Anchoring and Weather

A shed that is level and anchored will outlast the same shed that is not by a decade. This guide covers the anchoring methods for each kind of base, and what the weather in your part of the country does to a shed.

Anchoring: not optional

Every shed, enclosure and cabinet we sell should be anchored. A horizontal resin shed weighs well under 100 lb; a 70 mph gust on its side wall produces more force than that. Manufacturer wind ratings, where published on our product pages (65 mph for the Keter Factor 6 x 3 and the Lifetime 7 x 7, for example), apply only to anchored units, and manufacturer warranties generally do not cover wind damage to an unanchored shed.

On soil, gravel or patio stones

Use an auger-style ground anchor kit from a hardware store: four 15 in. auger anchors screwed into the ground at the corners with a steel bar, and a vinyl-coated cable run through the floor anchor points or around the base rail and clamped tight. Many resin sheds have molded anchor points in the floor for exactly this. Firm clay or loam holds best. In sandy soil, drive the augers to full depth and consider a longer 30 in. auger from a hardware store. In very loose sand or fill, augers do not hold; set concrete deadmen or eye bolts in poured footings instead.

On a concrete pad

Do not use augers. Drill through the base rail or the floor anchor points into the slab and set 3/8 in. wedge or sleeve anchors, at minimum one per corner and one every 4 ft along the walls. This is the strongest anchoring you can have and is what we recommend on the hurricane coast.

On a wood deck or platform

Lag-bolt the base rail or floor to the joists, not just the deck boards, with 3/8 in. by 3 in. lag screws and washers, one per corner and every 4 ft. Check that the deck itself is rated for the shed's weight plus contents; a loaded 8 x 10 resin shed can exceed 1,000 lb.

The base matters as much as the anchors

A shed on an unlevel base racks: doors stop meeting, panels pull at their fasteners, water pools on the floor. Aim for level within 1/4 in. over the length of the shed. The three bases that work: a concrete pad (best, most expensive), a treated-lumber platform on blocks (good, and needed for any shed without a floor), or 4 in. of compacted crushed gravel in a lumber or paver perimeter (good, cheap, drains well). In freeze-thaw regions, gravel over a landscape-fabric layer heaves least. Never set a shed directly on soil or turf.

Snow

Snow load is measured in pounds per square foot (psf). Wet snow weighs about 20 lb per cubic foot, so 12 in. of it on a roof is roughly 20 psf; light powder is a third of that. Snow ratings are set by each manufacturer and vary by model; where one is published, it is on the product page. Two examples from our catalog: the Suncast Modernist 6 x 5 is rated for 40 psf and the Lifetime 8 x 12.5 for 23 psf.

Northeast, upper Midwest, Rockies and the Sierra: ground snow loads in these regions run from 30 psf to well over 60, more than any kit shed is rated for. That is fine as long as you clear the roof after big storms, which takes five minutes with a roof rake. Choose a resin shed with steel-reinforced roof trusses and the highest rating you can find, clear anything over about a foot of wet snow, and never let ice dams build at the eaves.

Mid-Atlantic, Pacific Northwest lowlands, Southern Plains: occasional heavy, wet storms. Any shed we sell works; clear the roof after the rare big one.

South, Southwest, California coast: snow is not a factor. Buy on other criteria.

Wind

Florida, Gulf Coast, Carolinas and Atlantic coast: hurricane design winds run 115 to 180 mph. No kit shed survives a direct hit from a major hurricane, but anchoring makes the difference between a shed that is still there after a tropical storm and one in the neighbor's pool. Choose a walk-in resin shed with a steel-reinforced frame, anchor into concrete if possible, install all four ground anchors at full depth otherwise, and keep doors latched and padlocked when a storm is forecast. Bring deck boxes and cabinets into the garage before a named storm.

Great Plains and Texas: straight-line thunderstorm winds of 60 to 80 mph several times a year. Anchor every shed and check cable tension each spring. Any shed is fine here when anchored; unanchored, it will move.

Everywhere else: anchor anyway. The 70 mph gust that comes through once a decade is the one that matters.

Sun and heat

Arizona, Nevada, inland California, Texas, Florida: the UV index is the enemy of plastic. The brand-name resin sheds we sell are UV-protected, so they do not chalk or crack, but expect very slight color softening over many years. The interior of any shed can reach 130 degrees F or more in summer; site it in afternoon shade if you can, store chemicals and batteries elsewhere, and keep the vents open. Face windows and skylights away from the western sun.

Rain, humidity and coastal air

Southeast, Gulf Coast, Pacific Northwest: the issue is moisture at the base and inside. Set the shed on gravel or a pad that drains, not on soil, and leave the vents open. Resin does not care about humidity, but the contents do: keep the vents clear and lift tools and cardboard off the floor on shelves.

Freeze-thaw

Northern states: the ground heaves in winter and settles in spring, and a shed that is level in October can be out of level by March. A compacted gravel base over landscape fabric moves least; a concrete pad without footings can heave as a unit but stays flat. Re-check level every spring, shim the base rail if needed, and re-tension anchor cables.

A regional summary

Questions about your specific site? Contact us with your ZIP code and a photo of the spot.