Insulation, Radiant and Vapor Barriers - Can I blow insulation under floor of walk-up attic?

The title explains it all. Can I blow insulation under floor of walk-up attic?

There is already radiation barrier insulation, but that's not efficient at all in winter.

The house was built in 1930, has a great walk-up attic with really challenging tongue-in-groove floorboards. Pulling up even a few of these boards will be hard.

I noticed the photos on this site and others show workers blowing insulation only atop open joists. Looks easy! But I cannot remove the whole floor; that job's too daunting.

My idea is to remove six boards close to the centre of the attic (where the stairwell allows easy access to the board ends.

Then, to stick a hose as far as possible to either side, and blow insulation, pulling the hose out slowly for even distribution. Problems with this are:

1. How long do the hoses come? Can they extend 12 feet to reach the far end of the floor?

2. I'm afraid the hose will become tangled with the bumpy plaster ceiling and wiring.

3. Insulation may not be evenly distributed and instead pile up and compact in one spot.

So, with these potential problems in mind:

1. Has anybody attempted to blow insulation into tight horizontal spaces?

2. Has anyone attempted to insulate beneath a walk-up attic floor in general?

3. Will my insulation under the floor in any way affect the radiation barrier on the ceiling?

This looks to be a fun project. No, seriously. I'm looking forward to finding a solution. :)

J

Hey folks, any experts on blown insulation in the workshop this week? Now there are two questions about blown insulation on this forum awaiting replies.

With Sincerity,

J

Well, I got my own answer from a co-worker. In his house, workers ripped up a floorboard every five feet and blew insulation underneath. He was disappointed because they replaced the tongue-in-groove boards with plywood strips that look completely different.

Anyway, 2.5 feet in either direction is how the so-called professionals preferred to do it, so I get the impression that its not a good idea to blow cellulose or other insulation into spaces deeper than that. Or, the hose isn't long enough to reach into deep spots. I presume I have a tough job taking up some of those boards in my own attic.

J

Hey J,

I also have an older home with a walk up attic and T&G flooring. I am also thinking about insulating.

Is your attic finished? if not do you use it heavly for storage?
I plan on just rolling out R-38 insulation over the flooring. Then when I finish the attic in the future I can use the insulation for the roof. It seems like an easy way to get some good insulation up there.
I've posted a question on here if this is a good idea or not and haven't heard back yet. I'll see what the experts say.

deacon

Hello,

I guess there are no experts available to handle this issue, so that's why we've gotten no responses.

You know, I like your idea a lot. My attic is walk-up and I have all kinds of useless stuff up there. The flooring is covered with linoleum sheets but upon closer examination, it could be sanded and polyed into something really nice. I intend to finish it off one day, maybe a year or two from now.

I was thinking of doing the same thing: rolling the pink stuff over all and dealing with the issue later on. right now I have a couple of inches of foil-sided insulation in the rafters, which is more a radiation barrier in the summer than insulation for the winter.

But I wonder if its a good idea to have insulation underneath the finished attic floor anyway. I will have separate electric heating for the attic once its finished, and likely will close it off during the winter.

I'd prefer to keep as much of my furnace heat in the two lower floors as possible. I suppose its still the old question, will two different layers of insulation work against one another? I can't imagine it will, because there's ventilation between the two (and there will be even more once I redo the roof and add a ridge to this ancient edifice).

If folks are insulating their basement ceilings, then I should be able to insulate both my second-floor ceilings and the attic ceilings without worrying about moisture problems. I have my vapour barriers.

J

Having two insulated layers (one in the attic floor and one on the roof) doesn't seem like it would hurt anything. If anything the insulation in the attic floor would act as a good sound proofing.

the only reason I'm planing on doing the rolled method is to get some insulation up there quick as winter is fast approacing. Also it seems like I wouldn't be able to get the R-value I would want with just the blown in alone since the floor is your standard 2x6 joists.

deacon

to answer your question i am going to go on the guess that you have crawlspace access. Yes you can blow insulation under floors. Are you planning on using cellulouse or fiberglass? I personally recommend fiberglass in the attic and cellulouse in wall cavities. Owens corning has a product called atticat. Its an expanding blown in fiberglass system and it works great for your situation. Its more expensive then the green fiber cellulouse, but you only need half as much, so the cost works out. Do you have insulation in the roof rafters now?? If so, you might want to think about yanking it down. The trick is, you want to insulate the "living spaces", and let the roof vaults and eves breath appropriatly. Amnd id like to add that the atticat machine will blow insulation about 8 feet. just make sure that your wiring is in tact, because you dont want to mess with it once theres insulation packed under the floor.

You can buy 1/2 pvc pipe or chemney cleaning rods. Cut the pvc pipe into 5 ft or shorter lengths attach male and female threaded ends(conduit) with pvc glue. Attach to hose may need a small
sled under hose to slid over plaster ridges. Now
take up four feet of flooring or less. Push the hose
under the floor attaching the next pipe and next pipe until you hit the wall at the far end of the attic. Start the blower and slowly pull the hose back as the insulation packs the space under the flooring and between the joists removing each section of pipe as hose returns. Repeat for each joists cavity

I hope in the last 4 years the OP got his attic insulated. Good advice, but on deaf ears, I'm afraid. Check the dates of the posts to make sure they are current. And a hearty welcome to the forums for both of you. Hope to see you more!