Insulating a building question

[Finch]

Maybe I'm over thinking this which I sometimes do but I like to do things the right way. Working on wood framed 12x24 shed that has LP techshield roof sheathing with a tin roof. All the LP techshield sheathing is a foil backing that faces down on the inside of the building.

Technically, you are not supposed to have anything touching the foil within 3/4" so it can do its job and also not to create condensation between the hot or cold roof sheathing and the conditioned air space of the shed. I was planning on installing R15 batts of insulation (rockwool batts if I can find it in the 24" width) or faced fiberglass in the 24" width. Will also be putting in a minisplit to heat/cool the space.

I've emailed LP and they are no help. I even called asking how I'm to insulate the truss cavity with R15 insulation that is 3 1/2" thick without it touching the damn foil. He said just to pull it down a bit when installing. I asked about if I decided to install a ceiling paneling - that it would push it up into the foil. Crickets.

Am I over thinking this? Thoughts or advice? I even suggested adhering thin strips of foam insulation board in the cavities and then installing the R15. He didn't like that either.

Building Open or Exposed Ceilings with TechShield I LP Building Solutions

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[Whaledriver]

Not familiar with the LP stuff. In my shop I did 2" closed cell under roof and gables. Walls are r19 batt. With no heat it rarely gets below 35 degrees or above 70 in the shop. I live at 7900' in Colorado. If I need a little heat, I crank up the propane torpedo and it is 50 in 15 minutes. Shop is a 28x30 with 14ft ceilings and an attic room above. The foam is awesome. Would do again in a heartbeat.

 

[4rcgoat]

Maybe I'm over thinking this which I sometimes do but I like to do things the right way. Working on wood framed 12x24 shed that has LP techshield roof sheathing with a tin roof. All the LP techshield sheathing is a foil backing that faces down on the inside of the building.

Technically, you are not supposed to have anything touching the foil within 3/4" so it can do its job and also not to create condensation between the hot or cold roof sheathing and the conditioned air space of the shed. I was planning on installing R15 batts of insulation (rockwool batts if I can find it in the 24" width) or faced fiberglass in the 24" width. Will also be putting in a minisplit to heat/cool the space.

I've emailed LP and they are no help. I even called asking how I'm to insulate the truss cavity with R15 insulation that is 3 1/2" thick without it touching the damn foil. He said just to pull it down a bit when installing. I asked about if I decided to install a ceiling paneling - that it would push it up into the foil. Crickets.

Am I over thinking this? Thoughts or advice? I even suggested adhering thin strips of foam insulation board in the cavities and then installing the R15. He didn't like that either.

Building Open or Exposed Ceilings with TechShield I LP Building Solutions

Using LP® TechShield® Radiant Barrier for Impressive Energy Efficiency I LP Building Solutions

lpcorp.com

View attachment 310509

You really need to make the cavities where the insulation goes a little deeper. Picture the same construction, but instead of 2x4 rafters picture 2x12 rafters, gives you the space for insulation without touching bottom side of roof. You can make some rips from 1/2" plywood ( or any other ridgid material) and fasten them to the existing rafters to essentially "drop" the framing down to create a deeper cavity. Hope this makes some sense.

 

[Finch]

Not familiar with the LP stuff. In my shop I did 2" closed cell under roof and gables. Walls are r19 batt. With no heat it rarely gets below 35 degrees or above 70 in the shop. I live at 7900' in Colorado. If I need a little heat, I crank up the propane torpedo and it is 50 in 15 minutes. Shop is a 28x30 with 14ft ceilings and an attic room above. The foam is awesome. Would do again in a heartbeat.

What made you go with foam over regular insulation? I honestly don't know much about the closed cell foam.

 

[Finch]

You really need to make the cavities where the insulation goes a little deeper. Picture the same construction, but instead of 2x4 rafters picture 2x12 rafters, gives you the space for insulation without touching bottom side of roof. You can make some rips from 1/2" plywood ( or any other ridgid material) and fasten them to the existing rafters to essentially "drop" the framing down to create a deeper cavity. Hope this makes some sense.

That makes sense and honestly I'm a little embarrassed I didn't think of that. What is your opinion about adding that extra 1/2 to 3/4" material to the rafters and where they meet the top plate and vertical walls? I guess where I'm getting at is finishing purposes. Whatever I use on the walls (plywood, osb, drywall, etc) will then meet up with that added "shim" on the rafters. I was thinking once the roof was insulated, I'd install some kind of thinner 1/4" paneling to hide the roof insulation.

Does anyone actually think I'll have issues if the insulation is touching the roof sheathing? This is kinda turning into a PITA.

 

[Bubblehide]

Scab on 2x6's and staple your R15 to it.

 

[Warmsy]

You can buy a channel that runs the length of your rafter bays. I'm drawing a blank on what's it's called right now. Smart vent or something. Made for that exact purpose. I see a peak vent-do you have venting under the eaves?

 

[Warmsy]

Duro vent, for one.

 

[Finch]

You can buy a channel that runs the length of your rafter bays. I'm drawing a blank on what's it's called right now. Smart vent or something. Made for that exact purpose. I see a peak vent-do you have venting under the eaves?

What you staple between rafter bays when you use blown in insulation?

 

[Warmsy]

Don't know, but sounds about right

 

[Finch]

@Warmsy I'm not sure Id call that a vent. I know you're thinking like a ridge vent but it is not. No eave or soffit vents due to the lofted barn type of construction.

Couple pics to give you perspective. Looked at the roof just now. The ridge has openings but some kind of foam is sealed tight in the gaps.

 

[Clarkdale17]

What made you go with foam over regular insulation? I honestly don't know much about the closed cell foam.

We've used closed cell foam in situations just like yours for clients that need a vapor barrier. The closed cell foam acts as a vapor barrier once it reaches a certain thickness per the manufacturer, and provides the best R value of any insulation.

Closed cell foam would have likely met your design criteria for what you are trying to achieve with the LP and allowed you to put a finish on the ceiling without conflict.

 

[Finch]

We've used closed cell foam in situations just like yours for clients that need a vapor barrier. The closed cell foam acts as a vapor barrier once it reaches a certain thickness per the manufacturer, and provides the best R value of any insulation.

Closed cell foam would have likely met your design criteria for what you are trying to achieve with the LP and allowed you to put a finish on the ceiling without conflict.

Thanks. I'll look into it. Seems like that 3.5 inch of rockwool or fiberglass would be better but I'll do some looking.

 

[Clarkdale17]

Thanks. I'll look into it. Seems like that 3.5 inch of rockwool or fiberglass would be better but I'll do some looking.

Rockwool has an R value of 3 per inch, while spray foam is close to 7 per inch. It is expensive though

 

[Finch]

Rockwool has an R value of 3 per inch, while spray foam is close to 7 per inch. It is expensive though

Either way, this damn building will be better insulated than my 1979 home.

 

[Warmsy]

That foam at the ridge is just too keep bugs and whatnot from getting in. It's vented. Is there venting at the lower edges of the gambrel roof?

I'd don't know anything about closed cell foam, but you need ventilation, regardless.

 

[Clarkdale17]

That foam at the ridge is just too keep bugs and whatnot from getting in. It's vented. Is there venting at the lower edges of the gambrel roof?

I'd don't know anything about closed cell foam, but you need ventilation, regardless.

That would depend on if he wanted a sealed attic or a vented attic. Spray foam can be installed in an unvented attic

Edit: I apologize not trying to derail the thread just trying to bring up other options

 

[Finch]

That would depend on if he wanted a sealed attic or a vented attic. Spray foam can be installed in an unvented attic

Edit: I apologize not trying to derail the thread just trying to bring up other options

Honestly, i just want to insulate the building and move on with the rest of the project. Obviously, I don't want any condensation issues though.

 

[Elkdreamer]

Honestly, i just want to insulate the building and move on with the rest of the project. Obviously, I don't want any condensation issues though.

I should probably not say anything as I have no experience with this product.

However, is not the purpose of the product (TechShield) to keep the condensation between it and the metal roof? The only thing that should condensate is the metal. IDK

 

[4rcgoat]

Im kinda drawing a blank on this,on second thought that expanding foam might be better in this situation, or some ridgid foam cut into strips wide enough to fill the width,that stuff isnt cheap either.