How to Air Seal an Attic That is Already Insulated 

Hi there, thanks for the compliment! We certainly try, and effectively air sealing the attic floor of a home will often transform how that homes "performs" both in hot and cold temperature extremes. It will also reduce the chances for having mold issues on the underside of your roof. Good luck to you! Andy

The foam guns are helpful, but we do not always use them. We find many areas where they are too large and cumbersome to allow us to seal gaps and openings effectively. In these areas the small cans of Great Stuff come in handy. Andy

@@insulwiseenergycomfortsolu3293Interesting reply…based on vids of installers trying to demo different types of foam products, by creating several side-by-side “beads” used for comparison, without any nozzle attachment, those comparison beads were not uniform in depth, thickness or alignment. Kind of a mess without using the nozzle piece. IMHO

Don't the attachment nozzles want to plug up?

Thanks Paul! Andy

Thanks Jack! Andy

Good to point that out. For customers that expected to do wiring work later we have hung flags from the roof rafters to indicate where they were located. Otherwise it's going to take a bit more time. Thanks! Andy

Hi there, thanks for the compliment! We certainly try. Andy

Thank you!

Hi there Frank, thanks so much for saying! We certainly try here at Insulwise, and air sealing attic floors has been an integral part of our operation since we first began in 2009. Cheers my friend! Andy

Hey there Andy, thank you!

You're welcome, hope it helps! Andy

Thank you and I'm glad that you found this helpful. You definitely want to make sure that your attic floor is sealed as well as it can be before re-insulating. Andy

Hey thanks Paul, glad this helped you! Andy

Thank you Jordan, we certainly try! Andy

Hi Jack, I'm glad this helped you out! Andy

Hi there, thanks! Foam is definitely the way to go, and regular great stuff with a plastic straw works just as good. Draw a map from below, get a headlamp, knee pads, gloves, a good dust mask and have at it. The last important tip is ALWAYS keeping your weight on the floor joists. Things will go wrong in a hurry for you if you don't ; ) Andy

Thanks! If possible sure that certainly makes the air sealing easier. But if the team doing the work is used to air sealing when there is insulation down, are mapping the air leaks, and testing out with blower doors you can get the same result, and also save the homeowner a few thousand bucks while doing it. That said, I would not trust most of our local competition here to get the results that we get with the insulation still in place. Properly air sealing an attic floor is tedious, time consuming, methodical work -- and that's when the attic temperatures are "friendly".

Thanks, glad to be able to help!

Thank you! And yes, a new HVAC system can help and even mask a number of problems, but this solution dramatically lowers the heating and cooling load of a home, making the HVAC system's job A LOT easier. Andy

Thank you! One of our team members came up with it years ago. There are very, very few penetrations that cannot be mapped from below. You cannot see where every wire hole or plumbing stack pipe is, but if you are following your map of where the top plates of the walls are --- than you will absolutely find every wire hole and plumbing penetration. Thanks! Andy

Thanks!

You're welcome! Thanks for the shout out. Andy

Hi there thanks for the compliment! Yes I know exactly what you are talking about with low sloping roofs. It is exceedingly difficult to get access to these areas sometimes. Also where there are drop soffits (we call them bulkheads here), it is likely that the exterior wall stud bays are also open directly to the attic. What we try to do is make sure that any light fixtures inside the drop soffit are ideally IC rated, or at a minimum have LED bulbs installed in them (they don't create much heat). We then then insert a fill tube down into the exterior wall bays (usually while laying on your stomach) and dense pack the exterior walls that are open, and then blow the drop soffit full of cellulose. If the homeowner has plans to remove the drop soffits then we cap them with foam board and foam sealant like you see in this video. Either way, working in attics with low sloping roofs is usually quite tricky. Taking up a small board or sheet of plywood to lay on is often a great help. But once the air sealing work has been effectively done (and ideally the attic insulated to an R-49 with cellulose insulation), you will see massive improvements in your home's comfort as well as energy efficiency. Andy

Thanks for the valuable info AND the discussion in the comments. Just goes to show…few customers are 100% satisfied.

@@johnpacella9519 You're welcome John thanks. We try to satisfy everyone, but as you know that's tricky. I think we do a good job with most people who are reasonable however. At least that's what we shoot for! Andy

Hey there, we could actually do a video for that as we do what are called "encapsulated" crawl spaces. I'll put that on the list! Andy

Seconded

Hey there thanks for the comment! I will do another video that shows us doing a blower door test in and out with this type of job for sure. We often do also spray foam rim joists in houses. Your method of cutting the foam board definitely works, but can get tricky around wires and tough to reach areas. We spray foam rim joists with 2 part, closed cell foam for that reason. But you're correct in stating that the impact on comfort achieved from doing an attic and rim joists is often dramatic, not to mention the improvement in the home's energy efficiency. Thanks! Andy

Thank you! Our teams are pretty experienced and this is typically how the finished results look.

We certainly try!

Thank you!

Hi, if you're doing it solo than yes and it's going to take some time, but if you draw a map you can isolate the attic into quadrants and do it one section at a time. It is also true that power roof fans can depressurize an attic and pull the AC from the house or heat (if they're also equipped with humidistats for the winter). Best practice is to thoroughly air seal the attic floor, then get the roof properly ventilated, and then insulate the attic floor to an R-49 level (we prefer cellulose insulation). Andy

We only hire the best Jedi's here ; )

Thank you!

Thanks, when cellulose settles after getting blown in, it actually becomes fairly resistant to being blown around in attics, even when close to whole house fans. Blown fiberglass is much more likely to be "wind washed" like this. Andy

Thanks! The ceiling in this home was actually just regular drywall, it was built in the late 1960's. I would highly recommend that you seal the top plates. In many cases that we see, the allow significant amounts of heated air to escape from the home to the attic. Andy

@@insulwiseenergycomfortsolu3293Thanks, i'll start on it. I can tell it's bad when my whole house big ceiling fan is on, bathroom outlets lets the stinky attic air back down, it recirculates it.

You are correct, and I've seen that video. I believe that a MASSIVE issue that he leaves out is the type of foam that should absolutely be used if you insulate the underside of the roof. In his video I am almost positive that he used open cell foam, which is no no because it does not create a vapor barrier. That means water vapor can move through it and get trapped against the underside of your wooden roof. You DO NOT want this potential. The "hot roof" solution can work well, but it should only be done if you are going to use closed cell foam. Closed cell foam is much more expensive, but at 2" thickness creates an effective moisture barrier (last time I checked). We have seen roof rot issues in Pittsburgh from using open cell foam to insulate the underside of roofs. If you google this and sniff around on the web a bit, you can verify this quickly. Thanks! Andy

He used open cell because he's in Texas where I think they want it to breathe

Great question, but we only install soffit baffles when the home has soffit ventilation. Many of the homes in our area were built without overhangs or soffit vents. In this case we install slant back vents to add intake ventilation. Andy

Thanks! Polyurethane caulk would work just fine in some cases. The reason we like foam is because it is far less expensive, expands to seal all kinds of varied penetrations, can fill voids as wide as 4-6" inches when you learn how to use it correctly, the can and straw can fit into LOTS of tight and difficult to reach areas, like plumbing penetrations that are close to the edges of roof decks, etc, and the cans don't freeze. I've had tubes of caulk freeze in the back of a truck and then become unusable. Cans of Great Stuff can sit in a truck at 0 degrees for weeks, then after running some hot water over them they're ready to go. Hope this helps! Andy

Blower door test with no climate Folie sealed properly before you put the Gipsum board there? It’s useless….

Well, it’s a shame they didn’t air seal the attic first, but that is unfortunately quite common. It is still possible, but not easy. Our teams at Insulwise do it everyday, but it takes some training, patience, planning (as in mapping out the air leaks), and also a willingness to get dirty. It is also more dangerous as the floor joists are obscured. You’d need a headlamp, knee pads, minimum N95 respirator, foam, a willingness to get dirty and a bit uncomfortable for several hours, and some persistence. But it is possible! Andy

Thank you for your reply. That’s what I thought but was wondering if there was any trick. Know any highly recommended experienced technician around Seattle area? Just trying my luck.

Hi there, in your application I don't think it will matter much which side is facing outward to be honest. When we use foamboard to cover exposed walls in attics we face the foil side outward toward the roof because it then acts as a radiant barrier and reflects heat back toward the roof. In your situation it sounds like it will be covered with insulation on both sides? For the cathedral I would attempt to use 2" thick polyiso board. That will give you an R-Value of about R-13 and will likely not allow the inner surface to get cold enough to allow water vapor to condense on it. That's the theory anyway. Hope this helps! Andy

Hi there sorry for the delay. Before you add insulation to an attic you first want to air seal it like we do in this video. But yes, doing both air sealing and insulation work will definitely help the heat to stay in your home more efficiently. Most crawl spaces should be encapsulated. That means insulating and air sealing the walls and then installing a vapor barrier on the ground. Andy

Hi Dan, good observation. We didn't install ventilation baffles because this home did not have any soffit vents or intake ventilation of any kind. We added intake ventilation in the form of a series of slant back vents that we installed just above the insulation line on the back of the home. You can see some of these in the last segment of the video. We sealed the exterior side-wall top plates, but not the front or back exterior top plates due to the low slope. We sometimes offer to spray foam these difficult to reach top plates with two part foam, but due to the significant added cost we only recommend doing this in certain critical situations. That said, all of the exterior walls in this home were insulated with fiberglass batts. The presence of these batts does a decent, but not perfect job of knocking down air flow through them, so we didn't recommend the added expense of spray foaming them with two part foam. Hope this helps! Andy

Hi there, the foam gun that I use in the video is a basic Great Stuff foam gun that can be purchased in most Home Depot or Lowe's stores. However, we also often use the basic off-the-shelf cans of Great Stuff that go for about $5. The flexible plastic straws and smaller can size allow us to more easily air seal the air leaks that we find that are in tighter spaces. That stuff works just as well, just without the fancy gun. The guns like I use in the video also need to be cleaned after they're used or they clog up. Hope this helps! Andy

Hey there good questions. If you need to get through it I'd recommend getting knee pads, a dust mask, and a head lamp. You want your hands to be free in an attic. You will need to use your feet to feel for the floor joists while using your hands to hold onto the roof rafters for support. After you have looked at the area you can brush the cellulose back into place with your feet, hands, or a broom. It's easy to do. But --- BE careful. We are practiced at doing this, but novices can fall through their ceiling if they're not careful. Also, the cellulose should be fine. Here is a link to a video that I took that shows what happens to cellulose after a roof leak. It's fine so long as it can dry out. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-2XQK-Ba1hWc.html&pp=ygUXaW5zdWx3aXNlIHdldCBjZWxsdWxvc2U%3D Andy

You can do that and it may be better in some cases, but we do is inject the foam down into the top plate cracks, wire holes, plumbing penetrations, etc. That way if the batt falls back onto the area that you've just air sealed, it's far less likely to push the foam off of the air leak. Andy

Most foams harden within minutes

@@ajamesc55 My experience has been that foams used from guns like the one shown in our video harden / cure within minutes, but the cheaper foams like Great Stuff for $4-5 a can can take 30-60 minutes to cure depending on temperature. The cheap stuff works just as well, you just have to be a bit more cognizant of not smearing it until it cures. Andy

Hi, there's only a problem with moisture and water vapor if there is a surface present that gets cold enough for water vapor to condense. If this happens mold can start to grow. However, these "pockets" are fully within the conditioned space of the home, and there is a full layer of insulation on top of them. So there is no issue. These are common ways for air sealing cavities in floors of attics. We've been utilizing these same solutions for 15 years in thousands of homes, there's no issues. Thanks, Andy

Hey there, yes it is definitely a chore to air seal when blown in cellulose is present, especially when there is a lot of it. We do have to deal with this from time to time here. And it would be this type of situation where drawing a map of the air leaks before going into the attic would be most helpful. It's just too difficult to find them all otherwise. What we do is standard knee pads, gloves, headlamps, and respirator, and then move methodically through it, sealing as you go. You will be covered in cellulose as you move it out of the way. Your whole attic look like a series of lumps and piles when you're done. At that point we would move back through it and use something like a house hold broom to "swoosh" it back into place so that it's even. Air sealing an attic that is already blown with cellulose is definitely not for the faint of heart. I think it would be nearly impossible to do a good job air sealing from the inside once the house has been finished. You would never be able to get the top plates, wire holes, around bath fans, junction boxes, etc. There are types of recessed lights that can be sealed from the inside, but my guess is that you'd miss 90-95% of the penetrations in the attic floor. That said, I give you credit for trying! Andy

Wood is permeable, but drywall with a few layers of paint on it is generally a "pretty decent" vapor barrier. Think of your bathroom ceiling after taking a hot steamy shower if you haven't turned on a fan, it will be dripping. We seal the penetrations, and then make sure the roof is properly ventilated. If both of these measures are done correctly, it is exceptionally rare to later have a problem with excessive moisture or mold in an attic space. Andy

Hi Joe, you can definitely air seal if there is pre-existing cellulose insulation present. However, it is considerably more time consuming and less fun. Depending on how much is present, it can be a bit like pushing sand around at the beach where you move some, and then it falls back down into the area you were attempting to move it from. You just have to patient with it, organized, draw a good map from below so that you know where and what you're looking for, be methodical, and lastly double check your work --- even if you did it yourself. If a bit of insulation gets onto the foam it won't affect the curing. But if you completely swipe away the bead of foam with your glove or foot, that's a different matter. We air seal attics that are insulated with varying degrees of cellulose fairly often. Hope this helps! Andy

@@insulwiseenergycomfortsolu3293 Thanks for the quick reply! That's good to know, we had a company air seal our attic, add soffit vents/baffles, and add more insulation on top of our existing cellulose. But recently had a blower door test with thermal imaging and it looks like top plate spots were missed or the sealant didn't cure, so trying to get an idea of what's common practice.

@@joelalonde In our area, many of our competitors say that they "air seal." They don't (or at best they do a totally lamo job doing it). Air sealing an attic is difficult, tedious work and lots of companies 1) aren't truly committed to it 2) don't have staff that fully understand how to do it 3) don't want to pay the added expense of time and materials for doing it right, etc. Now, there are some places where we can't always effectively seal top plates, like exterior walls of a low sloping roof. But all of the other places we make a serious effort to get to. However -- it is easy to check to see if they hit the plates or not. If you put your hand down through the cellulose where the top plates, bathroom fans, plumbing stack pipes, etc are, you will either feel a bead of foam on the thing in question --- or you will not. If you don't feel a semi-hard bead of foam -- it didn't get sealed. Andy

@@insulwiseenergycomfortsolu3293 Appreciate the details, thank you

There was zero overhang on this house. If you had an overhang but no soffit vents, we would first stuff / block the overhang with fiberglass and then install roof ventilation in order to get the attic properly ventilated. Andy

You can do it this way too IF you are going to use closed cell foam. Many foam contractors will use open cell foam for this, which is a no no (can contribute to / cause your roof to rot and we have seen this happen in Pittsburgh). However, closed cell foam is very expensive, so most homeowners do not want to pay for this. In fact most foam contractors don't even bring it up. Our philosophy is to allow the roof to operate independently of the air and thermal barrier at the top of the home. When done correctly, this is far less expensive than using closed cell foam, far safer for your roof than using open cell foam, and a highly effective and economical solution. Andy

Hi there, good question. In this case we did not because this home did not have existing soffit ventilation. The gutters are hung literally on the tops of the exterior walls at the edge of the roof. That said, attics ALWAYS should have both intake and exhaust ventilation (but well sized gable vents on homes that have somewhat of an east/ west alignment to catch the breeze also tend to do extremely well). At this home we installed 4 slant back vents just above the insulation layer. You can see light pouring through some of them as I pan across across the back portion of the attic / home. Thanks, Andy

Hi there, we seal the plates regardless of the appearance of the plates in terms of visible gaps or no visible gaps. It's just a matter of habit and keeps our teams from trying to make that judgement. But if you're having difficulty getting the foam to lay where you want it to, you might not be able to do it. It doesn't sound like the plates in question are big leakers though so you may ok not doing them. Hope this helps! Andy

Thanks for the reply. I am actually really glad I came across this channel. There are many tips which I never found elsewhere (like the dust lines under the insulation). Do you have any tips for finding sections of the attic, which have no insulation under the top sheets?. While air sealing I have noticed some sections of the attic seem to have no insulation above the ceiling except a sheet of insulation, which is laying across the beams. Is the only way to really find all of them to pull back every sheet and lock? This wouldn't be a huge problem to do while putting up the baffles, but I was hopeful there was a better way. @@insulwiseenergycomfortsolu3293

@@xSatansGiftx Hi there and thank you! I'm not sure what you mean by sheets of insulation. Do you mean pink batts of fiberglass are laying across the studs? Sheets of foam board? Usually the ceiling fixtures, light switches, bulk heads, walls, etc give you a strong idea for where most of your air leaks will be from below. The ones you can't see from below are plumbing stack pipes that run up through the walls. But if you don't have a bathroom or kitchen in the vicinity of that area, you are likely to not have a plumbing pipe running up through a top plate there. Let me know about the sheets of insulation. Andy

Yes I mean the batts of insulation. In my attic there is some sort of older yellow fiber glass that looks like big cotton balls and the batts laying over top of this. I have noticed while air sealing, that some areas under the batts do not have this yellow insulation and I can see the bare ceiling (after pulling back the batts). I was just hoping you possibly knew a good way to find these spots without moving back every sheet to see the places missing insulation. I am going to be putting in blown in insulation and I am going to try and fill these empty areas under the batts. If the best solution is just to move every batt and look under it, I will just do that. I was just hoping there was some easy way to find these bare ceiling areas. Thanks for the reply again.@@insulwiseenergycomfortsolu3293

If there are air ducts that come up from the house and into the attic, we seal around the ducts with 1/2" foam board and then foam sealant, but any solid material can be used like plywood or even heavy cardboard in a pinch. The goal is to eliminate any way for air from inside the home to communicate with or transfer to the attic. Andy

In this video I used a great stuff foam gun and regular great stuff foam. That said, using regular $4-5 a can great stuff with the plastic straw works just as well, it just takes a bit longer to cure. The cheaper cans can also be more readily maneuvered into tight situations than the gun foam cans as well. Andy

Not a bad idea at all. If you add in a running blower door it gets even clearer. However, if you simply assume that every penetration in the attic floor that you find is an air leak (top plate, wire hole, plumbing stack pipe, gaps around bath fans, recessed lights, etc), and seal it with foam, you should have the same outcome. You're not going to get measurable air leakage through solid drywall, plaster, or framing lumber. Andy

@@insulwiseenergycomfortsolu3293 Like others, my rafter bays are not blocked so air will flow from soffit to soffit in this cape cod's upper floor. You can really see it with the thermal. Now I'm just trying to figure out which foam gun will work best. Looks like the Great Stuff Pro14 has the least offenses.

Hi there, the only time it could be recommended to insulate the underside of the roof deck is if the home has an extensive HVAC system in the attic. And if you do that you NEED to use closed cell foam (because it has a vapor barrier) and closed cell foam is very expensive. We believe in the vast majority of the time there is more risk and added expense than benefit to insulating the underside of the roof. When homeowners want to use the attic for storage we build them raised storage platforms. We have another video that shows that process if you're interested. Thanks! Andy

Lots of people ask this. This house was not built with soffit overhang, so we installed slant back vents on the back of the home to allow the ridge vent to draw outside air. You can see the light coming in from them toward the end of the video. We would NEVER block existing soffit vents. Andy

You could, but --- the reason that we are not proponents of using batt fiberglass in attics is because it's almost impossible to get the batts to conform around all of the miscellaneous obstructions that are located on the attic floor (plumbing stack pipes, wires, bath fans, recessed lights, the roof rafters at the edge of the roof) and you wind up with lots of gaps. I'll attach a link to my site and you can see some pics to see what I mean. That said, I would do the best that I could with fiberglass batts before I used blown fiberglass. But best choice, at least as we see it, is to use blown in cellulose insulation. Good luck to you! Andy

Every house is different, even with the specifications that you provided. If you are in the Pittsburgh area just give us a call and we'll happily come out and quote your project free of charge. Thanks!

Unfortunately almost never, unless it was built as an energy star home and tested with a blower door when finished. Usually if they do anything they will hit the wire holes and plumbing pipe penetrations. The top plates and lots of other misc leaks are almost never sealed.

This attic had zero intake ventilation. We needed to install it in order to balance the ridge vent (exhaust ventilation). We did this by installing a series of slant back vents along the back of the house. That is the light that you see coming through. Andy

Thank you for the compliment! It's tough for me to give an exact figure because every attic is different, even homes in plans that are next door to each other. We generally charge about $1 per sq ft for air sealing, and then extra for large items like stair well voids, bulkheads (dropped ceiling areas), recessed lights, etc. We then charge an additional amount for adding in the extra cellulose insulation at the end, and that depends on how many inches we need to blow in to finish with a combined R-49 insulation level (generally about 15" inches total). Hope this helps! Andy

@insulwiseenergycomfortsolu3293 7 hours ago It's tough for me to give an exact figure because every attic is different, even homes in plans that are next door to each other. We generally charge about $1 per sq ft for air sealing, and then extra for large items like stair well voids, bulkheads (dropped ceiling areas), recessed lights, etc. We then charge an additional amount for adding in the extra cellulose insulation at the end, and that depends on how many inches we need to blow in to finish with a combined R-49 insulation level (generally about 15" inches total). Hope this helps! Andy

You CAN seal around hot flues and chimneys, but it requires a specific process. We cut sheet metal to conform around or butt against the flue or chimney, and then seal the sheet metal to the flue or chimney using HTV (high temperature) silicone. We then wrap either a fiberglass or rock wool batt around the flue pipe or chimney before blowing in cellulose insulation around the area. The main thing is using something to air seal that either cannot combust (sheet metal) or is designed for high heat applications (htv silicone). Hope this helps! Andy

It certainly gets cold here during the winter, but we work in attics year round. There is definitely an adjustment phase to dealing with the heat! Andy

No, this home did not have any soffit vents whatsoever. We installed a series of slant back vents along the back of the roof to provide intake ventilation. You can see the light coming in from one of them in the final part of the video. Andy

@@insulwiseenergycomfortsolu3293 Thanks for the clarification!

We often just use regular Great Stuff for $5 a can. It does just as good of a job and is much less expensive. If your house has a fire, and won't be the type of foam that you used for attic air sealing that makes or breaks the damage the fire does.

@@insulwiseenergycomfortsolu3293 thanks for tip. Like your videos. I gotta say, you guys earn your keep! I am about sick of doing my own attic. I used to say if I went into a trade instead of a desk job I would have done HVAC. I recant my earlier statement after crawling around in our attic for several days. Lol

This house had no soffit vents. We installed intake vents on the back of the house.

This house had no soffit vents, the gutter was hung directly on the exterior wall (there was no overhang). We installed slant back vents on the back of the home to provide a means for intake ventilation. You can see light shining through from some of them at the end of the video. Andy

@@insulwiseenergycomfortsolu3293 wow ok nice, great work....really love the ceiling map idea too

This roof did not have any kind of soffit or perimeter ventilation.

We did not, We map out the air leaks, seal them, and utilize the existing insulation that is there. It makes the project less expensive for the homeowner.

@@insulwiseenergycomfortsolu3293 thank you.

Hi Tommy, what happens is that the drywall pulls away from the top plates, typically after the studs have shrank a bit from their original moisture percentage going down as they dry out. We have blower door tested these top plate leaks plenty of times, they definitely leak. On this other video here that I took from a home built in the 1990's you can see the black streaks running through the fiberglass immediately over top of the top plates. That is from warm air from the house passing through them and the dust in the air getting trapped in the fiberglass. As there is typically a 1/8" gap or larger on either side of the top plate, when added together the combined air leakage in attics from leaky top plates is typically substantial. Sealing top plates should be a major priority for anyone doing attic air sealing work. Link to top plate air leakage visual proof: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-X7GMG3T8cE8.html&pp=ygUrYWlyIHNlYWwgYW4gYXR0aWMgdGhhdCBpcyBhbHJlYWR5IGluc3VsYXRlZA%3D%3D Hope this helps. Andy

Hi, we encounter this type of home a few times every year. Definitely have the knob and tube wiring removed first. We insist on that being done in the homes that we work in. But, if you find a team that can effectively dense pack cellulose insulation, you first want to 1) plug the bottoms of the stud bays in the basement and then 2) use a fill tube and push it as far down the bays as you can and then dense pack the cellulose insulation into the vertical stud bays. If the team has the right gear and technique, they will be able to hit somewhere between 1/2- 1/3 of the exterior walls this way. We would still drill the entire first floor and beneath the windows. You can cap the tops of the stud bays with foam board and foam sealant if you want. But if the bays have been properly dense packed with cellulose, there will be no air or heat coming up through them once this has been done. Hope this helps! Andy

@@insulwiseenergycomfortsolu3293 thanks so much for responding. I just finished having the remainder of k&t removed. While clearing for their work, I realized I shouldn't ignore some of the attic issues much longer

@@insulwiseenergycomfortsolu3293 I also have been blocking and sealing from the basement, and am about 2/3 way around the perimeter. So much to do, so little time

@@SEaudiofan You're welcome, and this would be perfect timing for you to remedy the issues going on up there.

Read previous replies to this question, I address that several times. Thanks!

@@insulwiseenergycomfortsolu3293 Ok, I didn't read all of the replies. You explained what you did in this case. I'm trying to determine if I need to ventilate my soffits and then move back my insulation and install baffles in my attic, OR if it is MEANT to be this way for some valid reason and I should leave it alone. This house was built like this in 1978. It does have three vents near the ridge, but the soffits are all sealed up and there is insulation pushed out to the roofline. I'm in South Central Kansas, "Zone 4." We have brutally hot summers with humidity, and brutally cold winters. Both summer and winter can be VERY windy.

​@@dolfinwriter5389 Ahhh ok I totally understand. Yes -- if you have an unconditioned, vented attic like you have and the one in this video -- you absolutely want to 1) Have an adequate amount of roof ventilation and 2) make sure that that ventilation is balanced between intake (soffit vents) and exhaust (ridge ventilation). If you do not, the ridge vents have a tendency to exacerbate Stack Effect within the home during winter. This leads to added heat loss and increased risk of attic mold growth as additional water vapor from your home via attic floor air leakage gets deposited into your attic. However -- soffit vents DO increase the risk for a roof getting blown off in a high wind storm event. There is a good argument to be made for using closed cell spray foam (NOT open cell foam. Two entirely different materials) to insulate the underside of the roof in areas like this. It will not only insulate extremely well and also provide a vapor barrier --- but it will increase the structural rigidity of the roof --- and not leave soffit vents as a place where powerful gusts can enter and potentially lift the roof off. However, closed cell spray foam tends to be very expensive. If I were you and had an extra $15-25k sitting around this just might be the direction that I would go. Otherwise, you should find a way to install intake ventilation to balance your exhaust vents. At the home in this video we installed a series of slant back vents along the back of the home, about 4. It's not as good as continuous soffit ventilation or continuous under-shingle intake vents, but it far better than not installing them. After air sealing the attic floor, the exhaust vents will now pull their air from these slant back vents as opposed to the house. This helps to dry the attic from unanticipated moisture intrusion, and dissipate summer heat. You can see light coming in from some of them in the final part of the video. Hope this helps! Andy

Hi, not in this case. If you insulate the stairwell side walls and sloped ceiling you have FAR more area that is exposed to hot and cold temps, versus making it a flat plane on the top. So this method will allow for better energy efficiency. However, when stairwell voids like this abut exterior walls of homes, we do fill them in with cellulose insulation as opposed to capping them. Hope this helps. Andy

Thanks for the compliment, but for the time being we only work out of the Pittsburgh, Pa area. Andy

Hi Daniel, thanks for the comment. Yes air and thermal loss also occurs through the exterior walls, and we do also fix that, but this video was only intended to address air leakage that occurs through the attic plane of a home. And judging by a fair bit of the work that we have seen from our local "professional" competition, I would disagree that "everyone" knows how to do insulation. However I would agree that it that it often involves a fair bit of art in addition to science. There is A LOT of onsite problem solving that we perform. Andy

We have had to air seal attics that have already been blown in with a lot of material, typically blown in fiberglass. You have to displace it as you go, double check that you have in fact hit everything, and then rake it back into place. Cellulose is more difficult to displace, it acts like sand on a beach. But blown fiberglass is actually quite easy. The only drawback with blown fiberglass is that it can compact a good bit while doing this. When we retrofit attics, we always air seal them first, and then blow a fresh blanket of cellulose on top of whatever was there to get it 100% even again. But a homeowner likely would not need to get it that "perfect."

@@insulwiseenergycomfortsolu3293 I just had my attic redone this spring to R60 with blown in fibreglass. Before that I airsealed all I could think of myself, any light fixture, and any wiring holes. Thankfully there are no exhaust fans up there since I have a central exhaust system out the side of my house. But I am also not an expert at it either, so I assume I missed something. Having a energy audit done to get in with some govt grant, I have taken my house from 139 GJ of energy a year to 101 GJ a year, according to their before and after readings, and blower door test. So I must of done something right. But even so, I still have some attic frost (I check a few days into a cold snap when we get them) But I dont think its enough to accumulate into attic rain or anything, or if it does, its so light that it must dry out with ventilation. I have my head in my attic at least a half dozen times per year, just to check that things are ok. Would I like zero frost, 100%. But as well, when you have a low of -35 outside with sometimes relative humidity of 70%, that frost can stick to things inside your attic, just like hoar frost outside. Now that I would like to figure out how to mitigate.

Yes, it does. I had to try to convey in a short title that we were air sealing an attic that already had insulation in it. We are retrofitting the insulation in existing homes. Nearly all of them have insulation already in them.

Haha, I had to look up what those were, but I agree.

Thank you, in a simple attic with an experienced team you may be right -- most of the time. However, because of the importance of sealing these things we prefer the additional measure of redundancy. We believe there is a big difference between hoping that you got everything --- and knowing that you got everything. Thanks! Andy

@@insulwiseenergycomfortsolu3293 I understand. Our team uses blower door and thermal imaging for redundancy. But another step that is less costly certainly doesn't hurt.

@@cellocovers3982 We're are big fans of redundancy when it comes to this kind of work. We blower door test in and out a lot of homes that we work on, but not every one. We also perform zone tests on attics from time to time, and I plan to create a video for how that works as well. Thanks! Andy

Correct, that is why we are air sealing all of the penetrations that connect the home to the attic space.

We do it, but you're right it's not fun. You have to first displace the cellulose in the general area, do the work, and then rake the insulation back into place. It's a pain in the butt. We regularly change out bathroom exhaust fans for higher performing models, and of course it's ideal to do it before the insulation is blown in!

Hey there, I can't speak specifically for the work that you had done because we didn't do it, but it is known that cellulose settles by about 10% over time. In cold weather climates this is an actual advantage in attics because the surface of the insulation becomes more dense, making it less possible for colder, denser winter air to "fall" down through it and create convection currents (the R Value of blown cellulose insulation holds up FAR better at temperature extremes than does blown fiberglass). But as for the settling, we blow in about 15" inches of cellulose into attics to reach an R-49 level, knowing that it's eventually going to settle down about 13.5" inches (which is a settled R-49 - 13.5" x R3.6 is an R-49). The R-value of batt fiberglass on the other hand does hold up very well, you just tend to end up with a lot of voids, missed pockets, etc when you use it to insulate and attic floor. Did the guys who did your work for you install depth sticks when they did it? Andy

@@insulwiseenergycomfortsolu3293 Can someone address the sinking effect of cellulose please? I had over 10 inches blown in several years ago. They even left the paper sticks showing how much was blown in. Now it's all level with the rafter tops where you walk. Total waste of money. At least bats won't disappear over time like cellulose does.

@@insulwiseenergycomfortsolu3293 Yes they left depth sticks.

That's as I recall R-30. My issue with Cellulose as a Homebuilder was it blew around the attic. Far too light for a properly ventilated attic.

@@kylephillips9073 Hi Kyle, if you don't have baffles installed at the perimeter you can definitely have this. It's called "windwashing", and with blown fiberglass it's even worse. If the attic is properly baffled this shouldn't happen. We've blown cellulose around boxes that we've built around large, powerful whole house fans, and the air force produced by the fans blowing up into the attic from the home below has not moved the stuff. That said, you could have a different situation that I haven't seen before. I've been at this for 15 years now, and I'm still seeing new things on an almost weekly basis! Andy

Hi there, thanks so much! This attic was approximately 1,000 sq ft. For attics this size to get them air sealed, re-insulated to R-49 with cellulose insulation, the hatch insulated and sealed, bathroom fans vented out, additional roof vents installed, etc we're probably looking at a cost of $3-4k. But that will fluctuate a bit from home to home depending on how much existing insulation is there and what other extra items need to be addressed in the attic. To give an indication of the effectiveness, we have former customers in the Pittsburgh area who have not had to turn on their A/C this year as a result of the attic work we've done in their homes. And that is saying a lot. Thanks! Andy

@@insulwiseenergycomfortsolu3293 Thanks for the detailed reply and pricing. How does a homeowner check that a company has done a good job after air sealing the attic?

​@@palbergwerx.comcreativedir1338 Hey there you're welcome. It's actually very, very hard for a homeowner to confirm this. We have competitors here who've picked up (I believe from us educating homeowners) that air sealing is something that "should get done." But we've found that often that means just sealing around wire holes and maybe some plumbing stack pipes (and sometimes not doing any at all, unfortunately). Basically it's a garbage effort, but the homeowner, unless he's inspecting the the work as it's ongoing, is oblivious. The BEST method is to have the company test in and out with a blower door. We do this often. It tests the air infiltration rate of the house before to establish a baseline, and then we test out again when done. My teams get a bonus when they achieve a greater than 30% reduction. The ultra best method is to combine a test in / out with a blower door with an attic zone pressure test. We do this as well, but not on every house (it can be a bit tedious). But this method tests the house's level of depressurization against that in the attic when the blower door is running. If the house is at -50 Pascals, and the attic is at -48, -49, -50 Pascals that means you have pretty effectively separated the house from the attic. If the house is at -50 Pa and the attic is below -48 Pa (like -40 Pa, etc) that means you still have a fair amount of connection between the house and the attic (and that some big stuff was missed). This is pretty detailed and gets a bit deep into the building science side of things, but in essence you can perform a test using a blower door that will verifiably show you how well your attic has been air sealed. All of our teams carry these devices on their trucks for performing these tests. This equipment is NOT inexpensive, and it requires the teams using the gear to be pretty on their building science details. This is fairly rare in this space. If you're dealing with "Jim Bob's Insulation..." they're likely to look at you as if you're speaking Chinese if you bring this stuff up. You need to find a company that knows what a blower door is, and offers the ability to test in and then test out at completion. Hope this helped! Andy

@@insulwiseenergycomfortsolu3293 Thanks for the detailed explanation. I had my home blower tested (entire house using the front door for the test) and it couldn't reach 50 pascals (1874 Gothic revival). Unfortunately, I've had 3 attic insulation/air sealing quotes and none of them do the attic blower door test or attic zone testing (attic has door/stairs access) - and one of the companies that quoted are the official provincial government energy efficiency rebate tester who actually did my initial home baseline test...