Insulating a structure built with LP Smartside 4x8 panels for outside walls

[coolstreetrod]

I am building a recreational cabin and using LP Smartside panels nailed directly to the wall studs with no other sheathing. I have read a lot of posts about this and most feel sheathing is not necessary. My question is, can I use paper-backed fiberglass batt insulation between the wall studs to insulate it? The studs are 2x4 and I was going to use R15. Anyone see a problem with that? Thanks......

 

[rnixon]

I used Dura-Temp 5/8" [shiplap jointed] exterior siding ,screwed to the studs with no sheathing. 2x6 construction took R21, un-faced batts , then plastic sheeting for vapor and air infiltration barrier ,ceiling is R40 batts, finished interior with Smartside LP panels . building is super tight an very economical to both heat & cool
Fasteners , interior & exterior are square drive bronze screws, and I can easily remove a panel or panels to add to utilities . Built in 2017, It wasn't cheap ,but has worked out well

 

[coolstreetrod]

Thank you for taking the time to document your job and for including the great pictures. If I read this right, the last thing before the LP Smartside is plastic sheeting - is that correct? Also, it looks like you don't have any air space in the roof rafter space along with the R40. Do you not have any ventilated soffit and ridge vent on the roof? People tell me to put Attic Insulation Rafter Baffle Proper Vents in between the rafter spaces first to create an air pocket, then the batt insulation to fill the rest of the space. That way air comes up through the ventilated soffit, up the cavity created with the Rafter Baffles, to the ridge vent and out. I I already have the ventilated soffit and the ridge vent, wouldn't I do it that way? Thanks again. Super building!!!!!! It looks great. Here's a picture of where I'm at....

 

[mike93lx]

Smartside is OSB with water resistant glue. It's a good product that does last a long time, but the big thing you are missing is a water resistant barrier. Having sheathing be the only "barrier" to the elements will result in moisture entering the wall cavity at some point. That's why houses are built with multi layer sheathing/cladding

 

[BillK]

Do you mind my asking exactly which Smartside panels you used and maybe get a picture of the outside ? I need to re-side a garage that has real wood T-111 on it right now and was thinking about the Smartside Panels.

I cant tell from your pictures but is do you have anything behind the siding or is it directly on the studs ?

Thanks,

 

[billconner]

Thank you for taking the time to document your job and for including the great pictures. If I read this right, the last thing before the LP Smartside is plastic sheeting - is that correct? Also, it looks like you don't have any air space in the roof rafter space along with the R40. Do you not have any ventilated soffit and ridge vent on the roof? People tell me to put Attic Insulation Rafter Baffle Proper Vents in between the rafter spaces first to create an air pocket, then the batt insulation to fill the rest of the space. That way air comes up through the ventilated soffit, up the cavity created with the Rafter Baffles, to the ridge vent and out. I I already have the ventilated soffit and the ridge vent, wouldn't I do it that way? Thanks again. Super building!!!!!! It looks great. Here's a picture of where I'm at....

This is the classic cold roof vs hot roof debate, cold roof being based on theory of eave and ridge vents and hot roof filling the cavity to roof sheathing with insulation. In heating climates, both can work and both work better the better the interior side vapor barrier is.

Some more info on cold vs hot roof design: https://www.buildingscience.com/documents/reports/rr-0404-roof-design/view
Not saying I agree with all Joe Lstiburek says, but it's very good background and usually safe and tolerant of less than perfect workmanship.

 

[coolstreetrod]

Thank you Bill - I will check that out......Rick

 

[coolstreetrod]

BillK - the outside of the cabin is SmartSide 38 Series Cedar Texture 8 in. OC Panel Engineered Treated Wood Siding, Application as 4 ft. x 8 ft.. It came already painted from the factory because I ordered it in the color I wanted. The inside is SilverTech which is a reflective coating mostly for sheds to help reflect the light to make it brighter inside. The 4 x 8 panels were nailed directly to the wall studs (2x4's). Here's a picture.....this stuff is guaranteed for 50 years,

 

[BillK]

BillK - the outside of the cabin is SmartSide 38 Series

Thats why I asked. I dont think the 38 series is approved as a shear panel is it ? Might not matter in your application. I will probably use the 76 series but it is hard to find without special ordering it. I dont have anything behind the T-111 presently but thinking of using something behind the Smartside.

Building looks very nice by the way !!!!!!

 

[coolstreetrod]

Sorry - looked at my paperwork and I do have the 76 series, not the 38.
Rick

 

[billconner]

I wondered about it for lateral bracing as well. Do you put housewrap on the studs before panels, or are they intended to provide the function of an air barrier?

 

[coolstreetrod]

There was no house wrap - just the Smartside panels nailed to the studs.

 

[BillK]

Back to your original question . . . . . The attached garage on my house is T111 nailed directly to the studs and I insulated it with paper backed R15 right after we moved in 44 years ago I put inexpensive paneling on the inside and it has been that way and been fine ever since.

My detached garage is unfinished on the inside but I have been thinking of finishing off so I can put a mini split in it for heat and AC. I really dont use it that much because I have my business for any serious work.

 

[mike93lx]

Back to your original question . . . . . The attached garage on my house is T111 nailed directly to the studs and I insulated it with paper backed R15 right after we moved in 44 years ago I put inexpensive paneling on the inside and it has been that way and been fine ever since.

My detached garage is unfinished on the inside but I have been thinking of finishing off so I can put a mini split in it for heat and AC. I really dont use it that much because I have my business for any serious work.

Have you ever opened up those walls?

 

[rnixon]

My building is wrapped with a Tyvek type air infiltration barrier , then Dura-Temp siding , 5/8” real plywood,with a weatherproof hardboard face



Baffles extend from soffit vents toward ridge vent . Un-faced roll insulation across top of trusses and kraft faced batts in the bays under, and between the trusses



Interior is 38 series Smartside LP covering un-faced batts & plastic vapor barrier

 

[coolstreetrod]

Is that 1x6 knotty pine boards on the ceiling? Looks great. Thanks again for the additional info and pictures. I will study it all tonight.

Rick

 

[rnixon]

1400 sq. ft. 1x6 select, beaded eastern white pine, clear poly, 4 coats on the face, 2 on the back. Working alone, nights & weekends, start to finish 5 weeks

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[BillK]

Have you ever opened up those walls?

Actually I have and fairly recently. About 3 years ago I ran an additional circuit to my work bench / ham radio bench and when I did that I took off 1 piece of the paneling so I could come down from the attic. I didnt see anything unusual at all. Pretty much looked the same way as when I originally did it other than a little dust.

 

[JohnC1957]

I used the 76 series on a shed I just built. 10’ by 16’. I did wrap the building with Tyvek with taped seams before I sided it. Pay attention to the nailing requirements and the priming/ painting of cut edges and the bottom of the sheets. I hope it holds up

 

[Wiz02]

@rnixon , thanks for sharing, your interior finishes gave me food for thought and the 67 vette(s) ? are just icing on the cake.

 

[yeldogt]

I am building a recreational cabin and using LP Smartside panels nailed directly to the wall studs with no other sheathing. I have read a lot of posts about this and most feel sheathing is not necessary. My question is, can I use paper-backed fiberglass batt insulation between the wall studs to insulate it? The studs are 2x4 and I was going to use R15. Anyone see a problem with that? Thanks......

Did you try and contact the manufacturer ?

The problem is always water and moisture. Water that gets in from outside and moisture carried into wall cavities ... the later is normally in colder climates when conditioned.

 

[billconner]

It was the original promise of T 1-11 - siding and sheathing in one. (One of my FIL's many jobs - plywood salesperson. ) Can't say the concept appeals to me for a house. Garage or shed, maybe. Of course metal siding does siding and sheathing in one.

 

[mike93lx]

Actually I have and fairly recently. About 3 years ago I ran an additional circuit to my work bench / ham radio bench and when I did that I took off 1 piece of the paneling so I could come down from the attic. I didnt see anything unusual at all. Pretty much looked the same way as when I originally did it other than a little dust.

Glad it has held up.

I wouldnt count on that, though.