I've started constructing my riser for my rear seats. It is 10' wide x 5'4" deep. I'm using 2x10x10's and 3/4 plywood for the top. I decided not to add a step since it is less than 11" high and it would complicate things with the design and carpeting the step since this is really my first woodworking project. So it's basically just a simple rectangular box shape. I have a 2x10 brace every 16" off center. I'm putting it together with 3" screws. I wasn't thinking but I probably need to get 2" screws to secure the plywood to the 2x10's or would the 3" be ok? Probably just extreme.

Few questions:

1. Do I need to fill the cavities with insullation?

2. Any advice on how best to carpet it? Do I use staples or glue? The riser is against the back wall and the right wall. How do I make it look nice around the corners or at least the front left corner since this will be the only corner shown?

3. Any other things I need to consider?

Your framing should be 16 inches on center not 15 so that the edge of your plywood rests on a 2x10.

Any screw 1 3/4 or longer is fine for fastening the plywood. Fill it with the cheapest insulation you can find. Think about a double layer of plywood to make it quieter.

If you are going to carpet it you really should have a lip on all visible sides. Then the top carpet wraps around the lip and staples underneath where you don't see it. Then cut strips for the face and use carpet staples to hold in place. You need to plan for the lip in calculating 2x10 spacing or plan to add a lip by screwing a 2x2 to the edge of two layers of plywood. It will help if you round over the edges of the lip.

it will a big step off that thing and you may want to install a step light to avoid accidents in the dark. The step height is actually higher then code so let us hope none of your guests are lawyers and they break an ankle.

Your framing should be 16 inches on center not 15 so that the edge of your plywood rests on a 2x10.

If you are going to carpet it you really should have a lip on all visible sides. Then the top carpet wraps around the lip and staples underneath where you don't see it. Then cut strips for the face and use carpet staples to hold in place. You need to plan for the lip in calculating 2x10 spacing or plan to add a lip by screwing a 2x2 to the edge of two layers of plywood. It will help if you round over the edges of the lip.

it will a big step off that thing and you may want to install a step light to avoid accidents in the dark. The step height is actually higher then code so let us hope none of your guests are lawyers and they break an ankle.

Thx for the tips. Much appreciated. I goofed, they are 16" off center, not 15". I have a friend who's visiting this weekend that is good with stuff like this. He's going to help me finish it. I'll pass this info along to him.

A common suggestion is to make the top out of multiple layers of plywood. 3/4"-1/2"-3/4" in my case. You should leave a overhang although if you are covering it with carpet you really don't have to round over the edge. The carpeting pad and carpeting will roll over the edge nicely. The extra layers of plywood really stiffen it up nicely.

The length of the overhang varies.... some folks who want rope light underneath will make a longer overhang. In my case, I asked my carpeting guy what he wanted since he is installing it. Since I don't have any lights in mine, he said that a 1" overhang was enough.

Definitely fill the cavities loosely with insulation as recommended. There are other techniques for using the riser as a bass absorber/pressure reducer so if your interested in that you can do some more searching.