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Small Cabin Forum / Cabin Construction / Wall Sheathing from Rim Floor Joist to Top plate? Misc/Roof Qs...
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# Posted: 17 Sep 2022 21:34

Hey all,
I got two of my walls lifted today, had a bunch of friends come over to help. If weather permits, hoping i get the other two walls up very soon.

A) I'm assuming I would sheathe the walls before i install the rafters?
(I'm doing a lean-to shed style roof, 4/12 slope).

B) For the sheathing do I install it from the bottom of my rim joist all the way to the top of the cap/double top plate?
(I built on concrete piers then built-up beams on top and then joists perpendicular to the beams)
(attached a screenshot of the first tall 12' wall up to give an idea)

C) See a lot of guides on gable roofs but not shed lean-to roofs....

I'm planning on doing zip system 1/2" over 2x10 rafters with the air gap ~1". Put underlayment on top of the zip? Then metal roof on top of that. Do I need the underlayment if i'm using zip?

was also thinking of possibly doing exterior foam insulation on top of the roof deck but it's getting crazy high ~16' at the top point now so might forgo that...

D) Do I need Z flashing all around the roof edge? Also above all the windows/door? And also at the top of the wall siding? Seems excessive?

E) I'm using advantech subflooring. Now that two walls are up, do I need to tarp it or just let it dry out after each rain? It's just spruce 2x6s and the subfloor so far. Worried about making a wind sail...

Sorry for all the Qs. Braindumping all my anxieties here. And really thanks y'all, my carpenter friends and your advice has really saved my butt.

Winter is coming soon for me so hoping i can at least get it weather proofed before snowfall in about a month. (I'm in upper VT)
first wall up
first wall up

# Posted: 17 Sep 2022 23:04

Yo I am doing an almost identical build here. I attached the sheathing to the walls all the way to the bottome of the floor joists to help lock the structure together. I would suggest getting all 4 walls up so you can ensure your structure is squared up before sheathing. At least partial sheathing is suggested before getting at the roof. It really makes the structure more ridged when you start getting some sheathing on.
This is my first build though so I am pretty clueless compared to others on here. I did kinda a version of the roof you are suggesting against the advice of some folks on here. 3/4" wood boards, ice and water shield, foam insulation, strapping, tin roof. I have a pretty big overhang on the roof so didnt do z flashing on the windows and doors. Front wall looks really high outside but feels good inside. You doing a loft?
As mentioned this is what I have done. I would defer to some folks on here for proper procedure. Keep us updated. Looking good.

# Posted: 18 Sep 2022 13:43

Yes, that's a lot of questions. Here goes...

A) Put the sheathing on before the roof. It stiffens every thing up. I put the sheathing on even before raising the wall but the other way works too.

B) While you can use simpson ties to hold things together I always use the sheathing to do that. You can get 9' or even longer OSB that will be continuous from the top plate down to the rim joist.

C) No comment, never used Zip.

D) Not sure what the question is. However, properly done flashing is always a good thing.

E) Don't know about advantech, but with regular lumber, plywood/OSB, let it get rained on and let it dry out. Tarps invite mold.

# Posted: 18 Sep 2022 15:04 - Edited by: ICC

A) Always sheath the walls before the roof

B) Always a good idea to lap the sheathing over the joists/rim joists as it adds a great deal of raking resistance to a wall. But then if the panels are not long enough to reach top to bottom you should be installing nailer blocking where the panels' edges are not supported/fastened directly to the wall framing.

C) One of the purposes of using Zip panels is that when properly taped (or liquid flashed) the panels become a weather-resistant barrier. No extra WRB is needed, unless you are doing stucco or the local code insists on it.

zip system 1/2" over 2x10 rafters with the air gap ~1".
I don't understand what air gap you mean. ???

D) "Roof edge" to me means along the edge of the eve or the gable overhang. Perhaps you are thinking of drip flashing, at the roof edge? Perhaps a picture or link to one could help explain the question.

Metal roofing panels can be applied directly over Zip panels unless there is a local code requirement for a roll-out WRB regardless of the type of sheathing being used.

Window and door opening have their own flashing methods. A Z-bar type is normally used by conscientious builders. The idea is to do everything one can do to prevent the incursion of water.

E) One of the big advantages to Advantech is that it is highly resistant to moisture. That was the main reason we first tried it many years ago. Just be certain to let it dry out well once the structure is dried in, before installing wall and floor finish products.

# Posted: 19 Sep 2022 07:05

I would sheath the walls before you even stood them up. Less ladder work but a mit more to lift. That wall dosnt look to big for a few people.

I think your going to be cutting it very very close on getting this weather tight before snow.

# Posted: 21 Sep 2022 20:23

Yeah, i've been sprinting. I got the last fourth wall up today.

Got my 2x10 rafters delivery today.

Asked a handy friend if he'd come over this weekend to help me with the roof. Also ordered some Simpson VPA connectors that supposedly make the bird mouth cuts not necessary but also have their own complications. Hoping it saves some time but will see.

Walls aren't perfectly plumb/level. Today was a good cloudy day but no rain. Had downpour the previous few days where my horizontal wood was developing mold.

Hoping to sheathe it all up by saturday night and also get the roof sheathing done by sunday night if i can get enough people and we can crank it.

For (D) I meant whether i needed drip edge on all sides of the roof and seems like the answer is yes based on my lumber delivery guy.

# Posted: 22 Sep 2022 08:25

Quoting: cabinnewbie
Walls aren't perfectly plumb/level

I would fix that now. It adds so much more time and labor later.

# Posted: 22 Sep 2022 11:07

Quoting: cabinnewbie
For (D) I meant whether i needed drip edge on all sides of the roof and seems like the answer is yes based on my lumber delivery guy.

If you're going with metal roofing panels, you will want to use a drip edge on the eaves, but gable flashing on the gable ends. Z-channel 'drip-edge' would not be the ideal flashing on every side of your roof.

Here is a quick picture to explain the types/locations of flashing:

If you go to a metal roofing shop you will likely highly benefit from discussing all the particulars with someone with experience. There is a good chance they can beat the big box store prices and get you custom / single length pieces if needed.

I saved a few hundred on my place by going to a metal roofing shop, but the advice he gave me, a few custom pieces they fabbed up for me, and custom cut to length panels were invaluable!!

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