how to make attic floor usable storage space?

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Old 02-09-09, 12:10 PM
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how to make attic floor usable storage space?

my addition was built with 2x4 trusses. I wanted to know what best way to make part of it usable for storage. Since I will need R38 (I think), the insulation will stick way above the top of the 2x4 trusses. So I can't just put plywood over the trusses. Should I use 2x8 on top of the trusses, let them insulate, then put plywood on top of the 2x8? If so, do I just use some nailing plates (and of course some 2x8 going across the bays) to hold the 2x8 in place until they insulate and the plywood will really hold every thing together one finished. I would plan so that no electrical wires run under this plywood.

Is there a way to insulate up high (like you would do in a vaulted ceiling) when trusses are used? Didn't know how to support the insulation? In my garage, I already have some plywood on the trusses, but the garage is going to be insulated as I will have a propane garage heater in there. I sure hate to give up all that usable space, but didn't know if it was possible to somehow keep insulation high? How would you support it? the trusses are 24" OC. Could you just nail a "nailer" to the sides of all the trusses up high (but leaving at least enough space between the nailer and roof to fit insulation) and then just use those to staple the insulation to?
 
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Old 02-09-09, 03:12 PM
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You can sometimes sister 2x8's to a truss support, but there are right and wrong ways to do it. The wrong way could be disastrous, depending on the weight you intend to put up there. Adding the 2x8 space allows you to insulate where insulation belongs, then add a floor for storage. This is not recommended without consulting someone that knows of such things.

Insulating the rafter space rarely works well.
 
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Old 02-10-09, 04:46 AM
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Are they truss's or are the floor joists and rafter seperate? B/c truss's are only made to hold so much weight. So make sure you check that out. Also you could put down cellulose in between the 2x4's and then put dow blueboard ins. then plywood on top of that. GOOD LUCK
 
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Old 02-10-09, 08:41 AM
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they are trusses. I don't plan on putting a lot of weight. just bulky items. christmas tree. coolers, etc. what is dow blueboard? would the combo of cellulose and blue board meet code of R38?
 
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Old 02-10-09, 09:20 AM
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This is the DOW blueboard insulation. Dow at Lowe's: 1/2" x 4' x 8' RS Styrofoam

THis is for a 1/2" thick piece and its only an R-3. They make it up to 3" if I recall and it is sold at my local Lowes. That is like R-9.
When you say you wanna add 2x8's to the trusses, you going to install them on top of the joist part of the truss correct? If so that should work. There are braces/straps/ties that you can buy the will hold them on. I have done this before on walls at a friends house to give him more room for insulation for a higher R value. Worked great.

But this is a little different. You will need a heck of a lot of cellulose for R-38. You will get 16.6 sq ft a bag if you install it to R-38 which is 11.7 inches thick and after it settles will be 10.5 inches. Says if you have 1000 square feet to install you'll need 60 bags. This is based on a 2x6 16 oc spacing I went through about 60 bags to do my walls in my house and my attic. But its well worth it!! This stuff is better than fiberglass. Once settled it has less area for air leak than fiberglass.

SOURCE: GreenFiber.com || How to Install : Step One

Hope this helps ya out. I am no contractor, just so ya know. I have experience only.
Chris
 
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