AVS Forum banner
Status
Not open for further replies.
1 - 15 of 15 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter · #1 ·
A quick question about the best way to put the layers of plywood and roofing felt together. Are they simply glued? What is the best glue to use? Is it better to put the 2 layers together first before attaching to the frame or attach each sheet of plywood separately? I do plan to glue and screw to the frame as has been recommended many times. Thanks for all the help in this forum. What a great resource for newbies like me.:)
 

·
Registered
Joined
·
9,196 Posts
Glue the first layer of plywood down with sub floor adhesive. Additional layers of felt and plywood are simply stapled (felt) and screwed. The felt conforms to gaps and thus negates the need to glue the sheets together. Plus it absorbs minor vibrations.
 

·
Registered
Joined
·
3,639 Posts
I would think that if you are putting roofing felt between the layers, then glue isn't needed. Roofing felt is not that strong and would seperate easily if the 2 layers plywood were ever seperated. Just placing it between the plywood layers might absorb a little sound (probably upper frequencies) but would help against floor squeaks. I put roofing felt under the riser and none in the riser. I built the riser frame glued and screwed and just resting on top of the felt. Then glued the first layer down with only a few screws. I then glued the second layer over that with screws that went through both layers and into the framing. The glue I used was Liquid Nails subflooring glue.
 

·
Registered
Joined
·
219 Posts
How timely....as this is how I spent the past weekend. I have a question...I have the first riser done using the method above mentioned by Toxarch. I'm doing a second riser also. Does this second riser need to be attached to the first riser? And if so, what's the best method of doing so? I was thinking about just taking some angle iron pieces and going around the perimeter from within the frame. The second riser is 19'6" wide and 8'7" deep and 8" in height. Would attaching just the frame perimeter be ok or do I need to attach each joist to the lower riser?


Thanks,

Robert
 

·
Registered
Joined
·
483 Posts
I glued my first sheet down, and then used roof felt in-between. I used the Deck-mate screws to attach the plywood. I only used two thicknesses of 3/4" flooring plywood for my seating risers. IMHO, no need for a separate piece of 1/2" in-between the two 3/4".


It is a two level riser that has one Buttkicker2 each bolted to each level. In the interests of maximising the power of both Buttkicker's, I use 4 carriage bolts and washers evenly spaced (with nylok nuts to stop them coming undone) to bolt the two risers together. It works like a charm!!! No squeaks and rattles.
 

·
Registered
Joined
·
3,639 Posts
Robmark, I'm not quite understanding what you want to know and what you are planning. Do the 2 risers need to be attached to each other? I would say no but if they are not attached, be sure they aren't going to rub or rattle from walking on them or from LFEs. Also, are you using tactile transducers in the riser? Some people like seperate transducers for each row which can mean seperate risers. I framed both levels at the same time and then covered it with two layers of 1/2" CDX. If you are going to attach them together, then I would just glue it and use something like 3 inch decking screws. No need for angle iron inside.


And that last question you'll have to explain to me what you are asking.
 

·
Registered
Joined
·
219 Posts
Tox, et. al,


I have one level that is 19'6W x 14'L x 8"H framed w/2x8s. That riser has the 3/4"-1/2"-3/4" plywood sandwich, glued at the first layer, roof felt between subsequent layers and then screwed down.


The second riser sits on the back portion of the first riser, 19'6W x 7'8"L x 8"H, also framed w/2x8s. It will have the same plywood sandwich as the lower riser.


My question is: does the second level riser framing need to be secured to the deck of the lower riser and if so, what's the best way to do this? I will not be using any transducers.


Thanks,

Robert
 

·
Registered
Joined
·
3,639 Posts
Ah, I was thinking you had two risers both sitting on the floor next to each other, but you have one riser on a bigger one. I almost did the same thing but figured it would be easier and cheaper to frame both levels together and cover both at the same time.


Does it need to be secured? No, I wouldn't think it needed to be other than to prevent squeaks from wood rubbing or if the framing was a little off. But I would attach it to the lower riser if it were me. Then you never have to worry about it moving or squeaking. Best way to attach them together would be glue and then toeing in some 3" decking screws from the inside of the frame or wherever possible. It won't move much anyway once all that wood is on it and the seats are there. Plus that riser is a beast with 2x8 framing and 2 inches of wood on top. Mine's framed with 2x6s with an inch of plywood on top and it's not going anywhere.
 

·
Registered
Joined
·
483 Posts
I would also be connecting the two risers together, but I fail to see why you would build one riser, cover it with your three level ply/felt sandwich, then build another riser to place on top of that again? As Toxarch suggested, building two risers and then attaching them together would seem to be the more cost-effective and time-efficient method to use.


That's what I did and it worked out perfectly. I used 2x4's for the first and then 2x12's for the second. You also want to consider with using your method, that your second level of seating will now be 19" off the floor (plus another 1" for carpet) - is your screen going to be high enough in order that your second row occupants will not get sore necks looking 'down' to the screen?


And do you have enough headroom to accommodate the tallest person on the second row?


Cheers,
 

·
Registered
Joined
·
3,639 Posts
I actually built one big frame for the whole thing instead of two. It took a little more planning, but worked out great.


Also, my back row is 28 inches off the ground. My screen is around 34 inches off the ground (12 foot ceilings). We don't have any problems with watching from the back row even though seated eye level is right around even with the center of the screen. Many guests prefer the back row over the front and middle rows. I haven't figured out why yet, but I don't argue either.
 

·
Registered
Joined
·
219 Posts
I'm working off a DE plan and get very worried anytime I think about deviating from it. :)


The plan calls for the entire lower riser to be decked, thus creating a height of 9.5". The second riser goes on top of the back portion of the first riser, again with a height of 9.5". The ceiling height is 9'. The soffit height at the rear of the theater is 8.75"...so with carpet, I'd be at about 6.5" when directly under the soffit.


What you guys are saying is to not put any decking over the lower riser where the second riser goes...correct? I would pick up about 1.5".


When you do it this way, should the second level riser framing match up exactly with the first level? I know the perimeter framing would all of course match, but should I line up each joist? Would you only use roofing felt between the framing lumber or would you skip the felt and use glue between every board that comes into contact with another board?


Thanks,

Robert
 

·
Registered
Joined
·
3,639 Posts
If it's already done, then leave all the decking on the first riser and build from there. If the first riser is not decked yet, leave the decking off where the second riser frame goes and frame the second riser onto the back of the first riser. Your first riser frame would need to be 7.5" tall and your second riser frame would need to be 9.5" tall.


First riser = 9.5" high - 2" decking = 7.5" tall frame

Second riser = 2 x 9.5" = 19" high - 2" decking - 7.5" for first riser frame = 9.5" tall riser frame


It may have to change depending on how thick your carpet is and how exact you want it to be.


Your vertical studs should be lined up with the first riser frame and you could also line up the joist the same way since there is probably not a support across the center of the first riser. I would glue and screw the whole thing. Use the roofing felt between the decking layers like you planned originally.


I would frame both layers first and then deck the whole thing. That way you are not wasting wood by putting decking under the second riser.
 

·
Registered
Joined
·
219 Posts
Tox,


I've already got the 2x8s cut for the second riser. I was thinking about just sacrificing the 1.5". That would give me a bit more headroom on the back wall area. The deck is not on the first riser yet. In your version, I would need 2x10s for the second level in order to stay at the same height. I don't think Dennis would have a problem with the 1.5" lower second riser.


Robert
 

·
Registered
Joined
·
3,639 Posts
Oh, if you are just laying the 2x8 on their side to get the height, then make the joist run the opposite direction. In other words, if the 1st set of joists run front to back, make the second layer joists run side to side.
 
1 - 15 of 15 Posts
Status
Not open for further replies.
Top