# Frustration! Need help insulating fiberboard sheathing with board and batten



## Nealtw (Jun 22, 2017)

What answer have decided you would like to have so we can agree or disagree?


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## chandler48 (Jun 5, 2017)

On both discussions Fiberglas insulation and Rockwool were suggested. What do you need to proceed with your project? Rockwool gives an R value or 15 in a 3 1/2" wall cavity as opposed to an R13 for fiberglas. You don not want to pack insulation in the cavities as it will not increase insulation quality.

As Neal stated, you need to agree or disagree with the answers so we can proceed. Making more threads of the same project only confuses the matter. Stick with one thread and ask more questions if necessary.


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## NorCalNate (Jun 23, 2021)

Nealtw said:


> What answer have decided you would like to have so we can agree or disagree?


Thanks Neil and Chandler. I'll try to keep to one post next time. Based on your recommendations and my own research, below are the three options I'm considering:

*Super Cautions Option: *(see picture with white "snorkels" in upper plates and YouTube link to video) *1*) Drilling holes in top and bottom cladding and installing "snorkels" for air flow *2)* Using Dorkin Delta Dry polyethylene foam "mat" to create air gap *3*) Applying Dorkin Vent S vapor permeable material (or equivalent VPB) to create the air barrier *4*) Putting rigid foam over the VPB and sealing around the edges with insulating foam and *5) *adding Rockwool behind if there is room (YouTube Video which explains this option: 



)
*Cautious Option*: (see picture called "No_sheathing_1.preview.jpg") Applying 1/4 to 1/2" spacers between the sheathing and studs, and putting rigid foam and sealing with tape or caulk followed by batt insulation (Fiberglass or Rockwool).
*Easier Option: *Going with Neil's suggestion. Caulking all joints and using Rockwool or Fiberglass insulation

Thoughts?


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## Nealtw (Jun 22, 2017)

NorCalNate said:


> Thanks Neil and Chandler. I'll try to keep to one post next time. Based on your recommendations and my own research, below are the three options I'm considering:
> 
> *Super Cautions Option: *(see picture with white "snorkels" in upper plates and YouTube link to video) *1*) Drilling holes in top and bottom cladding and installing "snorkels" for air flow *2)* Using Dorkin Delta Dry polyethylene foam "mat" to create air gap *3*) Applying Dorkin Vent S vapor permeable material (or equivalent VPB) to create the air barrier *4*) Putting rigid foam over the VPB and sealing around the edges with insulating foam and *5) *adding Rockwool behind if there is room (YouTube Video which explains this option:
> 
> ...


No that is the last thing you want, I never suggested chalking anything. In fact code here required we leave gaps n the sheeting and we even drilled holes in the sheeting under windows to allow for breathing behind siding. That only changed with a new and better window installation.
Any holes thru the top plate like for wires are supposed to be caulked with a fire rated chalk. So I would not go with that plan.


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## NorCalNate (Jun 23, 2021)

Nealtw said:


> No that is the last thing you want, I never suggested chalking anything. In fact code here required we leave gaps n the sheeting and we even drilled holes in the sheeting under windows to allow for breathing behind siding. That only changed with a new and better window installation.
> Any holes thru the top plate like for wires are supposed to be caulked with a fire rated chalk. So I would not go with that plan.


Thanks Neal. In that case which option do you recommend, or would you modify one of the options I proposed?


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## Nealtw (Jun 22, 2017)

NorCalNate said:


> Thanks Neal. In that case which option do you recommend, or would you modify one of the options I proposed?


I would be real careful fitting rock wall in there so there are no spaces in it, then drywall it. You are spending way to much time over thinking this.


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## jim_bee (Feb 23, 2021)

I agree with Neal. Years ago we built homes with siding installed directly over fiberboard and insulated with fiberglass. If you aren't seeing any evidence of leaks, you will be fine.


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## NorCalNate (Jun 23, 2021)

I appreciate the responses. It might sound like I am overthinking whcih I probably am, but I'd much rather overthink now than underthink and screw something up. Anyways your responses were what I was looking for, just needed some reinforcement. Read so many articles about how insulating an old house can ruin it that it made me paranoid. Anyways, we are having a roof installed next week and I'm going to make sure they don't change the overhang size (they're currently 36") and will re-secure any battens that are pulling away from the house, but I will NOT caulk between the boards and battens. 

Thanks again


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## jim_bee (Feb 23, 2021)

NorCalNate said:


> I'd much rather overthink now than underthink and screw something up.


Absolutely!


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## Clutchcargo (Mar 31, 2007)

I was in a similar predicament as you are in and I as well over-thought (read project was stalled) what I should do.
If I were to do it again, I would just use pink or rookwool and be done with it. I believe pink comes in r15 now as well. Think about what they do if you get blown-in insulation anything you do is a step up because you're adding a vapor barrior.


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## Nealtw (Jun 22, 2017)

NorCalNate said:


> I appreciate the responses. It might sound like I am overthinking whcih I probably am, but I'd much rather overthink now than underthink and screw something up. Anyways your responses were what I was looking for, just needed some reinforcement. Read so many articles about how insulating an old house can ruin it that it made me paranoid. Anyways, we are having a roof installed next week and I'm going to make sure they don't change the overhang size (they're currently 36") and will re-secure any battens that are pulling away from the house, but I will NOT caulk between the boards and battens.
> 
> Thanks again


There is nothing to think about insulate it and drywall. 
Yes you can caulk the board and baton, keep the bug out and paints nice.


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## sparks in the dark (Aug 21, 2021)

Someone educate me here. Was my understanding that you need fireblocking from the wall to the ceiling, and those white pipes in one of the pics is purposely letting air flow from the wall to the ceiling. Isn't this against building code? Yes I understand some insulation (like rock wool) counts as a fireblock when properly installed, but sure seems like you still wouldn't want them pipes there, no?

Sent from my SM-G970U using Tapatalk


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## Nealtw (Jun 22, 2017)

sparks in the dark said:


> Someone educate me here. Was my understanding that you need fireblocking from the wall to the ceiling, and those white pipes in one of the pics is purposely letting air flow from the wall to the ceiling. Isn't this against building code? Yes I understand some insulation (like rock wool) counts as a fireblock when properly installed, but sure seems like you still wouldn't want them pipes there, no?
> 
> Sent from my SM-G970U using Tapatalk


He has been told that is a no no and would not be a good thing.


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## Shim-D (Dec 24, 2021)

Hi Nate,

I came across your question on here and on greenbuildingadvisor.com, and I am running into the same thing with my home. I have no insulation in the wall cavities, "beaverboard" sheathing, and not enough funds to rip down the siding.

I desperately want to insulate each room as I slowly remodel my 1960's home because it's always too cold and hot in the winter and summer, respectively.

I live in climate zone 4 (nearly 5, Central PA) - I was under the impression I would need an air gap between the sheathing and the insulation to allow for the sheathing to dry out after rain then sun as the water/vapor would migrate in towards the room. 

I just want to do it right and have some peace-of-mind. 

Appreciate the post.

- Destin


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## chandler48 (Jun 5, 2017)

Without the ability, funds, or desire to remove exterior sheathing, etc, you can always inject bulk insulation through 1" holes high up on your sheetrock walls in each stud bay. You can rent the machine and buy the insulation (which usually results in no rent for the machine). Patch the holes as normal and paint over them.


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## SW Dweller (Jan 6, 2021)

No air gap needed. 

One thing that I did not see was to use closed cell foam. This will give you the absolute best R value for the depth of your wall. Closed cell will also resist moisture and is stiff enough to help with the structure of your home, side to side.


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