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Most of the foams are really pretty similar, we like regular Great Stuff for about $5k a can. The biggest difference is that it takes longer to cure than the more expensive foams so it can be messier until you get used to using it. But for an attic application all of them do pretty much the same thing.

You're welcome! Yes, baffles are a tough deal with these (unless the inside sloped drywall section is removed or the roof area). We've done well over a thousand homes this way and it's a standard weatherization practice in our area. The biggest thing is having the lower knee wall attics AND upper main attic effectively ventilated.

Hi and thanks for your comment! We individually vent those knee wall areas and this case did that with slant back vents. The sloped bays are too difficult to attempt to retrofit baffles into (we used to try). Also, if you were able to put in a baffle, the 2" thick baffle would reduce reduce the R value of insulation in the slope bay by ( 2" wide baffle / 5.5" wide 2x6 joist) almost 40%. When both the lower and upper attic spaces of these homes are effectively vented we do not see moisture / mold problems. And the Pittsburgh climate is a mold maker...we get tons of precipitation and lots of cool (below dew point) weather. Also, here is a link to a fresh Cape Cod renovation video that shows the vent process more clearly. ua-cam.com/video/x_z9FLeg5AA/v-deo.html Andy

Thank you for the reply! How do you go about dense packing the floors? Is the foam board enough to handle the pressure? ​@@insulwiseenergycomfortsolu3293

Hi, glad that it helped!

In a much colder climate it could make more sense. Here I don't believe our customers would ever see the return on that investment (it would raise the cost of the hatch solution dramatically). Thanks for commenting!

All of your passive vents should stay open 365 days a year. In the summer you want the heat to escape, and during the colder months you want the ability for any excess moisture in the attic to be able to escape (as well as heat to help avoid ice dams).

Maybe in the southwest, but I believe in the utility of them up here.

That theory is right, the gable vents will partially circumvent the draw coming up from the soffit / intake vents. However --- we never seal gable vents when we work on homes. I would MUCH rather use the positive pressure from wind pushing through large gable vents then rely on weak stack effect. I have actually solved serious moisture problems in attics by removing the blocking on gable vents. Especially when gable vents are aligned east/ west -- they can work tremendously.

Correct, properly vented roofs do A LOT of good.

Interesting, it's amazing the differences you can see in homes that exist in different climate conditions. I personally don't have any experience with that.

Thanks so much! It only took a few thousand hours of working in attics to start connecting all of the dots between stack effect, moisture getting into attics from the home (and roof leaks), temperature variables, air sealing, proper ventilation, etc. lol. Glad this helped you!

Those aren't holes, they are black plastic plugs that were inserted into the holes by a duct cleaning team. They seal pretty tight and did show any effect of leakage.

The passive vents work together as a system with the roof power fan. If not configured correctly, the fan becomes wasteful at best.

My pleasure!

Thanks. We install these all the time in attics with tighter, trussed types of roof systems. But you do want to have at least a few feet of overhead room, correct.

You could certainly double, triple, quadruple the R-Value, etc by adding more foam board. But that 2" inches of XPS foam board will eliminate about 90% of the temperature transfer coming through from the attic. We do this to keep costs down for our customers and in my own mother's home I used the exact same design. Except in extreme situations, I would be surprised if you could notice a temperature / comfort difference or impact on a heating / cooling bill by adding additional layers of foam board to these hatches. They usually occupy about 1-2% of the attic floor area and the rest of the area is air sealed and insulated to R-49.

The first goal (generally) is to keep the house cool which we accomplish by air sealing and insulating the attic to an R-49 level with cellulose insulation. But if your goal is truly to cool your attic, then roof power fans can work well --- when they are sited properly with reference to passive roof vents for make up air --- and when there is enough NFA (net free air) being supplied by the passive vents to avoid the fan pulling air conditioned air up from the home.

@@insulwiseenergycomfortsolu3293 yeah, you can spend 20k trying to re-insulate your attic and save about $50 a month on your HVAC bill. Or you can just put in a $300 attic fan or even 2 for a total cost of $700 and accomplish 95% of what 20k gets you. The best you're ever going to do is cool your attic down to the temperature of the outdoors. If it's 110 outside, your attic is going to be 110 sooner or later in the day.

Hi there, thanks for the kind comment! We do everything we can to help homeowners understand why their homes are not as comfortable or energy efficient as they'd like them to be, and then show our unique and effective ways of remedying those issues. We look forward to seeing you in a few weeks!

With a well insulated attic -- and it sounds like yours is -- the higher thermostat setting is better. When our customers have these fans that is what we set them to after air sealing and insulating their attics. As you have found you will get a lot more longevity out of that fan.

These are what we use. They work quite well and are around $100. www.amazon.com/gp/product/B07MFNBV8D/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

You're welcome and thanks for the comment! I was air sealing an attic on a 90 degree day last week could actually feel cold air blowing up from some of the wire penetrations and top plate air leaks (not exactly what you would expect, but it happens). The homeowner saw an instant cooling improvement from the air sealing just like you did. Nice work! Andy

If you don't mind the extra work there's ways to make a system like that work, for sure.

The prongs were located about 2/3 of the way down.

Rockwool definitely ways more than cellulose does, it can be very heavy. Our homes in Pittsburgh can absolutely withstand adding 15" of cellulose insulation to dry wall ceilings.

If you have ridge and gable vents those are both considered exhaust vents (but east / west aligned gable vents can be highly effective). Without intake vents in the form of soffit vents or undershingle intake vents, it's likely that your attic isn't allowing much heat to escape it. Attic insulation can help A LOT. We insulate with blown cellulose to R-49 (about 15") and air seal the attic floor first. When this is done there will be virtually no heat transfer from the attic to the home. If you cannot insulate more, I'd definitely recommend finding a way to add passive intake vents. You could also add a roof power fan or solar roof power fan --- BUT, if the fan doesn't have enough make up air and / or is not drawing air from across the attic, the effect will likely be limited or worse you could draw air conditioned air from your home. In your situation I'd look into adding intake vents lower down on your roof, possibly with slant back vents (they're designed for exhaust, but will also work as intake vents) and possibly installing a solar power fan in the middle of your roof (in between the ridge and intake vents). That would produce the best effect for you. Good luck with your project!

Good luck!

Thanks! A few months ago we went back to a home and installed magnetic stickers to the louver. That made it a bit harder to "rattle" during wind events. The stickers were about $10 at Home Depot

@@insulwiseenergycomfortsolu3293 Now that’s a damn good idea! That would definitely be worthy of another video. But I would recommend talking on that video to help the viewer understand what you’re trying to demonstrate. Good luck!

Glad that you found it helpful!

I think it's just marketing muscle and if that's what your company sells that's what you push.

Hmm..I've seen a few houses where that was done, but you end up having a fair bit of useless space at the bottom of the triangle. I have also seen where shelving / dressers have been built into the knee walls to better utilize the space. Those things get tricky to insulate though on the back end / knee wall attic side. The simplest way IMO is to leave it as is. If you use the methods that I've shown here you'll have good results. There's always ways to optimize it / make it better, it's just a matter of the time and money that you want to spend on the project. Good luck to you!

Thanks!

That's not right. In the model number there should be a number that is divisible by 6 typically. If it's 18 that means 1.5 tons. If it's 36 that means 3 tons, etc.

@@insulwiseenergycomfortsolu3293 the M/N: ML14XC1-047-230A03

@@insulwiseenergycomfortsolu3293 M/N : ML14XC1-047-230A03 S/N : 1922A44682

Sorry for the confusion. This attic was already insulated years before we got there. The video was for showing people with an already insulated attic how to find and seal their air leaks.

We see this done from time to time and it depends on the type of ridge vent that was installed. Some of the fabrics allow plenty of air flow, but some of them (like home wrap or ice and water shield ugh) will be highly restrictive. You could always test it with an incense stick or something else that will produce a visible draft. On a warm day you should be able to see the smoke go right out if it is drawing air.

Glad that you found it helpful!

That is the correct theory. What I have found in practice on a number of occasions is that removing the covering (placed by roofers) over the gable vents allowed for a strong breeze to through the attic (very effective on homes with east / west alignments). My guess is this view will be contentious, but I've solved some nagging attic moisture problems by doing it.

Thank you, done and done. I got a mic a few months ago.

@@insulwiseenergycomfortsolu3293 awesome, look forward to new videos

We would not insulate the gable ends inside the knee walls in an attic like this.

I wasn't there to prove that the attic was depressurized when the fan was operating, I was there to show an example of how not install a powered attic fan (right next to a ridge vent) and also highlight that these fans CAN depressurize attics when not enough make up air is present.

In this attic we spray foamed the solid metal ducts, air sealed the attic floor, and then blew the attic to R-49 with cellulose insulation. That process dramatically reduced the cooling load of the home, and is highly effective at reducing cooling loads in nearly all the homes that we work in. Is that something that you've considered?

It sounds like you had a whole house fan. These are mounted in the ceiling of the home, not the roof itself and function the way that you describe. In dry climates they can work great (in humid climates they just pull hot humid air into the home..not the best feeling).

Thanks, the main thing is making sure your intake air is 1) enough to adequately supply the fan size and 2) that it comes in from as far from the fan as possible (ideal from the soffits

You're correct, we see insulation blocking soffit vents all the time and have to remove it and install baffles correctly

I'm aware of this "rule" with the vents, the idea being that gable vents short circuit some of the flow between ridge and soffit vents. I'm sure that is true. However, I have seen many cases where east/ west aligned gable vents do a phenomenal job of moving air through attics because they take advantage of natural air flows. I have even solved a few serious condensation issues by unblocking gable vents that had been blocked by roofers after they have installed ridge and soffit vents. The most notable being an obvious whoosh of cool outside air blowing through one of them as soon as I removed it. I no longer adhere to this rule. For me it's a case by case basis depending on the orientation of the home.

What my experience has been is that the air from the fan and ridge vent re-circulates in a relatively small area. And on a sunny day that air will be going over top of a roof that can be 150-170 degrees -- as opposed to coming in from soffit, undershingle intake, or even gable vents. The air in that one location could be cooler, but the air will not be getting drawn from across the attic --- which is what you want. We've worked in hot attics with these things running all day when they've been placed in close proximity to a passive vent (usually a ridge vent), and there's very little if any impact on temps in the rest of the attic (it was as annoying as it was enlightening!).

You're welcome!

Great question. I first saw an undershingle vent in 2014. The openings inside the attic seemed extremely restricted (we later had mold issues in this attic which is not a good indicator of effectiveness). Since then I have seen many more undershingle intake vents that were obviously moving air and appeared obviously effective. I don't have much experience with how snow impacts them tbh, but nearly all of them have a mesh layer somewhere that I think would reduce the level of snow that could get sucked in. I think the roofing companies would have headed off that problem a while ago (one would hope!).