To hopefully reduce my cooling load a bit this summer and to try to get another year out of my A/C system so I don’t have to deal with contractors coming in, I’m finally getting around to re-insulating the attic. The attic is currently insulated with just loose pile filling in between the rafters. The house was built in 1950, so there is no vapor barrier between attic floor and the insulation but the ceiling itself is plaster. There are no light fixtures protruding into the attic.
About 3/4 of the attic has a floor. I plan to just lay fiberglass insulation crossing the rafters and on top of the floor. The common advice is to use batted insulation between joists and unbatted insulation if you are laying it across joists. Based on that, I’m inclined to go with unbatted insulation but why is this the recommendation? Would batted insulation be better because I don;t have a vapor barrier in the attic currently?
Also, I know I’m not supposed to block the soffit vents. Other than that, it seems insulating is just laying the insulation down and putting each piece snuggly next to the prior piece. Don’t smoosh it down. Cut it to fit around obstacles. Anything else i should know? Thanks in advance.
I did a similar project and was advised to use unfaced, rolls. Rolls eliminate many of the joints as it goes across the attic floor. It’s also much faster to install on top of a plywood floor.
Faced means there’s a vapor barrier. It could trap moisture between the plywood floor and sheetrock ceiling.
You want moisture to enter the attic and exit through the soffit and roof vents.
I hired a company to vacuum out the old insulation. It was full of dust, compacted, and had broken down.
OP, I get the impression (perhaps wrongly) that you think batt insulation means a vapor barrier. Batts are just blankets or rolls and can be faced or unfaced.
You should not use a vapor barrier above existing insulation. It will trap moisture.
I’m just tired and loopy. I’m getting rolls instead of batts. My question was whether I should get the faced or unfaced insulation. I thought this was probably the answer but i wanted to learn why. This is consistent with what aceplace57 learned as well.
I’m leaving the old insulation in place. It’s full of dust but it’s not hurting anyone just lying there. it’s not compacted as far as I can tell. It completely fills the gap between the joists right to the top (except near the soffits) and I assume that’s exactly where it started. I’m sure I could get someone to suck it out but then I have to hire a contractor and the whole point of this is to avoid bringing laborers into the house right now.
I appreciate the tip. I know it’s an irritant so I’ll wear gloves, long sleeves, eye goggles and a mask. Ironically, I’m down a bunch of N95 masks because I donated some to my friend who is a hospital physician. However, I have enough that I can sacrifice one to getting this installed.
For my house, I did the unfaced insulation it was fine. You have all the right info.
I know you not asking this, but I’m going to suggest you check out getting blown in insolation as an alternative. I reinsulated my parents house 2 years ago and it was cheaper (and obviously easier) than doing it myself with FB batts from Home Depot.
I was walking out of Costco and the Insulation services guy just happened to be standing there so I thought may as well get a free quote. Turned out they were about $150 cheaper than DIY and they were completely done in two hours. They did all the standard venting protection etc.
I was at Home Depot recently and noticed that they also have a Home Services blown in company now plus DIY free rental of the blowing machines if you buy X amount of “blow-able” bags. From what my store manager has told though is these kinds of services vary somewhat by location depending on what contractors they can find in the store vicinity. They didn’t have that at my store when I arranged my parents house.
I’d suggest it’s worth getting a free quote from you’re local Costco, HD or Lowes offers it.