt types of lumber, and I've had good luck with the pine boards there - you can tell they are different in an instant - each has a label with a upc and description. the boards are clean cut with very sharp corners and are pretty much perfectly straight.

other home improvement stores have similar boards in shrink wrap.

also - if you are going to use regular lumber, you can use things like drywall corner bead to give the edge a clean sharp line to pull the fabric over.

**LewisCobb** · **02-03-07, 03:51 PM**

Jack - I literally just got back from HD where I saw some of these boards that you are talking about and I was thinking about this soffit build as I was looking them over. There's 2 versions that I saw -

1 - Shrink wrapped pine boards that are quite wide - maybe up to 18-24". They are laminated from smaller pieces and could be ripped to width nicely on a table saw.

2 - Some un-shrinked wrapped boards of 12" width x 8' long - same construction - imported from Brazil no less.

I didn't calculate the price of constrcting my soffit with this stuff but as I have been learning from reading the home theater construction forums, price is never a factor once you get going ....

Not to hi-jack this thread - but - I wonder if anyone has built a procenium arch with this sort of lumber as well? I'd like to see some pics if you fellows have any links.

Cheers,
Lewis

**Bob_99** · **02-03-07, 06:09 PM**

Thanks for the information Jack. I was at Home Depot but will also check out Lowe's. I still have to chuckle at what passes for a piece of wood.

Bob

**bpape** · **02-03-07, 09:57 PM**

That's why so many people are switching to metal studs. They're cheaper, straighter, etc. Personally, for soffits, it's easy enough to pick through some wood to find a few that you'll need for the bottom corner. Everything else is short pieces where you can work around the twists.

2x2's are the pits though. I find it easier to rip 3/4" MDF and glue it together to make what I need for those kinds of dimensions.

Bryan

**Bob_99** · **02-04-07, 07:14 AM**

Bryan,

If I may impose upon you one more time. When you build soffits covered with cloth, do you make them broad band or do you put anything over the fiberglass to reflect mids and highs? My soffits will be behind the listening area on the left and right sides, so my thoughts are that I can leave them broad band.

BTW That's a good thought about the mdf and I agree about the short pieces which eases the problem tremendously.

Thanks again.

Bob

**Bob_99** · **02-13-07, 03:01 PM**

Bryan,

I have gathered almost everything to put the soffit up and was wondering if I could bother you once again to answer my previous question. I was going to just put it up but decided that it would be better to know that I did correctly the first time rather than have to pull it apart and change it.

Thanks again for your time.

Bob

**bpape** · **02-13-07, 04:37 PM**

Sorry - missed it the first time around. Whether you bond an FSK scrim to it or not will depend on what else is done in the room and what is left to do. If you have a bunch of 1" on the walls, you'll likely be better putting scrim on the bottoms but leaving the sides unfaced.

Bryan

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