Attic Insulation Blown In Cellulose vs Fiberglass?

[NY_Yankees_Fan]

Getting quotes to insulate the attic in an 80 year home, R49 is the plan, home is in the Philadelphia area. Based on research both products have advantages and disadvantages. Leaning towards cellulose insulation. Wondering what you think what should I go with. Because of cost do not plan on going with spray insulation. The contractors say fiberglass is better, less settling over time. This is our retirement home and plan to be here for a long time. Quotes are being prepared I asked them to quote both products.

Thanks

Tom

 

[M5farms]

Its an easy DIY job. Search for ATTICAT in your area. owens corning loose fiberglass blow in insulation. I did mine several years ago it took me about 3 hrs to do r60 in 2500sqft attic space. I had the machine here at work and bought the insulation cost was about 1000.00 bucks

 

[Gary Fowler]

I think Lowes will furnish or rent the machine when you buy the insulation. I think I would go with fiberglas over the paper. I have it in my attic and it also settles a bit but not like the cellulose. My Dad had that in his house and over the years it settled from 12" to about 6"

 

[EddieWalker]

If you go with a name brand and you install it or have it installed according to their recommendations to get the R value that you want, it probably doesn't really matter which one you go with. I think you are a little light with R49 because the more insulation that you have in the attic, the less energy it takes to heat and cool the living areas.

Owens Corning AttiCat Fiberglass Expanding Blown-in Insulation System-L38A - The Home Depot

AttiCat is what I use on my house, my parents house and for clients. I don't do a lot of insulation jobs, but clients claim that they see their energy bill decrease by a third after I'm done. Most houses already have something else up there that has settled or just just gone in places with less then 4 inches of insulation, so the difference is pretty significant once I'm done.

Here in the South, they recommend R60 or about 24 inches of insulation. I've seen where contractors that specialize in insulation have done it and they are a lot more fluffy and thin then I am when I do it. I'm not sure if I'm using too much material or they are getting by using less. In my opinion, I want it to be thick, uniform and everywhere.

Before you do this, be 100% sure that you do not need to go back into the attic. Walking through the insulation is like opening up a window in your house and leaving it open. It really doesn't matter how good the rest of it is, that trail is where you will lose all your energy. Never store anything in the attic over an area that you are heating or cooling unless you have a raised platform and you can insulate under it. Do not block your soffit vents with insulation. The air has to flow in through those vents and out through your roof vents to keep the rafters and decking dry.

Eddie

 

[Industrial Toys]

I have had the misfortune of working in enough attics. Blown Rock Wool is my favourite, hands down.

 

[truckdiagnostics]

If it was me I would take out what is there foam small layer for vapor barrier blow in fiberglass on top, with out good vapor barrier have to worry about insulation getting damp, no vapor barrier go fibreglass

 

[QRTRHRS]

If you have vented eaves and access to the plates on top of your walls, you may want to upgrade that area to start. Some foam blocking sealed in place with some sort of roof rafter baffles will allow you to go with deep insulation while preventing "wind washing" and maximize your efforts to make the home efficient. Wind washing is when extreme air flow through the eave vents blows the insulation away from the wall plate area decreasing your thickness. There are baffles made with a more rigid plastic rather than the foam baffles commonly seen at the big box stores. The baffles are molded with a curve that is meant to fasten to the outside of the top wall plate. Though more easily installed during new construction, this type of baffle allows blowing loose fill right over the wall plate negating the painstaking work of installing foam blocking.

I agree about walking in the attic insulation. You may want to install some sort of elevated walkway and blow in underneath it if you need access say for a HVAC system in the attic.

 

[NY_Yankees_Fan]

Thanks for the comments. One more question...

We have a roof ridge vent would it be advisable to install a powered roof fan ? It would activate at 120F. Because of the design of the home it does not have gable vents. The design of the home limits soffit vents. I have a small 1" gap visible from the attic. The home is a cottage style with extended overhang of the roof with the side wall tight to it. I will post a picture the next time I am at the home it is 2 hours away.

Sent from my iPhone using TractorByNet

 

[truckdiagnostics]

With a ridge vent the idea is the air comes in the soffit follow the rafters and then out the ridge. If you have enough soffit area and the ridge vent is installed correct with the proper amount of installation venting should be fine. I do believe there are tools out there to calculate that. A power vent it just going to pull it in from the ridge. You want it coming in the soffit following the rafters then out the ridge.
Prop the soffits, foam it for good vapor barrier, insulate to R60. And depending on your roof pitch you may have to provide an air gap from the soffit all the up to the ridge! I have run 2 x 2 as spacers then ridged insulation in between the rafters in some places. You want the air coming in the soffit following the roof, cooling it, then out the ridge. There really is no substitute for good venting. Good insulation does decrease the amount of venting you need. Idea being if you keep the heat and moisture from getting in the attic you don't have to vent it out. Also chances are when you are done, attic won't be used for storage any more. I am a firm believer in foaming it, not going to be cheap, and especially if venting area is questionable. When I was younger, block I grew up on, older homes ice would build up, everybody installed roof heaters, dad and I insulated our attic correctly that winter no ice. That summer I must have done 6 homes on the block, paid for a years college tuition. Getting it right on the older homes is not easy! and there are a lot of hacks out there.

 

[EddieWalker]

There really is no way to cool an attic other then encapsulating it and running cool air into that area. Venting is not for cooling. No amount of air flow in an attic is going to lower the air temperature up there. Venting is designed to keep the framing dry. Attics without proper venting have condensation, which leads to mold, rot and shingle failure. Adding a fan might increase air flow, depending on it's location, but it will never lower the temperature. It's one of those things people sell because people will spend money on it hoping it will do something when it doesn't.

Eddie