Foundation Options WWYD and Why?

[Pack Rat]

I want to do a new build on a small shop building.
The primary use would be a hobby shop for woodworking and other small projects.
I'm located about 500 feet from a river on the high bank side so there is no danger of flooding.
Because of the river the ground is mostly clay and silt. The topsoil is 8 inches to 1 foot of thick black dirt.
The building will also be located over where a large maple tree was cut down and the stump ground a few years ago.
Now I have to decide what to do for a foundation. I have trhree choices.
A perimeter foundation with footings, a slab on grade, or pole building type of structure.
Which one would you choose, and why? The building will be just over 500 sq.ft.
While cost is always a consideration I want to avoid costly mistakes.

 

[tlmartin84]

It is really a preference vs cost thing.

Easiest/cheapest - pole barn.

Typically most structurally stable/cost a little more - foundation.

 

[8man]

X2, like he said.

 

[kbs2244]

First you have to rid of all remains of the stump.
Anything that can rot has to be removed or it will cause a void if left in place.

Then I expect a slab over a crushed ston bse and with a thickened edge will be the best choice.
It provides both a support for the building and a finish floor for the room.

 

[theoldwizard1]

The building will also be located over where a large maple tree was cut down and the stump ground a few years ago.

This will become a problem eventually as the rest of the stump and roots rot !

 

[boiler7904]

First thing is to completely remove the stump and all roots - they'll just rot over time leading to settlement of the slab.

Second thing is to check with your zoning and/or building department especially if you are inside city limits. Some places do not allow pole barns in town and also limit the size of detached garages/ sheds and/or total garage space on a lot. They will also likely have a maximum building height to deal with. Some go to ridge height, some go to an imaginary point between the eave and the ridge.

Between the two, I'd rather go with a full footing below frost design depth and foundation wall. Finish the exterior to match or complement the home.

 

[Pack Rat]

I knew the stump and roots would be problematic. The topsoil will all have to be scraped off too.
What I want as far as an outbuilding meets all the zoning requirements.
Pole building structures are allowed as long as they meet the setback, size and height requirements.
Crushed stone under concrete seems to be a standard practice around here, even under sidewalks.
My foundation concerns are with the clay/silt ground. My first preference is a slab on grade and stick built structure.
But then again I don't want problems with the slab because of the ground or the freeze/thaw cycles.

 

[kbs2244]

A well done slab will not have any freeze/thaw problems.
They are oftem called "floating slabs" because they go up and down with the frost.
That sounds scary, but it is only fractions of an inch.
If you do a good under slab preperation for good drainage it may be nothing.

 

[JCfreak]

Get a soil report. Too many variables with your situation. It's called a foundation for a reason.

 

[Pack Rat]

Get a soil report. Too many variables with your situation. It's called a foundation for a reason.

That sounds like some very good advice.

 

[drivesitfar]

PackRat: another thing to spend the money on is making your slab for the floor and probably the aprons too at least 5 and probably 6 inches thick with some rebar and or steel netting inside it. you won't want to have a crack in your floor and pouring it thicker is usually the best way to keep the floor nice and flat.

find a great dozer guy to pull the stump and roots and do the prep before having the crushed stone and then the foundation and slab poured. great prep work is always a must for a great finished product. if you are handy and want to do it yourself just take your time to do it right.

i'm guessing you'll need engineering for your permit no matter which style building you attempt to build so figure in that cost and get some recommendations from friends or others in your area that might know a good person to do that for you.

 

[dutchgray]

A well done slab will not have any freeze/thaw problems.
They are oftem called "floating slabs" because they go up and down with the frost.
That sounds scary, but it is only fractions of an inch.
If you do a good under slab preperation for good drainage it may be nothing.

We do these here in the UK a lot on clay or running sand ground, to build houses on as well as outbuildings, 1' thick, top and bottom standard fabric mesh and a good concrete on 4" min compacted stone layer and you can pretty much put what you want on them. The best bit is its minimal digging and that's what costs the money.