Building a couch riser (1 Viewer)

[James Gurney]

Hi folks, I'm planning to build a riser for my rear row of seating, and I'm looking for suggestions. A few searches seem to indicate several people have built risers, but I wasn't able to find specifics.

Anyway, the idea I have in my head is to use 2x10 topped with 3/4" ply. The 2x10 would run all around the outside, and also cross brace about every 18", so the frame will look kind of like this from above: (some imagination required):


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I'm a little worried that a fully loaded couch could have as much as 600lbs of people sitting on it. Is 3/4" ply sufficient to support that much weight? The couch has 4 feet, each of which would not have direct support from the 2x10 underneath.

To address this, I was thinking I might add 2x4 bracing as well, so it would look something like this :


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Is this overkill? I worry that maybe I'm overdoing things a bit and it's going to end up weighing so much it's impossible to move it into the basement (the basement is finished, so I don't want to build it down there).

Also, since I plan to cover it with carpet, I'd like to route the corners to get a nice smooth turn, which will prevent the carpet from looking nasty as it turns to go down the side. The problem is, you can't really route plywood, so I'm thinking of somehow working an inch or so of mdf into the top corner, so I can easily mould it. Anyone have any comments on that idea?

Thanks in advance,

James

 

[Jay Mitchosky]

Traditional framing is based on studs mounted 16" on center. Generally it is recommended that theater risers (and stages for that matter) are framed at 12" on center. 18" is too wide, and you certainly don't need to crisscross. I would suggest you glue and screw end to end.

For the deck standard practice is not one but THREE layers of plywood. First 3/4", then 1/2", then another 3/4". Each layer offsets the seams of the one below. You also sandwich a layer of 15 or 30 pound roofing felt between the layers so they don't creak when walked on. Everything is screwed down tight. Here's what it looks like when complete (the edges have been rounded over with a 1/2" router bit in preparation for carpet). You can view stages of construction on my site.

 

[Jimi C]

It will be enough. We have 1/2in plywood on a 10 ft high steel shelf at work with bracing every 18inches and it is holding thousands of pounds of merchandise and not bowing, bending or sagging at all. Not to mention the weight will be well distributed because of the sofa. Personally, i think your plan is overkill if anything.

 

[James Gurney]

Jimi - the couch actually has 4 feet, so the weight isn't evenly distributed.

Thanks for the info Jay. Your HT looks fantastic! It's interesting that you were able to succesfully round the plywood fairly easily by the look of it. I expected it would splinter more than that.. so at least I don't need to worry using mdf for the corners.

3 layers of plywood seems an awful lot. Is this to a specific building code? With studs every 12", I would have thought a single 3/4" sheet would be sufficient. The riser I'm building will be 6' x 4'8", so there will be only one seem in the ply.. As I said before, this is a finished basement, so I'm planning to build in the garage and then bring it down the stairs. I'm a little worried about it ending up weighing too much to move..

 

[Jay Mitchosky]

Good luck. That will be a big challenge because of the weight and the awkward size. If you're worried about dust I feel your pain. Which is why I had Home Depot cut everything for me. Then it was a matter of putting it together. Drilling only left no dust. Particularly for the deck sections where they have a nice panel cutter (unless you already have a table saw). Regardless, your time is valuable and unless you have the proper equipment it's very convenient for your lumber provider to cut for you. Just triple check your measurements first!

 

[James Gurney]

Hm, hadn't actually planned to have any overhang - I was thinking of making it come right up to the edge. Although, doing it this way, I can make sure the 2x10 at the edge is directly under the legs of the couch.. to be absolutely certain of the support.

As far as constructing it, the local Home Depot does indeed have a panel cutter, so I can have them do most of the cutting. I do have enough tools to do it myself if needed. I guess the thing to do would be to prepare it in the garage, and then assemble it in the basement.

Actually, another question arises - where did you find the insulation you used? Is that a standard type I can also pick up at the Home Depot?

 

[Jay Mitchosky]

HD. Everything HD. I used basic insulation specified for inner walls and sound transmission. I think I went through 2 1/2 bags for the stage, riser, and counter. Get some paper masks and work gloves as well for working with it.

 

[Andrew Stoakley]

I guess that depends on where your riser is going to be. I have a riser that is built directly into the back of the home theatre and I didn't bother overhanging the edges and with the comments I've received from people on the theatre, I'm happy with my decision . I was more afraid of people tripping on the lip and then smashing into my subwoofer :frowning:. Anyway, Build you riser in the room that you are working in. Cut your lumber in the garage and assemble it in the final area. I used the standard wall practice for the riser with studs 16" on centre. 2x6's for the framing, and two layers of 3/4" construction grade plywood. The construction grade is a little cheaper here in Toronto and with the rough side down on the framing wall, the adhesive really sticks nicely! I filled the cavities with Roxul's Safe and Sound batting and screwed down the top layers with 2 1/2" decking screws. The riser is 9x5 and has a 3 person leather couch on top. Nothing moves, nothing shakes and nothing creaks when there are three people up there watching a flick.

Check out my pics to have a look.

Cheers,
Andrew

 

[Jay Mitchosky]

But if there are ropelights to illuminate the edge you wouldn't have to worry about it.

And don't forget steps as well depending on the height of your riser. Use the stairs in your house as a reference.

 

[James Gurney]

Well I'm convinced.. I like the rope light idea, and I've got to admit, the overhang looks good. I've drawn up new plans and I'll head out to the HD soon to buy lumber. Thanks for all the advice

 

[Travis_R]

Take it from a carpenter, 2x10 with 12 inch spacing and 1 sheet of 3/4 inch plywood is more than enough, honestly in my opinion anything more than that is overkill, you could go 18 inch spacing and be fine, it will never sag, think about it, does your couch go through the floor in your house, thats just 3/4 or 5/8 on more than likely 18 inch spacing or close to it depending on code in your area and builders preference. Plywood routes just as easily as any other wood but like jimi said it will splinter a bit on the corners but nothing you cant pull off with your bare fingers, this is what I am going to do, 3/4 inch plywood on 2x10's with 16 inch spacing, put liquid nailes on top of the 2x10's before you lay plywood down so they will be glued and screwed, "in all reality when liquid nails dries it is stronger than the wood itself" so no squeaks, the overhang for rope light only has to be a bit bigger than the rope light diameter itself which is about a half inch if I remember right, so make the overhang about 3/4 of an inch, then you put a piece of trim on the edge "front" of the plywood, so basically the top of the trim is even with the top of the plywood but hangs down to hide the rope light, with only 3/4 of an inch hangin over it wont get worn down, you may even want to think about buying some cheap metal handles and you can place them on the sides or inside the 2x10's from underneath on the inside that is, so you have a good hand hold whenever you want to move it, oh yeah and the 2x10 on each end of the riser, make them 3/4 inch longer than your inside ones, or whatever the size of your overhang is make them that much longer, basically so the end of those 2 is even with the front of the plywood, that way you cant see the end of the overhang of the plywood, makes it easier to trim out too

 

[Scott Tucker]

I just finished mine. I used 2x12's on 12" centers and one sheet of 3/4" plywood. I screwed it together with 3" screws. Filled with fiberglass insulation. This thing is rock solid with no squeaks. I would definately assemble it at the final location. Make sure 2x10's are enough. The job is no harder with 2x12's.

Scott

 

[Larry Chanin]

Hi James,

Dennis Erskine, a highly regarded home theater designer, had an article in Home Theater Builder Magazine in which he recommended construction as described by Jay. I used a similar design for my stage.

However, Mr. Erskine's article had an alternate design for those folks who plan on installing tactile tranducers in the platform where the intent is for the platform to move, but not rattle or resonate. For this application he recommended joist spacings of one foot with a 3/4 " plywood deck. He also recommended making the outside perimeter two inches deeper than the joists.

For my seating platform with tranducers I followed Mr. Erskine's recommendations, but instead of a single layer of 3/4" plywood I used two layers of 1/2". I used a 2" lip but instead of routing the edges I ripped closet hanger poles in half and glued them to the edges. Like Andrew and Scott I cut the lumber in my garage, drilled and screwed the platform together there, then disassembled it and reassembled it in my home theater. My room was already carpeted so this helped reduce the mess.

I thought I would mention the alternate design because now is the time to decide if tactile tranducers interest you versus retrofitting later. Whereas folks have installed transducers on more rigid platforms, it ends up inhibiting performance.

Good luck.

Larry

 

[James Gurney]

I ended up building it with just a single layer of 3/4" ply on 16" spacing. I did like the idea of the more solid construction, but it was getting very expensive/heavy, so I decided against it. You can see a photo of the result on my gallery page (riser.jpg). Since taking the photo, I've routed the edges, and all that remains is to cover with carpet and figure out some way to make sure the couch doesn't slide off the back

Thanks for all the advice.. Definitely some great tips in this thread for anyone else who might want to build something like this.