I got more out of this one video than I did from dozens and dozens of other videos. The price breaks are fantastic! You just saved me days of work. Please do more.
I have 3 crews doing 3 places right now and was thinking of doing this. I’m not doing it. Not for these. I’ll wait for a halo project and up my game in efficiency. But, damn if that wasn’t the most informative video I’ve seen on double studding. I’ve watched a bunch of videos that were much longer and did not give the details that I needed to feel confident enough to try it without the moisture issues that pop up in every other video on this subject. It’s like these builders wanna ACT like they’re showing you how to do a new and awesome technique, while at the same time, withholding those details that complete the picture. Then, they do a commercial. Great video. Very informative and eye opening. THANKS!
@@ASIRIDesigns Very good presentation. I built with double stud walls spaced 4.5" apart for R-44 insulation. Did not spring for the triple pane windows so that is my weak point but with 9.9kW solar array my house generates more energy than it uses each year- with enough extra to power two EVs. The double stud walls do help a lot with noise and since I built them myself the extra cost was not all that bad in 2014. Lumber has gone up a lot since then. Really any competent framing crew should be able to build double-stud and watching this video will educate them on how to install the windows. Thanks for providing the numbers also. One thing people should think about is the long term cost of poor insulation- it is so nice to never have any electric bill.
I could be wrong, since there are so many different materials involved, but I think the double wall system also allows for more acoustic insulation. That may be a consideration for some people, particularly in an urban or busy suburban area.
The stud is the main transmission of sound vibration from side to the other. When the two sides of the wall aren't connected to the same stud, sound is dramatically reduced. Interior walls can use staggered studs, where they are alternately moved a half inch off center from the previous stud. You would need stronger wall material to span twice the distance or put the studs more frequent, like 12 or 8 inches apart.
@@redneckcoder Both contribute, and the dampening effect of insulation helps a lot, but wood is a far greater conductor of sound than air. That's not my opinion. There's charts you can refer to with real measurements of many materials. Having wallboard connected to the stud makes it move together as one, whereas sound hitting between the studs has to transfer from air to board to air to board and then to air again, each time losing energy.
I built custom homes until the mid 1990’s, I am now researching building a 1200 sf dwelling with about 30% of that as a garage. I’m amazed at the changes in the building technology. My design started with high ceilings with lofts and is now no vaulted ceilings. Thanks for the video. I can envision a world in the near future where all dwellings are modular and/or pre-fabled.
Great stuff as always. Double walls also provide a huge reduction in sound transmission for those in noisy neighborhoods. If maximum thermal efficiency is the goal, then double walls are practically impossible to beat. However... the labor costs are a HUGE factor here. The cost to install exterior EPS/XPS will be drastically cheaper than having a crew frame out double walls and the extra details for fenestrations. And for most areas of the country, the difference between R40 (R21 cavity + 4" of rigid foam) and R60 might not even be noticeable. You'd probably be better off putting that extra money into upgraded windows and doors. Building double walls with double-pane windows would be pretty pointless, for example.
Neat stuff! We added 20 inches of insulation outside our log cabin, and to avoid the 'tunnel effect' out of the existing windows, we flared out the window openings horizontally at 45 degrees. The very thick walls then don't block your view!
I built my home in 1985 with 2 2x 4 walls 5” apart, w/ staggered studs & 2 overlapping layers of 6” fiberglass. Clad with 1x6 t&t pine over Tyvek , 6mil poly continuous envelope & 2x2 strapped for wire chase. The only issue I have had is the open nature of the stud arrangement is when a mouse gets in it can freely travel through the entire exterior wall cavity. Today I would build with a 2x4 wall with 3” polyiso in between and 2” over the interior strapped for wire and SR nailing
Even on an R-20 wall most of the energy loss occurs at the windows and doors. Upgrade them and make them smaller for real energy savings. Energy analysis will identify when it makes sense to upgrade the R-value of the walls.
Yes, this touches on something a lot of people don't understand with thermal efficiency. Very small inefficiencies in design can have huge effects. A single double glazed window in a wall can easily reduce the wall's effective R-value by 25-50% depending on wall and window size. The thermal bridging of fasteners for exterior insulation have an outsized effect as well, as well as metal flashings that go from the exterior to the sheathing, bypassing exterior insulation.
Well done! I built in1986 , staggered 2x4 stud walls 5” apart with 2 r19 fiberglass batts. 1 disadvantage is if or when mice get into the wall cavity they can travel freely. Otherwise I would do it again!
I'm totally sold on the double wall design. At the cost is daunting. I have to pay for it as I go. I don't have any kind of a construction loan. And I'm on disability so it's limited funds every month.. my idea was to put up a steel building, like a pole barn, and then frame up a house on the inside. Because I can do that out of the weather. And I can also leave a big enough walkway all the way around for maintenance on the inside of the pole barn. Not your typical construction project LOL. But doing it that way it gets me out of the weather, and I can put it together one room or wall at a time.
Not an expert but it looks to me like the design would be different considering your house is never exposed to the weather or sun? Moisture transfer would be much less of a problem, if any at all. I am researching because I want to build a bedroom and small living area inside a large steel building. I want it well insulated so that it cools easily with a mini-split AC unit in the Texas heat, cold weather is nonexistent therefore not even a thought. Seems with no sun and weather exposure the walls and ceiling could receive the same insulation R value. Just trying to figure out what R value is the most cost effective and efficient?
We have worked with both double wall and exterior Ci. And I would agree with your assessment in terms of cost. Another benefit of a DSW is that at least from the exterior is that flashing and finishing while extremely important to do correctly is quite simple and familiar to most trades.
You know what I would love to see you do? A similar video on the all-out best wall assembly you can imagine, disregarding budget. Joe Lstiburek has a brief mention of the "institutional wall" but really doesn't go into details. I'm curious what something like that would look like. Basically infinite budget, but using actual building materials (no stuffing theoretical aerogel in the wall or something like that).
@@mindtrap0289 Interesting, could you explain more? I'm not a builder or structural engineer or anything, but just curious. I tried googling "p perfect block" and "perfect block wall" and nothing specific really came up.
I would love a video on leaving rafters exposed and insulating outside of the roof. We haven't figured out best way or a way we like yet. Being able to leave rafters exposed with roof board saves finishing money.
In Germany there is a type of wood based insulation popular that you can install onto the rafters. (Steico Dry) It is so stable that you can walk on the temporary wall and is weather proof for a couple of weeks until the finished roof is installed. As a bonus: If you use these wood based insulations you can build you roof without a vapour barrier because it is permeable and capillary active so that condesing water is transported to the warmer (and dryer) side of the insulation. Steico offers details for timber framed buildings on their website, the roof is basically from the inside to the outside: Rafters, Insulation (Steico Dry), sarking membrane (for weather proofing), roof battens, some sort of roof tiles. It is a more expensive type of insulation but you can renovate your roof completely from the outside and keep your rooms as they are without having to worry about the correct vapour barrier.
I was building one of double wall house. Same idea but just regular vapor barrier (polyethylene)inside and regular membrane outside. Wood siding. Blown in cellulose insulation. So many moments about moisture removal weren't addressed a way video suggest. But it has continued insulation through gap between wall and ventilation in attic, so in theory moisture can get out this way, not horizontally, but vertically.
You answered all of my questions about windows and building science (i.e. how is the water management addressed at the bottom of windows to prevent moisture from entering the house.) and I like the price breakdown of the different wall assembly options.
If i was building a double wall assembly, which i always thought of. There would be NO insulation between the interior wall stud, and the vapour barrier would be behind the interior wall. That reduce the potential of hole and leak in the vapour barrier caused by simple things like hangers, frame hooks, electrician, plumber etc... it would leave 2.5 or 3.5inches to run utilities, to install blocking, to hang stuff without perforating the vapour barrier
We installed all our services (plumbing, electrical etc.), then installed the drywall before dense-packing cellulose in our walls. The walls are solid insulation. In a cold climate, anything less would be crazy.
Great video love the density of information here, as well as great explanations on issues with the double wall system, and why they exist. Regarding the 27% increase in material cost however, the amount of cost for labor will be significantly higher then the exterior insulation option, As that requires no special planning, education or oversight of the workers. I will say that, at least theoretically, the performance of this double wall can vastly exceeded that assembly, But I think it’s gonna be roughly a tie cost wise.
Does double wall system retires entirely on competent workers the more importantly experienced supervisors. You're only as good as your weakest link. If you can find a foreman who has done this many times over he will be worth his weight in gold.
There are so many critical areas in this system that have to done precisely. Good luck in trying to find a contractor that will get every detail executed properly. If done improperly, failure can be very expensive to mitigate.
I actually have an article breaking down my thoughts on the T-Stud that I wrote a while back, you can find it here: asiri-designs.com/resources-1/f/is-tstud-wall-framing-worth-it?blogcategory=Walls
Very nice! One thought I'd like to run by you is regarding the windows. Living near a major airport, I've seen some applications where two dual pain windows are installed, one behind the other. The deep walls in your application look like a perfect fit for this, but I was wondering what your thought is on it? Thank you kindly
Thank you for your thorough explanation. My concern is finding tradespeople to do the work exceptionally well at an affordable rate. It would be interesting to know how many years the return on investment would be. It seems the more innovative ideas in reducing electricity costs the more the power companies raise their prices. One must factor in the added increase in power in the ROI.
Great, informative video mate. Been designing my off grid home for over a year and the insulation part has been a nightmare. Prices for exterior insulation are near highway robbery.
For the people living in the US this will of course make your house hurricane-proof as well, which is a nice side-benefit. As a person living in Sweden the shoddy building standards in the US honestly amazes me, triple-glazed windows here are standard, our house is 16 years old now and has triple-glazed windows all-around, proper insulation and a ground-source heat pump, something only a fraction of all the new homes in the US seemingly have. Seems very short-sighted since it saves you so much money in the long run.
Sweden is not even close to the USofA with regard to climate conditions. In the US, the demand is on cooling the indoor environment. In the sunbelt we can have up to 8 to 9 months of cooling required where in Sweden one may never see the need for additional cooling for interior spaces.
@@Wegl79 Well insulation works both ways. It has the same effect in reducing the amount of AC you need to use as it does in reducing the amount of heating you need to use. If you'd place a Swedish house in Arizona it'd still use less than half as much electricity as a US house, because it'd barely heat up in the first place and as such wouldn't need much AC.
i did precast wall with styrofoam as the bottom mold. It got me 4" of styrofoam all around my house and another 4 inches of concrete. I feel the materials are a bit more expensive than wood, but my walls went up in one day and are made in a factory so far less labor mistakes.
Great job. I've been looking at 2x6 24 OC walls with Zip and rigid wood fiber insulation on the exterior but now I'm looking at double stud walls again. So many choices and so hard to decide.
Wow! What an awesome video! Thanks so much for sharing your expertise! It’s given me a lot to think about for when I start the build on my lot here in Texas! 🤠
Blown in cellulose, wool, and other loose fill insulations settle over time meaning the top several feet of a wall may not have any insulation after a few years as it all settle downward compressing the insulation in the lower part of the wall lowering its R-value. Two ways to make a super efficient house ICF construction uses lots of highly insulative foam and the thermal mass of the 6 plus inch thick concrete core plus the fact that ICF homes are super air tight or just use 2x12's and have spray foam installed in two 5.75" thick applications a week or so apart so off gassing can occur after the first application.
What are your thoughts on using a Zip (R6) sheathing instead of the wrap and plywood if building a home in Climate Zone 3 (northern Oklahoma)? We run AC about 90% of the year and turn the heat on maybe 5% of the year. Big fan of your videos… thank you.
Zip-R provides a nice thermal break. But you can get the same or better results with OSB/CDX sheathing + WRB + rigid insulation. Go with whichever is most cost effective. Prices fluctuate a lot these days.
We use square notched timber frames. Window and door bays get spray foam and the bays next to them. The doors and windows get thermal breaks not thermal gaps around them. Usually zip sheating and mineral wool. The timber frame actually saves money on labor and lumber. The mineral wool in my masonry north wall and under slab was expensive. Building a passive solar earthship like Goldie and Matt's but no berm or tires. Plus their framing wasn't well thought out and I needed more roof pitch. I need 70 psf snow loads and 6 foot frost depths also. We use glulam 2x10's or 12's for beams. At 50-75$ for 16 foot beam and can make longer. Lvl need too much lateral bracing. A.I. really helps with cost and design considerations. Sure you have seen how flimsy lvl can be. Which glulam beams allow for 2x4 or less on the flats for double stud walls since not structural. Price goes up on wood every time it gets milled down and more wood stamps cost money too. But if you don't have local lumber mills the price for timber frame jumps. As the cost of shipping increases. It's why we use local masonry material and timbers. Right now shipping on rock and stone cost as much as the rock and stone. 800$ for 40 tons cost 800$ to be dropped on site. We do a lot of masonry work. Why give the cement company the money we could get for labor. We build a lot of A frames and skillion designs. I see where the double studs would be better like earth quake zones. If I build a walk in cooler I will use double studs for sure. Because hvac equipment hanging and on top of them. Set of framing for equipment and one for structure. Minimize the vibrations.
Amazing information and presentation. You helped me to understand a couple B.S. concepts i've been curious about for a while. I've been building with an emphasis on exterior permeability for a few years now. But what happens if you go to all the trouble to make the interior permeable, and then paint over it with a plastic (Acrylic latex) paint? It cuts off all permeability through the drywall, no? I personally like mineral-based paints, but that's certainly not the standard. Thanks again!
Great video. I appreciate the detailed wall assembly diagrams. The pace, visuals, explanations, all good. Question: Do you use standard sized outlet boxes or a smaller box to fit into the service cavity depth?
Thanks so much for the excellent details on this and the cost comparison. I'm interested in discussing a project and filled out the form on your web-site.
Most of the pictures shown when he talks about "dense pack" cellulose are actually "damp spray" cellulose...water is sprayed on the cellulose as it is being sprayed into the wall cavity, which activates an adhesive in the cellulose that bonds it together. It is much less dense than a dry "dense pack" cellulose.
Windows are never efficient compared to even the most basic wall. Installing any window is a sacrifice to efficiency in exchange for beauty. So design your building accordingly. Smart, minimal, and small, and non-operable window placement will always beat trying to increase the efficiency of a window itself. It's possible for double-pane to be the smarter (more economic ROI) choice over triple-pane if you optimized accordingly, and I'm not talking about the whole "passive" house element: which is a good option when you really value beauty, but are still moderately concerned about efficiency. A modern non-window home will always perform better than a window home, regardless of how well you place the windows, or how much money you throw at the windows.
To make an apples to apples comparison with external insulation, you need to include the cost of extending your foundation/slab/floor by at least 7.5" to maintain your interior square footage. Then the double wall requires more labor so exterior insulation might be quite a bit less expensive than you calculate.
I believe that using 4inch poly iso, Zip R 12 sheathing and an r16 2x6 wall will be the cheapest option to get r 53. If your using poly iso as an owner you should look for reclaimed 4 inch poly iso at about $20-$25 a sheet.
Very informative video. I could be mistaken, but I thought it was recommended to use real plywood when is comes to sheathing since it has faster drying time in the event it gets wet. If so, wouldn't that rule out using ZIP system sheathing since it is OSB covered with a fluid air barrier?
Great video!!! Very informative. I wonder if you can do a similar video taking into account the cost of labor (even if it's just the cost of labor in your immediate area, just for comparison) and compare the single wall with exterior insulation, to this double wall system, to a SIP wall system, ICFs systems and perhaps even a HempCrete with Just BioFiber System. Even if you didn't go into all the details as thorough as what this video has, it would be tremendously informative for anyone looking to build a new house to see what the ACTUAL cost of a wall system per square foot is. Again, even if you compare it only in your area, at least, people can gauge apples to apples in one area. They can just do calculations for their areas afterwards.
Wow; that's a lot to take in. I would not want to make a single mistake. Really gave my brain a jog. I know that even the pros can make bad mistakes with moisture.
So, the Intello Plus acts to minimize vapor penetration to the interior of the wall, yet allows any vapors which may accumulate, to migrate from within the wall to the interior space. In the meantime the Blueskin VP100 prevents vapor penetration from the outside environment to the interior of the perimeter walls. Is this a correct understanding?
Thanks for the additional details and process. I've been looking at how to do this on the cheap, especially as we're just doing overbuilt, and I'm doing the labour myself, so I don't mind the extra nuance of making sure we just do it right the first time, and have something that just insanely outperforms at a very modest price bump. Plus, with the way operating costs are going, it seems to make so much more sense to crush it at the onset, and see your savings pay off over time. Who doesn't want to heat an entire space with a small space heater? =p LOL
I'm so glad I stumbled upon this video. Consise, up to the point and covering all details. Subsribed. One note- the l double stud wall will be more labor intensive, would be nice to get a rough idea of increase in man hours.
I designed an built my house starting at 25 yrs old after reading Mother earth news and everything I could find on super insulating and the local building codes for guess 5 ish years, I am a millwright so the drafting, building ect... was something I was comfortable with, also I live in Canada which is very dry in winter with short summers, the foundation is 24 inch thick cement with a floating cement pad sitting on 8 inchs of foam with vapour barrier , the walls are typical 6 inch studs ,outside plywood, tar,papered , then flagstone, they have firestops,insulated,then vapour barrier, then 3 inch airgap , then built another wall 2/4 with firestops holding the electrical , insulated , vapour barrier , drywall , took 10 years to build 2 summers were digging the foundation by hand , it's 2 1/2 storys and about 3000 sq ft , the roof is trussed an comes out to r 60 , the walls r40 , half the house has a crawlspace, insulated and vapour barrier where the plumbing ect... are under the kitchen,bathroom area , the windows are glazed double pane, I think the outside walls breath through the tar paper and cement somewhat and the inside walls I dunno, so far no mold , unless your really anal and seal all the electrical outlets an stuff your going to have air movement , also you have to consider the dewpoint in the wall, where it is, mine is on the outside face of the vapour barrier on the outside wall that breaths, your wall is solid insulation so ? third of the way in I dunno something like that though, finished this house 35 years ago an have no regrets, some things with what is available today I would probably change , mostly the mechanical it has come a long way , I used pink fiberglass insulation today would use that green steel stuff that doesn't burn and is sound deadening, used that in my workshop an it's good stuff but wasn't made when I built the house, the house is very slow to change temp and in the winter if it's sunny will heat itself , it has heavy thinsulate curtains that keep cold/heat out/in, dunno what it would cost to build today i'm guessing alot, the inside walls are fully framed with headers ect... you could remove the outside framing an still have a house as they are framed today, anyone building their own house um if you want to save some miserable work hire someone to do the drywall because that really sucks, aside from that i'm pushing 70 and the work was worth the effort my wife of 49 years an I love it an would never move unless forced by old age. my 2 cents
Amazing information and presentation. I subbed after your vid on vapor barriers being used incorrectly. Your channel has an in credible amount of informative videos and it is going to get big. How would you go about insulating a timber frame home with fully exposed interior framing (posts, beams, bracing, rafters etc)? Structural insulated panels (SIPs) over the outside of the timber frame seems to be the standard, but I don't see many references to SIPs outside of that use case. SIPS seemed to be a hot topic about 15 years ago as the new wiz-bang super-insulation solution but I wonder if there are vapor problems with OSB glued to rigid foam on both sides and why they don't seem to be common? How would you tackle a timber frame?
Great video. I have a brick veneer 100mm cavity, 75mm stud walls with Gyprock interior sheet walls. How's best way to insulate these walls? Will blow in cellulose works?
The cost of this breaks down alright if you've got the money. I'm really curious as to the cost of repair however. Someone with a handheld drywall saw can poke thru that vapor barrier inside. and if you live somewhere with hurricanes. the outer wall could easily be hit and damaged with debris. again damaging the vapor barriers. Not much you can do when your house gets wacked with debris and you've got 7 more hours of whirling rain and wind to go. basically blowing it into the damaged area. Cost of repair is very important to me.
I have an idea for a video if you are intrigued by my question: What would be the optimal way to blend high performance wall design with low frequency acoustic absorption? I would think would would need to move the air sealing barrier further into the cavity, and keep an porous membrane as the interior finishing. Obvious it wouldnt need to be the whole wall assembly - but there must be a good tradeoff to make. Regards - Home theatre/ Hifi enthusiasts everywhere.
Awesome video, I was curious the difference between using a separate ply and air barrier for sheathing on the exterior wall instead of using zip sheathing?
Thank you - Simply put, plywood has a significantly better drying potential compared to OSB, as plywood can become up to seven times more permeable when it gets "wet", whereas OSB does not. The self-adhered membrane is also more vapor open than the coating on the ZIP sheathing. When it comes to these super insulated walls, it's crucial that they have the ability to dry out if/when they get wet.
I recently built a 14'' double stud wall for a slab on grade house. The outside load bearing wall is 2X6, 2' OC with 1/2'' plywood. It is cantilivered 2'' past the foundation and then the foundation is wraped in 2'' of insulation that then has stucco applied to the exposed areas. Another practice I use is to not stagger the studs as it is not necessary with all the insulation in between. Crowned studs can be crowned opposing each other then tied in the centre with a narrow piece of plywood to straighten them out.
You leave the underside of the window frame open to allow any moisture that may penetrate the primary seal around the window to drain out to the exterior, but doesn’t this gap (free of insulation) defeat the purpose of using triple glazed windows and generate a condensation issue? Wouldn’t it be wiser to spend greater efforts eliminating the risk of water penetration in the first place, and filling the gap around the window frame with a closed cell foam insulation? Would like to hear your thoughts on this issue.
maybe consider "celit" as a wheather proof sheating on the outside. or using an extra rigid wood fiber insulation board on the outside. this olaso helps with condesation problems.
Wonderful video and amazing diagrams. Very clear and simple to understand. How does using something like Zip R-9 and 2x6 wall compare to a double wall assembly? Do you have a sense of where it would be as cost comparison?
Could your insulation choices include any kind of hemp product ? Hemp or Hemp-crete lime additive based products don't get used much in north America YET but is hemp insulation even on your radar ?
I’d love to see the cost calculated with labor and materials added… Just in his location, All the additional requirements in the specs cannot be compared apples to apples .
Can you speak to the labor cost between double stud and double outer layer rock wool? Seems like you might end up saving money on labor and window products with ridged rock wool. Also, if you’re going past R40 on the walls.....do you need to?
What is the cost impact of a larger foundation if you need to maintain a minimum interior size footprint. Also, can you provide any insight into how this transitions to an insulated riof with conditioned attic space, continuity of your barriers and ecternally attached eaves? Awesome video BTW showing multiple ways to achieve outcomes.
A larger foundation if building from scratch, is not really a cost at all. Adding more foundation to an existing foundation will cost a bit. Unless you've already maximized the footprint allotted by your State. For example, In some States the maximum is 5000sqft footprint (measured by exterior walls) before taxes go up and environmental land needs to be allotted for wildlife refuge open space. Then the cost is just a waste of money. But, ppl looking to save money probly dont have 5000sqft home to begin with. I may be the exception to that. Looking for 160+ acre land to build now, and I dont have millions to invest in it. But still need a huge house for all the family members. Another topic entirely.
How do you guarantee that the installers won't leave any gaps in the air barriers or flashing? This method is dependent on getting those details perfect.
