Need to Add Attic Insulation

[ddurrett896]

Had a 100 degree yesterday and AC had a little trouble keeping up. Set to 73 and held at 75 until the sun went down. Attic has 2x6 joists with maybe 4-5" of blown in insulation that's 50 years old and my zone calls for adding R38.

Home Depot shows the below options. First 3 blown in gets R38, last is R30 with that being the thickest unfaced I can find locally.
1) Greenfiber Cellulose Blown In: $471
2) Owens Corning AttiCat Pink Expanding Fiberglass Blown In: $969
3) Johns Manville Attic Protector Fiberglass Blown-in: $917
4) Johns Manville R-30 Unfaced Fiberglass Insulation Roll: $1,555

I like the idea of unfaced so I can grab a bat and move is needed plus its a 1 man job, but frankly digging thru blown in isn't that bad. Any recommends? Thanks!

 

[WisJim]

Around here the cellulose blown in is the standard for attics. It's hard to get full tight coverage with rolls of fiberglass, and blown in fiberglass always seemed messier and itchier to me. You should make sure that the attic floor is sealed tight, especially around the perimeter, before you go to the trouble and expense of adding more insulation.

 

[strutaeng]

Finally! Someone asking to add more insulation instead of adding more ventilation thinking that will do a lot!

 

[Sumboodie]

Home depot offer to install it?

 

[ddurrett896]

Home depot offer to install it?

Might but I prefer to do what I can myself

 

[FredWanaker]

I would go with blown in cellulose since you already have that. Make sure that the company who does it also protects or adds baffles to the soffit vents. If there is any sign of mold in the attic or signs of too much heat on the wood, add additional venting. I added rolled up batts over cellulose in 1992 in this house. It helped. In 2018 I had an insulation company vacuum out the old, seal all wire and hose penetrations, add missing baffles, and blow in R50 fiberglass. Also added a new roof, and a ridge vent was required so the attic is very well vented, since it was already upgraded in vent area for a Triangle Mfg six blade whole house fan 25 years ago. I also added a catwalk from end to end and to the areas that might need future service. An electrician came in and inspected all the attic wiring and house wiring at that time as well. Total insulation cost was about $4K. I have already recooped about 1/2 of the money in lower utility bills. Batts are easy but they will not seal as well as blown in will. It was 111F yesterday here and the HVAC ran about 25% of the time, maybe 15 minutes per hour. The walls are 2x4 and have R13 in them. They originally had R-11 but I upgraded it and tyveked the house when I put on new siding and dual pane windows about 20 years ago. Energy prices are only going to go up so don't be too concerned that the money is being wasted. We can keep the house at 70F - 73F most of the day for much less than my neighbors pay to keep theirs at 80F, Also sealed all the bathroom vents and replaced kitchen vent hood pipe since it had 40 years of ick in it. If there are any other projects up there you want to get done, now is the time. Make sure they inspect for vermin and seal any entry points.

 

[mrbill55]

I would go with blown in cellulose since you already have that. Make sure that the company who does it also protects or adds baffles to the soffit vents. If there is any sign of mold in the attic or signs of too much heat on the wood, add additional venting. I added rolled up batts over cellulose in 1992 in this house. It helped. In 2018 I had an insulation company vacuum out the old, seal all wire and hose penetrations, add missing baffles, and blow in R50 fiberglass. Also added a new roof, and a ridge vent was required so the attic is very well vented, since it was already upgraded in vent area for a Triangle Mfg six blade whole house fan 25 years ago. I also added a catwalk from end to end and to the areas that might need future service. An electrician came in and inspected all the attic wiring and house wiring at that time as well. Total insulation cost was about $4K. I have already recooped about 1/2 of the money in lower utility bills. Batts are easy but they will not seal as well as blown in will. It was 111F yesterday here and the HVAC ran about 25% of the time, maybe 15 minutes per hour. The walls are 2x4 and have R13 in them. They originally had R-11 but I upgraded it and tyveked the house when I put on new siding and dual pane windows about 20 years ago. Energy prices are only going to go up so don't be too concerned that the money is being wasted. We can keep the house at 70F - 73F most of the day for much less than my neighbors pay to keep theirs at 80F, Also sealed all the bathroom vents and replaced kitchen vent hood pipe since it had 40 years of ick in it. If there are any other projects up there you want to get done, now is the time. Make sure they inspect for vermin and seal any entry points.

The above is 100% sound advice, listen to it.


Bill S.

 

[larry4406]

Last year we had an insulation company unblow the attic.

Then framers fire stopped off all the open chases from the 1987 build and built an elevated cat walk. Then electricians replaced all of the non-IC rated cans that were in place.

Once attic was ready, they fixed all the soffit baffles, then sprayed foam from plate to plate across the entire house. About 4-5” foam build. Fully encapsulated attic truss bottom chord. Then overblew with cellulose

I think we are somewhere around R56 now.

The dust in the house has decreased greatly. The filters now go 3-4 months vs monthly.

Oddly the heat pump water heater energy use (I keep it in heat pump mode only) immediately reduced. The WH is the basement. We heat and cool house using a heat pump. I can’t explain the correlation of attic insulation improvement to basement WH energy usage reduction.

Electric bill has reduced from the insulation improvement and the AC performance has improved.

I can’t remember if it’s open or closed cell. I would have to pull the invoice.

 

[dcg9381]

I like blown in cellulose for attics also. Home Depot rents blowers.
The pink stuff, I use that between studs where you can just roll it in, but it's no fun to work with.
Prices look great to me, but I'm used to paying to spray foam.

Anyone got an opinion on adding a radiant barrier? We've had that installed in our "high temp" state and it seems to make a difference, but I've never done it post construction. If you're worried about heating, probably wouldn't be on my list.

 

[PoorUB]

Before you DIY, call and get quotes from insulation contractors. Pre-Covid I had my attic blown in with more fiberglass and it was $50 more to pay someone to do it than what it would have cost to do it myself. Post-Covid prices might be a bit crazy, bit I would find out. It costs nothing to get a quote.

 

[larry4406]

Older homes like my 1987, were poorly fire-stopped to the attic, so lots of air movement upwards thru walls.

More blown insulation in the attic will not stop this.

Give some thought on how you proceed. For me it was to go backwards (remove all), correct all the sins (proper IC cans and fire-stopped chases), then move forward.

 

[The Cobbler]

10+ years ago I ripped out all the batt insulation in my attic.it was a wopping R-8! caulked all the holes where there were wire penetrations. sealed poly over electrical boxes ( no vapour barrier in the attic, old house) added a catwalk as attic is walkable. added ( forget the r value) fiberglass insulation. could have had it blown in to the same level as I did with batt for less $$ but I needed to do sections at a time so I didn't have to take all the stored items down to the main level.
new windows, framed & insulated basement walls, new attic insulation, new furnace ... cut my heating consumption in half

 

[billconner]

If you have insulation now, look for the dirt. That will show where air is escaping. (Along with large insulated areas like attic hatches.) Around pipes and chimneys, light fixtures, as well as tops of all interior and exterior walls are likely spots. Painted drywall ceilings do a good job of stoping air and vapor. Spray foam around pipes and electrical boxes and over walls. Drywall boxes over recessed lights. Aluminum flashing and a fire rated caulk around chimneys and flues. You really want to stop air flowing into attic.

Do that air sealing, add rafter baffles if required (they were not in my last house - 1904 - since top plate was 2' over ceiling joists but probably ceiling joists are sitting on top ate in 1984 house.) Pump in cellulose. I'd hold off on venting and see if there is a problem moisture. Venting can sometimes cause problems.