Sheathing orientation, horizontal and vertical vs. diagonal sheathing?

[Piston]

This question is about using nominal dimension 2x8, 2x10, and 2x12 for sheathing; both for roof and walls.  (specifically, how to orient it)

I want to put the sheathing on vertically or horizontally, I don't like the 'looks' of diagonal sheathing.  I'd like to use vertical boards for the walls and horizontal boards for the roof.  I know the braces add the structural rigidity to strengthen and prevent the frame from racking, but is it recommended to use diagonal sheathing on the walls to help stiffen the frame even more?  
As for the roof, I don't have roof braces for the common rafters and no ridge beam, so do I have to put the sheathing diagonally for it?  I would think so because there wouldn't really be much stability in nailing them horizontally, for the roof, I don't mind the look of it diagonally, but for an overhang it may be problematic.
I want a roof overhang on the ends and sides, but how do I get a roof overhang on the sides if I use diagonal sheathing?

I finished drawing my frame in Sketchup and now I'm just 'playing around and ran across this 'dilemma'  
I'm going to post the frame file in the proper thread if anyone wants to take a look.  It has all the joinery drawn in but I'll remove all the sheathing and extras for the frame file.  

[witterbound]

What are you going to use on your walls, between (or outside) the posts?  2x4s?  The engineers all say that the rigidity of the frame comes from the sheathing, and that they ignore the braces in their calculations.  I think you need to run everything horizontally.  Any why 2x material for sheathing.  Got to be a lot more expensive that OSB .....

[Jim_Rogers]

Most, if not all, of the sheds I have done have had horizontal 2" roof decking, as most have been common rafter roof systems. Usually tongue and vee grooved. This t&g was so that the load is spread out to more than one plank. Sometimes the frame designer specifies that this should be done.

That is the planks run gable to gable. The only time you'd run planks ridge to eaves is when the roof system is a principal rafter with purlins roof system.

Most, if not all, of the sheds I have done have had vertical siding. Some have had vertical ship lap, some have had board and batten.

With vertical siding you need to have nailers at least every four feet. Sometimes every two feet depending on details. Ok, I know someone will ask what detail will make it necessary to have it every two feet. Well, if it's vertical tongue and groove you could have them every 4'. But if it was board and batten, you may need it every 2' to hold the boards in line with each other. I guess it would depend on how dry and straight the siding is when installed.

Only one barn I helped on many years ago, did diagonal sheathing. And I sold them wide pine boards for that. The waste pile out back was huge.

For the roof deck to overhang you can just make the sheathing a little longer, but to secure these overhanging ends you can put on "rake" boards. These rake boards will tie each piece of roof sheathing to the one next to it, holding them in line. There is a limit to how much you can overhang without some support.

Sometimes when you want a large gable end overhanging roof, you add another rafter outside the vertical gable wall to support the overhanging roof decking. To do this you extend your plate beyond the end bent, to catch the foot of the end rafter.

One of the first questions I ask a client when designing a structure is: "what is the amount of roof overhang you want? eaves side? gable ends?" The answers to these questions help me to determine the plate lengths and sizes. The longer the deck has to overhang the last rafter the more it needs a rafter to support it. The longer the plate overhangs the last supporting post the larger it has to be. ("Edit" and sometimes this extended plate has an external brace to hold it up.)

Sometimes between posts we add nailers for the vertical siding. Some nailers are planned into the timber frame. That is they have tenons on the ends and mortises in the posts. Some nailers are just toe nailed into the posts. It depends on where it is in the frame or the client, or the budget.

I just added an album to my gallery called "Enclosing a frame". It shows some 62 photos of doing a shed for a client.
It includes decking the first floor deck with 2" tongue and groove decking. The loft decking and roof decking.
Also, adding the toe nailed blocking to create the surface for the siding. Also, the raised strapping for creating a surface for the siding to create a shadow line.
Shots of the shed with the siding just finished, both inside and out. And then some shots of the finished shed. Also at the end the shed some 2 years later.

Here is a link to that gallery: https://forestryforum.com/gallery/thumbnails.php?album=3415

If you have any questions about any photo, site the photo name or id number and I'll explain if I can.

[Piston]

Another great post Jim, thank you for taking the time.  I'll spend some time looking at the photos you just posted and let you know if I have any questions.  I'm glad I'll be able to use the horizontal on the roof and vertical on the sides.  I am planning on 2x material for all the sheathing.  I will try to get as much as I can off the logs when I mill the timbers out of the centers. 
I'm glad I asked, thanks again. 

[witterbound]

I guess I'm confused.  You asked about sheathing, not siding.  Are you planning on having sheathing under the siding, or just siding?

[ballen]

Jim,
I am interested in very deep gables and eves but do not want to extend the purlins, plates or rafters because of thermal bridging.  If I stop the main timbers at the siding and wrap the whole house in insullation, etc., what's the best way to then extend the gable roof and eves without tying into the main timbers?  Have you ever done something like this where the main concern is creating a thermal break?
Bill

[Dave Shepard]

If it is sheathing, as in a structural member of a house, I think it has to be diagonal. A TF doesn't (typically) rely on the sheathing for support, so you can go whichever way you want.

2" hemlock roof decking:

[Piston]

I think maybe I'm using the term incorrectly.  By sheathing, I meant the first layer that goes on the outside of the frame to close it in, I will put siding over the sheathing.  I'm leaning towards using the following method to insulate and enclose the frame.....except instead of using drywall as the drawing suggests, I will be using the 2x boards (vertically on the inside, as well as on the outside in place of the OSB mentioned)





Is there any reason this method is a bad idea?  I don't have any experience with it but it sounded good in the description  :D


When I'm milling the timbers out of the logs I will try and get as many 2x's as I can out of the logs, and hopefully get enough to enclose the frame with, this way will be a lot cheaper than buying plywood, osb, or other types of sheathing (if I'm using the term correctly) plus I think it would be a sin to enclose the frame with plywood.  This will also be the interior wall so I want it to look 'cabiny' (that's a word right?  :D)

[Piston]

How far do you think I could overhang the gable ends using just 2x material if it is/isn't tongue and grooved? 

Jim, Do you remember the wall height on this shed?



Nice job by the way, I really like the false beam up top with the block on it.  ;D

Did you place the sills on concrete, and then put crushed stone around it?
I went through all your pics you linked to and that is pretty much exactly what I want to do, and then put the above mentioned insulation method on the outside of that, but maybe not until a year later or so after the sheathing dries out a bit. 

Please correct my terminology of 'sheathing' if I'm using it wrong  ;)

[icolquhoun]

this is very similiar to the way i'm sheathing and finishing (yes you are correct in your usage of sheathing) my cabin.   

in order from inside to outside on mine (yours differs slightly)

-post/frame
-1x t+g sheathing milled on my mill and t&g'd on a tablesaw (easiest/fastest/cheapest way I've found) as interior wall oriented vertically
-2" foam board running horizontally
-2" foam board running vertically with all seams staggered
-builder's felt
-1x2" furring strips to strap the exterior on 12" centers vertically
-3/4" clapboard siding horizontally with trim

to frame windows/etc...i planned on having the interior girts running at 32" off the floor to act as the lower interior sill as well as the girt for the 1x vertical T&g and another at the window top height.  once the sheathing is roughed out to size, a true 2x5 would then be screwed to the rough opening on the outside of the sheathing which is then flush with the back of the exterior clapboard and provides a nice flat area to attach the window trim/framing....

[Jim_Rogers]

How far do you think I could overhang the gable ends using just 2x material if it is/isn't tongue and grooved?

How far would you like to have it overhang? If you have a rake board holding the end together then you could probably go at least a foot, maybe more.

Do you remember the wall height on this shed?

Yes, this shed has a wall height of 12' 8" from the bottom of the sill to the top of the plate.

Did you place the sills on concrete, and then put crushed stone around it?

This client made his own foundation by digging some trenches and then creating some form planks on the top of the trenches. He poured concrete into the trenches and up to the top of the forms.

Here are some photos of this system:








I'm not sure if he made the top of the forms 8" above finish grade or not. He should have.

After the concrete set up and the form boards were stripped he attached pressure treated stock to the top of the concrete to be the "sill" of the building. The outside of these PT sills were exactly the size of the frame 14' x 16', so that the siding, which in this case was shiplap siding, could extend beyond the sill timber, the PT sill and down over the concrete a little.

Here are some photos of this:






After that he added the crushed stone. Which would appear to be too thick and this raised the "finish grade" up which caused the water to splash back onto the siding creating the stain.

[Jim_Rogers]

This shed that I have shown above, and is in my gallery in the "enclosing a frame" section is the shed that Jack Sobon used to use as a "workshop frame" at his once a year workshop held at the shaker village in Hancock, MA.

When you take this workshop you get a copy of the plan to use as a working drawing to write on and make notes.

You also get a copy of the plan to take home and have.

We used this plan as a "workshop frame" several times when I was teaching timber framing here at my sawmill yard. I know this frame quite well.

One of the "enclosing" problems with this frame is that the walls are measured from the top of the sill. What I mean is that the distance from the top of the sill to the top of the plate is 12'. So when you add the sill height of 8" then the subsill of 1 1/2" of PT, the siding has to cover all that and hang down some more.

So, 12' 8" + 1 1/2"+ 1"= 12' 10 1/2" or so. Siding comes in even foot lengths. That means you have to buy or make 14' siding and cut it back to 12' 10 1/2" if you want to put the siding on fully up to the top of the plate and have it hang down beyond the bottom of the PT sill.

You could lower the post heights to compensate for this. But then you run into problems with clearances inside the shed at the first floor level. If you lower the post height and maintain the tie beam height, thus lowering the plate height you reduce the amount of room on the second floor loft area.

Usually these sheds have exposed rafter tails. Jack likes to make a fancy curved tail and it's ok but I don't care for it much.

See this:



And:



So, in order to not have this happen and to be able to use 12' siding, I decided to try and figure out a way to make the tails to be enclosed with some fascia and soffit boards.

I created this drawing:



Here we can see the roof decking which is 2" tongue and groove, with the down hill edge cut plumb for the fascia, the fascia board and shadow trim board, the soffit board and the top of the 12' siding board.
This saves a lot of waste and money.

I haven't as yet done this with anyone's shed, but this would be the plan should they want to not have exposed rafter tails.

Proper planning of the entire enclosure system is a good thing to do.

Jim Rogers

[Jim_Rogers]

In one of the foundation shots above the forms had not been stripped.

Also, there were some threaded rods up through the PT sill and left very long. This was to we could attach the timber sills to the foundation on each side.

To do this we assembled the sills on blocks above the PT sills and transfered the threaded rod location to the top of the timber sills and bored holes through the timber sill.

Like this:



After all the holes were bored, and we could sight down through them to see the tops of the threaded rod, we lowered the sill assemble down onto the PT sill:



Here I am using one of the floor joists as a lever to lift the assembly up to remove or lower some of the blocking. By using a lever and lower blocks, I could lowered the assembly down step by step to the PT sills.





As you can see the threaded rod was very long.
After we had the timber sills down onto the PT sills and all was square and true, (some of the form planks/boards were removed to inspect) we chiseled out the top of the timber sill the depth of the nut and washer so that they would be below the top of the timber sill. (You have to be very careful doing this, as it is very easy for the chisel to slide into the threaded rod and damage the chisel. Don't ask me how I know.)

Next, using a sawzall we cut off the threaded rod to the top of the timber sill and then decked over it all. You can see the deck over in a shot above in this thread.

We stood each post up on the timber sill, and scribed onto the top of the sill the outline of the post. Then we cut the decking to the outline. This left a notch in the decking for the post to set into when we raised the bents.

I just wanted to share some of the details of doing this installation.

Jim Rogers

PS. you can see some water in the foundation hole. The site was quite wet as it had rained a day or so before the raising. And it was quite muddy. The client sent one of his workers out and got several bales of hay and we spread it out all over the muddy areas. This was great. And I highly recommend doing this on muddy sites. It is natural and doesn't cost that much. It makes the site easy to walk on and safe. We have done this at other sites since this project. And it works every time.

[witterbound]

I've got 3 ft eaves and 2 foot on the gable ends, overhang.  I built brackets to hold up the overhang, and bolted them onto my 2x6 walls that surround my frame, from the outside.  I still can't figure out the ff photo thing, so I can't post pictures.

[Jim_Rogers]

  I still can't figure out the ff photo thing, so I can't post pictures.

What's the problem? It's easy. Create an album and the click on java uploader. It resizes all the pictures for you.

Then just highlite the picture address or use the "insert photo" option and it stores your picture address to your clipboard and then you just paste it into a post.

Do you need a training session to learn? I can teach you....

[witterbound]

Mental block, I guess.  Seemed much easier than when I tried it before.  Thanks Jim.

Here is a pic of my frame, and my brackets.

[Piston]

How far would you like to have it overhang? If you have a rake board holding the end together then you could probably go at least a foot, maybe more.

I'd really like as much as I can, 2' would be nice but I would be happy with 18" 

So, in order to not have this happen and to be able to use 12' siding, I decided to try and figure out a way to make the tails to be enclosed with some fascia and soffit boards.

I like the idea you came up with in your drawing.  Using this method would also give the shed the "look" of a lower roof height as well right? 

One of the "enclosing" problems with this frame is that the walls are measured from the top of the sill. What I mean is that the distance from the top of the sill to the top of the plate is 12'. So when you add the sill height of 8" then the subsill of 1 1/2" of PT, the siding has to cover all that and hang down some more.

So, 12' 8" + 1 1/2"+ 1"= 12' 10 1/2" or so. Siding comes in even foot lengths. That means you have to buy or make 14' siding and cut it back to 12' 10 1/2" if you want to put the siding on fully up to the top of the plate and have it hang down beyond the bottom of the PT sill.

You could lower the post heights to compensate for this. But then you run into problems with clearances inside the shed at the first floor level. If you lower the post height and maintain the tie beam height, thus lowering the plate height you reduce the amount of room on the second floor loft area.

Jim, can you read minds?  The reason I asked about the wall height was exactly what you posted about adding the sill height to the wall height and ending up with a rather 'tall' looking structure, that was going to be my next question!  :D  This is also one of the reason's I added the farmer's porch to my frame design.  By increasing the rafter tail and enclosing it like you did, I would think that would make the building look shorter to the eye? 
I'm trying to get the entire frame and enclosure planned out for my cabin/workshop frame before I actually start cutting anything.  I want to 'build' it in sketchup so I know exactly what I need for materials, as well as to catch any mistakes or major issues prior to erecting the frame.


I guess there is no reason for me to use 2x material for the initial sheathing?  Maybe instead of 2x I'll mill all 5/4 material and tounge and groove it for the sheathing, I'll still use 2x for the roof and floor decking.  What are your thoughts on that? 

I built brackets to hold up the overhang, and bolted them onto my 2x6 walls that surround my frame,

I like your idea with the brackets, thanks for taking the time to post the pics!  Nice looking frame, that compound joinery intimidates me :D

When you take this workshop you get a copy of the plan to use as a working drawing to write on and make notes.

One of these days my schedule will line up so I can actually get into one of these classes!  I've been trying for 3 yrs now  >:(

[Jim_Rogers]

Using this method would also give the shed the "look" of a lower roof height as well right? 

It could.

can you read minds?

No.....

I would think that would make the building look shorter to the eye? 

It may.....

I'm trying to get the entire frame and enclosure planned out for my cabin/workshop frame before I actually start cutting anything.  I want to 'build' it in sketchup so I know exactly what I need for materials, as well as to catch any mistakes or major issues prior to erecting the frame.

Good plan.

I guess there is no reason for me to use 2x material for the initial sheathing?

It seemed a little thick but I didn't know your reason for doing that. At the recent conference I attended they talked about "plank" houses. And one fellow, who some said he didn't know what he was talking about, said that the reason why "plank" houses were made with 2" vertical planks was to prevent "tomahawks" from penetrating the walls.

Maybe instead of 2x I'll mill all 5/4 material and tongue and groove it for the sheathing, I'll still use 2x for the roof and floor decking.  What are your thoughts on that? 

Usually in our area, 2x roof decking is preferred. As you know, we call it 2" tongue and groove, but when it comes out of the four sided planer it is usually 1 1/2" thick or so. I think I have a sample here that I could measure, it maybe 1 5/8" thick.

5/4 for tongue and groove sheathing would be good. Again when they run it through the machine it may finish at 1" thick or less. It maybe best if you find the planer millwork shop you intend to use, first. And find out from them what thickness it will come out. If they are a standard shop they should use standard thickness from the "pattern book". But it doesn't hurt to just ask.
Usually when they make the t&g both sides are planed. If you want it thicker you could go with shiplap and that would be only one side planed. Then comes the question of which side in or out. In the enclosing gallery pictures he put the rough side out, planed side in. It was 7/8" thick shiplap.