# T-Studs, new method of framing minimizing thermal bridging



## begreen (Jul 14, 2019)

This product looks very interesting. With an insulation value of R20 instead of thermal bridging and a great increase in load handling the small increase in price should easily be offset by the gains.


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## SpaceBus (Jul 14, 2019)

The dollar savings in less energy used should offset any additional costs of the product.


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## SpaceBus (Jul 14, 2019)

I made my comment before the end. The price difference comes out to pennies on the dollar. Amazing. I'm actually pretty salty I hadn't seen this before we bought our house!


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## begreen (Jul 14, 2019)

Not to mention the savings for what should be faster electrical and mechanicals going in, though I'm not sure that would get passed on to the homeowner.


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## Seasoned Oak (Aug 1, 2019)

Can achieve the same effect just staggering the 2x4s .Use a 2x6 plate and 2x4s along the outside and also staggered along the inside leaving a continuous void in the middle for wiring and blown insulation.


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## peakbagger (Aug 1, 2019)

The problem with staggered studs is the siding tends to telegraph the span anything over 16" on center. It may meet code but looks cheap in my opinion. Unless someone does an expensive full foam job or a proper flash and bat, I think the potential for thermal leaks through fiberglass or cellulose is still high with a stud type wall. If going with full foam job why not go with stress skin?. 

I am far more of fan of stress skin construction for new or my renovation approach which is put 1/2" of isoboard under the dry wall. Its quite noticeable how the cold spots from the studs thermal bridging is minimized with 1/2 inch of foil faced foam on top of them. The last reno I did was flash and bat with 1/2" of iso foam under the drywall. I haven't had an IR camera to check it but take half the baseboard out of that room wit no noticeable effect.


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## Seasoned Oak (Aug 1, 2019)

You can use 16 or 24in centers with staggered studs. The method im talking about is essentially a double wall ,you using more studs, not less. What your staggering  is the stud placement between the outside wall and the inside. But yea i like a 1 in sheet of foam in addition to the wall insulation more than any of these alternate stud plans. With just dense pack cellulose in the wall and ceiling i was able to eliminate all the baseboard in a large 8 by 9ft  bathroom. Room stays same temp as the rest of the house. I put a switched 500 watt infrared heater in the ceiling just to bring it up above the house temp when the shower is in use.


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## SpaceBus (Aug 1, 2019)

Seasoned Oak said:


> You can use 16 or 24in centers with staggered studs. The method im talking about is essentially a double wall ,you using more studs, not less. What your staggering  is the stud placement between the outside wall and the inside. But yea i like a 1 in sheet of foam in addition to the wall insulation more than any of these alternate stud plans. With just dense pack cellulose in the wall and ceiling i was able to eliminate all the baseboard in a large 8 by 9ft  bathroom. Room stays same temp as the rest of the house. I put a switched 500 watt infrared heater in the ceiling just to bring it up above the house temp when the shower is in use.



What's the average price for 1" foam boards? Is this a polyiso or polystyrene type? I'm trying to learn as much as I can about this stuff before we do the inside of our house.


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## begreen (Aug 1, 2019)

Seasoned Oak said:


> Can achieve the same effect just staggering the 2x4s .Use a 2x6 plate and 2x4s along the outside and also staggered along the inside leaving a continuous void in the middle for wiring and blown insulation.


Yes, that is how my BILs house is built, but this T-Stud process is less labor and materials intensive and evidently stronger too.


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## Seasoned Oak (Aug 1, 2019)

SpaceBus said:


> What's the average price for 1" foam boards? Is this a polyiso or polystyrene type? I'm trying to learn as much as I can about this stuff before we do the inside of our house.


The best value where im at is the 1in.DOW pink foam 1/2 is $15, 3/4 is $17 and one inch is $20 a sheet. From there it goes way up for 1.5 inch at $32 a sheet. Best if its installed on the outside but it can be installed on the inside. I normally dont do this as the dense pack cellose alone is very effective. If i were using fibreglass batts(which i dont use) i would definitely consider additional insulation.


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## SpaceBus (Aug 1, 2019)

Seasoned Oak said:


> The best value where im at is the 1in.DOW pink foam 1/2 is $15, 3/4 is $17 and one inch is $20 a sheet. From there it goes way up for 1.5 inch at $32 a sheet. Best if its installed on the outside but it can be installed on the inside. I normally dont do this as the dense pack cellose alone is very effective. If i were using fibreglass batts(which i dont use) i would definitely consider additional insulation.



We are using Rockwool Batts for the cavities. In a different thread we considered using the mass loaded vinyl, but we've since changed our minds. Exterior foam is not really an option for us. We no longer trust it as we had a massive carpenter ant infestation in the foam and house. Thanks for the heads up, I'll see if I can find any locally.


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## Seasoned Oak (Aug 1, 2019)

I believe the DOW 1 inch is 6.5R.


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## venator260 (Aug 3, 2019)

peakbagger said:


> I am far more of fan of stress skin construction for new or my renovation approach which is put 1/2" of isoboard under the dry wall. Its quite noticeable how the cold spots from the studs thermal bridging is minimized with 1/2 inch of foil faced foam on top of them. The last reno I did was flash and bat with 1/2" of iso foam under the drywall. I haven't had an IR camera to check it but take half the baseboard out of that room wit no noticeable effect.




Is there something more to this than just screwing the foam to the studs and then topping over with drywall? I would have thought that the insulation board behind the drywall would not be a strong enough base if someone were to lean up against it or something.


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## Seasoned Oak (Aug 3, 2019)

venator260 said:


> I would have thought that the insulation board behind the drywall would not be a strong enough base if someone were to lean up against it or something.


 I dont think it would make any difference at all. I cant see the foam collapsing under the drywall. Plus the Foam board fasteners are right under the drywall as well.


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## peakbagger (Aug 4, 2019)

Its pretty simple. The biggest hassle is the electrical boxes. You can either use standard boxes and space them out from the wall to account for the extra thickness or you can buy box extenders that screw onto the face of the box. I use 1/2" foil faced isoboard which is pretty dense and the foil tends to spread point loads out plus the dry wall works pretty well to spread the load. I use 1/2 drywall, I dont know if 3/8" is still made but would suggest 1/2" is better choice. I use a couple of roofing nails to hold the iso board up, then tape all the seams and breaks in the foils with foil tape then use long drywall screws with a dry wall screw gunto hold the dry wall up. I did my office (bedroom) exterior walls and have had a couple of nail pops and my living room wall with no nail pops. Its been 10 years and I dont see a lot of difference between the new walls and the old walls with respect to nail pops.


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## Seasoned Oak (Aug 4, 2019)

peakbagger said:


> Its pretty simple. The biggest hassle is the electrical boxes. You can either use standard boxes and space them out from the wall to account for the extra thickness or you can buy box extenders that screw onto the face of the box. I use 1/2" foil faced isoboard which is pretty dense and the foil tends to spread point loads out plus the dry wall works .


I use adjustable electric boxes. They have depth adjusting screws right in the face,can adjust out an extra inch at least. Yes always use at least 1/2 in drywall. 5/8 is stronger and is Fire Rated as well but very heavy.  3/8 is only for use over a solid material like plaster walls IMO. They make special nails with large washer for fastening foam board. You can buy these where you get the board.


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## Seasoned Oak (Aug 4, 2019)

I find insulating issues a fascinating subject when it comes to construction. I have always been amazed at how little energy it takes to keep a well insulated space comfortable.I have personally witnessed a ranch house with a full underground basement stay above freezing with no additional heat over the worst 2 months of winter in central PA. With single digit temps outside,just from the 50 deg. ground heat coming from the (uninsulated)basement floor and walls. If the basement walls were insulated in this case the house would probably have frozen water pipes.


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## SpaceBus (Aug 4, 2019)

Seasoned Oak said:


> I use adjustable electric boxes. They have depth adjusting screws right in the face,can adjust out an extra inch at least. Yes always use at least 1/2 in drywall. 5/8 is stronger and is Fire Rated as well but very heavy.  3/8 is only for use over a solid material like plaster walls IMO. They make special nails with large washer for fastening foam board. You can buy these where you get the board.


Thanks for this tip! I'm looking into replacing the majority of my outlets and boxes soon. Any tips on exterior outlet boxes? I just removed one that was spliced into a kitchen outlet.

I'm trying to talk my wife into using the pink or blue foam inside the house, but we do not want drywall. Will the foam work well with wood tongue and groove or board and batten? We plan on finishing the inside of our house as if gets too cold to work outside. Before then we are filling our cavities with rock wool but haven't made up our minds on what to do next.


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## begreen (Aug 4, 2019)

There's been an interesting discussion on t-stud construction and insulating in very cold environments in the green building forums
https://www.greenbuildingadvisor.com/question/anyone-seen-or-used-tstuds-thermally-broken-studs-yet


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## peakbagger (Aug 4, 2019)

I dont think foam can be installed inside a living space without dry wall on top of it, if there is a fire the foam puts out  toxic smoke.


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## SpaceBus (Aug 4, 2019)

peakbagger said:


> I dont think foam can be installed inside a living space without dry wall on top of it, if there is a fire the foam puts out  toxic smoke.


Well, I guess that answers the question then. Is there anything else we can do besides insulate the stud cavities?


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## begreen (Aug 4, 2019)

SpaceBus said:


> Well, I guess that answers the question then. Is there anything else we can do besides insulate the stud cavities?


Rockwool Comfortboard 80 exterior insulation
https://www.rockwool.com/a/s/comfortboard-exterior-non-structural-insulation/


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## SpaceBus (Aug 4, 2019)

begreen said:


> Rockwool Comfortboard 80 exterior insulation
> https://www.rockwool.com/a/s/comfortboard-exterior-non-structural-insulation/



I hadn't seen this before on their website. So far we have house wrap on most of the CDX. Is it too late to apply something like that product? Could it be used on the inside of the house instead?

Edit, just read the installation instructions. We could definitely still make use of this product.


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## Seasoned Oak (Aug 4, 2019)

SpaceBus said:


> Well, I guess that answers the question then. Is there anything else we can do besides insulate the stud cavities?


Are your stud cavities 5.5 in or 3.5in  ?  If 3.5 you may need something more get to the required wall R value. May need at least R30 walls or more in Maine .Even a 6in stud walls plus one inch of foam is only roughly  R29 since rock wool is about R23.


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## bholler (Aug 4, 2019)

peakbagger said:


> I dont think foam can be installed inside a living space without dry wall on top of it, if there is a fire the foam puts out  toxic smoke.


It just needs to be covered not nessecarily with drywall.


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## Seasoned Oak (Aug 4, 2019)

bholler said:


> It just needs to be covered not nessecarily with drywall.


But something fireproof perhaps.


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## bholler (Aug 4, 2019)

Seasoned Oak said:


> But something fireproof perhaps.


Drywall is not fireproof it is just rated tonresist burnthrough for a certain period of time.  Just as solid wood is.  Actually 1" of solid wood is pretty close to 1/2" drywall.


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## SpaceBus (Aug 4, 2019)

bholler said:


> Drywall is not fireproof it is just rated tonresist burnthrough for a certain period of time.  Just as solid wood is.  Actually 1" of solid wood is pretty close to 1/2" drywall.



Good to know since I'm sure the rockwool exterior panels aren't cheap. We really like the idea, but we will have to see what the budget will allow when the lumber yard tells us the price.


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## Seasoned Oak (Aug 5, 2019)

bholler said:


> Drywall is not fireproof it is just rated tonresist burnthrough for a certain period of time.  Just as solid wood is.  Actually 1" of solid wood is pretty close to 1/2" drywall.


Fire rated is drywall is at least 5/8" thick. Not aware of any 1/2 fire rated drywall. Probably a better term is fire resistant not fire proof. Off gassing of Foam board would be another good reason to apply it to the exterior of the wall under the siding. The main reason is to satisfy the 1/3 - 2/3s rule for severe climates.


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## bholler (Aug 5, 2019)

Seasoned Oak said:


> Fire rated is drywall is at least 5/8" thick. Not aware of any 1/2 fire rated drywall. Probably a better term is fire resistant not fire proof. Off gassing of Foam board would be another good reason to apply it to the exterior of the wall under the siding. The main reason is to satisfy the 1/3 - 2/3s rule for severe climates.


1/2" drywall is fire rated as well.  Most products have a fire rating.  But yes if you are building an actual fire wall you need 5/8" but you need 2 layers with the first taped then staggered seams.  I believe that gives you 2 hours.  1/2" is 30 mins I believe.  But it has been a while since I have done any of that work so my numbers could be off


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## venator260 (Aug 7, 2019)

peakbagger said:


> Its pretty simple. The biggest hassle is the electrical boxes. You can either use standard boxes and space them out from the wall to account for the extra thickness or you can buy box extenders that screw onto the face of the box. I use 1/2" foil faced isoboard which is pretty dense and the foil tends to spread point loads out plus the dry wall works pretty well to spread the load. I use 1/2 drywall, I dont know if 3/8" is still made but would suggest 1/2" is better choice. I use a couple of roofing nails to hold the iso board up, then tape all the seams and breaks in the foils with foil tape then use long drywall screws with a dry wall screw gunto hold the dry wall up. I did my office (bedroom) exterior walls and have had a couple of nail pops and my living room wall with no nail pops. Its been 10 years and I dont see a lot of difference between the new walls and the old walls with respect to nail pops.




Got busy and just saw the replies.

I'll have to try this on the next room that gets remodeled. Two of my upstairs rooms have knee walls with an angle at the top that is just the roof joists. I just did the smaller one earlier this summer, but the larger one still needs done. I'd like a way to add a bit more insulation at that point and cut down on the thermal bridging caused by the joists.

And 1/2 inch is the thinnest drywall that I use. Some of my rooms have 5/8 on the ceilings, but with my last remodel, I just used 1/2 and put more screws in; I had no desire to wrestle a full 5/8 sheet overhead.


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## begreen (Aug 7, 2019)

venator260 said:


> And 1/2 inch is the thinnest drywall that I use. Some of my rooms have 5/8 on the ceilings, but with my last remodel, I just used 1/2 and put more screws in; I had no desire to wrestle a full 5/8 sheet overhead.


Would 3/8" cement board suffice? Is this process less expensive or faster than using the Rockwood exterior Comfortboard?


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## walhondingnashua (Sep 27, 2019)

I think this is a great, simple example of how simply looking at how something can be done differently, and making basic, inexpensive changes, can help with a lot of the energy/ environmental issues.  There are two reasons why something like framing has always been done the same way... its the right way to do it or its just how its always been done.  To much of what is done in our society is only done because that's how it was always done.  If we start applying some creativity and problem solving skills (2 things that the next generation lacks), so many issues can be solved.  
I spend a lot of time in my classes trying to build my students problem solving skills.  

Sorry for the rant lol


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## Seasoned Oak (Sep 27, 2019)

Theres more ways than one to increase wall R value but at some point all yur heat is going out thru the windows and doors. saving  another .001 on the walls makes no sense. The saying goes the worst wall is a higher r value than the best window.  First air sealing, then ceilings ,then walls then floors ,in that order .


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## Ashful (Sep 27, 2019)

walhondingnashua said:


> There are two reasons why something like framing has always been done the same way... its the right way to do it or its just how its always been done. To much of what is done in our society is only done because that's how it was always done. l


I know this is aside from your primary point, but this is not correct. Nothing is done just because that’s how it was always done. If it’s not presently the “right” way to do it, it likely once was the “right” way. It’s just a matter of timing and technology. 

And you forgot the third reason, someone profiting from it. [emoji14]


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## walhondingnashua (Sep 27, 2019)

Ashful said:


> I know this is aside from your primary point, but this is not correct. Nothing is done just because that’s how it was always done. If it’s not presently the “right” way to do it, it likely once was the “right” way. It’s just a matter of timing and technology.
> 
> And you forgot the third reason, someone profiting from it. [emoji14]


 Yes I left that part of the point I was trying to make out.  Things change over time and unfortunately we take to long to change simply because it is change.

I've heard a story about a little girl asking her mom why she cuts the ends off of the ham before she puts it in a pan and then into the oven even though there is plenty of room in the pan?
The mother replies that it is how her mother taught her mother did it so she just does it that way.

The little girl asks her grandmother why she cuts the ends off of the ham before she puts it in a pan and then into the oven even though there is plenty of room in the pan?
The grandmother replies that it is how her mother did it so she just does it that way.

So the little girl asks her great-grandmother why did she cut the ends off the ham?  The great grandmother replied that she was to poor to buy a bigger pan so they had to cut the ham to fit.


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