How to Air Seal an Attic that is Already Insulated!

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Insulwise is air sealing an attic floor that has already been insulated with fiberglass batt insulation. Andy Haak demonstrates clear evidence of air leakage occurring up through the wall top plates. Some people falsely believe that insulation itself will stop air leakage in attics, but we show here that that idea is a falsehood. The black streaks on the underside of the fiberglass batts (that perfectly line up with the top plates) are proof that air from the home is escaping around the top plates. The black streaks are caused from the dust in the air getting trapped in the fiberglass.
Insulwise air seals every attic floor prior to insulating the attic. We do this because air sealing not only reduces energy loss from the home and improves comfort, but also greatly reduces the transfer of water vapor from the home to the attic (this is a primary cause of attic mold). In this case we are using Great Stuff foam sealant to seal these air leaks before adding additional insulation to the attic floor.
Good luck sealing your attic air leaks!
Andy Haak

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Опубликовано:

9 май 2022

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Комментарии : 28

@MegsCarpentry-lovedogs Год назад

Yup! I have a lot of work to do up in my attic to get ready for an attic renovation with building pony wall....Glad that post covid pandemic building supply material is Slowly coming down in price.....what a journey we all had! Thanks for this Cheers East Canada🙏🇨🇦🍁

@insulwiseenergycomfortsolu3293 11 месяцев назад

You're welcome, hope this helped you! Andy

@retsof1922 7 месяцев назад

Same here. My home was built in the 70's and have been doing lots of renovations UNTIL the covid prices hit. But, my attic needs attention like this as well

@edwardluth7740 Год назад

The cellulose dust if in attic can also get in your house and venting and create terrible dust allergies if not air sealing well.

@insulwiseenergycomfortsolu3293 Год назад

That's correct. A good attic air sealing job will have positive benefits for interior air quality. Andy

@StephenOwen 5 месяцев назад

Is there any special insulation you should do for electrical fixtures from the attic? For instance, when I’m in the attic, I can look down into the bathroom heater, and the same thing for the ceiling fan.

@insulwiseenergycomfortsolu3293 5 месяцев назад

Hmm, if you see big gaps like that, you should first cover them with something like a piece of foam insulation board or possibly plywood. But you don't want to inject foam directly down into something like that.

@drummer1388 8 месяцев назад

I’ve heard once blown insulation is blown, you should never disturb it as it will lose its effectiveness. Is this correct? Or can it be moved so work like this could be performed, then shoveled back into an even layer? Thank you in advance! These videos are excellent

@insulwiseenergycomfortsolu3293 8 месяцев назад

Thank you! You can disturb it and move it back no problem. I've had to do it a bunch. Biggest issue is being careful you don't fall through your ceiling. But you can move it out of the way with a broom, kind of like raking leaves, do your work, then brush it right back into place. I can do it well enough with my hands that you'd never know I moved through the stuff. Andy

@mae2759 3 месяца назад

Is this able to be done with blown in insulation?

@insulwiseenergycomfortsolu3293 Месяц назад

Yes, it's just more time consuming a bit of a pain, but we do it every day. You want to make a map of the air leaks from below before going into the attic, then you'll know where you need to go. Andy

@loganschlabach3899 11 месяцев назад

How does the air move through the drywall mud and the multiple coats of paint? Around the top plates

@insulwiseenergycomfortsolu3293 11 месяцев назад

Great question, it doesn't move through drywall and paint. When those 2x4 top plates were installed new they had a moisture content of 18-20%. After a few years of air drying in that attic that moisture content drops to 7-10% --- so they actually shrink a bit. That opens a gap on either side of the top plate. Than the air from inside the house naturally gets into and travels up the walls bays and exhausts into the attic. Stack effect during the winter is the primary driver of this, but I've felt cold air gushing from these things during summer from unbalanced duct systems. Most of the attic floors that we encounter are incredibly "porous" when you pull back the insulation. Andy

@erwynn Месяц назад

They get through the electrical outlets and switches, then through the side of the top plates into the attic. Electrical boxes have a lot of gaps around them and also the punch out at the back of the box. Most houses have an outlet every 6ft or so (basically every wall). Sealing the top plate separates the interior wall from the attic so air in the wall cavities stay as part of the interior space

@peacew6 Год назад

A question for you. Obviously, since the rafters sit on the outer walls, there is no way to seal the gap of the outer walls. Right?

@chuckhall5347 Год назад

It depends on several factors. What is the slope of the roof? What kind of insulation is over it? How much are you willing to pay or do yourself? Also there are foam guns that have a 2 or 3 foot nozzle. That would help.

@insulwiseenergycomfortsolu3293 Год назад

It depends. On many homes we can get to them, usually the homes with the steeper roofs. For homes with low sloping roofs it becomes much more difficult. In some cases we use actual spray foam to seal those top plates. In other cases the homeowners will have us dense pack the exterior walls with cellulose insulation. That process essentially air seals the stud bay, so the top plate gets sealed. Thanks! Andy

@Faruk651 7 месяцев назад

Are you in a warm climate? Isn't there supposed to be a vapour barrier on that ceiling?

@insulwiseenergycomfortsolu3293 7 месяцев назад

Hi there, Pittsburgh is a temperate climate. We get hot and humid summers, and cold, wet, and snowy winters. In climates where it gets cold the vapor barrier should be on the interior walls because vapor drive and diffusion happens from the inside out during cold temperatures. In the case of homes here, the "vapor barrier" largely consists of drywall, plaster, etc that is primed and has a few coats of latex paint on it. Newer homes have a layer of plastic put over the studs before the drywall goes onto the studs. Either way, the goal is to retain as much moisture and conditioned air inside the home as possible (understanding that some leakage will occur) --- and for the water vapor that exfiltrates into the walls and attic spaces there needs to be a clear pathway to evaporate to the outside. When water vapor gets trapped in an area where there is a surface that goes below dew point temperature, that is where the trouble starts with mold growth. Andy

@yanbaihuzxzxzx 11 месяцев назад

I always do a removal, that insulation is a pain to work around. just throw it out which makes airsealing a breeze.

@insulwiseenergycomfortsolu3293 11 месяцев назад

We don't recommend removal as a default practice due to the added expense for the homeowner. It nearly always requires a full day with a 3 man team. I agree the air seal is easier with no insulation present, but we've been doing it this for years and have developed practices that allow for a quality end result. We often do blower door test ins / outs on these homes as well and sometimes attic zone pressure tests with them. A post- air sealing zone pressure test is super effective for determining attic floor tightness. Thanks! Andy

@yanbaihuzxzxzx 11 месяцев назад

@@insulwiseenergycomfortsolu3293 yeah we got by with 2 people but it takes all day. Helps to have the right equipment, volumatic blower really knocks out attic quick

@powerbroker1000 Год назад

So that dirty insulation is a spot where my clean money is escaping! Ugh!!!

@insulwiseenergycomfortsolu3293 Год назад

That is indeed correct. Those dark stains are visible proof that your clean money is exhausting straight up and out from the top of your home! Andy

@Inkling777 10 месяцев назад

That canned foam is expensive and can itself leak around the edges particularly as it ages. The proper approach is to seal what leaks *where it leaks* and do it in a better way. Sheetrock itself does not leak. It is the openings the wall and ceiling that leak. That's air vents, light fixtures, and power outlets. Get the aluminum tape used for duct work (not the colored and misnamed duct tape). Use it to completely seal of the cracks between those openings and the sheetrock. That is easy and all you need are scissors. Doing it that way has an enormous advantage. You can work inside your house in a comfortable environment rather than stumbling around in an attic and inching from fiberglass. In short, tape the limited number of openings below rather than foam all the cracks above. Less work and less expense. You might also put attic foil on top of the insulation. It's made in varieties that allow you to select the right amount of air flow for your climate. In some climates you want some air flow to keep the insulation from getting soggy. Details at: www.youtube.com/@AtticFoil

@insulwiseenergycomfortsolu3293 8 месяцев назад

Hi, I respectfully disagree. If you want to try taping penetrations you're welcome to have at it, but I would not expect this to work well in an attic. There's simply too much dust for the tape to stick well, and I have never seen any tape adhere well to wood or drywall to any extent. Foam is expensive, but we have not seen a product that is even close to as effective. I have also not seen foam shrink or allow for leaks around it as it ages. I have had to check attics where we've done work years prior, and reaching down below the cellulose I've always felt that the foam was still right where we'd installed it, and attached firmly to whatever it was initially attached to. There are also relatively few air leaks that are accessible from inside home that has already been finished, for example plumbing pipe penetrations, wire holes, bathroom fans, drop ceilings / bulk heads, etc. Trust me, if I thought there was an easier and cheaper way to accomplish this work, I would gladly try it. It is very hard and expensive work to properly air seal an attic.