Flat, level and built to size
A slab for the shed, the hot tub or the equipment, measured to the thing going on top and poured level where it has to be.
Shed and hot tub slabs
A shed set on blocks shifts. The doors stop lining up, the floor gets soft at one corner and mice move in underneath. A hot tub is fussier. Filled with water and people it can weigh several thousand pounds, and the maker will tell you it needs a flat, solid surface under the whole base. In both cases the slab is the part nobody looks at and everything else depends on.
An eight by ten shed slab takes about one yard of concrete. Few contractors will send a crew for that, and fewer will tell you so. They just do not call back. Small slabs are ordinary work for us. We pour them on the day we are already in your town, off the same truck as a sidewalk or a patio down the road. All we need is the footprint of what is going on top and a photo of the spot.
Common sizes
- Equipment pad, 4 by 4
- A small pad for an air conditioner condenser or a generator.
- Hot tub slab, 8 by 8
- Fits many mid size tubs, but check the footprint on your model before we set the size.
- Shed slab, 8 by 10
- A common garden shed size, poured to the dimensions the shed kit calls for.
- Large slab, 12 by 16
- For a workshop shed, or a tub with steps and a place to stand beside it.
How the job goes
- 1
Get the footprint
We start with the shed plans or the hot tub spec sheet. The slab is sized to the exact base, and we ask where the door, the power and the tub cover go to help everything land in the right place.
- 2
Level the ground
Sheds and tubs often go in a back corner that slopes. We cut the high side, build up the low side with compacted gravel and set forms. The forms are checked with a level, since this slab is judged by a bubble.
- 3
Pour and finish
Small slabs usually go in by wheelbarrow through the gate. We screed, float and give the surface a light broom finish. For a shed we can set anchor bolts in the wet concrete if the kit calls for them.
- 4
Cure before loading
Forms come off the next day. Light use is fine after about a week. For a hot tub, we will tell you when the slab is ready to fill. The full weight of water is a heavy load, and concrete reaches full strength at about a month.
What makes it last
Concrete fails from the bottom up. These are the parts you will never see once the job is done, and they decide how the slab holds up.
- Thickness matched to the load
- Four inches is typical for a shed and what you store in it. A hot tub slab may need more thickness or rebar, depending on the weight in the spec sheet. We ask for that number before we pour.
- Level, with a way for water to leave
- A tub needs to sit level or the water line shows it. We pour tub slabs flat. A shed slab follows the floor requirement from the shed maker. In both cases drainage is handled by grading the ground around the slab.
- Top of slab above the yard
- We set the top of the slab a couple of inches above the surrounding ground. Water running across the yard goes around it, and the bottom edge of a shed wall stays out of wet dirt.
- Solid base under the corners
- Shed and tub loads sit on the edges and corners. We compact the gravel right out to the forms, and past them, so the outside of the slab is supported as well as the middle.
Start with a photo.
435·220·5536Text us a photo of the spot and rough measurements. We will tell you what we can from the photo, or come out and take a look. Rather type it out? Use the form.
Shed and hot tub slabs: straight answers
Does a hot tub need a special slab?
It needs a flat, level one that can hold the filled weight, which the spec sheet for your tub lists. Many tubs do fine on a well built four inch slab. Larger ones call for more thickness or rebar. Send us the model and we will size it from those numbers.
Should the slab be bigger than the shed?
It depends on the shed. Some kits want the walls to overhang the slab slightly so rain sheds past the edge. Others bolt down inside the edge. Read the kit instructions or send them to us. Guessing here is how sheds end up with wet floors.
Can you run conduit under the slab?
We can leave a sleeve or pour over conduit that your electrician sets before the pour. If the tub or shed needs power, get the electrician's plan first, because cutting concrete later to add a line is a bad day for everyone.
Can you get concrete to my back corner?
Usually. If a wheelbarrow fits through the gate, we can reach it. Long runs, stairs and soft ground slow things down, and a very hard spot may need a pump. A photo of the route from the street to the spot tells us most of it.