DIY Home Improvement Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
I am replacing insulation in the attic floor. The initial plan was to install R-49 or R-38 fiberglass batts but after clearing the space of the old stuff, it appears to be a harder job that i thought: spacing of ceiling joists is all over the place from 16" to 22", many of them are doubled up, and there are quite a few boards nailed on top of the joists going across. Cutting the thick batts around this obstacle course seems like a nightmare.

I am hesitant to just go with blown cellulose or fiberglass, because I am afraid wind will blow it around the attic through soffit vents and dust will seep into the house.

So the options I'm considering are:

1. Stuff unfaced R-19 fiberglass batts between the 6" joists (should be about the same height) and top off with R-30 batts going across

2. Same idea but use blown fiberglass to the top of the joists and top off with R-30 batts going across

3. Hire a contractor for a damp-spray fiberglass application like Climate Pro (i read about but haven't actually found anyone in the area yet).

Which of these approaches (or perhaps a different one altogether) seems like the most sensible option?

Here is some additional info which may be relevant:
- Attic is 1000 sqf
- I'm in Upstate New York, climate zone 5
- House has a hip roof, not very steep, so attic is quite cramped
- No plans for storage use
- HVAC air handler is in the attic, so I'll need access for maintenance
- I'm not considering foam due to off gassing concerns (which may or may not be warranted but i'm not taking the risk)

Thanks in advance!!
 

·
Registered
Joined
·
10,774 Posts
Add a nearby big city to your profile so we will see your climate region and know your code requirements.
You will want baffles to help keep the wind washing to a minimum and definitely if you do blown-in.
I'm not a fan of fiberglass even though it is popular, primarily because it is less expensive. I do like cellulose and it can be a DIY but your attic doesn't sound friendly. Get a few quotes for contractor installed both batts and blown-in. I suspect they will all want to do the blow. But make sure they all include baffles in ALL rafter bays. Nice part is they have skinny installers to a tight attic is not a problem.

Now, before you bury that attic address air sealing, especially if you go fiberglass. Cellulose might accomplish some of the air sealing but the big air leaks need to be sealed in all cases.

Bud
 
  • Like
Reactions: Fix'n it

·
Registered
Joined
·
6,164 Posts
Since you're here and asking. Maybe take few months and plan again. PHoto will help.
1. why remove old insulation?

2. those boards. What happens if i remove them?

3. soffit vent on hip roof. Soffit vent is passive cold roof fix. So, do i have ice dam problem? Having venting is a good thing, although it must be used correctly. Also are there enough intake area? Some vent covers are inadequate for cold roof.


If yes/no answer is all you wanted,:smile: option 1 for me. You can stuff fiberglass insulation and not lose the r value. Esp along the eave vents, what you want is sealing the air leaks and keeping the roof deck cold so heat from downstairs don't melt the iced up snow and create dams.


About #2 above, my attic is 100% covered with plywood. Maybe there was a plan to convert, plan for storage or just the owner's idea of not wasting space. Pull down attic stairs access only. I want to remove most of the plywood and add insulation. Some 12" metal vents here and there but somehow no ice dam leaks. In nj but no big snows past 5 years i was here. Plan is to insulate with foam boards along 12" or so of the outer wall plates then add insulation on top.



HVAC appliance and access. Unless you raise them for more insulation, there's nothing you can do but live with the r value you can get.
 

·
Registered
Joined
·
1,449 Posts
Before I'd consider doing anything, I'd ask myself whether I would save enough in energy costs to make it worth the what it costs. With the heating system in the attic, how much improvement in heat loss would there be by adding the insulation? How much will you save on your heating bill each year if you do it? How many years will it take to break even? Do you plan to be in the house that long?

The house I grew up in had a setup like that, with the furnace in the attic, other than the roof pitch was fairly steep, giving it nearly 9' of headroom at the ridge. We added about a foot of blown in, but our gas bill only dropped by about 10%. The addition of a couple extra ceiling fans paid for itself in one winter. Granted, we had 9' ceilings in that old farmhouse, and the vents were in the ceiling. So before the ceiling fans, it was about 85 degrees at the ceiling and 60 degrees at the floor.
 
1 - 4 of 4 Posts
Top