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Foundations and Anchoring Tips For Your Shelter

We often get asked what kind of foundation or anchoring is needed for carports, garages, sheds and greenhouses. Often locations that are near water can experience high wind gusts and will require different  anchoring than less exposed areas. Also, ground conditions can dictate what anchor or foundation is needed.  A soft soil will require different anchors vs compacted soil or gravel for example. 

Typically the anchors required are quite product specific, and can be found in the manuals which you can download at our product listings. Review the parts listing in the manual for your kit to see what anchors are provided.  That said, there are some general rules for what kinds of anchors best suit different shelters and what foundations are appropriate for each type of shelter. 

Sheds & Garages

Shed Foundation Gravel

Generally, sheds are relatively light-weight shelters and don't come with a floor (with the exception of our Skylight and Pent polycarbonate sheds by Palram). For sheds and garages there are 3 main options for a foundation.

  • Cement Slab or Patio Stones
  • Wood Frame or Platform
  • Directly On Ground 

NOTE: Just be aware that having your shed absolutely level is key, otherwise your shed frame can "rack" off centre and cause the doors (swing or sliding) not to be able to close and secure properly.  Always check your foundation with a level before you build.

Cement Slab or Patio Stones

Concrete Shed Foundation

A concrete slab should be at least 3 to 4 inches thick for a shed, and often recommended 6 inches if supporting the weight of a vehicle in a carport. If your base is going to be weight bearing, rebar is also recommended, tied together in a cross-hatch fashion with bailing wire and at least 1 inch buried or away from ground or surface.  Patio stones are also a very inexpensive, less  messy and fast option for your foundation.  You can place 1 inch thick patio stones for your entire found, or just even around the perimeter of your shed (ensuring they are level of course) and fill the middle with gravel.  

Wood Frame or Platform

Metal Floor Frame Kit

A more economical method of a base is a pressure-treated wood frame around the wall perimeter of your shed.  Often 4x4s or 6x6s (the more weight the better) on a level surface will suffice for attaching shed walls to.  Typically all that is required is wood screws to fasten the shed wall or framing to the pressure treated wood perimeter and you can fill the middle with gravel.  You may also want to create a grid of pressure treated wood, and place 1/2" plywood on top for an even floor solution. If you buy an Arrow shed from us, you can buy a metal flooring kit based on the size of your shed purchased.

NOTE: Just know that galvanized or stainless steel fasteners, anchors and hardware are recommended next to pressure treated wood, given it's corrosive nature on untreated metal surfaces.

Directly on the Ground

Another option is attaching your shed or garage directly to the ground.  However, this can be problematic for a number of reasons and should be your last resort based on a tight budget or good ground conditions.  If you have a door (sliding or outward opening) there is a big risk of your shed or shelter not being level, and your doors not closing properly.  At minimum we would recommend using one of the ground anchor options further below.

Foundation or Concrete Slab for Sheds or Carports

Carports, Gazebos or Awnings

Carports most often are installed directly onto the ground, asphalt or a cement slab of concrete. For a ground attachment, all you really need is a set of anchors.  Many of our products come with ground anchors included, such as our steel carports.

Duck-bill or Easy Hook Earth Anchors

Easy Hook Anchors

These easy hook anchors come with a steel rod to help drive them directly into relatively soft ground.  Once pounded into the ground by ideally a foot or so, they have a 300 lbs pull strength.

Concrete Anchors


Cement anchors are useful for attaching a carport or gazebo or awning to existing concrete.  You will first need to predrill using a 1/2" or so carbon tipped cement drill bit.  You then insert the concrete sleeve and then screw in the anchor bolt through the feet of your carport posts. For many of our gazebos and carports, these anchors are often included in the kits.  Download the manual and review the parts list to confirm what is included.

Asphalt Spikes

Asphalt Spikes

Since asphalt can be softer and more malleable than concrete, you may need to buy a specific anchor for this application. Asphalt spikes are available at your local hardware store, and have a rough surface that bites well to prevent pulling out.

Greenhouse or Shed Top Anchors

Greenhouse or Shed Anchor Straps

We also provide greenhouse or shed anchor strap kits for high wind areas such as cottages near water or lakes. These kits have ground anchors and include straps that go over the top of the shelter you are securing. 

Greenhouse Foundations

Greenhouses are a bit of a different animal, given the amount of moisture and drainage needed with irrigation systems.  A concrete slab can work, however, it most likely will require a sloped cement pour towards a drain or off to the side. Here is a customer photo of our Bella Greenhouse with a very well designed raised bed system and a drain set into a poured cement foundation.  Certainly a lot more work than a bed of earth or gravel, but the end result is very nice and clean.

Greenhouse Cement Drain Slab

Wood 6x6 Foundation for Greenhouse

This Glory Greenhouse was installed with a wood foundation using 6x6 wood timbers for a more heavy-duty wind resistant base.

Glory Greenhouse 6x6 Wood Foundation

Anchoring Guide Summary

Anchor Guide for Securing Shelters - Grizzly Shelter Ltd.