Post frame vs foundation

[LD1]

I maybe changing the design of the building I am planning for this spring. Looking for some feedback.

I am considering doing a 6 row block foundation instead of post-frame. I like the idea of having a few rows of block inside the building around the base. Seems it would be alot better for hosing down and cleanup, as well as lots more fire resistant when cutting, welding, and grinding out there.

I still want to go with steel siding and OSB interior. But what is the best way to construct the walls ontop of the block. I have never seen a metal siding building in person that had a block foundation, so not sure what the common method is.

Right now, I am thinking 2x6 studs on 2' centers with sheathing on the outside to attach the metal to. And trusses on 4' centers with conventional 2x4 purlins for roofing.

So some questions. Is the sheathing required? or does metal siding offer enough shear protection? And if I dont need sheathing, I would have to do something different to attach the metal to, as 36" spans of metal dont work out with 2' or 16" OC studs. So possibly running purlins outside the studs like a typical post frame? Would that offer enough lateral strength without the sheathing?

What about setting "posts" comprised of 3 2x6's on top of the block wall every 8-12' or so and building up like a post frame? 8 or 12' OC trusses would save money on the roof system, but will a block wall handle the less distributed loads of 40' span trusses?

So far, what I have calculated is only about $200 more on the 40x72 building to go block. Still factoring in other variables, but on a building this size, if block foundation is gonna be no more than ~$1000 more, I think I will go that route. I dont want to be worried about fires, or rotting out the inside from hosing out because I wanted to save $1000 on a $25k building.

 

[roadhunter]

We bought a pole barn kit 2 winters ago and are just now getting around to putting it up. The owner decided to pour a regular foundation instead of setting the posts in the ground. They welded up some brackets and are just using the same posts but putting them on top of the slab. It should work fine but IMO it will need quite a bit for extra bracing. I'll try to get some pics the next time I'm out there.

 

[Cat_Driver]

I think it would be easier to just place a "barrier" of block, poured concrete, steel sheeting etc. in front of the traditional wall build.
Building on top of block is less strong than building directly for a solid foundation.
Also you can soak the wood inside with fire retardant to further safety. Fire retardant comes in five gallon buckets and it's pretty cheap, and cheap insurance for any wood in a structure.

Why you need a strong foundation

 

[LD1]

I think it would be easier to just place a "barrier" of block, poured concrete, steel sheeting etc. in front of the traditional wall build.

Not looking to do what is easier. Looking to do what is best within reasonable cost.

Building on top of block is less strong than building directly for a solid foundation.

Are you saying that a post-frame construction method is stronger than typical house construction? And if that is the case, why arent houses built post-frame style instead of walls ontop of block foundations or basements?

 

[fordmantpw]

Our shop is built on a solid concrete foundation that sticks up 12-18" above the concrete floor. Then, the 2x6 walls (2' center IIRC) are attached to the top of the foundation walls. 2x4 perlins are run across the wall to attach the tin to. Trusses are 2x6 on 4' center with a 40' span. The shop at our other house was built the same way and it was great for hosing it out.

 

[Egon]

Are there any code requirements?

The stud wall will require lateral bracing of some type.
Wind loading will be a factor.
Also, wall to joist may require bracing.
Seeing as you will not have a continuous wall there may be design issues there.
You can run a special row of top blocks that can be filled with concrete and rebar and plate connections.
Can you check with your materials supplier for proper design?

Sorry that I've no answerers but 50 year old stuff may have changed for today.

 

[LD1]

So far, here is what I have figured:

For post frame build:
12' OC posts 18' long, set on 2' diameter concrete pads in bottom of hole
12' OC trusses
2x6 wall girts, laid horizontal and flush with both inside and outside of posts
2x8 treated band board
2x6 purlins in saddle hangers
And additional 2x4 and 2x6 lumber between 12' OC trusses to attach interior ceiling to
Liner panel around perimeter inside building

Total cost for that framework: $6802

For block foundation:
8.5 yds concrete foundation
942 block
22 bags mortar mix
4-ton sand
treated 2x8 sill plate
2x6 walls
OSB sheating
headers to clear 12' doors on eave ends
4' OC trusses and 2x4 purlins

Total cost: $7163

There are some things that I havent calculated on the block yet. Rebar for foundation. Filled cores with anchor bolts. But there are also some savings that I havent calculated yet. With 2 row of block above grade, It cuts out 16" of insualtion all the way around, probably shorten the metal by 12" all the way around, and with the inside wall being 8" smaller, will save a tad on he concrete floor too. A 40x40x4" pad is 19.75yds.
A 38'8"x38'8"x4" pad is 18.45yds. Surprising but shaving 8" off all the way around saves about 1-1/4yd of concrete....

 

[LD1]

Are there any code requirements?

The stud wall will require lateral bracing of some type.
Wind loading will be a factor.
Also, wall to joist may require bracing.
Seeing as you will not have a continuous wall there may be design issues there.
You can run a special row of top blocks that can be filled with concrete and rebar and plate connections.
Can you check with your materials supplier for proper design?

Sorry that I've no answerers but 50 year old stuff may have changed for today.

No code requirements, not much wind loads. No hurricane area.

I dont think there is any issue with design as it is exactly how houses are built. Unless I explore other options like I mentioned. (posts on the block instead of stud-wall).

 

[LD1]

Our shop is built on a solid concrete foundation that sticks up 12-18" above the concrete floor. Then, the 2x6 walls (2' center IIRC) are attached to the top of the foundation walls. 2x4 perlins are run across the wall to attach the tin to. Trusses are 2x6 on 4' center with a 40' span. The shop at our other house was built the same way and it was great for hosing it out.

I though about using 2x4 purlins outside the studwall, but surprising when I calculated it, there wasnt much savings. OSB sheathing was $600. 2x4's on 2' centers totaled $550. I supposed I could cheat them out to 30" centers and save a bit, but I think a stud wall relys alot on the sheathing for lateral stiffness?

 

[fordmantpw]

I though about using 2x4 purlins outside the studwall, but surprising when I calculated it, there wasnt much savings. OSB sheathing was $600. 2x4's on 2' centers totaled $550. I supposed I could cheat them out to 30" centers and save a bit, but I think a stud wall relys alot on the sheathing for lateral stiffness?

The tin will provide the lateral stiffness necessary once it's all screwed together. I was thinking my perlins in the wall were at 4' centers, but don't remember for sure.