We have some issues and questions I’m hoping GBA can help answer. We built a very small (less than 150 square feet) backyard building during the pandemic and are now in the process of finishing it it off. For background, this is what we’ve built:

 

FLOOR:

Plywood sturdifloor

Framing with 9.5 r-38 rockwool 

2″ comfortboard r-8.4 underneath joists

Exterior plywood underneath covered with oil based paint

Joint and seam to air seal, and fast flash along the sides of assembly as it’s near ground level.

Concrete pier foundation with skids 

Gravel under structure

 

ROOF:

Cathedral ceiling with exposed ridge beam / rafters 

 

Conservation technology building gaskets on top of rafters, gable ends, and top of wall

Plywood sheathing with gaskets and prosoco cat5 (joint and seam + fast flash where applicable)

Continuous exterior insulation:  6″ of rockwool comfortboard 80 r-25.2

Vented standing seam metal roof: furring for ventilation channels, plywood roof decking, underlay – furring supports 8″ overhang

 

WALL:  

2 x 6 framing 24″ oc, building gaskets at top and bottom of wall

Plywood sheathing 1 1/8″. Sheathing extends over the entire side of the floor assembly.

Prosoco cat5 (and joint and seam + fast flash where applicable)

Door and windows installed, also used gaskets.

Exterior: facade grade cork 2″ r-8 partially applied

 

 

Issues and questions:

 

1. Door awning with cork facade

We were planning to add a freestanding step/deck (larger than a step but smaller than a regular deck) and a post supported awning that projects 4 ft. (not attached to building either). 

We recently came across the “Stratton Bracket” for attaching ledgers and are considering them to replace two of the four awning posts.  https://pastratton.com 

Would  it be possible, or rather sensible, to use this bracket over 2″ of cork? They say it  “Bolts directly against most types of siding; Vinyl, Aluminum, Steel, Wood and Masonry”

 

The awning will be on the short wall (not gable) and there is a limited amount of space above the door. It’s a single story so there are no floor beams to attach to. The roof has a ridge beam and our rafters end at the wall (trying to remember if they’re 4×6 or 4×8). The rafters have a sort of heel, not sure what you call it, it’s not a truss, its the angle they were cut at creating a raised end. If this bracket could be used, would we attach it through the cork and sheathing into the heel of the rafter, or into rafter blocking, or door header?

We’re doing some digging in the yard and need to resolve, as soon as possible, where and how many the post bases will be

 

 

2. Screws went through the cork facade, cat5, sheathing, and into the wall cavity.

Unsure of how to best apply the cork facade, we called the distributor and someone recommended to apply with cat5 and screws for good measure. The panels are lapped and our plan was for longer screws to go through the full thickness of the panel. So, starting at the bottom of the wall working up, it’s at least 25% covered. Sometime later I realize the fam used 4 screws per panel, primarily through the lap of the panel, which is half as thick. There are many screws going through the sheathing into the wall cavity. No doubt the screws are also in the floor assembly, but there is no way to see or reach inside there (no crawl space).

 

The panels are lapped, and they are really stuck on with cat5 (so much that the screws seem a bit superfluous). The screws couldn’t be removed without tearing up the whole facade and maybe damaging the sheathing in the process. We cut off the ends of the screws in the wall cavity and went over the spots with joint and seam filler. I would welcome any opinions and advice as to whether this will work? Should we spot treat with fastflash also? Or do something else? How much do I need to be worrying about the inaccessible screws in the floor assembly?

 

 

3. Interior air barrier questions, plywood 

Regarding plywood, I’ve read about it’s ability to be used as an air barrier and vapor retarder, but all air sealing instructions are for drywall.  It basically seems like the process is doing what we did for the sheathing, for the interior? (minus the cat5, fastflash, and those random screw intrusions).  Does anyone have any specific words of advice for installing a plywood air barrier?  

 

-Is a plywood air barrier installed before or after a partition wall? A small loft?

 

-Is the installation order be the same if using Intello instead of plywood as the air barrier?

 

-Regarding the integrity of an air barrier, is it simply no holes through the wall, but screwing into the studs is always okay? What about a screw or trim nail going halfway through plywood (not near a stud)?

 

 

4. Cathedral ceiling

GBAs favorite topic 🙂 The roof has been on for 3 years and that’s going good. The exposed rafters and plywood look nice. Now that we’re finishing the interior and will be more regularly heating it, I have some concerns. Will it be ok with just our exterior insulation, and the exterior sealing and gaskets? We will be ventilating the space. We also have a dehumidifier we can put in there if necessary, but would prefer avoid over reliance on that.

 

What more could we do for the interior ceiling? Is the choice just leave it as it is vs. cover up the rafters, or are there steps in between?

 

I was trying to wrap my head around the logistics of adding blocking to the rafters and blowing in a couple inches of insulation,  air sealing with intello, and then attach something to the blocking to hide all that, while still being able to see the ridge beam and some of the rafters? Do people do stuff like that? Any foam-free ideas?

Thank you!