Placement of your Gardensheds™ building will require a solid, flat, level site with proper grading. We recommend a professional landscape installation of your building foundation. It’s important to note that what often appears level to the eye is often not level when measured. A line level or laser is often the best means for determining if a site is truly level or not. To determine if a foundation pad is square the diagonals should be equal in length. Proper attention to your site preparation will result in an attractive installation and will require less maintenance on your part. We suggest you check with your local Building Office to comply with ordinances pertaining to foundations.
In layout of your foundation we often encourage clients to run corner stakes with perimeter mason string. This will also help you to better visualize the footprint of your building and will give you a better sense of scale and proportion and to determine if the size is adequate for your intended needs. When in doubt it is always advisable to go larger than smaller as it is better to have space to grow into.
If you live within a 90-mile radius of our NJ/PA locations we have independent contractors we can recommend for your foundation installation. Otherwise, we are happy to speak directly with your contractor to review foundation requirements.
Building Underside: Gardensheds™ buildings are constructed on a “skid” foundation of pressure-treated 4x4’s. The open ends of the 4x4’s are covered by finished trim boards that are installed at time of delivery. Floor joists at 16” on center are placed on top of the 4x4’s. (see schematic below). We use a vapor barrier and closed cell foam insulation on the building underside to make water-tight and critter-resistant. This will protect your floor boards from moisture and humidity changes.
Installation of building skirt boards at time of delivery
click to view Delivery/Installation photos
Optional Door Ramp: When your building is placed on the foundation the interior floor will be approximately 8” off the foundation or grade level. As a point of reference, this is similar to the a standard riser on a staircase. The lower front edge of your door will cover approximately 4” of this measure. If you will be using your building to store lawn mower, tractor, golf cart, motorcycle, etc. you may want to consider our optional door ramp that will allow for easy entrace and exit.
Building Anchors: The majority of our buildings do not require anchoring to the foundation unless it is a requirement of your area. Our buildings are rather robust and heavy (unlike typical “sheds”). A 10x10 building for example weighs approximately 2,500 lbs and is not going anywhere! If required, we have optional means to anchor and secure your building to the foundation. One method is interior; the other is exterior. Anchoring method also depends on type of foundation pad you have. Contact us for more details and information.
Type of Foundation
We suggest you work directly with a local landscape contractor to determine the foundation that will best suit your needs. There are different types of foundation, each equally suitable. The choice is really a cost and aesthetic concern, more than a structural concern. The size of a building will also dictate the best suitable foundation. For buildings measuring 10x20 and larger we typically see these on concrete footings or full concrete slab. Buildings less than this are typically installed on a gravel or crushed stone foundation. For any size building a concrete slab is always a preferred foundation.
Crushed Stone Foundation
To properly prepare a gravel or stone base, will require an excavation of approximately 4-5” of top soil. The size of your foundation pad should be approximately 2’ larger than your building footprint to allow for proper drainage. If your building measures 10x16 your foundation pad should measure 12x18. Alternatively, if you intend to have landscape beds with mulch your pad does not have to be larger than the building footprint as this will suffice to catch water runoff from roof. While not required, we suggest a solid and secure perimeter frame to hold the stone in place. Options for the perimeter fram include pressure treated timber (4x4, or 4x6) secured in place with 3’ rebar; wet or dry laid Belgian block, granite, brick or paver. The purpose of the frame is to hold the 3/4” stone in place. It also makes for a more finished landscape appearance. The excavation of your pad should be 4-5” with a 1” layer of sand applied to the base. The 3/4” stone should be flush to the top of the perimeter frame. The top of the foundation can be dressed with a finer 3/8” stone or millings/stone dust if desired. Rake and tamp down the stone as you fill until it is evenly distributed and the site is level and flat. Crushed stone provides an ideal drainage for rain or snow melt around the perimeter of the building, especially if gutters will not be installed (not required). Water that splashes directly on the ground will eventualluy create a muddy area that will splash up onto the building walls unless covered with mulch or stone. Finally, make sure the grade of surrounding area does not pitch or drain into your building foundation. Depending on the grade of your property your foundation pad may or may not require installation of a retaining wall.
A 3-4” concrete slab is suitable for any size building. Installation of a concrete slab is typically undersized 2” from your building footprint. Thus for a 10x16 building your concrete slab would measure 9’-10”x15’-10”. Professional installation of a concrete foundation, depending on your site conditions, will vary so it’s best to consult with your local contractor for cost estimate.
Concrete footings or piers are another suitable foundation. Let us know if you are installing piers or footings so that we can provide you with schematic of your building foundation underside. This will allow you to properly locate footings to support your building. Footings should be at or near grade level. The area between footings should be backfilled with 3/4” stone per crushed stone foundation description above.
If you prefer the look of a brick or paver perimeter outside your building this is an attractive alternative. Typically a 18”-24” course of brick or paver is placed outside your building footprint, with the interior fill either stone or concrete slab. There is no sense is paving the entire foundation with pavers or brick when this will be covered with your building.
A less common, but acceptable foundation is a wood pier construction with frame support (much like a deck without the decking floor). This is typically a raised foundation and will have a lattice perimeter covering on the sides. If installing this type of foundation let us know so we can make sure the deck is properly framed to support the building.