We pour slabs and footings for garages, shops, sheds and additions around Anchorage. Frost depth, soil and earthquake rules shape the design, and permitted work is built to the approved plans. Tell us what the slab will carry and whether the space will be heated.
A slab that carries a building is designed from the frost down. In Anchorage, footings for a heated building have long been set at least 42 inches below grade, and deeper where the soil under them is allowed to freeze. A floating slab for a small unheated shed is a different thing and can sit on a thick gravel pad. We start by asking what the slab is for, because that decides which of these you need.
Under a building floor we place a vapor barrier so ground moisture does not come up through the concrete, and often rigid insulation so a heated floor does not lose its heat to the ground or thaw frozen soil unevenly. Reinforcing steel and tie-ins between the footing, the wall and the slab matter here for a second reason: this is a high earthquake area, and the code expects the parts of a foundation to be tied together.
Inside the Anchorage Building Safety Service Area, building foundations need a permit, plans and inspections, and we pour to the approved drawings. In Chugiak-Eagle River and other areas outside it, the rules differ and a land use permit applies. Either way we look at the soil first. Peat and soft clay have to be dealt with before a foundation goes in, sometimes with an engineer's input.
Slabs & foundations in Anchorage: common questions
How deep do footings have to be in Anchorage?
Anchorage has set the minimum frost depth at 42 inches for a warm foundation, where the soil under it is kept above freezing, and 60 inches for a cold one. The current requirement for your project is confirmed with Development Services at permit time.
Can a shed or small garage sit on a floating slab?
A small unheated shed often can, on a well-drained gravel pad. A garage attached to the house, or any heated building, normally needs frost-protected footings. The permit rules and the size of the building decide it.
Do I need insulation under a slab?
For a heated floor, a heated shop or a slab used as a living space, yes in most cases. It saves heat and helps keep frost from getting under the edges. For an unheated pad it is usually not needed.
How it works
- Free estimate: Call, text or book online. We visit and measure.
- Written quote: Clear pricing with finish options.
- Prep & forms: We excavate, grade, compact the base and set forms and reinforcement.
- Pour, finish & cure: We pour, finish, cut control joints and tell you when you can use it.