Shed and Garage Slabs Hamilton

$110 to $135 per square metre for a pad at 100 to 150 mm on a prepared base, and $140 to $170 where it is built to an engineered detail. Site preparation is separate and often the bigger variable: stripping topsoil and forming a compacted base runs $35 to $60 per square metre, and an imported gravel raft runs about $100 per square metre at 200 mm deep. Council consent fees sit outside our price. Guide ranges, quoted in writing.

It usually comes down to floor area and who designed it, not the slab. A detached single storey building of not more than 10 square metres is exempt under Schedule 1, subject to conditions. Between 10 and 30 square metres the exemption depends on the design route, whether that is a Chartered Professional Engineer, a Licensed Building Practitioner or a proprietary kitset with the right documentation. Above 30 square metres you will need one. We check where yours sits before quoting.

It comes off what goes on it. A pad for a garden shed and a floor carrying a vehicle and a jack are two different slabs. We pour at 100 to 150 mm on a prepared base for most residential pads, thicken the edges where the frame and bolts land, and go to an engineer detail for large sheds, tall buildings, mezzanines and portal frames. Tell us what parks in it and what gets stored.

If the building is enclosed and used as living or working space, yes. Moisture moves up through concrete from the ground, and it will reach whatever is stored or built on that floor. The membrane goes over a sand blinding with laps of at least 150 mm. An open sided implement shed is a different case. Tell us the intended use, because it changes the specification and sometimes the consent position.

Yes, and that is how we prefer to do it. Kitset suppliers issue a slab plan with exact dimensions, bolt positions and edge details, and we build to that document. We check it against site levels before pouring, because a pad 40 mm out of position is a pad that gets broken up on erection day. Send the plan with your enquiry.

Slightly bigger is usually money well spent. An apron beyond the shed line gives somewhere dry to stand, keeps a roller door track clear of mud and stops the slab edge being undermined by runoff. How much depends on the door position and how you use the building. We will suggest a figure at the site visit, and it is often the cheapest improvement available on the whole job.

Good ground under the acceptable solution means ground with an ultimate bearing capacity of at least 300 kilopascals. It explicitly excludes topsoil, soft or mouldable clay, uncompacted loose gravel, expansive soils and ground that could move 25 millimetres or more. A cleared, levelled section is not automatically good ground. Hamilton ground is highly variable, so we check it on site, and where it is not good ground the pad is designed for what is actually there.

The concrete is damp cured for seven days from the pour, and reaches about half its strength in the first week. Light foot traffic goes on after a day or two, staying off the edges and corners while they are green. Erecting a building and drilling holding down bolts puts real load into the slab edges, so that waits until the concrete has gained proper strength. Full strength is 28 days. We give you the date at handover.