Insulation for old house (confusion!)

[Dakota46]

Ok, the more I read on the subject the farther I am from a solution..

I have removed the lathe and plaster from the exterior wall of a bedroom. 1920 house, no existing insulation or vapor barrier/retarder.

I am looking to insulate the wall and drywall it, but keep finding conflicting information on the acceptable method to do so.

When I did this previously I used 2" foam board sealed with caulk and then stuck a 1" piece of foam board on top of that(all fitted inside the 2x4 stud bay). My thinking was this gave good air seal and good r-value. Because of the original window frames and the way it gets trimmed I can't really fur the wall out.

Would it be adequate to just fill the stud bays with roxul or mineral wool and cap the wall (interior side) with 1/4" fan fold foam to seal the air? This is in Michigan.

It's just about 11' wide and 8' tall wall.



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[willbird]

Those look like some good honest native timber honest to gawd 2" x 4". For that little bit honestly I'd just go and get R13 and put it in there with the vapor barrier on room side. Those little narrow ones you might just cut the 16" stuff in half and use 1/2 in each ?? Nothing wrong with using the rigid foam either.

If your house is like the one I grew up with those studs are actually 2" x 4" rough sawn...often cut and built with green sawn timber, then hand plastered to make it straight. if so then two layers of this may fit like a glove, then use plastic film as a vapor barrier maybe ??

https://www.homedepot.com/p/Owens-C...ared-Edge-Insulation-Sheathing-52DD/202085962

 

[Kaizen]

Looks like my house. Your confusion comes in when you try to stop air. The previous way you did it stopped air movement and created a vapor barrier.
But a pita to do well.
I would use can spray foam and seal up what you can like the sheathing cracks and top of bay if ballon framed. Then use roxul. Think I’d still make a vapor barrier inside of that out of plastic or foam like you are talking.
Since using roxul in my garage I’m never going back to fiberglass. I noticed an audible reduction immediately like you get with spray foam.


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[ddawg16]

Looking at the pic, I see a few places where water was coming in at some point. That has to be resolved before anything else is done...What is on the exterior?

Both of the above suggestions are good. Personally, I'd use craft faced insulation with the craft face to the inside. Except in the summer, you source of moisture is going to be from inside the house.

 

[Voi]

I have removed the lathe and plaster from the exterior wall of a bedroom. 1920 house, no existing insulation or vapor barrier/retarder.

Do you know if there is anything on the exterior side of the plank sheathing that might be acting as a vapor retarder? I would want to know that before using any sort of kraft paper or other vapor barrier on the interior side.

 

[chaosracing]

You can buy spray paks and spray foam yourself. It is a little more expensive, but you will get good air seal and insulation R factor from that. Better than cutting foam and caulking it.

This is just being posted as an example.
https://www.lowes.com/pd/Dow-FROTH-PAK-200-Sealant-Foam-Insulation-Kit/50375630

 

[yeldogt]

If nothing has been done to the outside -- it's not going to have any VB to cause any problems. Sometimes when siding was added over existing -- a thin sheet of foam is applied. This was common years ago and can cause issues if you create another VB. Thankfully most leak.

Your system will work .. done correctly --- going to provide both better R value and air sealing vs fiberglass batts. The foam is the VB.

Having someone do spray foam is going to be expensive ... the fixed cost of the equipment and setup is too high for such a small job

 

[Kaizen]

You can buy spray paks and spray foam yourself. It is a little more expensive, but you will get good air seal and insulation R factor from that. Better than cutting foam and caulking it.

This is just being posted as an example.
https://www.lowes.com/pd/Dow-FROTH-PAK-200-Sealant-Foam-Insulation-Kit/50375630

Curious if anyone knows how many tuff stuff cans it takes to cover one of this kits? The can is 16oz but does not say area covered like those big kits do


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[kbs2244]

Use the tuff stuff to hold/seal the foam boards in place.
It is a good glue

 

[Dakota46]

Those look like some good honest native timber honest to gawd 2" x 4". For that little bit honestly I'd just go and get R13 and put it in there with the vapor barrier on room side. Those little narrow ones you might just cut the 16" stuff in half and use 1/2 in each ?? Nothing wrong with using the rigid foam either.

If your house is like the one I grew up with those studs are actually 2" x 4" rough sawn...often cut and built with green sawn timber, then hand plastered to make it straight. if so then two layers of this may fit like a glove, then use plastic film as a vapor barrier maybe ??

https://www.homedepot.com/p/Owens-C...ared-Edge-Insulation-Sheathing-52DD/202085962

The 2x4s are 3-5/8x1-5/8". Definitely a little bigger than today's 2x4

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[Dakota46]

Looking at the pic, I see a few places where water was coming in at some point. That has to be resolved before anything else is done...What is on the exterior?

Both of the above suggestions are good. Personally, I'd use craft faced insulation with the craft face to the inside. Except in the summer, you source of moisture is going to be from inside the house.

In a 100 years, yes the occasional bit of water has gotten in. There was an upstairs window above this room that wasn't trimmed out for quite some time. The house has 2' overhangs which helps a lot except for wind driven rain.

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[Dakota46]

Do you know if there is anything on the exterior side of the plank sheathing that might be acting as a vapor retarder? I would want to know that before using any sort of kraft paper or other vapor barrier on the interior side.

Looking through the back of the 1x6 exterior boards there is (surprisingly!) a very old looking layer of kraft paper that is very brittle and probably has hundreds of nails through it.

So the exterior is 1x6--kraft type paper - - asbestos tiles--vinyl siding directly over the asbestos with no special underlayment.

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[Dakota46]

Use the tuff stuff to hold/seal the foam boards in place.
It is a good glue

Is Tuff Stuff you referring to like great stuff?
I'm pretty sure great stuff actually sells a version of their product specifically for adhering foam boards. I think I've seen it at Menards.

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[jhvander6864]

I vote for the spray foam. It is a bit more expensive but you are only going to expose the studs once and foam will work very well.

 

[Voi]

Looking through the back of the 1x6 exterior boards there is (surprisingly!) a very old looking layer of kraft paper that is very brittle and probably has hundreds of nails through it.

So the exterior is 1x6--kraft type paper - - asbestos tiles--vinyl siding directly over the asbestos with no special underlayment.

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You might do some searching around on GBA or other building science sites & see what they say. Note that they tend to take conservative approaches in these situations, especially in this era of questioning if & when vapor retarders are a good idea.

You likely have a more than sufficient drying path to the exterior but please don't take my word for that.

 

[ddawg16]

You might do some searching around on GBA or other building science sites & see what they say. Note that they tend to take conservative approaches in these situations, especially in this era of questioning if & when vapor retarders are a good idea.

You likely have a more than sufficient drying path to the exterior but please don't take my word for that.

I agree.........

In regards to anything asbestos....it's generally accepted as long as it's not disturbed, it's fine where it is. Same with Lead paint.

I would want the drying path to work it's way out....you never want the inside of the house to be the 'moisture sink'........

 

[Dakota46]

Thanks for the input everyone. Here is my plan so far.

Air seal the gaps between the 1x6 on the exterior wall with either caulk or low expansion great stuff (window and door version). Fill stud bays with unfaced mineral wool insulation (r15). Cap the wall with 1/4" foam board and tape any seams. I needed the 1/4" + 1/2 drywall to bring the wall flush with window jamb.

I love the idea of spray foam but it sounds like those froth pack kits are pretty temperamental and messy. I'd want to use every last bit of a kit and would have to open another wall to make use of it all. Add to that, a kit with decent coverage is at least $600 at Menards even with the 11% rebate.

Let me know if this is a horrible plan? Thanks!

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[yeldogt]

Thanks for the input everyone. Here is my plan so far.

Air seal the gaps between the 1x6 on the exterior wall with either caulk or low expansion great stuff (window and door version). Fill stud bays with unfaced mineral wool insulation (r15). Cap the wall with 1/4" foam board and tape any seams. I needed the 1/4" + 1/2 drywall to bring the wall flush with window jamb.

I love the idea of spray foam but it sounds like those froth pack kits are pretty temperamental and messy. I'd want to use every last bit of a kit and would have to open another wall to make use of it all. Add to that, a kit with decent coverage is at least $600 at Menards even with the 11% rebate.

Let me know if this is a horrible plan? Thanks!

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If you want to create an impenetrable VB -- foam works at the inside sheathing level because it is inert and allows for drying to both the inside and outside. You will never seal with caulk .. and foaming all the wood joints is problematic.

With typical insulation you are trying to retard ..but not stop moisture movement. Walls can leak and they must dry. Closed Foam is inert and does not hold water ... it does not need to dry.

Your original ways is better ... if you seal the sheets

 

[klassenl]

I live on the cold prairies in Canada. The code around here would call for insulation (most guys wold use pink fibreglass bats) then 6 mil poly (vapor barrier) sealed around the wundows and top/bottom plate with acoustical sealant (caulking). Thus is also how I would do/have done it in my house

 

[NUTTSGT]

My house sits on 10" wood beams atop a stone foundation. I filled the bottom 3" of the stud cavity with Great Stuff to help seal the leaking air.

 

[walta]

When I look at your wall what I do not see is a good water barrier. That is not a problem when the stud bays are open and lots of air is leaking thru the wall as any water that gets in can and will dry up before the wall gets moldy and rots away.
Your plan needs an air space to allow drying.


https://www.finehomebuilding.com/2016/05/17/insulating-walls-no-sheathing

Walta

 

[The Cobbler]

^^ I don't agree with that logic or placing the XPS board on the cold(unconditioned) side of the wall since it will act as a vapour barrier & hold moisture in the insulation