# Question DIY Riser, U-Boats & Carpet



## scottieGGGG (Nov 17, 2010)

Hello to all,

New to the forum, and have found some great information here. I've searched for this everywhere and cannot find anything concerning my issue. I feel that I must be missing something!!

I'm doing a basement HT setup. I planning to lay down some DRI-core sub-flooring as well as build a riser for my back row seating. When those are completed, I plan to have carpet installed.

Originally planed to build in the riser, but I've now heard about floating risers and discovered Auralex U-Boat Floor Floaters. I'm considering these between my riser and my sub-floor. However, I wondering about the gap (1/2" thick) that will occur between the riser and the DRI-core sub-flooring. Of course this gap is a good thing, as it leads to the "floating" riser. But what's the best way to carpet after the riser is in place?

Do I just terminate the carpet immediately in front of the riser? Wouldn't the gap be seen, and perhaps even a few of the U Boats installed around the perimeter of the riser?

Do I waterfall over the whole setup, similar to a staircase? While I never done the waterfall install myself, I would expect some wedging into where the riser meets the floor. Wouldn't the 1/2" gap make that difficult, if not visible, post install?

Riser is expected to reach the back wall and go edge to edge, so I need worry about the sides of the riser.

I certainly don't expect to carpet the entire floor (beneath riser), then carpet the riser by itself, and then place the riser on top of the carpeted floor. Seems like the U Boats are intended to work between riser and sub-floor.

I feel like I'm missing an obvious solution? Or I'm not realizing that it will all just work out (i.e. the gap is not that big and it's not noticeable).

Thanks for any feedback, suggestions, or photos.

Scott


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## bpape (Sep 14, 2006)

Welcome to the Shack Scott.

For the perimeter U-Boats, you can cut off one side and use a screw into the inner portion of the riser frame to mitigate that problem. 

What I've seen some people do is just do the riser as you normally would - then add another board around the perimeter that's slightly wider so it comes down almost to the floor with that small gap. This maintains isolation between subfloor and riser (which honestly, IMO, isn't necessary when you're already floating a floor. 

Personally, I would use the Dri-Cor, then just build the riser right on top of it but not connect it to the walls. That's where you want to help with isolation a bit. Just a small gap is all that's needed around the perimeter to the wall. The baseboard will cover it with no problem.

Bryan


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## jhbrandt (Oct 28, 2009)

Scott,

Agreed.:T Be careful upon building your riser that you do not build a resonant structure. Apply appropriate damping material internally and brace any panels so that they are rigid and do not 'bonk' when knocked on. 

Cheers,
John


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## scottieGGGG (Nov 17, 2010)

Thanks John and Bryan for you thoughts,

The belief that the use of DRI-core is already "floating" the floor, also made me wonder if the U-Boats are necessary. I might just skip them altogether. I've sent an email to manufacturer, but haven't heard from them in days.... which kinda soured me a little.

As for damping, I've heard that you can put some rolled insulation inside the riser. I've heard that even rolls of R-13 is enough, which is what I plan to do. (quick, cheap, easily available) Any thoughts?

Thanks

Scott


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## bpape (Sep 14, 2006)

Fluffy insulation is fine. All we're looking to do is damp the cavity. I would recommend thicker though depending on riser height. No need to cram it in, just fill it. 

If you want it to do double duty, you can carve out larger holes in the face of the riser opening up the joist cavities so that it also acts as a broadband bass absorber. Carpet will go right over it but the bass will pass through like the carpet isn't even there.

Bryan


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## grinthock (Dec 17, 2010)

Scott;

Glad I came across your thread, as it seems you are doing exactly what I am planning as well.

My plan was two (or three) large chairs in front and a couch in the rear, on a riser, I am also building my floor using Dri-Core.

So were you planning to secure the riser to the floor or have it just sit on the floor as basically a carpeted box with insulation inside.


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## MatrixDweller (Jul 24, 2007)

You should be framing on top of the dricore for the best effect. That being said the riser should go on top of the Dricore. You could carpet the whole room and under the riser. You would then wrap the riser in carpet and "float" it on top of the floor. That would be the easiest way to carpet, but would use a bit more of it.

The other option would be to fix the riser to the Dricore and carpet over and around it. If you haven't done carpeting before you might want a pro to do it. It would be worth the couple hundred to install because a small mistake in measuring could cost you a bundle in carpet. I don't think U-Boats would do a whole lot since the dricore is already doing similar.

Remember to stuff your riser with insulation so that it doesn't resonate. It will also make it sound really solid.

Another alternative to dricore is Delta FL. You lay it down first and it's like the plastic side of dricore. You then put OSB or plywood on top and in some cases the flooring can go right on top of it. It's a bit cheaper and accomplishes the same task.


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