“This is going to be a Bomber system” looks like Matt’s starting to rub off on you 😉 Interesting detail. Looking forward to seeing the result on the blower door
So tight if you slam the door the toilet flushes, hope you have a rock solid make up air system. Always looking for a system that works since we stopped building good houses.
Jake, please follow up on this, in particular the insulation detail. From this video it looks like insulating is going to be a challenge around the plenum.
@@jake.bruton.aarow.building What I still am not understanding is if there’s a risk of the blown in insulation tearing the smart vapor barrier if there is strapping underneath it once all the weight of the blown in cellulose is sitting on top of it. Couldn’t it sag from all the insulation weight until it hits the drywall and possibly tear? Maybe im not picturing it properly or it’s stronger than it imagining but I’m trying to understand as this is the detail I’m wanting to do on my new house build.
Sorry for the lack of detail in this video on the insulation. The attic is vented and insulated with blown-in-place cellulose. The cellulose was installed after the ceiling was in place and from the top side with a single access point from the exterior. This was then closed and sealed on the way out. The remaining space was small enought to not have code required access later. There is enough space from the ceiling to roof deck to get plenty of insulation on the topside to meet a R-60 minimun everywhere. We also supplied insulation shoots to keep things from affecting the air flow of our venting.
Plenum is a great idea. Would cladding the whole ceiling in something like 1/2 ply and taping the seams control vapor well enough for your climate (zone 4)? That seems to be the greatest benefit of the smart membrane. With ply and strapping you’d probably make the trades happy they can staple wires and hang ducting or plumbing anywhere. Cost is probably cheaper than siga too. Thanks to you and Steve for all the teaching you do!
Potentially. We like the Siga products because they limit moisture migration in that smaller cavity space more than simple plywood can. The framing members are easily spotted through the Siga membrane as well so mounting isn’t tough. However, what you are describing would probably work fine.
Can you do a video that will show how the attic will be insulated. I am little confused after closing in the ceiling how to get some areas insulated. This is a vented attic right?
Better to have the mini split unit in attic. I did this same thing with a mini split in a false ceiling in a basement. Works well but is loader than I like. If it’s in an attic it will be quieter. I’m overly sensitive to noise so likely not a problem for others. These units are intended to be mounted in an attic space. I think it is louder than a standard wall hung mini split.
I have a couple units like this in my home that are in spaces like this and do not notice the noise issues you describe. Manufacturer, install, and overall location surely play a roll. Totally understand what you are saying though.
I’m not super thrilled with the triple top plate as it allows a lot of thermal bridging, especially compared to a super efficient advanced framing approach of a single top plate with trusses and studs in vertical alignment for maximum efficiency. You’re doing some really nice pocket headers to maximize the amount of insulation and then kind of undoing the benefit by putting back all that solid framing (and then some) with the triple plates. I love that you’re trying hard to refine ways to incorporate good building science in creative ways (and sharing it with us 😊); I encourage you to carry that thinking through in every detail. I don’t have a solution to offer, just the observation that what you’re trying to accomplish at the transition from wall framing to ceiling/roof framing can surely be done more efficiently. Thanks for the opportunity to learn and share.
Hey Jake - Really like the content. Do you happen to know of any builders south of you in the Northwest Arkansas/Missouri border area that share your attention to detail and energy sensibilities?
Yo Jake. First, thank you. Second, how do you feel about the following OUTSIDE of the air control layer: 1. Mini-split line sets 2. Bath fan duct work 3. Range hood duct work?
I’m not concerned about the lineset. It has to leave at some point. The bath fan actually doesn’t exist, it runs from our ERV system which also doesn’t penetrate the lid. Our range hood in this home doesn’t actually vent. We have electric appliances, and a small filtering hood. The clients don;t cook much.
Even cooking with electric appliances produces lots of compounds and odors you don’t want inside your extremely tight house. Corbett Lunsford documents this thoroughly in various videos on his Home Performance RUclips channel. Besides that, code is most places that I know of no longer allows a non-venting range hood and requires makeup air (separate from the ERV system which is not intended to provide that much makeup air). Not trying to be a troll; you MUST provide proper range hood design and operation in a high-performance home in order to adequately address IAQ.
Siga Majrex is a smart vapor retarder and is air tight. It is similar to poly however allow for moisture flow in one direction. Meaning from the attic into the building moisture can move but from the building into the attic. Science. It laps across the top plate of the wall prior to the trusses being set and tapes to the exterior zip and that is where our continuity of control comes from.
@@jake.bruton.aarow.building and the trippy thing about it being "smart:" in cold weather it actually tightens up and blocks cold infiltration and moisture from the outside coming in... but when things warm up it loosens up and diffuses vapor/etc. from inside to outside. Truly amazing stuff
Any membrane can be an air barrier - that’s the easy part. What’s more difficult is to have selective humidity flow. In general I’m rather skeptical about “smart” vapor retarders. I’ve read up on them a bit, and their behavior is NOT well described in most online materials. In any climate zone where you put a vapor barrier on the interior side of the insulation, the membrane will be at the same temperature year-round, so it’d be pointless if the membrane’s “smart” behavior was based on temperature. And none of the manufacturers really claim that they only let moisture migrate in one direction. From what I can tell from reading online materials, the “smart” membranes vary their permeability based on the humidity level. If it’s more humid (really humid, like when condensation is starting to form), they become more permeable. If it’s less humid, they become less permeable.
I feel like thats just a great forward shift from drywall. Drywall or Poly just isn't going to last the longterm with future renovations. Interior Reno's are more common than exterior so having the air barrier in an area that should stay untouched is better. I like the raised truss idea!
2:07 So if this ducted minisplit unit ever needed servicing or replacing the entire ceiling has to be removed? What is the cost savings of having trusses recessed and still having to frame a second ceiling vs just insulating the roofline and gaining even more storage space and ease of maintenance/retrofit/replacement of HVAC? Seems like its way too much hassle to me.
I believe all duct work should be insulated to be preserve the temperature running through the ducts on its way to distribution. I want that air to hold temp as long as possible. This duct work is no different. As to sweating, probably in this location, it is slightly stale air space, it is probably the hottest part of the house being on the second floor ceiling, and it is high risk if it does sweat because it would stain drywall and potentially mold if it did.
Top notch air barrier system for sure. I can't help but wonder if cost is ever considered when using name branded building materials, and extra materials and labor to achieve these results. ie. if the homeowner saves $1000 per year in heating and cooling but pays an extra $80,000 for the home, is it really worth it?
I would say your example is extreme. This detail probably cost the client $4k, over and above what a competitor would have charged to place a unit in the attic. However, the ROI isn’t the issue at play here. We have the misconception that we build effcient homes for return on investment only. We build for health and comfort. Energy is a by product. Our home is going to be substantially more comfortable than the leaky building with an air handler running through the attic. The return on investment is probably there over a few years but we don’t look at things that way. The same way folks purchase a BMW for something more than a Honda our clients purchase a home from us because their expectations are higher for comfort and performance.
So called branded products are rigorously tested and warranted as a system to assure compatibility. Yes, you are paying a relatively small premium for the assurance that the documented products and installation procedures are compatible as a system rather than guessing and hoping for the best. I learned this the hard way early in my career as an owner’s project manager for commercial/institutional projects and I have no reason to doubt that the same principle applies to residential construction.
Jake, I’m curious about the differing permeability characteristics of the Zip sheathing and the Siga Majrex. Majrex is considered impermeable from inside to outside (0.097 perms or less) and semi-permeable from outside to inside (greater than or equal to 4.25 perms) so the ceiling cavity can dry out if needed. The OSB in Zip, especially with the adhered WRB, is considered impermeable in both directions. This can be beneficial on the exterior envelope-at least in climate zones 4 and below-but may lead to unintended consequences when used in the manner you are using it. From a building science perspective, it seems more prudent to stick with one strategy and design the envelope accordingly rather than mixing and matching approaches and hoping for the best. If I were the owner of that house, I wouldn’t want you to be experimenting with air barrier approaches on my house. Just go with the Siga Majrex to do exactly what it’s designed to do. Otherwise, I love the approach of creating the plenum with the air barrier protected up above all the “stuff” that can be challenging to seal around in the ceiling plane AND allowing your ductwork to be in conditioned space without having to heat and cool an entire attic.
Our homes are very close in cost with any other custom home in the market. Furthermore I would suggest that cost to build vs cost to operate vs comfort is a lot more complicated. I spent a lot more on my home and probably wouldn’t see a ROI however, I would do it all again in a heartbeat because the comfort is incredible.
Hmm…highly flammable light wood framed construction with zip OSB sheathing, probably zip OSB roof sheathing, OSB floors, etc. Will you have fire rated walls or fire resistant roofing? You must be aware of the LA fires. Granted you’re not in the same environment as Southern California, but it amazes me why US hasn’t moved onto more fire resistant houses using mass timber, ICF, CMU, adobe/rammed earth type construction, etc. If these types of construction is out of your scope, at least use fire resistant treated lumber like TechWood. Costs a little more because there’s no economy of scale for these types of construction in the US, but if more builders adopt these alternative methods, prices will drop, the houses will be much more resistant to natural disasters, and last a lot longer than your typical US house that will last around 30-40 years before falling apart.
I would make the arguement that we dont make a return on investment arguement for almost any other feature that a home offers. Countertops? Faucets? Cabinets? Nope, they are all what the clients want. Well, our clients want better comfort, health, and lower energy costs. ROI is a secondary concern. Nice things cost money. To us it seems foolish to build poorly when we know how to do things better.
“This is going to be a Bomber system” looks like Matt’s starting to rub off on you 😉
Interesting detail. Looking forward to seeing the result on the blower door
I can tell you we hit .50ACH50 on this project at final.
So tight if you slam the door the toilet flushes, hope you have a rock solid make up air system. Always looking for a system that works since we stopped building good houses.
An ERV is an important aspect of every effcient home we build.
Jake, please follow up on this, in particular the insulation detail. From this video it looks like insulating is going to be a challenge around the plenum.
The insulation was simply blown in place on the top side of the plenum and wasn’t an issue.
@@jake.bruton.aarow.building What I still am not understanding is if there’s a risk of the blown in insulation tearing the smart vapor barrier if there is strapping underneath it once all the weight of the blown in cellulose is sitting on top of it. Couldn’t it sag from all the insulation weight until it hits the drywall and possibly tear? Maybe im not picturing it properly or it’s stronger than it imagining but I’m trying to understand as this is the detail I’m wanting to do on my new house build.
@@jake.bruton.aarow.building what about the sides of the plenum
is this a vented attic..From the pics it looks like the eaves are vented?
Sorry for the lack of detail in this video on the insulation. The attic is vented and insulated with blown-in-place cellulose. The cellulose was installed after the ceiling was in place and from the top side with a single access point from the exterior. This was then closed and sealed on the way out. The remaining space was small enought to not have code required access later. There is enough space from the ceiling to roof deck to get plenty of insulation on the topside to meet a R-60 minimun everywhere. We also supplied insulation shoots to keep things from affecting the air flow of our venting.
Plenum is a great idea.
Would cladding the whole ceiling in something like 1/2 ply and taping the seams control vapor well enough for your climate (zone 4)? That seems to be the greatest benefit of the smart membrane.
With ply and strapping you’d probably make the trades happy they can staple wires and hang ducting or plumbing anywhere. Cost is probably cheaper than siga too. Thanks to you and Steve for all the teaching you do!
Potentially. We like the Siga products because they limit moisture migration in that smaller cavity space more than simple plywood can. The framing members are easily spotted through the Siga membrane as well so mounting isn’t tough. However, what you are describing would probably work fine.
Ah ya got it. Good point. Someone needs to spray some variable membrane on plywood. That’d be pretty slick. Maybe we can get Steve to invest…
Can you do a video that will show how the attic will be insulated. I am little confused after closing in the ceiling how to get some areas insulated. This is a vented attic right?
the boxed in area at the
perimeter seems like a weak link for insulating
How tall are those c railings ? They look a bit short to me like 8 feet at most ?
Better to have the mini split unit in attic. I did this same thing with a mini split in a false ceiling in a basement. Works well but is loader than I like. If it’s in an attic it will be quieter. I’m overly sensitive to noise so likely not a problem for others. These units are intended to be mounted in an attic space. I think it is louder than a standard wall hung mini split.
I have a couple units like this in my home that are in spaces like this and do not notice the noise issues you describe. Manufacturer, install, and overall location surely play a roll. Totally understand what you are saying though.
I’m not super thrilled with the triple top plate as it allows a lot of thermal bridging, especially compared to a super efficient advanced framing approach of a single top plate with trusses and studs in vertical alignment for maximum efficiency. You’re doing some really nice pocket headers to maximize the amount of insulation and then kind of undoing the benefit by putting back all that solid framing (and then some) with the triple plates. I love that you’re trying hard to refine ways to incorporate good building science in creative ways (and sharing it with us 😊); I encourage you to carry that thinking through in every detail. I don’t have a solution to offer, just the observation that what you’re trying to accomplish at the transition from wall framing to ceiling/roof framing can surely be done more efficiently. Thanks for the opportunity to learn and share.
We do have exterior insulation cutting down on the thermal bridging here. That third top plate is added cost, effort, and reduced insulation though.
Hey Jake - Really like the content. Do you happen to know of any builders south of you in the Northwest Arkansas/Missouri border area that share your attention to detail and energy sensibilities?
Check out Jason and the folks over at Monticello Custom Homes. They work in the Branson and Ozark area. If they can’t help, they might know someone.
@@jake.bruton.aarow.building Thanks a million! I will check them out
Yo Jake. First, thank you.
Second, how do you feel about the following OUTSIDE of the air control layer:
1. Mini-split line sets
2. Bath fan duct work
3. Range hood duct work?
I’m not concerned about the lineset. It has to leave at some point. The bath fan actually doesn’t exist, it runs from our ERV system which also doesn’t penetrate the lid. Our range hood in this home doesn’t actually vent. We have electric appliances, and a small filtering hood. The clients don;t cook much.
Even cooking with electric appliances produces lots of compounds and odors you don’t want inside your extremely tight house. Corbett Lunsford documents this thoroughly in various videos on his Home Performance RUclips channel. Besides that, code is most places that I know of no longer allows a non-venting range hood and requires makeup air (separate from the ERV system which is not intended to provide that much makeup air). Not trying to be a troll; you MUST provide proper range hood design and operation in a high-performance home in order to adequately address IAQ.
Can we get more details on the SIga being an air barrier?
Siga Majrex is a smart vapor retarder and is air tight. It is similar to poly however allow for moisture flow in one direction. Meaning from the attic into the building moisture can move but from the building into the attic. Science. It laps across the top plate of the wall prior to the trusses being set and tapes to the exterior zip and that is where our continuity of control comes from.
@@jake.bruton.aarow.building and the trippy thing about it being "smart:" in cold weather it actually tightens up and blocks cold infiltration and moisture from the outside coming in... but when things warm up it loosens up and diffuses vapor/etc. from inside to outside. Truly amazing stuff
@srchubz Siga’s website seems to contradict what you are saying. It says Majrex is basically impermeable from inside to out (
Any membrane can be an air barrier - that’s the easy part. What’s more difficult is to have selective humidity flow. In general I’m rather skeptical about “smart” vapor retarders. I’ve read up on them a bit, and their behavior is NOT well described in most online materials. In any climate zone where you put a vapor barrier on the interior side of the insulation, the membrane will be at the same temperature year-round, so it’d be pointless if the membrane’s “smart” behavior was based on temperature. And none of the manufacturers really claim that they only let moisture migrate in one direction. From what I can tell from reading online materials, the “smart” membranes vary their permeability based on the humidity level. If it’s more humid (really humid, like when condensation is starting to form), they become more permeable. If it’s less humid, they become less permeable.
I feel like thats just a great forward shift from drywall. Drywall or Poly just isn't going to last the longterm with future renovations. Interior Reno's are more common than exterior so having the air barrier in an area that should stay untouched is better. I like the raised truss idea!
It certainly is more protected.
2:07 So if this ducted minisplit unit ever needed servicing or replacing the entire ceiling has to be removed?
What is the cost savings of having trusses recessed and still having to frame a second ceiling vs just insulating the roofline and gaining even more storage space and ease of maintenance/retrofit/replacement of HVAC? Seems like its way too much hassle to me.
Access panel will be provided.
Will that sweat if it's inside the envelope? Does it still need to be insulated?
I believe all duct work should be insulated to be preserve the temperature running through the ducts on its way to distribution. I want that air to hold temp as long as possible. This duct work is no different. As to sweating, probably in this location, it is slightly stale air space, it is probably the hottest part of the house being on the second floor ceiling, and it is high risk if it does sweat because it would stain drywall and potentially mold if it did.
Top notch air barrier system for sure. I can't help but wonder if cost is ever considered when using name branded building materials, and extra materials and labor to achieve these results. ie. if the homeowner saves $1000 per year in heating and cooling but pays an extra $80,000 for the home, is it really worth it?
I would say your example is extreme. This detail probably cost the client $4k, over and above what a competitor would have charged to place a unit in the attic. However, the ROI isn’t the issue at play here. We have the misconception that we build effcient homes for return on investment only. We build for health and comfort. Energy is a by product. Our home is going to be substantially more comfortable than the leaky building with an air handler running through the attic. The return on investment is probably there over a few years but we don’t look at things that way. The same way folks purchase a BMW for something more than a Honda our clients purchase a home from us because their expectations are higher for comfort and performance.
So called branded products are rigorously tested and warranted as a system to assure compatibility. Yes, you are paying a relatively small premium for the assurance that the documented products and installation procedures are compatible as a system rather than guessing and hoping for the best. I learned this the hard way early in my career as an owner’s project manager for commercial/institutional projects and I have no reason to doubt that the same principle applies to residential construction.
Jake, I’m curious about the differing permeability characteristics of the Zip sheathing and the Siga Majrex. Majrex is considered impermeable from inside to outside (0.097 perms or less) and semi-permeable from outside to inside (greater than or equal to 4.25 perms) so the ceiling cavity can dry out if needed. The OSB in Zip, especially with the adhered WRB, is considered impermeable in both directions. This can be beneficial on the exterior envelope-at least in climate zones 4 and below-but may lead to unintended consequences when used in the manner you are using it. From a building science perspective, it seems more prudent to stick with one strategy and design the envelope accordingly rather than mixing and matching approaches and hoping for the best. If I were the owner of that house, I wouldn’t want you to be experimenting with air barrier approaches on my house. Just go with the Siga Majrex to do exactly what it’s designed to do. Otherwise, I love the approach of creating the plenum with the air barrier protected up above all the “stuff” that can be challenging to seal around in the ceiling plane AND allowing your ductwork to be in conditioned space without having to heat and cool an entire attic.
How did you do concrete floor over basement ?
I don’t believe I follow your question.
@@jake.bruton.aarow.buildingI thought you said you had concrete floor on 1st floor with a basement how did you do that ?
I may have mispoken. We have a wood assembly after the basement elevation.
Access to the mechanicals after drywall?
No access to the duct work, of course it doesn’t require any service. The mini-split has an access panel in the hallway after everything is finished.
Pro builder but legend salesman
This sounds like a job for Big Red and Steve to show us the truss and framing layouts
And exactly what does all this cost per SF?
Our homes are very close in cost with any other custom home in the market. Furthermore I would suggest that cost to build vs cost to operate vs comfort is a lot more complicated. I spent a lot more on my home and probably wouldn’t see a ROI however, I would do it all again in a heartbeat because the comfort is incredible.
Firefighters night mare!
Well they do get to sleep at work so ya
Why are almost all American homes a fire hazard?
I’ll bite. Why is this a fire hazard?
Hmm…highly flammable light wood framed construction with zip OSB sheathing, probably zip OSB roof sheathing, OSB floors, etc. Will you have fire rated walls or fire resistant roofing? You must be aware of the LA fires. Granted you’re not in the same environment as Southern California, but it amazes me why US hasn’t moved onto more fire resistant houses using mass timber, ICF, CMU, adobe/rammed earth type construction, etc. If these types of construction is out of your scope, at least use fire resistant treated lumber like TechWood. Costs a little more because there’s no economy of scale for these types of construction in the US, but if more builders adopt these alternative methods, prices will drop, the houses will be much more resistant to natural disasters, and last a lot longer than your typical US house that will last around 30-40 years before falling apart.
So it’s like a dry wall drop ceiling 🙄
All this extra work, money and time to save a couple hundred dollars a yearin energy? Seems foolish
I would make the arguement that we dont make a return on investment arguement for almost any other feature that a home offers. Countertops? Faucets? Cabinets? Nope, they are all what the clients want. Well, our clients want better comfort, health, and lower energy costs. ROI is a secondary concern. Nice things cost money. To us it seems foolish to build poorly when we know how to do things better.