Great stuff as always. In my area of New England the vast majority of framers are still doing 16" and honestly I'd rather have my builder do what's comfortable for them and add some extra exterior insulation to make up for it. And for triple glazed... I want them for the comfort and lack of condensation.
Yep can’t wait to do 24” OC double 2x4 staggered wall system for my forever home some day. All exterior walls like that but then might do that for bedrooms or at least master to help with noise too.
Good Stuff! The other thing to point out when you "unbalance" the wall with crappy windows and high R value in the rest of the wall, is that heat flow will take the path of least resistance, the greater the delta-T the greater the movement. R40 wall with R-3; you could probably see air movement in the house ;-)
Steven: When you started talking window performance, I got curious, so I popped open a blank spreadsheet. I used your percentages for opaque, cavity, and windows/doors. And I used your numbers for R-values. My total effective R-value for a complete wall assembly with studs on 16-inch centers is *15.0.* And my total effective R-value for a wall with studs on 24-inch centers is *16.2.* I then asked myself how that would change if the windows were not R-3, but R-6. With R-6 windows total effective R-value for a 16-inch O.C. wall is *15.4* and total effective R-value for a 24-inch O.C. wall is *16.6.* That Minnesota study is both sorta right, and terribly wrong. If looking only at the power bill, improving total R-value by *0.4* is hardly worth it. However, plunk a couch down in front a picture window then set your butt down to watch watch a movie on your big-screen TV.... Yeow! Minnesota is so very, very wrong.
@@stevenbaczekarchitect9431 Thanks. I'll look into it. I've read somewhere that R-value was invented by fiberglass batting companies to make their product look good, and that they wrote the rules on how R-value is measured. What I know is it only covers conductive heat flow, and then in a limited way. Again to make fiberglass insulation look better than it really is. Windows are never sold by R-value.
@@ScottyDMcomNo, R-value was created to make the complex heat transfer math easier. The R-value is derived from various physical properties (primarily thermal conductivity) in order to get an equation similar to Ohm's law used in electricity where the driving force of voltage is represented by the temperature difference across the wall, the energy flow of current is represented by the heat transfer, and the resistance to that flow is represented by the R-value of the materials that make up that wall. This gives an equation that says the heat transfer through the wall is equal to the temperature difference across the wall divided by the R-value of the wall. Thus, to reduce the heat loss (or gain during summer) you have to increase the area weighted average R-value of the entire wall assembly. That is why continuous exterior insulation is one of the best things you can add to a home to improve its thermal efficiency, since it contributes to raising the R-value of both the opaque and cavity areas of the wall. It is also why you have to use U-value (which is just the inverse of R-value) to calculate the average R-value of the wall assembly, because you are adding resistances in parallel, not series. In other words (1/R_total) = ((1/R_opaque)×area%_opaque)+((1/R_cavity)×area%_cavity)+((1/R_WD)×area%_WD). Using this formula and Steve's example numbers gives a total wall assembly effective R-value of 8.48 for 16 inch on center framing, 9.26 for 24 inch on center framing, 10.76 for R-6 windows with 16 inch framing, and 12.06 for R-6 windows with 24 inch framing. However, code in climate zone 6 where I live requires at least R-5 of exterior insulation, so if we add Zip-R6 sheathing to the wall assembly with 24 inch on center framing and R-6 windows we get a total wall effective R-value of 15.83, which is a pretty decent wall assembly compared to the original 16 inch on center wall assembly.
@@r.j.bedore9884 Thanks. Mathematically I knew U and R were reciprocals of each other. But the biggest question in my mind had been, is it truly as simple as that? I was under the impression that U-value for windows took into account factors like frame vs glass, low-E coatings, etc. That U was more than simple heat conductivity. I didn't keep my original spreadsheet, but I'd be worth recreating it and doing all the calculations as U-values.
@@r.j.bedore9884 Wow… Thank you for that !! Fantastic write up…! Very helpful description & analogy, & now I can calculate and analyze budget vs cost and savings over time…!
Got a question from my younger days: in the 80s, my friend had a home built using 24" and it was terrible. Now I'll give you it was built by a production builder, but the walls sagged, the floor shook when anyone walked anywhere in the house. Of course that told me to never use 24". What did they likely do wrong; what would have made it a solid house?
Great video Steve. Side Question: In a double wall scenario, would you offset the interior wall to be 12”oc to the exterior wall? I want to find some way to make the double wall an added strength component, but I’m not sure that benefit can be gained while trying to avoid thermal bridging, whether the walls are staggered or not. Thanks
Would you favor or oppose the inclusion of a gusset plate tying each 24” oc stud between the ext & int framed walls? Looking for ways to increase structural performance in a windy Midwest plains environment.
Hey Steve, great video. Maybe when they did their window calculation, they also did a long-term calculation of the difference in cost between upgrading upgraded windows vs. just paying a higher energy bill, and maybe the breakeven point was too far in the future for them to care about. But that doesn’t take into account at all wasted energy and an inefficient home being a bad idea to start with. I’d much rather have low energy bills for the lifetime of my home, then worry about it being a problem way down the road.
Love your channel and great information. Have you ever discussed an interior rigid foam insulation under the sheetrock and what does that look like for adding R factor? Thank you
That’ll result in two vapor barriers with building materials sandwiched between I would imagine. Your exterior vapor barrier and your rigid foam inside. If you don’t have a vapor barrier outside, it’s a silly place to put it. Not helping either side of the wall system.
Putting foam under the drywall like that will increase the average R-value of the wall assembly, but it will also cause your studs and sheathing to be colder and increase the likelihood of condensation forming inside the wall. A better place to put that foam board is on the exterior between your WRB and your siding, preferably with a rain screen between the siding and insulation as well. This will give you the exact same effective R-value, but will significantly reduce the chance of condensation and moisture buildup within the wall.
We use 24 inch stud spacing on our post and beam timber frames. The studs are just there to attach insulation and sheating. The timber frame takes care of the structural loads. We use thermal breaks around windows and doors. To keep low r value windows and doors from cooling or heating the wall around windows and doors. It takes care of the condensation zone around windows and doors. I agree it's worth getting the better r value windows and doors. Windows and mineral wool insulation are the most expensive part of my cottage.
Doing staggered 2x4 @24"OC in a 2x6 wall with R9 ZIP on the outside, then 2" of closed cell, followed with open cell to finish. I will then do Quicktie cables to give me the uplift and shear needed, along with appropriate nailing for the exterior. (Structural and Mechanical PE here) My price on triple glaze from EAS was 50% more than top of the line Kolby. Hard to justify. Nice Haircut
@@stevenbaczekarchitect9431 if you can get me a better price on 19 doors and windows from them that would be great. And, I cannot get a wind and hurricane impact from them.
In my area 2' on center studs has been common for 30+ years. It does cause issues with the stacking of the studs with the 16" on center floor joists, they don't all line up and carry the load vertically down through the structure which is not a big deal the house won't fall down, but it can be unhandy having the stud in the middle of a floor joist cavity if the mechanical contractors and plumbers need that cavity for a duct or a drain to go down thru the wall and will be forced to move the stud. The biggest structural issue I see in these videos is this foam backed Zip sheathing and it's shear value being rather poor compared to wood sheathing properly nailed directly to the studs. Nails going through foam is not a good sheathing.
on the shear concerns, I guess it depends on the risk factors of your area. Some localities have allowed for just a few shear components (two outbound sheets of plywood on any given wall or let in bracing) and houses have withstood decades without the modern shear components assumed. While you would never get away without some good engineering letters in doing your own 'stand-off' sheathing installation, I would think a full covering of zip would counter most risks of shear.
I just saw a video where the framers used an LVL joist as a rim board for the trusses on a monopoly framed house. He said that it increase R-value and you don’t have to building headers. Anyone ever tried that? How did it go?
On paper the whole wall R-value of double glazed + R40 cavity insulation seems a lot better than triple glazed with R21 cavity. They probably just did this math and figured it is purely a numbers game. Total R-value came out at R29 vs 17R in my calculations. I think that they underestimated the comfort triple glazed windows offer. It seems to me that a balanced wall with an R-value that's pretty balanced between windows, studs and cavity would offer far more comfort and maybe better real life results than making up for 'bad' studs and windows with a higher cavity insulation (considering the total R-value of both walls is the same). Someone I know build his house with continious 6 inch polyiso around his masonry walls but opted for double glazing cause he figured triple didn't make financial sense...
a comment above mentioned that heat will find the path of least resistance. The whole wall R-value is a flawed concept in that regard. The heat doesnt encounter R29 vs R17. The windows are always the weakest link in the assembly and making those better improves real world performance beyond the modest uptick in whole wall R Value
I don't know how to 'average' the R values. But most people don't recognize that insulation R value is basically in the middle of the cavity. If you have a bigger cavity then you get a bigger middle. Okay, we are talking 6 inches from the edges. Top bottom left and right,Right? If you get X with 6 inch insulation, it stands to reason you have to go sideways from your stud as well. The opaque stud isnt just transferring heat from drywto outside sheathing across 1.5 inches. Heat is also leaving the sides into the insulation. Remember, 6 inches deep. The first couple of inches of cheap pink stuff is just letting heat flow thru it at its edges. But lets say you have 140 feet of exterior walls, and we want basic simple math. Obviously it is 70 boards for 24 o.c. Change up to 105 boards for the 16 o.c. Sure, there may be extras at corners. But that's the case regardless of your spacing; lets not count them. Multiply you board count by their width which is 1.5 inches then divide by 12 inches to get the length of wall that is opaque. Then consider the extra 35 boards and the edges of insulation; equal to another 35 feet of less than what you Thought you were buying. The approximate answer is 9 ft versus 13 feet. Now, let's say you can choose 2x4 if 16 o.c. Your R value just declined even more. Yeah, some may only say R6 or R4, no big deal. But isn't sweet sounding to say R6 in 9 feet of walls compared to R4 in Thirteen feet of walls - that's like a big sliding glass door you cannot open or see thru. Steve designed Jakes House in Missouri. Matt R and Jake had a very exacting conversation about these dimensions, right down to lumber cost and labor. The difference is Jake used 2x8 and ended up with R42 walls. So he is toasty in sub zero January And he can't hear a nearby busy road. See 'Why would you use 2 x 8 walls Matt Risinger'. Its about 3 years old. Find a video of someone using a thermal imaging device outside of a house in the winter. It will demonstrate the heat loss isn't confined to 1.5 inches.
Great stuff as always. In my area of New England the vast majority of framers are still doing 16" and honestly I'd rather have my builder do what's comfortable for them and add some extra exterior insulation to make up for it. And for triple glazed... I want them for the comfort and lack of condensation.
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Thanks for showing the math and concept behind the r value equation. Great stuff!
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This also does a good job showing how huge of a benefit staggered wall framing is. 👌
AGREED
Yep can’t wait to do 24” OC double 2x4 staggered wall system for my forever home some day. All exterior walls like that but then might do that for bedrooms or at least master to help with noise too.
Good Stuff! The other thing to point out when you "unbalance" the wall with crappy windows and high R value in the rest of the wall, is that heat flow will take the path of least resistance, the greater the delta-T the greater the movement. R40 wall with R-3; you could probably see air movement in the house ;-)
Excellent video, keep making them like this, showing the difference on paper
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Steven: When you started talking window performance, I got curious, so I popped open a blank spreadsheet. I used your percentages for opaque, cavity, and windows/doors. And I used your numbers for R-values. My total effective R-value for a complete wall assembly with studs on 16-inch centers is *15.0.* And my total effective R-value for a wall with studs on 24-inch centers is *16.2.* I then asked myself how that would change if the windows were not R-3, but R-6. With R-6 windows total effective R-value for a 16-inch O.C. wall is *15.4* and total effective R-value for a 24-inch O.C. wall is *16.6.*
That Minnesota study is both sorta right, and terribly wrong. If looking only at the power bill, improving total R-value by *0.4* is hardly worth it. However, plunk a couch down in front a picture window then set your butt down to watch watch a movie on your big-screen TV.... Yeow! Minnesota is so very, very wrong.
No offense your numbers are probably wrong, you have to convert to U value, do the average, then convert back.....can't use R Value numbers
@@stevenbaczekarchitect9431 Thanks. I'll look into it.
I've read somewhere that R-value was invented by fiberglass batting companies to make their product look good, and that they wrote the rules on how R-value is measured. What I know is it only covers conductive heat flow, and then in a limited way. Again to make fiberglass insulation look better than it really is. Windows are never sold by R-value.
@@ScottyDMcomNo, R-value was created to make the complex heat transfer math easier. The R-value is derived from various physical properties (primarily thermal conductivity) in order to get an equation similar to Ohm's law used in electricity where the driving force of voltage is represented by the temperature difference across the wall, the energy flow of current is represented by the heat transfer, and the resistance to that flow is represented by the R-value of the materials that make up that wall. This gives an equation that says the heat transfer through the wall is equal to the temperature difference across the wall divided by the R-value of the wall. Thus, to reduce the heat loss (or gain during summer) you have to increase the area weighted average R-value of the entire wall assembly. That is why continuous exterior insulation is one of the best things you can add to a home to improve its thermal efficiency, since it contributes to raising the R-value of both the opaque and cavity areas of the wall.
It is also why you have to use U-value (which is just the inverse of R-value) to calculate the average R-value of the wall assembly, because you are adding resistances in parallel, not series. In other words (1/R_total) = ((1/R_opaque)×area%_opaque)+((1/R_cavity)×area%_cavity)+((1/R_WD)×area%_WD).
Using this formula and Steve's example numbers gives a total wall assembly effective R-value of 8.48 for 16 inch on center framing, 9.26 for 24 inch on center framing, 10.76 for R-6 windows with 16 inch framing, and 12.06 for R-6 windows with 24 inch framing. However, code in climate zone 6 where I live requires at least R-5 of exterior insulation, so if we add Zip-R6 sheathing to the wall assembly with 24 inch on center framing and R-6 windows we get a total wall effective R-value of 15.83, which is a pretty decent wall assembly compared to the original 16 inch on center wall assembly.
@@r.j.bedore9884 Thanks. Mathematically I knew U and R were reciprocals of each other. But the biggest question in my mind had been, is it truly as simple as that? I was under the impression that U-value for windows took into account factors like frame vs glass, low-E coatings, etc. That U was more than simple heat conductivity.
I didn't keep my original spreadsheet, but I'd be worth recreating it and doing all the calculations as U-values.
@@r.j.bedore9884 Wow… Thank you for that !! Fantastic write up…! Very helpful description & analogy, & now I can calculate and analyze budget vs cost and savings over time…!
Got a question from my younger days: in the 80s, my friend had a home built using 24" and it was terrible. Now I'll give you it was built by a production builder, but the walls sagged, the floor shook when anyone walked anywhere in the house. Of course that told me to never use 24". What did they likely do wrong; what would have made it a solid house?
That sounds more like a floor joist problem
Great video Steve.
Side Question:
In a double wall scenario, would you offset the interior wall to be 12”oc to the exterior wall?
I want to find some way to make the double wall an added strength component, but I’m not sure that benefit can be gained while trying to avoid thermal bridging, whether the walls are staggered or not.
Thanks
You can, in a double wall there is less need
Would you favor or oppose the inclusion of a gusset plate tying each 24” oc stud between the ext & int framed walls?
Looking for ways to increase structural performance in a windy Midwest plains environment.
Hey Steve, great video. Maybe when they did their window calculation, they also did a long-term calculation of the difference in cost between upgrading upgraded windows vs. just paying a higher energy bill, and maybe the breakeven point was too far in the future for them to care about. But that doesn’t take into account at all wasted energy and an inefficient home being a bad idea to start with. I’d much rather have low energy bills for the lifetime of my home, then worry about it being a problem way down the road.
Great video!
What is the actual “Whole Wall” r-value of each wall in your comparison?
THANKS FOR JOINING IN
The whole wall average R-value is 8.48 for the 16 inch on center wall and 9.26 for the 24 inch on center wall, using the numbers in Steve's example.
Thank you - exactly the info I was looking for!
Love your channel and great information. Have you ever discussed an interior rigid foam insulation under the sheetrock and what does that look like for adding R factor? Thank you
I haven't, not a path I'd subscribe to
That’ll result in two vapor barriers with building materials sandwiched between I would imagine. Your exterior vapor barrier and your rigid foam inside. If you don’t have a vapor barrier outside, it’s a silly place to put it. Not helping either side of the wall system.
Putting foam under the drywall like that will increase the average R-value of the wall assembly, but it will also cause your studs and sheathing to be colder and increase the likelihood of condensation forming inside the wall. A better place to put that foam board is on the exterior between your WRB and your siding, preferably with a rain screen between the siding and insulation as well. This will give you the exact same effective R-value, but will significantly reduce the chance of condensation and moisture buildup within the wall.
We use 24 inch stud spacing on our post and beam timber frames. The studs are just there to attach insulation and sheating. The timber frame takes care of the structural loads. We use thermal breaks around windows and doors. To keep low r value windows and doors from cooling or heating the wall around windows and doors. It takes care of the condensation zone around windows and doors. I agree it's worth getting the better r value windows and doors. Windows and mineral wool insulation are the most expensive part of my cottage.
Thanks Steve, great explanation!
Doing staggered 2x4 @24"OC in a 2x6 wall with R9 ZIP on the outside, then 2" of closed cell, followed with open cell to finish. I will then do Quicktie cables to give me the uplift and shear needed, along with appropriate nailing for the exterior. (Structural and Mechanical PE here) My price on triple glaze from EAS was 50% more than top of the line Kolby. Hard to justify. Nice Haircut
No way on the window pricing - I have priced that comparison a dozen times, it always pencils out - there's something there?
@@stevenbaczekarchitect9431 if you can get me a better price on 19 doors and windows from them that would be great. And, I cannot get a wind and hurricane impact from them.
On my personal house walls I'm using the 5.5 Tstuds on 24" centers with TimberHP TimberFill dense pack.
In my area 2' on center studs has been common for 30+ years. It does cause issues with the stacking of the studs with the 16" on center floor joists, they don't all line up and carry the load vertically down through the structure which is not a big deal the house won't fall down, but it can be unhandy having the stud in the middle of a floor joist cavity if the mechanical contractors and plumbers need that cavity for a duct or a drain to go down thru the wall and will be forced to move the stud. The biggest structural issue I see in these videos is this foam backed Zip sheathing and it's shear value being rather poor compared to wood sheathing properly nailed directly to the studs. Nails going through foam is not a good sheathing.
on the shear concerns, I guess it depends on the risk factors of your area. Some localities have allowed for just a few shear components (two outbound sheets of plywood on any given wall or let in bracing) and houses have withstood decades without the modern shear components assumed. While you would never get away without some good engineering letters in doing your own 'stand-off' sheathing installation, I would think a full covering of zip would counter most risks of shear.
Nice class as usual!
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I wish you would have included data on the double exterior stud wall that you had in another video to compare the various options.
Steve, what about using 2x6 top & bottom plates with 2x4 studs staggered front to back every other stud? Can this be done on 24" centers?
sure
@@stevenbaczekarchitect9431 You are awesome brother! Keep up the good work!
how can we improve the window insulation, is there a r10 window insulation.
So you gain 1 r value for the entire wall? That’s comparable to a single window someone forgets to insulate around
Uncle Steve doesn't build houses with leaky windows.
I agree, I am designing with 24 o.c. 2" x 6" walls..Liked#38 N Subscribed!!!
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Steve are you taking on clients looking to build in Pennsylvania
I just saw a video where the framers used an LVL joist as a rim board for the trusses on a monopoly framed house. He said that it increase R-value and you don’t have to building headers. Anyone ever tried that? How did it go?
Do you have a link to that video?
It’s called “Rebuilding after CO fire” it’s a Risinger video, the framing discussion starts at 7:30
@@jackjmaheriii Thank you!!
I have done rim joist headers........gets pricey potentially
To calculate whole wall R value, first convert R values to U values using U=1/R formula. Then multiple the u value by percentage of each component, add up all 3 values and convert back to R value using R=1/U.
Opaque 2x6 = R1.25 per in x 5.5in = R6.875, 1/6.875 = 0.145U
Cavity R21, 1/21 = 0.0476U
Window R3, 1/3 = 0.333
16oc
Opaque = .22 * 0.145 = 0.0319
Cavity = .63 * 0.0476 = 0.029988
Window = .15 * 0.333 = 0.04995
0.0319+0.029988+0.04995 = 0.111838U, 1/0.111838 = R8.9
24oc
Opaque = .14 * 0.145 = 0.0203
Cavity = .71 * 0.0476 = 0.033796
Window = .15 * 0.333 = 0.04995
0.0203+0.033796+0.04995 = 0.104046U, 1/0.104046 = R9.6
With R7/0.143U triple glaze windows:
16oc = 0.083288U = R11.9
24oc = 0.075496U = R13.2
With R14/0.0714U LiteZone windows:
16oc = 0.072598U = R13.8
24oc = 0.064806U = R15.4
On paper the whole wall R-value of double glazed + R40 cavity insulation seems a lot better than triple glazed with R21 cavity. They probably just did this math and figured it is purely a numbers game. Total R-value came out at R29 vs 17R in my calculations. I think that they underestimated the comfort triple glazed windows offer. It seems to me that a balanced wall with an R-value that's pretty balanced between windows, studs and cavity would offer far more comfort and maybe better real life results than making up for 'bad' studs and windows with a higher cavity insulation (considering the total R-value of both walls is the same).
Someone I know build his house with continious 6 inch polyiso around his masonry walls but opted for double glazing cause he figured triple didn't make financial sense...
Christine Williamson has a great video on how windows change whole wall R-value and shows the math. Windows matter the most.
ua-cam.com/video/zJRsmiaqh6A/v-deo.htmlsi=NFYRqN99nHri2H1T
@@Krunch2020 Agreed - they are ALWAYS the worst part of the wall
a comment above mentioned that heat will find the path of least resistance. The whole wall R-value is a flawed concept in that regard. The heat doesnt encounter R29 vs R17. The windows are always the weakest link in the assembly and making those better improves real world performance beyond the modest uptick in whole wall R Value
Im 96" oc on my house.
A post frame house. People claim 24oc is "advanced framing" I just laugh 🤣
Wish I knew the math to merge those 3 values into a single Whole Wall number so I can compare apples to apples
ua-cam.com/video/KTBYB664fFE/v-deo.htmlsi=RwryodA8a25VfOp5
Maybe a future video
I don't know how to 'average' the R values. But most people don't recognize that insulation R value is basically in the middle of the cavity. If you have a bigger cavity then you get a bigger middle. Okay, we are talking 6 inches from the edges. Top bottom left and right,Right? If you get X with 6 inch insulation, it stands to reason you have to go sideways from your stud as well. The opaque stud isnt just transferring heat from drywto outside sheathing across 1.5 inches. Heat is also leaving the sides into the insulation. Remember, 6 inches deep. The first couple of inches of cheap pink stuff is just letting heat flow thru it at its edges.
But lets say you have 140 feet of exterior walls, and we want basic simple math.
Obviously it is 70 boards for 24 o.c. Change up to 105 boards for the 16 o.c. Sure, there may be extras at corners. But that's the case regardless of your spacing; lets not count them.
Multiply you board count by their width which is 1.5 inches then divide by 12 inches to get the length of wall that is opaque. Then consider the extra 35 boards and the edges of insulation; equal to another 35 feet of less than what you Thought you were buying.
The approximate answer is 9 ft versus 13 feet.
Now, let's say you can choose 2x4 if 16 o.c. Your R value just declined even more. Yeah, some may only say R6 or R4, no big deal. But isn't sweet sounding to say R6 in 9 feet of walls compared to R4 in Thirteen feet of walls - that's like a big sliding glass door you cannot open or see thru.
Steve designed Jakes House in Missouri. Matt R and Jake had a very exacting conversation about these dimensions, right down to lumber cost and labor. The difference is Jake used 2x8 and ended up with R42 walls. So he is toasty in sub zero January And he can't hear a nearby busy road. See 'Why would you use 2 x 8 walls Matt Risinger'. Its about 3 years old.
Find a video of someone using a thermal imaging device outside of a house in the winter. It will demonstrate the heat loss isn't confined to 1.5 inches.
any GC or builders in the comments here working in south eastern PA
Building science = BS 12:40 😁🤣
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