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By Brennan Deitsch

 

Before your dream shed takes shape, a solid shed foundation is crucial to ensure longevity. Here are a few tips to make the process simple.

Why shed foundations are important

Before we get started, let us explain why building a foundation is important. It might seem easier to place a shed directly on the ground, but that’s a bad idea for two reasons. First, the build site should be a level surface so the shed is stable and the doors function properly. Secondly, any wood that has direct contact with the ground will absorb moisture and cause premature rot and decay. A shed should be raised slightly so there is proper water drainage and ventilation underneath. Building a shed foundation might seem like more work, but it’s well worth it.

Determine if you need a building permit for your shed

Before you choose a location to install your shed, consult your local Home Owners Association (HOA) or Building Department to see if you will need a permit and what guidelines there might be. Every county has different guidelines, so we strongly suggest to not skip this step. Confirm the following with your HOA/Building Department:

  • Shed type and size
  • Frost line
  • Location
  • Foundation Type
  • Required building permits

Do you need a foundation for your shed?

Typically, small sheds in the size range of 6×8 or smaller do not require a foundation. However, we suggest placing all sheds on a foundation for structure and ventilation purposes.

Where should you build your shed foundation?

Choose a spot that is within 6” level* and does not collect large amounts of water. Make sure there is 3’of clearance from other objects such as trees and other buildings.** For 10×16 sheds or larger, give yourself 4’ of clearance so there is adequate space to move.

Heartland Sheds Foundation Requirements: *Prior to the arrival of the installer, your build site must be level within 6”. Additional charges may apply if this requirement is not met. We require 3ft. of clearance on all sides for installations and 4’ for buildings 160 square feet or larger.

Frost Line:

Frost line is known as the depth at which water in soil is expected to freeze. In areas with colder climates, structures may move due to seasonal freeze and thaw changes and that makes your frost line crucial. In general, frost lines get deeper the closer you get to the poles. Be sure to contact your HOA to determine the frost line for your area. Or view this frost line map to see the frost line for your state.

 

Tools needed:

Chalk Reels

Concrete Leveling
Blocks

Tape Measure

chalk reelsconcrete leveling blocksshed level

Hammer

Level

hammerlevel for shed

Shed Foundation Types:

Sheds can be built on the following type of foundations:

We are going to focus on wood and concrete foundations in this article as that is our preferred type.

Wood Shed Foundations

Wood shed foundations are typically built using solid concrete blocks measuring 16”W x 8”L x 2”H, pea gravel, 4×4 pressure-treated lumber and a wooden floor frame. Concrete leveling blocks can be purchased separately with any Heartland order.

  1. Begin by laying out your floor size and locating pea gravel and concrete blocks. Play each block 12” from each corner of the floor frame.
  2. Place the concrete blocks on pea gravel.
  3. Use the pea gravel to level your foundation. Blocks along the same floor joist should be a maximum of 72” apart. The spacing between blocks on different floor joists should be a maximum of 48” apart (See floor layout below).
  4. Once all blocks are located, place the 4×4’s onto the blocks and continue by building your floor frame and securing the frame to the 4×4’s. The 4×4’s allow proper ventilation underneath your shed. Once the floor frame is built, you can easily level your shed using more or less pea gravel at various locations.
wood shed foundation

Estimated number of concrete blocks based on shed size (more will be required for any surface that is unlevel):
Shed SizeNumber of BlocksShed SizeNumber of Blocks
6X6812x1216
8X8812x1622
8X6812x2026
8X101012x2430
8X121216x2050 — *Piers or foundation may be required by state
10X101416x2455 — *Piers or foundation may be required by state
10X1216
10x1620

wood shed foundation diagram

Click on image to see enlarged.

Concrete Shed Foundations

We also recommend our customers to use a concrete slab for their shed foundations.

Heartland does not employ, endorse or in any way recommend any qualified concrete specialists for sheds. It is the responsibility of the homeowner to assure compliance to these specs.

concrete shed foundation

Concrete Foundation Guidelines:

  1. The build site must be level and should have natural drainage and no standing water. This will keep excess moisture away from the foundation and extend your sheds’ life.
  2. Your concrete slab should be minimally the same width and depth as the shed. We use MCA or ACQ treated plates around the entire perimeter of the walls. Customers can choose to leave the bottom plate attached behind the door or have it cut out.
  3. The slab can be no greater than 1/2” out of “square” and no more than a 1/4’’ out of “level.” Any variation to this will cause delays or even stop the installation process. 1/4” out of level at the floor can lead to more than 1” out of level at the roof depending on building size and roof style.
  4. Based on “local code requirements” wedge style anchor bolts should be set in the concrete around the entire perimeter (12” from corners and 4’ on center thereafter) of the slab (except where the door goes) projecting approx. 2 ½” above the slab grade and approx. 1-3/4” to 2” from the edge of the slab. Minimum anchor embedment should be 2-1/2”-3” into the concrete. We recommend ½ diameter x 8-1/2 long Simpson Wedge.
  5. Your finished concrete slab surface needs to be at a minimum of 4″ above grade.

REMEMBER: You should ensure that your region allows this type of foundation as well as conformance to all applicable zoning and/or building codes.

concrete shed foundation

Best Shed Foundations

These are our preferred types of shed foundations. See how they compare.

WOOD FOUNDATIONSCONCRETE FOUNDATIONS
AdvantagesDisadvantagesAdvantagesDisadvantages
Most economicalCan sink slightly over timeCan place wood frame directly on concrete slabSoil can cause settlement over time
Easy to move concrete blocks to desired locationNot suitable for slopes greater than 24”Full support of shed frameMore costly
Great for most shedsNot suitable to store cars or boatsCan secure shed/walls to concrete floorMay require professional help that further increases costs
Does not require much excavatingCan store cars or boats

Purchasing a shed can be a big investment. However, preparing your foundation properly will help ensure your shed is ready to handle the elements 365 days a year. If you have any questions, feel free to give us a call at 800-234-6167.

HELPFUL RESOURCES:

How to Level a Shed

 

How our Built-on Site Shed Installation Process Works

 

How to Build a Storage Shed

 

How to Shingle a Shed

 

Other Links:
Shed Buyer’s Guide
FAQ’S

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