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Small Cabin Forum / Cabin Construction / A few remaining planning questions
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# Posted: 2 Mar 2023 13:09

Hi y'all - I've got the floor done, and I'm ready to move onto the walls and roof and start getting my lil 12x16 dried in before it really starts getting wet down here. I'm learning a lot as I go, but I've got a few remaining questions that I'm trying to get figured out before I start in on the next steps.

Feel free to answer one or a couple of these - any advice helps! My plan so far is to do 8 foot walls with a gable roof, and then a covered porch on the 16 foot side with a the roof for that extending out from the top of 8 foot wall there.

1. Siding. I think I'm going to go with T1-11 or a similar kind of sheet siding. For a while I was thinking of doing something else, but I feel like this will be the easiest solution for getting something up quick, cheap, and easy on such a small building. The issue, however, is that I can only find 8 foot sheets around here, but I have read that you should have this siding covering your rim and end joists. I'm unsure to do this without having a seam 6 inches down from the top of my walls, which I really wouldn't love.

Is it fine to just paint the rim joists? Should I just cut 5.5 inches off my wall studs? Is there another good solution in this situation? Furthermore, for the z-flashing I do have on the gable ends, are those fine to be covered with a trim board?

2. Roofing: As I said above, I want to do a gable roof with an attached covered porch on the long side. There's lots of old cabins around here in Arkansas in this style, but I'm not sure the best way to go about it.

I think I understand how to frame the gable roof, but I wanted to know if there were was any good advice or resources out there about doing the connected porch roof (with a slightly flatter pitch). I was planning on just doing addition birdsmouth rafters coming off from the top plate for the porch, tied to the roof rafters, and with bird blocking in between each pair of rafters. Is there a better/easier way to do this? Do I just slice off the ends of the roof rafters at the end of the porch rafters?

Furthermore, are there any good resources y'all can recommend about roof venting? Do I need to worry about venting if I'm not planning on a loft? Would I just install some screen covered holes in the bird blocking?

Appreciate y'all looking at this longer post. Any other advice/resources you have are much appreciated - I'm still doing a lot of my own research, but thought I'd go ahead and look for some advice here.

# Posted: 2 Mar 2023 14:54

There are two choices concerning the siding. One, it's available in 9 or 10 ft, you just have to order it. I ordered 9'. However, after I finished the structure, without the siding, I realized my soffit came down far enough (4/12 pitch with 18" overhang) due to the rafter tails extending down far enough and then the return of the soffit. I really only needed 8' and this went below the rim joist about a 1/2 inch (creating a drip edge) covering everything. So, see if that might be your case too.

As for the porch, I think you will find it will depend on the wall height. You will most likely have to tie into the roof and come out if you want it to have a decent pitch. Otherwise, if your porch is low enough and you don't mind a step up into the cabin, you can come off the end of the rafters/fascia board with a light weight framing (like 2x4). Others probably know better, since I too wanted to do this, but chose not to in order to finish up my project as fast as I could. I've been thinking about incorporating it into the structure now, though. But, in my case, I set the deck about 4 inches below my door threshold, as you can see in my pic.

Cedar Fever
# Posted: 2 Mar 2023 19:05

You can cut more siding to cover the rim joist with. I plan on doing that and just caulking the gap.

# Posted: 2 Mar 2023 20:32 - Edited by: ICC

When the panels overlap the rim joists, the wall becomes much stronger, providing racking resistance. It is best to look for a supplier of 9-foot sheets. That will not be a big box store, but usually a lumber-only dealer.

If you cannot get 9-foot panels the second best thing will be to place cut strips at the top but there must be blocking 2x's inside the wall framing for the panel edges to be nailed to. This will help regain some of the rigidity of the cut panels. The top edge of the wall panel, either a full sheet or an added strip must be nailed to the top wall plate to achieve full strength as well. Installing a panel shifted down the wall as was described with the idea of covering the missing length with the soffit might appear ok but that is deficient as far as anti-racking goes, not to mention what then seals the wall, and holds in the insulation.

Also, there are metal strips, called "Z-bar flashing" which are made to be used between the horizontal edges between panels. That keeps water out and is much more dependable than just caulk. The upper panel must be spaced upwards at least 1/8" to keep the panel from sitting on a wet metal edge and absorbing moisture.
**EDIT** I re-read the OP and see you know about z-bar flashing. Sorry about that. You could trim over but we always left it open and everything painted.

Re the porch roof: attaching the porch roof to the rafter tails or fascia is not usually a great plan. One reason is fascia boards don't offer a lot of strength as the fasteners are nailed into the end grain of the rafters. Very little pull-out resistance.
**EDIT** Oops again. Cutting the rafter tails off at the wall top would be better with the porch rafters side nailed to the rafters. There still could be a problem with the porch roof pitch, though

A second reason is that a roof attached to an eve or top plate like that often ends up with very little pitch unless the porch floor can be dropped considerably. More so if you shorten the wall studs as first mentioned. I would suggest drawing that out to scale, or mathematically computing the pitch of the proposed porch roof, then checking the minimum allowed pitch for the type of roofing you are considering.

**EDIT** I forgot to add a comment for the porch floor. The connection of a porch or deck floor is often a weak point. Normal rim joists are most often nailed to the floor joist ends. That joint has very poor pull-out resistance, as I mentioned for fastening to rafter tails. So the question is, how to fasten the porch floor to the cabin floor or foundation so the porch won't pull loose? There are special Simpson connectors for securing a deck/porch floor assembly to the main structure. I have a shaky internet connection at present and cannot get search for a reference to work. Search for Simpson DTT Deck Tension Tie

# Posted: 3 Mar 2023 07:06 - Edited by: Tim_Ohio

My sheathing went to the top of the wall top plates down to and just below the rim joists, connecting the entire wall system together and to the floor system which was connected to the concrete piers with J-bolts embedded into the top of the pier. The siding then just became mostly cosmetic and could be more easily replaced, since it does not go under the channel supporting the soffit on the outside of the wall. Since sheathing went up first drying things in, that gave me time to carefully finish the siding before installing it.

# Posted: 3 Mar 2023 08:42

I would use the 8' if that is all you can get. Your 12x16 building will be very strong against any racking with the sheeting. And the walls will be fastened to the floor. It would take a huge wind force to lift it.
I would put flashing under the siding that also covers the rim. This would seal it and also provide an insect barrier. So the Arkansas bugs can't climb in as easy. Probably help with mice too.
Yes you should vent. Depends on how you insulate. A ventilation space above the insulation from the soffit to the peak. Or insulate the roof. The dept of energy has information.
Id try to not complicate things. I'll also probably get whipped up on for suggesting this. But I've built a few things also. And confident in my suggestions. I suspect that there are a of cabins, storage sheds n such just like this.
Good luck n have fun

# Posted: 4 Mar 2023 11:23

Quoting: Cedar Fever
You can cut more siding to cover the rim joist with. I plan on doing that and just caulking the gap

Dont do that. When pannels meet you need to use proper Z flashing with a gap.

This was also my issue with useing T1-12 siding. We are going to do a "belly band" of metal pannels with proper Z flashing.

# Posted: 4 Mar 2023 15:38

I would want any seam of T siding to be up high and under the eaves (imo do Not do short eaves) where they wont get much weather/water.

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