Home Improvement

Insulating the attic

By October 2, 2019 15 Comments
Insulating the attic

I recently had an energy audit done and they found that my attic doesn’t have enough insulation. I live in Connecticut. It currently has 4 inch batts (not sure what the R# is). They recommended me to add more insulation along with a pull down stair cover and baffles. For 900 sq feet, They quoted me R60 cellulose – $1915. This price is after the CT rebate. They will not be removing the old insulation claiming it’s for moisture control.

I got quotes from a couple of other companies and one company is 3 times the price, $6638, of the above quote. They said they will remove the old insulation. There are mouse droppings in there. Install barriers for the light fixtures and cover the ducts and floors with foam. They will also install an attic deck and blow in R60 (16”).

My questions are:
1) does mouse dropping old insulation need to be removed? It’s not much and you have to look for those droppings.
2) should I just do this myself? I am kind of handy if I watch a few YouTube videos, I think I can do it. But time is the problem. I have limited time with my kids on the weekends. How much is material costs if I were to do it myself? <$700?
3) if I do it myself, should I just install thicker batts instead of cellulose? It would be easier without needing the machine.
4) if you were to choose, which one would you pick? I am also waiting for 1 more quote from an all foam installation but my guess is that it will be around $7000.


Pics – https://imgur.com/a/iEgVKOB

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  • Tedmosby9931 says:

    Do it yourself with blown in cellulose for $400. Watch YouTube videos and make sure to air seal. Do rigid foam on the access hatch and weatherstrip the opening.

  • empowerapp says:

    go for it man! but do it now before it gets too cold. pull all the old nasty shit out. have the kids clean the attic. put all new batts down. Probably < than $1000 and if you went with r-30 probably less than $600

  • Jessie_James says:

    > 1) does mouse dropping old insulation need to be removed?

    No, and you don’t want to anyway. Mouse droppings can contain hantovirus. Wear a painters respirator, $20 at Home Depot. The effort and cost to remove is high and has no benefit anyway.

    > 2) should I just do this myself? I am kind of handy if I watch a few YouTube videos, I think I can do it

    Yes. Read the reviews for blown-in cellulose on Home Depot’s website – people will tell you everything you need to know.

    > But time is the problem. I have limited time with my kids on the weekends.

    Start at 6am and you should be done by noon if you have a helper.

    > How much is material costs if I were to do it myself? <$700?

    I spent $600 or so to add 6″ to an 1100 sq ft attic, but my AC usage dropped by something like 70%, the house was way more comfy, and I could set it to any temp I wanted. TOTALLY WORTH IT. It paid for itself in 4 months or so in electric bill savings.

    > 3) if I do it myself, should I just install thicker batts instead of cellulose?

    No. That is a HUGE pain in the ass, super messy, and super difficult.

    > It would be easier without needing the machine.

    LOL. Sorry. No. You really want to drag, what, 30, 40, 50 rolls of insulation into your attic, roll it out, position it, and so forth? Or just stand up there with a hose like watering your garden?

    > 4) if you were to choose, which one would you pick? I am also waiting for 1 more quote from an all foam installation but my guess is that it will be around $7000.

    I did it myself. So easy. $7000? LOLOLOL. Fuck no!

    Go do it. Super easy, super worth it.

  • Hozer60 says:

    Much better job removing old insulation then spray foam ductwork and any other penetrations, but just blowing in more is still great improvement. What is the ventilation situation?

  • Desoto61 says:

    The expensive quote is doing a lot of work for that money. Pulling out the old and air sealing, then building a new floor before blowing in the new insulation and then putting down decking.

    As for DIY, it’s definitely something you can tackle yourself. I’m not convinced you have to pull out the old, but there are health concerns both ways.

    I’d go with batts over batts personally, less mess should you need to do any future work up there. Run them perpendicular to the previous layer, unfaced only, and be careful not to block the roof ventilation. Pay attention to the details, making sure you get good coverage, eliminate gaps, and seal anything that’s not supposed to have air moving.

    It’s not a fun job, you want head to toe coverage, and at least a good dust mask.

  • edw6buffalo says:

    Most of the comments here cover the high points but make sure if you have any recessed fixtures that you use baffles to protect them and avoid fires.

  • Landbuilder says:

    Blow the attic insulation on top of the existing batts, get to a combined depth of 20”. They should have cardboard attic rulers that you can staple in areas.
    Use bright lighting while up there and be aware of your surroundings.
    Staple blanket insulation on the access panel using a thick plastic sheet or bag.
    Add weather stripping along the access opening for an air tight seal.
    If you get insulation in the eve vents then use a blower to clear them from the outside of the home.

  • Hfftygdertg2 says:

    You need to air seal the attic to get the full benefit of added insulation. Air sealing means sealing all the gaps where wires and plumbing come through the walls and into the attic, and everywhere the walls meet the ceiling drywall. That keeps warm air (in the winter) from rising through the house, getting pulled through electrical outlets and other holes in the drywall. That keeps conditioned air from getting sucked out of the house. Conditioned air in the winter also brings humidity into the attic which can cause mold problems.

    Air sealing doesn’t mean closing off the soffit or ridge vents to the outside. You need ventilaton there.

    It will be easier to air seal if you remove the old insulation, but I guess you could just push it to the side.

    A couple other comments mentioned hantavirus in mouse droppings. I read that it’s not infectious after it dries out for about two weeks, so as long as there is no active mouse infestation you’re good. But do your own research because it’s nothing to mess with.

    Air sealing is almost as important as insulation. If you only want to do the job once, you might as well do it right.

  • gravityisweak says:

    Do your energy companies have a program where they offer a discount? I got air sealing, blown in insulation, attic baffles, exterior wall insulation, and a cover for my attic for about $1200

  • FlartSimpson says:

    Were it me I’d convert to spray foam. The vast majority of attics have blown in insulation which is a nightmare to remove. You’re the exception with only batts. While not a fun job by any means, you could remove all those in less than a day. With an enclosed attic there’s no need to worry about sealing it off from the house. A house as small as that I’d bet you could have closed cell foam installed for under $2K. Spray foam is particularly efficient at holding heat, so you’d likely notice quite a savings in heating costs this winter. You get to keep your attic storage, you don’t have to worry about covering your light fixtures, you don’t have to worry about sealing anything – to me it’s the easy choice.

  • panthersex says:

    What type of respirator do you recommend for DIY cellulose? A Lowe’s or HD link would be great. Also, do I need to build barriers stopping it from getting into my ridge vents?

  • DSJ13 says:

    Your duct work will still be in uninsulated space.

  • mathspook777 says:

    You need to do more than just blow in some insulation. Think of insulation like a fluffy sweater. Sweaters are great at keeping you warm—unless you go outside in the wind, because the wind will blow right through it. If you go outside, you’ll want to wear a windbreaker on top of your sweater. Your house is outside, and air sealing is its windbreaker.

    The dirty black areas on your insulation are where air is leaking. The air flows through the insulation, carry dust and dirt with it. Some of that dust and dirt gets deposited on your insulation, making it dirty. All the dirt on your insulation is proof that your attic is leaking air.

    You have two major options for air sealing your attic. One is to create a conditioned and unvented attic by covering the roof in spray foam. In this scenario, you get to use the attic as livable space; it will be the same temperature as the rest of the house. I don’t know what’s appropriate for your climate, but you could probably get to R60 with 1′ thick closed cell foam over your rafters. (The rafters cause pretty substantial thermal bridging, which is why the foam needs to be that thick.) However, you would have to be confident that you would not cause moisture problems in your roof, and you would need a professional to do the installation. (Also, maybe foam that thick would be too heavy. I don’t know.) This option would be expensive, but it would give a very good result, and it could be done quickly, probably in less than a day. (It has the additional benefit that the air ducts in your attic would be in conditioned space, so the air in them would lose less energy while it’s being transported.)

    The other option is to leave the attic vented, but carefully seal every gap between the attic and the rest of the house. To do this, you go around the attic, looking for gaps where air can leak from your house to the attic, and you seal every one you find with caulk or canned spray foam. This is labor intensive but something you can do yourself. It can be done piecemeal, a little bit at a time whenever you get a chance, and every session will make your house better. The contractor mentioned light fixtures because recessed can lights are notorious for leaking energy. (If you have old recessed can lights they need special treatment; but anything that old should be replaced with something rated for insulation contact.) Other common air leakage sites include attic stairs or hatches, chimney flues, plumbing and electrical penetrations, ventilation ducts, soffits, kneewalls, the top plate, and bathroom fans.

    One downside of leaving the attic vented is that, as a practical matter, you can’t really add more insulation until you’re done sealing. You have to remove the insulation so that you can get to the parts that need sealing. So if you want to reach R-60 before winter, and if you want to do the work yourself, then you’d need to invest a lot of time starting now.

    For an attic like yours, which is basically a wide open space, blown-in insulation is much easier to install than batts. It’s easy to install batts poorly and make them ineffective; blown-in insulation is more forgiving. However, before you can blow in the insulation, you need to install baffles around the soffit vents. The soffit vents are part of the ventilation system of your attic; if you have blown-in insulation over or next to them, then the air flowing in through the soffits will blow through the insulation. This effect, called “wind washing”, diminishes the effectiveness of your insulation. In the long run it can even blow your insulation out of place, leaving cold spots on your ceilings near the exterior walls.

    If you are really keen on air sealing yourself, I suggest that you read the following pamphlet:


    If you want a comprehensive checklist of things that need to be air sealed, see:


  • 87880917 says:

    This quote sounds a little high. FWIW I paid about $1300 to have fiberglass blown into my attic. They brought it up to R60 and it’s probably close to 2 feet deep now. My attic is roughly 1200 sq. feet and, like you, I only had 4” batts between the joists to begin with.

    I thought about getting R60 batts and doing it myself and I thought about renting the machine to blow it in myself, but both of these would have involved a lot of time and multiple trips to the store (about 20 minutes one way) or renting a truck for the day if I wanted to cut down on all the driving back and forth. To me, $1,300 was worth every penny not having to deal with any of that. Plus I was their first stop for the day, they arrived at 7:30am and were gone in under 45 minutes. Still made it to work on time that day!

    I’d get a couple more quotes.

  • motorowerkaskader says:

    It depends on your expectations. IF you want to throw some insulation into the attic then you basically needs two hands to get it done. IF on other hand you expect to thermo-insulate the attic then I suggest pay pro to do that, except you will never know if they know what they are doing. Price range – expect $2-4K on average for average service scope of work. GC

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