Post frame vs foundation

[KennyG]

Full length studs on the ends will be fine. You just need a horizontal tie member at the same height as your bottom member on the truss. (You probably want this anyway). If you have openings (doors) in the end walls you will need to provide sturdy beams above the door openings now since you have to transfer the roof load down to the remaining studs/posts. If you have roof trusses you can go a lot lighter on the beams over the doors since they don't pick up as much load.

 

[roadhunter]

As I said earlier the company I work for purchased a cheap menards pole barn kit a while back and we are just getting around to putting it up. The owner decided to pour a regular footing around the whole building and just use metal brackets for the posts to sit on. This is nice but it took a lot of strength away from the wall because the posts are not in the ground to add stability. We ended up adding their flat strap diagonal braces to help.

By the time it is all said and done we could probably have put up steel for the same cost and have a much better product. I hear steel prices are dropping so it might get more affordable to put up steel buildings moving forward.

 

[LD1]

Doesn't the top plate help hold the other 2 walls together? They should be interlocked. I could be wrong, but I think the trusses are designed for a verticle load and not so much for a "stretching" load. You may not need a truss, but should probably do a top plate and jack studs or some other means of tension between the walls.

Sorry if my terminology is not correct.

I think jackstuds would eliminate the my reasoning for going full length for rigidity. The sidewalls will be tied to the gable wall the full length of the 2x6 studs where the two wall sections meet. And everything is tied together with sheathing. Here is a top down view of how I will do the corners

Red is Sheathing Black is the studs

 

[LD1]

Full length studs on the ends will be fine. You just need a horizontal tie member at the same height as your bottom member on the truss. (You probably want this anyway). If you have openings (doors) in the end walls you will need to provide sturdy beams above the door openings now since you have to transfer the roof load down to the remaining studs/posts. If you have roof trusses you can go a lot lighter on the beams over the doors since they don't pick up as much load.

Even end trusses? Seems they just transfer the load straight down.

Only one end will have doors. But even then I wouldnt think I would need a massive header, cause once its all framed and sided, the sheathing and siding should act like a super strong truss.

Picture taking a truss, removing all the webbing and replacing that with OSB and metal siding. I would think that would be plenty stout?

 

[truckdiagnostics]

Another design question.

Since I am doing 4' OC trusses for a 72' building, that requires 19 trusses.

BUT, since the endwall trusses are sitting on top of an end wall, do they really need to be trusses?

So here is my thought. Instead of 12' 2x6's for the end wall with a truss on top, why not use full length 2x6'x all the way to the top. The peak will be 18'8" from the foundation wall. Which will require a 20' board cut to length. Then 8" shorter for every 2' out down to 12' for the side walls.

Doing this will save 2 trusses, but at the added expense of longer lumber. End result is saving $50 for each gable. But it isnt really about the savings. My though is having the full length wall will be more like having full length posts (if going post style) to help stiffen up the roof structure and just make a stronger building in general. Besides, Endwall trusses are basically just that. Not really designed to carry a load the way they are designed, since all the roof load gets transferred to the wall.

Thoughts?

Don't know how you would go about framing it. Going to want the top plate going all the way around. I was always under the impression the reasons for the poles going to the top on the end walls for pole buildings was wind load. Here is the pic of wind bracing on one we have going up now. There is still corner bracing to go. We have 16 ft side wall so little more wind load. I have always been paranoid about opening the doors or having strong wind blow the doors in and finding the roof next door. On the design it looks like you are headed towards, ring shank nails on the roof sheeting, hurricane clips on the trusses, walls anchored to the footings. We have had couple of tornados go through here, and you could tell the buildings that were built for the wind load.

 

[LD1]

Don't know how you would go about framing it. Going to want the top plate going all the way around. I was always under the impression the reasons for the poles going to the top on the end walls for pole buildings was wind load. Here is the pic of wind bracing on one we have going up now. There is still corner bracing to go. We have 16 ft side wall so little more wind load. I have always been paranoid about opening the doors or having strong wind blow the doors in and finding the roof next door. On the design it looks like you are headed towards, ring shank nails on the roof sheeting, hurricane clips on the trusses, walls anchored to the footings. We have had couple of tornados go through here, and you could tell the buildings that were built for the wind load.

View attachment 412705

Basically it is going to be built just like a normal building with an endwall truss. Only without the bottom cord of the truss, and the vertical members of the truss extending all the way to the foundation.

Yes, the rest of the building will be built appropriately. J-bolt anchors to the foundation, hurricane ties on the trusses bottom cords tied together and angle bracing from bottom chord of truss to top cord of next, etc etc.

Roof wont have sheathing. IT will be purlins like a typical pole barn. Only the walls will get the OSB sheathing for the siding.

 

[KennyG]

The way a truss is designed, the bottom chord is pretty rigid and prevents localized load from being transmitted to the studs. Sheathing with OSB will help with this. I was assuming this was a building with only metal siding. I'd still keep the headers pretty strong, just on principle. If you are framing with 2x6s, your headers will be pretty thick anyway.

 

[Billrog]

Shting will deal with the spreading but I wouldn't be framing in the end walls until the trusses were on sight so you could measure and allow for the height of the heel on the truss. Framing the wall all the way up would give you something to anchor the trusses to when standing them and any openings in these end walls would require the same size header as the side walls eg. 2x10 or 2x12 depending on size of opening.

 

[s219]

Another design question.

Since I am doing 4' OC trusses for a 72' building, that requires 19 trusses.

BUT, since the endwall trusses are sitting on top of an end wall, do they really need to be trusses?

So here is my thought. Instead of 12' 2x6's for the end wall with a truss on top, why not use full length 2x6'x all the way to the top. The peak will be 18'8" from the foundation wall. Which will require a 20' board cut to length. Then 8" shorter for every 2' out down to 12' for the side walls.

Doing this will save 2 trusses, but at the added expense of longer lumber. End result is saving $50 for each gable. But it isnt really about the savings. My though is having the full length wall will be more like having full length posts (if going post style) to help stiffen up the roof structure and just make a stronger building in general. Besides, Endwall trusses are basically just that. Not really designed to carry a load the way they are designed, since all the roof load gets transferred to the wall.

Thoughts?

I did this for the barn at my previous property, and it worked out great. Have no idea if it's up to code. But wall sheathing should provide plenty of shear/spread resistance.

Top plates aren't really expected to provide that shear/spread resistance -- they rarely stretch wall to wall without a joint anyhow -- so I wouldn't be concerned about the lack of a top plate. But I would make sure that the gable wall "rafters", or whatever they end up looking like, have a proper ridge tie and/or collar tie that handles spread loads of the roof. Even at gable ends these loads exist, though gable ends don't always get ties.

 

[LD1]

any openings in these end walls would require the same size header as the side walls eg. 2x10 or 2x12 depending on size of opening.

Why? With a truss and exterior sheathing, the header could be minimally sized. What is the difference. Instead of truss webbing, I have a completely sheathed truss "frame" so to speak. Basically think of an I-joist. Only tapered where its depth is greater in the center. (similar to I-beams in a steel building but to a greater degree.)

Door opening will be 18'. If that were on a side wall, (without crunching the numbers) would likely require a header on the order of 18-20" depth and full 5-1/2" width. That would be asinine for a sheathed end wall IMO.

I did this for the barn at my previous property, and it worked out great. Have no idea if it's up to code. But wall sheathing should provide plenty of shear/spread resistance.

That is what I am thinking

Top plates aren't really expected to provide that shear/spread resistance -- they rarely stretch wall to wall without a joint anyhow -- so I wouldn't be concerned about the lack of a top plate. But I would make sure that the gable wall "rafters", or whatever they end up looking like, have a proper ridge tie and/or collar tie that handles spread loads of the roof. Even at gable ends these loads exist, though gable ends don't always get ties.

"rafters" is pretty much what they will end up being. But sitting on top of a vertical wall and all the load being transfered straight down, I just dont see there being much spreading load. If it was just rafters without all the joists coming up to meet it, I could see the spreading load. But with all the joists coming up + sheathing + metal siding + the fact that the walls are tied together in the corners, I dont think spreading should be a concern.

Even so, I could still throw in a 2x4x8 to "tie" the "rafters" together if I dont like the way things are going