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Thank you! I've seen some videos of roof designs in the UK and they are definitely a bit different. In terms of your questions: 1) Yes you can blow and dense pack rock wool into the sloped ceiling bays, but I don't know how that will interact with "channels" that it seems like are designed to funnel air up through that space. If the channels are closed off from that sloped bay you should be fine. However if they get blocked things may still function ok. We isolate the lower attic from the upper attic when we do our system and it has worked consistently well (the sloped bays are effectively unventilated). 2) You will have to seal off the bottom of the slope bay because otherwise anything you blow in will just blow out into the knee wall space. We usually extend fiberglass batts from the knee walls upward and then "mush" them into the bottoms of the slope bay to create a plug that we can then blow against from above. You don't have to seal anything from the upper attic. That insulation will "integrate" in with whatever you're insulating that upper attic space with. Hope this helps! If you have other questions let me know. Andy

I guess my only follow up, is to point out that i would be manually shoving the rockwool (or fibreglass) insulation down the gap, trying fill as much of the space as possible, using extending tools and flexible rods, rather than 'blowing' the material into the gap. Assuming i can get enough insulation into the gap, I guess it doesn't make too much difference? Thank you Andy for your help 🙏

@@nickbrett5645 Wow Nick, that sounds awfully difficult. If the rock wool is "loose fill" meaning not in pre made batts that would make it much easier, but still not easy. This project is doable, but it won't be for the feint of heart! A great tool for "stuffing" is using an old crutch. When we find them in attics we always keep them for odd purposes like this. Are there not places in the UK where insulation blowing machines can be rented? Are there any contractors there that seem like they may be knowledgeable about this stuff? Andy

The electrical outlets are fine in this process, no fire risk. The process usually blows some dust into the boxes -- which indicates that the holes in the backside of the box have been sealed. That said -- you don't want to do with knob and tube wire present, doing that is against code. Old knob and tube wire does get insulated around all the time, but it's not a "preferred" practice.

@@insulwiseenergycomfortsolu3293 Thank you. So what kind of wire do you have and was there any special set up like putting spray foam around the wires or a special kind of box?

We actually tried. But when the walls are completely empty you actually don't see cold spots, everything is "monochromatic" orange / yellow. You can just see the studs. When the wall bays are partially insulated, like with a bad blown in job, then you can see the blue areas in contrast.

Great question and thank you! The vast majority of bulk heads that we encounter have accessible "open-topped" stud bays down inside them. The top plate for the wall is located at the same plane as the ceiling, so 12" inches or so down the stud bay is wide open down into the house. When bulkheads are sealed off you're right, they're probably not going to leak. We typically seal them anyways because they often have recessed lights in them or as a best practice because they're often removed during remodeling jobs, and when they cut the ceiling open the guys won't have cellulose from the attic dumping on them.

Well thank you. And yes, the surface of the drywall was likely getting cold there, dropping below dew point temperature, and then creating a moist spot on the surface. It doesn't take long to grow mold there when that's happening.

Hello and thank you. This is the link for our attic hatch solution. It requires some carpentry and is designed for a pull down ladder. But it could be just as easily implemented for a smaller "gravity hatch." th-cam.com/video/1CoYbMxrkXM/w-d-xo.html The zippered covers will work better than nothing in a jam. Hope this helps!

Hahaha...I like your plan better with the dual direction roof solar fans. I have not seen an array like that before, but my basic understanding of physics suggests that it would work. Power fans sucking air conditioned air from the home is a disaster -- and it's common. To optimize this I'd think you'd ideally want the fans far from each other, and also far from passive vents (it's all a bit relative) to maximize "cross flow" inside the attic space. Thanks for commenting

Our pads tend to be built over top of interior walls. Those walls provide a solid level of structural support. We've built these in a variety of attics and have not yet had an issue with them stressing a ceiling. I can't say that this would never be a problem, but we've not experienced one, and we've built hundreds of these platforms in attics. Hope this helps!

Thank you for watching! I'm glad you found it helpful.

Great question, I used to do this. Stairwell voids are very difficult to work in and move around in so there's a danger factor (if you slip and fall through, you're then going down a flight of stairs). Other factor is this is FAR more energy efficient. Capping voids reduces their surface area that is exposed to outside temps. All four surrounding walls are interior walls here.

There's no such thing as dry rot. Rot is a function of fungal growth/ ie mold. If you see it rotted and dried later that's because the wood was able to dry. Also, air sealing attic floors prior to insulating has been commonly understood as necessary process for about 30 years now. In fact -- not air sealing attic floors in cold climates -- and having a well insulated attic -- adds significantly to the risk of mold growth in the underside of the roof (stack effect driven air leakage from the home depositing moisture on the underside of a cold roof).

Thank you! Great question. If your knee walls are already insulated with batts the BEST step is to then cover them with a layer of foam insulation board. Here we use 1" thick polyiso board. We leave the silver faced side facing the attic / roof and it then acts as a radiant barrier during the summer. This will help ALOT and is also relatively easy to install.

Thank you for taking the time to reply. I will start with the transition gaps and move on to adding a road radiant barrier (although the stuff I have had foil on both sides….). I have one more question please: I has some old paper backed insulation i side the rafters, it looks like it is part of the roofing felt. From what I have learned so far, this actually serves no purpose so I am thinking it should be removed. Have you seen this type of install before?

@@davidbayes2521 You're welcome. It's best to remove insulation that's against the roof deck, otherwise it can trap moisture against the roof. I have pulled insulation out of roof bays in knee walls and found mold growing behind it on many occasions. Another touch I'd suggest is using foam / caulking to seal the backside of any electrical outlets/ switches in the knee walls before attaching the foam board. Good luck! Let me know if other questions. Andy

@ Thanks Andy. I will keep watching and learning. Looking forward to starting my project.

Haha that's a new one.

Great questions and thanks for commenting. We see this all the time. The attached garage attic only needs insulated if your garage is roasting in the summer and you want to block the heat transfer from the garage attic to the garage below. You just want to make sure that the house is truly sealed off from the garage area as well as you can. Once the attic is insulated with blown cellulose, you can move through it either by walking carefully with feet on the studs or using a kitchen broom to whisk a path. Once done, you kick or broom the material back into place. I've had to touch up / inspect attics that we've already blown many times. Once you get a little bit of a feel for this it's not too difficult, you just need a few things: headlamp so your hands are free, knee pads so you can work, gloves, and definitely a good dust mask / respirator. Let me know if other questions. Andy

You need to have an effective vapor barrier between the conditioned space and the underside of the roof, and you'd also ideally want the baffles to continue all the way to the upper attic (verrry hard to do if drywall is already on the sloped ceiling part). So baffles, insulation, drywall and then drywall sealer/ primer/ layer of latex paint OR spray foam the underside of the roof with closed cell foam (if you're in a cold climate it has to be closed cell foam). When water vapor hits the underside of the roof in a cold climate that's when you get mold growth. Andy

You're welcome! It's all about proper ventilation and air sealing up there, even in Colorado (I'm jealous that you live in CO...one of my favorite spots in the US!)

Great question and no. One slant back vent for each smaller knee wall attic or 2-3 for larger ones will effectively ventilate enough so that moisture does not build up to the point where mold growth can occur. Slant back vents work incredibly well in this role. Undershingle intake vents also work great for this. Andy

You can certainly do it, but you'd most likely need to spray foam the underside of the roof with closed cell foam (for sure closed cell in a cold climate) and that alone is a very expensive endeavor.

Thank you! Yes this can be done in the winter for sure. In many ways it's easier because the attic isn't going to get too hot. We're doing this every day in homes year round.

Water lines not freezing is the first priority here. After we made a "heat tunnel" to trap the heat using fiberglass batts we blew about 9" of cellulose insulation over top of them. It still insulates effectively. This homeowner sent me his utility bill the following month. In concert with our other improvements there his usage dropped 46% year over year --- and that was with colder temps this year And him upping his thermostat from 66 to 70 degrees. This process does not negate anything. The thermal barrier is simply a few inches higher than the air barrier for less than 1% of the attic floor.

@@insulwiseenergycomfortsolu3293 Sorry I came off a little snarky there. Thanks for the explanation. Glad to hear it only 1% of the insulation is above the air barrier and it worked as expected. I work in building performance in AZ and it gets hot here. I love learning how it is done in colder climates. It is amazing how fast you can use R-Value when there are voids/compaction, etc. Thank you.

@@danielboyle2323 No worries at all. I know what you mean. This voided area had no connection to the outside (with batts in garage ceilings that sit on the drywall we see massive issues with convection currents via air infiltration from the exterior rim joist). Voids are not ideal, but in this case it's better than a frozen / burst pipe. I made a longer video doing this at this house where I show a section of burst copper pipe that we found nearby that had been repaired by a plumber). And yes, definitely interesting hearing and seeing how things are done differently in other climate zones. I'll bet those attics in AZ in the summer are a delight ; ) Andy

Thank you for the compliment, we try (and that's what I try to impress on my guys ; )!

No, it's not better. Putting insulation between the heated surface and the water lines is not "more" it's actually "less." The lines previously had pipe tube insulation and fiberglass all around them --- and they froze and burst. After air sealing the attic floor and creating "heat tunnels" with the fiberglass we blew 9" of cellulose over top of this for a combined R-49.

@insulwiseenergycomfortsolu3293 ya ya ya Pipes fully inside the envelope are preferred, but that space between the drywall and the insulation is a grey area. To do it right you need to build a perfectly air-sealed box around the entire length of the pipe AND then fully heat/cool with conditionef air ventation from the inside. Insulation without air sealing works poorly.

Ahhhh the most common question I get here. The house had no overhangs. We installed slant back vents on the back of the home to provide intake ventilation. I point this out at the end of the video..you can see light coming in from the vents.

Thanks for commenting..that should work well for you, cheers.

Thanks for the compliment. Most insulation crews perform a cursory at best air sealing job before blowing in more material. It's half assed at best and will cause your roof to rot at worst. If you live in a cold climate and your attic is well insulated, the attic floor needs to be air sealed.

The insulation apples he is describing are in the attic. Your oranges are in a crawl space. The physics are, you know, different.

The insulation apples he is describing are in the attic. Your oranges are in a crawl space. The physics are, you know, different.

If it's a vented crawl space and gets as cold as the outside, and you're not running that water during a cold snap, they can definitely still freeze. I've seen this happen Many times. If your crawl space has been encapsulated and is now semi-conditioned you'll likely be good.

Every house is different depending on what's there, but usually a few K. Garage ceiling bays are usually 2x8 or 2x10...they eat A LOT of material. The team also has to map the return ducts to make sure to avoid filling them. Garage ceilings are often technical fixes.

Great question and Yes. The wiring is not an issue, but the any ductwork that is not fully sheet metal (panned returns here in Pittsburgh), those bays need to be figured out and avoided. If you dense pack a return it's a straightforward but miserable process to remove the cellulose.

It's definitely worth it. It's an inexpensive way to gauge your home's energy efficiency.

There were no soffit vents, intake vents were installed on the back of the house to provide intake ventilation for the ridge vent. Watch the video until the end and you can see them.

Sometimes yes, but if there is enough room in the door jam between the storm door and the main door it will.

Not a bad idea at all! Hip roofs will have some low clearance areas for sure.

When there are soffit or under shingle intake vents --- yes absolutely. This house did not have soffit vents so we installed a series of slant back vents on the back roof of the home to provide intake ventilation. I point that out at the end of the video and you can see light coming in from them. Thanks for commenting! Andy

Yes and yes. I'll add a link for the youtube short blower door test that we did here. The reduction was around 36% I think for the whole attic. The homeowner sent me a snap shot of their Dec energy bill and we lowered his gas usage (a FAR better metric than gas bill because gas prices fluctuate) by 46! AND that was with Nov/ Dec weather being colder this year than last year AND with him upper his thermostat settings from 66 degrees to 70 degrees. It was an incredibly effective upgrade. Thanks for commenting! Andy Blower Door short shot at this home: th-cam.com/users/shortsTh1R3jz75eU

@ that is a significant reduction!! Great work.

@@kiltedpiper98 Much obliged..the homeowner couldn't believe the results lol. Andy

You are absolutely correct, it brings it "into the envelope / conditioned space of the home." It sounds like you've been reading up on your building science, nice work! So yes if you foam board off / isolate the sections that you can't get to with foam board and foam sealant that will be a huge boost in efficiency for you. Andy

@insulwiseenergycomfortsolu3293 haha, thank you. Yeah, i got an obscene quote to seal and insulate my attic (35k for 2500 sq ft of a challenging attic). so I'm DIY and learning a lot from your videos. Do you have an opinion on froth packs vs the newish Spray foam can insulation likely stanely has? other vidoes on youtube show they work well enough and little more beginner friendly. plus its easier to carry a foam gun around an attic vs two little propane tanks. thanks for all the videos, they're very appreciated!

@@donjay5216 You've just educated me. I've never seen this product before but just watched a video. For a homeowner I would definitely recommend using this over tanks. The tanks are HARD to maneuver in an attic and make the chances of a slip and fall through a ceiling higher for sure. Definitely use a good respirator with chem rated cartridges (full face is the best option) and also make sure to get that duct fairly clean first. If there's duct wrap on it now remove that stuff first. That's an obscene quote to do your attic! We would come in at half that and likely even less. What part of the country are you in? Fire away if you have more questions. I also just added links to a few products beneath the video. Andy

@@insulwiseenergycomfortsolu3293 awesome thanks for the advice on that foam, i'll go in that direction. im in Long Island NY, quote was by a franchisee of the other guy with all the good videos, but i think i got the "we're busy go away quote". it is a complicated attic though. 2400 sq ft, 3 separate access points. pull out old stuff, air seal, add soffits, 40' of knee wall, 80 recessed lights, need to build access to one part of attic. the works. happy new years and thanks for all the help

Great question. The answer is -- it depends. If the batts in your wall fully occupy the stud bay (we see pretty effective batts in walls in Pittsburgh after about 1965) than you're not going to have much luck. If you have a shabby, crappy "first generation" batt that doesn't take up the whole stud bay than you absolutely can still dense pack the bay. Here's the pro tip. When there's existing insulation in the wall you have to drill the wall HALF WAY up the wall, NOT at the bottom. You do this so that you only have to fill tube 4ft up or down, rather than 7-8 ft. This sharply reduces the odds of the batt bunching up in the bay and yields FAR better results. This is where doing these types of retrofits becomes a true art form. Low knowledge, wrong equipment, wrong technique, poorly motivated staff companies will screw this process up at least half the time. Andy

Haha! Yes Bubba was definitely there. It almost looked as if the home was flipped. The duct system wasn't more than 10 years old -- I don't think. And I was stunned by how poorly it had been put together. The improvement in comfort and energy efficiency that this homeowner saw from our attic upgrades there was stunning. Andy