Block foundation or Poles with slab

[rwa2004]

Hi - I am on track to build a 28x44 shop that will be used as a machine and fab shop.

I'm having trouble deciding between a block foundation on a footer with slab poured inside or a pole barn and slab. The main reason I want a block foundation is so that I can have 2 courses of block above the floor so that the stick frame wood and outside metal siding is up off the ground. The main reason I want poles/slab is because I want low cost.

What do you think?

Location is Western PA, where the frost line is 3' down and the ground is always wet. The property/area is pretty flat which means no retaining walls but also poor drainage. Shop will be heated, but not through the floor. I planned on insulating the floor vertical on the perimeter and under the slab on the outside 3-4 feet.

I do have a Cincinnati mill and plan on a few lathes and mills, so slab stability is important to me. I do understand that regardless of poles or block that the slab will float separate from the walls. I fear that a slab inside of poles will not be well protected.

 

[marklc]

I'm in the same situation you are. I'm also in western PA. Interested in seeing the replies. Good luck!

 

[matt_i]

My quick opinion is that the concrete will be forever resistant to the groundwater. The wet soil with low-bearing may not play nice to provide a good tipover moment that the posts need to have in a post-frame.

Since you are insulating the slab and "wings" you are almost to the point of a frost-protected shallow foundation "FPSF" The HUD has a nice .pdf file that boils down to a cookie-cutter method of designing the building for your local area.

I also built my shop to house machineshop & metalfab equipment, in addition to the load of the equipment, rigging by forklift has to also be considered as it puts even greater stress on the concrete (front tire loads). So, I poured a 6" thick slab with rebar on 16" centers. Whatever you choose I recommend steel reinforcement of the slab.

 

[bad_idea]

I am having a block foundation with stick frame built this summer. So, I may be a bit biased. I am in a wet area also and want the garage to match the house. In my research I found the cost of buying the materials to build either way was close to the same.

 

[kbs2244]

Far NE corner of IL

I went with 3 rows of block and an 8 foot stick wall on top of it.
Mostly because that was my comfort zone and that of the labor I had available.
Easy to insulate and dry floor.

 

[ConCretin]

Any reason you aren't considering a monolithic slab with a block or concrete curb wall? Rigid insulation underneath would protect it from frost movement. Seems this would meet your criteria regarding cost and framing height.

I built one of similar size. I Ran a 24" form around the outside and placed the slab with a 12" thickened edge. Stood an inside form on the finished slab a placed a 12" curb wall. Pretty simple to build, low cost and works great.

 

[spudley]

Far NE corner of IL

I went with 3 rows of block and an 8 foot stick wall on top of it.
Mostly because that was my comfort zone and that of the labor I had available.
Easy to insulate and dry floor.

Exactly my plan. Did you waterproof the block? Insulate on the inside?

 

[rwa2004]

I was not too concerned about the wet ground affecting the treated poles - more desire to keep the framing lumber, insulation, and steel siding up off the ground.

I considered pouring a concrete curb. I helped with a few solid concrete walls in the past, but in this case on level ground solid concrete wont have much to offer beyond block. Plus, someone mentioned block would be more flexible for adding doors, additions,etc.

Im surprised material costs came out similar, I would fear all the block for 3' down and 2' up would cost a lot.

Does anyone ever spray foam into the core of blocks? And benefit?

Sent from my SAMSUNG-SM-G920A using Tapatalk

 

[rburke65]

I need to redo my garden shed "foundation" and was going to use the Versi-Loc...?... Manufactured block, but now I think I will just used some OSB for forms and pour/place foundation and pad all in one shot.