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Discussion Starter · #1 ·
Putting up a new workshop .... 3500 sq ft .... 16 ft walls ... 1000 sq ft attic for storage (so 4500 total).


So, I have been reading posts for two days and am completely confused.


I was looking at blown fiberglass in the ceiling but I read that fiberglass losses its R value as the temp drops ... and we do get cold here in Vermont .. like -30 cold.



With batts it is hard to insulate between the trusses.


So it looks like blown in Cellulose ... about 20"


The walls are confusing me ...


Fiberglass batts are easy to put in and relatively cheap.


I read about dry packing blown cellulose but am not sure. Seems after a few years it settles and you can get a gap at the top of the wall.


I read about wet packing .... I know they say you can't do it yourself but I would be willing to try (a water spray nozzle on the end of my blower hose).


Again, I read two posts talking about settling even with it being wet. Plus I am not sure about mold .. they talk about 6 months to dry out.


I did read one post where someone mentioned "glue" ... could you add something like white glue to the water when spray .... maybe just say 2 to 5 % ????



Plus I keep thinking,if they are getting settling on an 8 ft wall ... how much will I get on 16 ft ?



This is a shop and I am on a budget so things like spray foam are out of the question.


I am a DIY guy ... just finished building a 4800 sq ft house ... so I will be doing this myself.



Any thoughts or ideas ?????


Thanks .... Mike
 

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it makes zero sense to use blown cellulose in walls for a new build.
 

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it makes zero sense to use blown cellulose in walls for a new build.
Dense pack cellulose, done correctly, fills every nook and cranny in the wall (such as around electrical boxes) and is more effective at stopping drafts. But it's not for DIY or piecemeal installation--schedule a contractor and have it done all at once.

OP: Make sure air sealing is done to the exterior before any insulation goes in. Otherwise your fiberglass or rock wool will function as an outside air filter.

I redid my kitchen with rock wool in the walls, but I firestopped every cable and pipe penetration and caulked every seam to block infiltration. I also caulked the perimeter of the ceiling to the top plate before installing drywall. It adds up.

Also look into vapor retarder requirements for your area. Certainteed Membrain likely meets your local code and is a better solution than straight polyethylene.

Can you add an extra 2x3 thickness to your walls? Then you could have uninterrupted exterior insulation and air barrier and run your electrical freely afterward.
 

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Discussion Starter · #5 ·
Interesting ... that is one of the changes I made to my design last week.


I was going to have a cathedral ceiling. At first because I thought I could use wood I for the truss ... nope ... I would need a center beam (and my wife says I can't read instructions ... that was in the manual).


Then I thought well maybe sloped flat trusses ... but the more I look at this, the more it seems hard to insulate.


OK so finally a "normal" (flat bottom) truss.


I will get two prices this week ... one with a three piece truss ... each side and the center. This will require me to use wood I or a truss for the center attic floor.


The second price will be for a truss with the attic floor truss built into it. Not sure how this will work but the lumber yard suggested it.


One more question ... vapor barrier .....


I will use house wrap on the outer wall ....


I have always used poly on the inside. Good or bad?


The new "thing" seems to be letting the house breath.


What about putting house wrap up instead of poly inside?


It will let moisture though unlike poly but it should still stop air movement .. not air tight but no wind whipping through.


Mike


Thanks again !!!!!!!!!!!


Mike
 

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The new "thing" seems to be letting the house breath.

What about putting house wrap up instead of poly inside?

It will let moisture though unlike poly but it should still stop air movement .. not air tight but no wind whipping through.
The middle ground in that argument is a Class II vapor retarder. Faced fiberglass or Membrain over unfaced rock wool is a Class II. In your climate you can probably get by with poly (Class I or near-total vapor barrier) but you could get mold behind it in the summer if any outside air leaks in.
 

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Discussion Starter · #7 ·
Houses up here have been built with poly for years and year.


But I have seen mold in walls.


This is why I am thinking house wrap instead ... still slow down the air movement but allow moister to wick through.


Again ... it is a shop .. does not have to be perfect ... but I want to do a decent job.


Mike
 

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There is a product that is like Batts.

It is recycled cotton ( think denim), in a plastic sleeve made to fit in the walls.

I have wondered how it does.

As for the cellulose, it does settle after a few years, and what they did ( back when I was involved with it ,( late 70's early 80's ) , what they did was come back and bore a hole in the top plate for the nozzle, and refill the cavity.

Speaking of that, we were filling walls on an old apartment complex, when one took significantly more cellulose to fill.

Went inside and looked around, and found a secret "stash" hole, in a bathroom wall, that had magnetic closure doodads.

It had blown open and fill was knee-deep in the bathroom.

As well as a kilo of weed.:vs_laugh:

The owner was looking for a new tenant the next week.

ED
 

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Dense pack cellulose, done correctly, fills every nook and cranny in the wall (such as around electrical boxes) and is more effective at stopping drafts. But it's not for DIY or piecemeal installation--schedule a contractor and have it done all at once.
Dense pack is great for retrofits.

For new construction, better to use batts and plastic barrier on inside with drying potential to the outside.
 

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There is a product that is like Batts.

It is recycled cotton ( think denim), in a plastic sleeve made to fit in the walls.

I have wondered how it does.

As for the cellulose, it does settle after a few years, and what they did ( back when I was involved with it ,( late 70's early 80's ) , what they did was come back and bore a hole in the top plate for the nozzle, and refill the cavity.

Speaking of that, we were filling walls on an old apartment complex, when one took significantly more cellulose to fill.

Went inside and looked around, and found a secret "stash" hole, in a bathroom wall, that had magnetic closure doodads.

It had blown open and fill was knee-deep in the bathroom.

As well as a kilo of weed.:vs_laugh:

The owner was looking for a new tenant the next week.

ED
The blue jean stuff (made out of actual blue jean material all sliced up) is a pain in the butt. Very dusty, virtually impossible to cut despite what their website says, hard to fasten. Just finished doing a duplex with it and will not try that again. I would personally have no problem with fiberglass batts which is what is in my own house, r-38 walls, r54 attic....in MA
 
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