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Berkshire 09-17-2010 09:58 PM

Attic makeover
I'm looking at my currently unused attic in a wood frame 60 year-old home as a great space for additional storage closets for clothes and other items. The attic is currently poorly insulated with old fiberglass bats that are paper backed and look like they were installed in the 1950's. There are a few floorboards down the center but the rest of the floor is exposed joists and insulation. There is no insulation at all below the roof or on the walls. New roof with ridge-vent was recently installed and soffit ventilation is good. I live in Massachusetts so cold winters and a few hot summer days.

My idea is to floor over most of the attic with plywood and possibly carpet in the traffic areas, build a "box" with studs and wallboard within the space large enough to create my closets/storage area and leave the attic around the box unfinished. In the process I'd like to improve the energy efficiency of my attic to cut my heating costs.

My question is about insulation. Should I leave the old fiberglass bats in the floor undisturbed and just lay my floor over them? Should I invest in Prodex or similar foil faced polyethylene foam to apply under the roof joists and on the uninsulated exterior walls?

Any thoughts?:huh:

ogagnon 09-23-2010 11:15 PM

The insulation for your attic is in the floor? Thats ok as long as you aren't using the attic much, otherwise your house is going to become rather drafty, and heat loss is going to be an issue. As long as your insulation isn't interfering with any electrical (old wires), hasn't seen much moisture, and you don't think it'll bother future renovations, there shouldn't be a problem keeping it.

However! There's no way in hell I would keep it if it was in my home, I'll tell you why. When you want to remodel in the future, you want to pass wires, etc, even venting plumbing, insulation is a pain in the ass, and the old batts they used to use just fall apart and are really messy. Plus, when you rip out the old insulation you sometimes get surprises that you're glad you found, such as structural issues, dry rot, or messy electrical. I'm ripping apart my second floor in our country style home, knee walls with slanted ceilings. Given my insulation is stuck to the underside of the roof, I'm dealing with dry rot, mold and an unventilated ceiling, 60-70 years worth. I also found some really bad electrical work, so I'm glad I decided to rip it all out, or the place could have burned down.

Either case, that old crappy insulation you have has a low R-value, whereas the 5.5" "Roxul" I'm putting in my attic is rated at R-22... for about 75 cents a sq ft, I think it's worth it. It's mold resistant and I couldn't light it on fire with a torch. As a matter of fact, the sales rep kept a torch under it for 90 minutes and it still didn't light, lol.

I'm not trying to sell you a particular product, I'm just still amazed at this stuff. Also you mentioned trying to bring down the heating costs so I think this products fits your needs.

Since you have soffit intake ventilation, plain and simple: Get a very good exhaust vent at the top that is appropriate to the square footage, put in some baffles under the roof to allow proper air flow, insulate to at least R-20 (this can be done a variety of ways), polyethelyne moisture barrier, well taped off, forens, and drywall. I have the reflective vapour barriers in my garage and there was some on the second floor... I wasn't very impressed with it.

Some variables that will affect some steps are if you have a hip roof, the size of the rafters (2x6?).

Here's what I used:

Gary in WA 09-26-2010 11:24 AM

Will this room be heated and ventilated to counter mold?

If the storage space is 70 square feet or larger, it may have to meet the new Code for attics: floor live loads, egress (escape), etc., contact your Building Department for rules:


Berkshire 10-03-2010 07:11 PM

Attic makeover
Thanks for the god info guys.:thumbup:

Jim F 10-05-2010 05:19 PM

Storing stuff in an unheated space in the attic is a bad idea in the northern climate. The cold and warm cycles will result in water condensation on the items and mold. My wife went to retrieve her prized dolls that her idiot stepfather stored in the attic for her only to find that they turned black with mold.

ogagnon 10-05-2010 05:37 PM

The attic will definitely smell old and might smell a little humid, but as for actually having real moisture up there, that's not normal. With clear soffits and a good exhaust ventilator that aspirates the air, there's no way you should actually get condensation.


Originally Posted by Jim F (Post 512049)
Storing stuff in an unheated space in the attic is a bad idea in the northern climate. The cold and warm cycles will result in water condensation on the items and mold. My wife went to retrieve her prized dolls that her idiot stepfather stored in the attic for her only to find that they turned black with mold.

steveel 10-05-2010 05:52 PM

What I'd do is to write up your plan with pics and drawings and go talk to your building deptarment as Gary suggested. This is the plan I would run by them:

First keep the fiberglass. However, I'd go read up on "air sealing" and first crawl around diligently doing all those things, and then lay the fiberglass back down.

Next, I'd check for blocking foam on the outter top plates and insulation baffles around the perimeter.

Next, sounds like you have batts to the top of the joists. I could be mistaken but I don't think that's enough for you area. You might want to look into sistering the joists or adding some lumber on top of the joists to build up a higher floor surface. Then build a attic hatch cover with a box the height of the new joists, and then blow cellulose across the fiberglass. Don't forget about sealing and insulating any heat ducts up there. After the cellulose, THEN lay your new floor at the new higher level. Too bad about losing some headroom, if you need more insulation you need it.

To help protect stuff from extra hot temps you may want to look into a radiant barrier and an attic fan. Or not. I don't know anything about them, its just on my list to read about.

I agree that molding in the attic indicates a serious problem. I am working on my attic as store space for office files. They better not mold and if they do, so are the rafters. Ick.

Steve El

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