Attic insulation

1137 Views 14 Replies 8 Participants Last post by Nealtw, Mar 5, 2020

Erfogrof

Discussion Starter · Mar 4, 2020

2

I have a walk-up attic in Albany, NY (pics attached). It is completely un-insulated, except for the void created by the planks sitting on 6-inch joists. I'd like to fix that so I'm hoping for some advice as to best options in a climate that is very cold in the winter, but warm, sometimes hot and humid in the summer. The attic gets extremely hot in the summer, to the point that we can sometimes feel it when touching the ceiling from below. I'm sure we're losing heat on cold winter days as well, but it's less noticeable.

So with that, here are some questions I'm hoping to find answers to:
1- Would it make sense to blow in insulation under the plank floor? Or should I be expecting to take the floor out? We don't absolutely need storage space up there, but it is nice to have.

2- If I wanted to go quick and cheap for a short term improvement (anything's better than what I have now), would it make sense to lay batts down on top of the plank floor?

3- Should I use a vapor barrier? If so, on top or on bottom? (I see most advice suggesting one way or the other depending on warm or cold climates, but I feel like I have both)

Any other general advice on this is welcome.

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Nealtw

· #2 · Mar 4, 2020

Air sealing need to be at the top of the ceiling so you could remove boards to access around plumbing and light fixtures and what have you. Then if you remove a board every 2 ft or so you might get insulation under the floor and above it.

For storage you could build anther floor platform out of 2x8s and the salvaged boards.
The stairs are another problem likely not an exterior door at the bottom and un insulated walls .So maybe build small insulated room around the stair top with an exterior door and remove the lower door.

It looks like you do have high and low vents already.

Bud9051

· #3 · Mar 4, 2020

Can you tell us what is currently in place for attic ventilation, maybe some pictures?

Just guessing but code level insulation is probably in the range of 12 to 14". Are you pulling any permits where inspectors will be concerned?

Bud

APA

· #4 · Mar 4, 2020

Not sure about the loads, but tearing up that floor and laying another set of 6-in joists perpendicular to the originals would give you 11-in for insulation. Blow in some cellulose and it will be a world of difference. You could even do high-density batts.

Nealtw

· #5 · Mar 4, 2020

Bud9051 said:
Can you tell us what is currently in place for attic ventilation, maybe some pictures?

Just guessing but code level insulation is probably in the range of 12 to 14". Are you pulling any permits where inspectors will be concerned?

Bud

See 1st picture, chutes and box vents.

Missouri Bound

· #6 · Mar 4, 2020

Any chance you may want to use that attic space?
You could more easily insulate the roof and side walls than tearing up the floor.
It may cost you a bit more to do that but you would have a space that wouldn't be subject to temperature extremes.

SPS-1

· #7 · Mar 5, 2020

Missouri Bound said:
You could more easily insulate the roof and side walls than tearing up the floor.

Ceiling plus walls is perhaps double the square feet of the floor. So with the same thickness of insulation, you would get double the heat flow out of the house, plus whatever you lose through the windows.

Missouri Bound

· #8 · Mar 5, 2020

SPS-1 said:
Ceiling plus walls is perhaps double the square feet of the floor. So with the same thickness of insulation, you would get double the heat flow out of the house, plus whatever you lose through the windows.

OK. For some odd reason I don't feel confrontational tonight.
But I think you missed my point.

Bud9051

· #9 · Mar 5, 2020

Nealtw said:
See 1st picture, chutes and box vents.

Yes I saw those but they doesn't tell me how much vent area is represented, plus I wanted to get the op started thinking about ventilation for the entire attic or possibly leaving the floor in place and insulating below the roof. I'll wait for him to reply.

Bud

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APA

· #10 · Mar 5, 2020

Bud9051 said:
Yes I saw those but they doesn't tell me how much vent area is represented, plus I wanted to get the op started thinking about ventilation for the entire attic or possibly leaving the floor in place and insulating below the roof. I'll wait for him to reply.

Bud

2x6 rafters. He will be dealing with getting condensation.

Bud9051

· #11 · Mar 5, 2020

Too early for any red flag we haven't even begun the discussion.

Bud

user_12345a

· #12 · Mar 5, 2020 (Edited)

SPS-1 said:
Ceiling plus walls is perhaps double the square feet of the floor. So with the same thickness of insulation, you would get double the heat flow out of the house, plus whatever you lose through the windows.

Except plumbing/electrical penetrations increase leakage and reduce actual insulation value.

A foamed roof performs much better than loose insulation on the attic floor.

-------------------------
A good option may be to put a vapour barrier on the existing decking, doing it in such a way that sealed off all the penetrations below and putting batts over top.

snic

· #13 · Mar 5, 2020

One thing you could consider: get a home energy assessment done. Because you line in NY, the state will pay for all or a good chunk of the cost:

https://www.nyserda.ny.gov/All-Prog...ow-the-Residential-Energy-Audit-Program-Works

The contractor will give you a detailed report on what needs to be sealed, what ventilation needs to be added, and what sort of insulation to install. Of course there are many ways to skin a cat (erm, insulate an attic), and ultimately their goal is to get you to pay them to do the work - so their recommendations might be a bit biased.

Still, it's an excellent starting point, and the information you get will come from a trained expert. You'll get a lot of detailed information about air leakage (not just in the attic - the entire house). You don't have to hire the same contractor - you could just use their detailed recommendations as a guide and do the work yourself, or hire someone else to do it.

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Erfogrof

Discussion Starter · #14 · Mar 5, 2020

2

Thanks for all the responses so far. I'll try to answer all the questions that have come up:

The stairs are another problem likely not an exterior door at the bottom and un insulated walls .So maybe build small insulated room around the stair top with an exterior door and remove the lower door.

Correct, the door at the bottom is an interior door and only has some cheap weatherstripping. I don't know if there's enough height to fit an exterior door at the top, but sounds like an idea worth looking into. I had been planning to look into stair tents.

Can you tell us what is currently in place for attic ventilation, maybe some pictures?

Just guessing but code level insulation is probably in the range of 12 to 14". Are you pulling any permits where inspectors will be concerned?

I don't currently have any plans so no current need for permits or inspections. I'm not sure I understand what you're asking regarding ventilation. Other than the two box vents, chutes and the windows, there's a small space at the apex of the roof that I think is intended to vent (see first photo below). Please let me know if there's more I can share here.

Any chance you may want to use that attic space?
You could more easily insulate the roof and side walls than tearing up the floor.
It may cost you a bit more to do that but you would have a space that wouldn't be subject to temperature extremes.

The height at the center is only about 6 1/2 feet so the space isn't very usable. Additionally the stairs are steep and narrow. The old doors were there when we bought it and we store the air conditioners there in the winter. They can both easily go elsewhere. So, at least for now, I'm not going to be sad if the space is not usable.
When we purchased the home about 2 years ago, there were batts (thin and probably not very effective) attached to the roof and our inspector found mold behind them. The sellers had the mold taken care of and the insulation was thrown out. I'm assuming if I wanted to go that route and avoid the mold problems I would have to seal everything up, take out the vents, put in better windows, etc.

One thing you could consider: get a home energy assessment done. Because you line in NY, the state will pay for all or a good chunk of the cost...

Nice, I'll look into that!

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Nealtw

· #15 · Mar 5, 2020

So you could make a real nice closet down stairs with an attic access, if you just took the stairs out.
The air chutes look good , what does that look like from out side.

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