Do I need a concrete slab for a portable shed?

No. Most portable sheds in North Texas do not need a slab. A level gravel pad works well when it is compacted, drains away from the structure, and extends 1 foot beyond the shed on all sides.

How do I prepare a gravel pad for a shed?

Grade the site, compact the base, add 4 to 6 inches of crushed limestone or 3/4 inch clean gravel, and keep the finished pad within 2 inches of level across the full building length.

What drainage slope should I use on shed and slab sites?

Grade water away from the building at a minimum 1 percent slope. Do not allow standing water under the building footprint or against slab edges, especially at door openings.

When is concrete required for steel buildings?

Concrete is typically required for enclosed garages, buildings with overhead doors, and buildings over 24 feet wide. Use the exact outside-to-outside frame dimensions when laying out the slab.

What is the standard concrete spec for buildings up to 30 feet wide?

Use a 4 inch slab with 3,500 PSI concrete, plastic vapor barrier, 3/8 inch rebar on an 18 inch grid, and 12 by 12 inch perimeter footings. Texas Style layouts also need interior beams under center base rails.

How does slab sizing work for vertical wall buildings?

The slab matches the outside-to-outside frame size. On vertical wall buildings, the panel ledge is 1.5 inches down and 1.5 inches out on each side, so total footprint grows by about 3 inches overall.

What is the correct garage door tray detail up to 30 feet wide?

For square tube framing, form with a 2x6 board, nominal 5.5 inch wide, and make it 6 inches longer than the door. Cut a 2.5 by 3 inch front notch so the 2.5 inch tube frame fits, and form the 2.5 inch wide by 4 inch tall water ledge before pour.

What changes on 40 foot wide and larger span door tray setups?

Large span ladder leg setups use a full-width tray across the entire door opening. The door track sits in a 3 by 3 inch channel behind the ledge, with a sloped apron running across the full opening width.

What footer size do I need for a 32 to 70 foot wide steel building?

Buildings 32 to 70 feet wide require footings that are 26 inches deep and 30 inches wide with 8 continuous number-4 rebar bars. This applies to both double leg buildings (32 to 40 feet wide) and ladder leg buildings (42 to 70 feet wide). The larger footing handles the increased load from wider spans and ladder truss roof systems.

Does a small shed like a 10x12 or 12x20 need a foundation?

No. Small portable sheds do not require a concrete foundation. A level gravel pad is the standard and usually the best option — it drains better than concrete and costs far less. Concrete becomes necessary when you add an overhead roll-up door or need a building certified for permits.

What is the cheapest foundation for a steel building?

Gravel runners under the base rails are the most affordable option for open-sided carports and equipment covers. For enclosed buildings with garage doors, a concrete slab is required — but you can keep costs down by sticking to exact frame dimensions and not oversizing the slab.

Can you deliver to an unprepared site?

No. The site must be ready before we schedule delivery. For portable sheds, that means a level gravel pad or cleared, level ground. For steel buildings, the slab must be poured and cured at least 7 days minimum (28 days for full strength). We cannot install on an unlevel site — it causes return-trip fees and can compromise the structure.

What should I put down before laying gravel under a shed?

Compact the native soil first. For weed and moisture control, a layer of landscape fabric under the gravel is a good option but not required. Avoid plastic sheeting — it traps moisture. The most important step is grading the subgrade to drain away from the building before the gravel goes down.

What are the most common foundation mistakes for sheds and steel buildings?

The top mistakes are: pouring the slab too close to delivery day without letting it cure, not accounting for the panel ledge overhang on vertical wall buildings, forming the garage door tray wrong before the pour (it cannot be fixed after), skipping the drainage slope so water pools under the building, and not confirming site access for the delivery truck or SkyTrak telehandler on larger buildings.

Do I need a 6 inch slab for a vehicle lift?

Yes. A standard 4 inch slab is not adequate for a vehicle lift. The anchor bolts and point loads a lift puts into the concrete require a minimum 6 inch slab with rebar grid — not just fiber mesh. If you are planning to add a lift now or later, pour 6 inches from the start. Breaking out and repouringafter the fact is expensive and disrupts the whole floor.

Do I need a permit for a shed or steel building in North Texas?

It depends on your city or county. Many rural properties and unincorporated areas have no permit requirement for outbuildings. Incorporated cities typically require permits for buildings over a certain square footage. If a permit is required, we can provide a certified building with engineering drawings stamped to local wind and snow load requirements.

North Texas site prep guide

Shed & Metal Building Foundation Guide: Gravel, Concrete & Site Prep for North Texas

Most portable sheds do not need a concrete slab. A level gravel pad works fine. Steel buildings and garages over 24 feet wide usually require concrete with footings. This page gives the exact specs to use before you pour.

Portable sheds Steel buildings Delivery details Carports

1) Portable sheds: gravel pad is fine

Portable skid sheds sit on grade and do not need slab footings. Keep the site within 2 inches of level across the full length so doors close correctly.

Use 4 to 6 inches of compacted crushed limestone or 3/4 inch clean gravel.
Extend the gravel pad 1 foot beyond the shed footprint on every side.
Grade drainage to the edges at 1 percent minimum. Never let water pool under the building.

2) Steel buildings and garages: concrete with footings

Concrete is the standard for enclosed garages, overhead doors, and buildings over 24 feet wide. Slab size is always outside-to-outside frame dimensions.

When to pour 6 inches instead of 4

RV covers, enclosed garages, vehicle lifts, 12-gauge frames, buildings over 24 feet wide, and any site with expansive clay soil (common across North Texas) all require a 6 inch slab. If there is any chance you will add a vehicle lift later, pour 6 inches now — upgrading after the fact means breaking out and repouringthe floor.

Single leg buildings — 12' to 30' wide, legs ≤14'

4 inch thick slab minimum, 3,500 PSI concrete — 6 inches required for RV covers, enclosed garages, vehicle lifts, 12-gauge frames, or any building over 24 feet wide
Plastic vapor barrier under slab
3/8 inch rebar on 18 inch grid throughout
12"×12" perimeter footings — industry standard square footer, runs wherever a base rail sits
Texas Style buildings: footings under main structure AND under each lean-to; interior beams required under center section base rails
Lean-tos: full concrete slab or runners required
Anchor bolts: 1/2 inch diameter, within 6 inches of every post along sides and end walls
Slab thickness can be increased per buyer request

Double leg & ladder leg buildings — 32' to 70' wide

Larger spans require a heavier footer and more rebar. Same slab spec as above except:

Footings: 26 inches deep × 30 inches wide (engineered spec)
Concrete: 3,500 PSI (exceeds 3,000 PSI engineering minimum)
8 continuous #4 rebar bars in each footing
Anchor bolts: 1/2 inch diameter × minimum 7 inch A307 expansion anchors, within 6 inches of every post
32'–40' with legs ≤14': double leg frame (two galvanized square tubes welded together)
32'–40' with legs ≥15': ladder leg frame
42'–70': ladder leg frame regardless of height
All 32'–70' wide buildings use ladder truss roof structure

Width	Leg height	Frame type	Footer size	Rebar
12'–30'	≤14'	Single leg	12"×12" square	3/8" on 18" grid
32'–40'	≤14'	Double leg + ladder truss	26" deep × 30" wide	(8) #4 continuous
32'–40'	≥15'	Ladder leg + ladder truss	26" deep × 30" wide	(8) #4 continuous
42'–70'	Any	Ladder leg + ladder truss	26" deep × 30" wide	(8) #4 continuous

Slab sizing rules

Horizontal wall: slab equals exact outside-to-outside frame dimensions
Vertical wall: slab equals exact frame dimensions — tin ledge adds 1.5" down and 1.5" out on all sides outside the slab edge
Example: 30'×40' vertical wall building → 30.25'×40.25' actual footprint (slab + ledge overhang)
Horizontal wall buildings have no tin ledge — slab equals exact frame size

Texas barn layouts require footings under the main structure and under each lean-to wherever base rails run. Interior beams required under center section base rails.

3) Garage door slab prep: two tray methods

Up to 30' wide, square tube method

Use 2" x 6" board form, nominal 5.5" actual width
Form length is 6" longer than door width
Front notch is 2.5" x 3" so 2.5" square tube drops in cleanly
Water ledge profile is 2.5" wide x 4" tall
Include upright tab at far end for door track contact
Recess is formed before pour, cannot be fixed after concrete sets

40' wide frame and larger span, ladder leg method

Door tray runs full width of door opening
Door track sits in 3" x 3" bottom channel behind ledge
Concrete apron slopes from tray ledge to slab edge
Slope runs across the entire opening width, not just edges
Example: 12' door uses full 12' tray width with recessed track channel

Door tray and water ledge details must be formed before concrete pour. If this is wrong, door seal and tracking issues are expensive to correct later.

4) What you need before delivery day

Portable sheds checklist

□ Site graded and level within 2 inches
□ Gravel pad installed if soil is soft
□ Access path 2 feet wider than building on each side
□ Overhead clearance confirmed with our team
□ Gate width at least 10 feet for most setups

Steel building checklist

□ Slab poured and cured, 7 days minimum and 28 days full strength
□ Slab dimensions verified outside-to-outside of frame
□ Footers match frame type and width
□ Garage door recess and tray formed correctly
□ Vertical panel ledge accounted for on vertical wall buildings
□ Utility conduit and other stubs set before pour if needed
□ SkyTrak telehandler access confirmed if building is 32' wide or has legs 15' or taller
□ Firm, level ground access for equipment (soft/muddy sites need gravel approach)

⚠️ SkyTrak Telehandler Requirement

A SkyTrak telehandler (6,000 lb capacity, 36-ft lift) is required for all 32' wide buildings — these use a ladder truss that requires overhead lift — and for any building with side legs 15' or taller. Make sure your site can accommodate the equipment before scheduling delivery.

5) Common mistakes that cause delays

Pouring slab without the door tray or water ledge detail
Sizing vertical wall slab wrong and forgetting ledge footprint growth
Leaving gravel out of level so shed doors rack and bind
Pouring too close to delivery date without minimum cure window
Skipping access checks so truck cannot reach install location

Related planning links: delivery process, Texas shed permits guide, rent-to-own pre-approval.

Need a fast slab and site prep check?

Send us a photo of your site and we will tell you exactly what you need before delivery. It usually takes about 5 minutes.

Get Instant Quote Denton (940) 320-9377 WF (940) 249-5015

Foundation and slab prep FAQ

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