While there are a few different ways to build a shed floor, building a shed floor on skids is the least expensive choice. And if you’re looking to save a few bucks, than skids will be the best the choice, as well your shed will be portable making it a good option if you want to take your storage shed with you when you move, or maybe your renting and don’t want to leave it behind.
In this article I’m going to look at “what exactly a skid foundation is” “do you have to have a foundation under your shed” “how to build a shed floor on skids” and “how to attach the shed floor to the skids securely”.
What Exactly is a Skid Foundation?
A skid foundation is basically 2 or more 4x4s, 6x6s or larger pressure treated beams that the shed floor is built on. The skid foundation allows for the shed to be moved to another location and in some cases can be hoisted onto a flatbed truck and be moved to another location.
Years ago logs where used as skids and supported the shed floor framing and are constructed in such a way that they can be pulled by a piece of equipment if needed. You can expect a pressure treated skid foundation to last for 20 to 30 years, so they make building a shed floor much simpler and cheaper than normal foundations.
You’ll often see the skid foundation used for tiny houses, small cabins and a variety of outdoor storage buildings. Another advantage is many authorities don’t classify a structure on skids to be a permanent building and can mean you won’t have to have any permits to build it. Always check with your local authorities before going ahead with the build.
Another advantage because it’s not classified as a permanent building you can build a shed without following the required setbacks and zoning bylaws. If there’s a problem with its location… Just move it! Some folks have chosen to live in the structure and they may not be subject to taxes. Check first with local authorities.
No worries about frost moving the building, come spring all you need to do is re-level it if required. You can set-up the skid structure easily on even ground, and uneven ground isn’t a big problem either. If you need more information on where you can put your shed you can read my article “How To Prepare The Ground For a Storage Shed” where I go over using gravel as a base, leveling a shed on uneven ground. You can read it here.
Does a Shed Built on Skids Need a Foundation?
While it true that most storage sheds will have to have some type of foundation, another advantage of a shed built on skids is it doesn’t have to have a foundation. The sheds skids become its foundation.
You can place the skids on the ground, on a gravel base, on concrete blocks or a concrete pad and you’ll still have the option to move the shed. If you’re going to go thru all the trouble of installing a foundation there would be no need for skids. That being said it can be a good idea because you don’t want the skids sitting on the ground.
Building a Shed Floor On Skids Considerations
– How’s The Ground?.. Are there shrubs, hanging tree branches and maybe tree roots to contend with? Do you have access for a machine to get to the location without tearing out half the yard?
– How Level is The Ground?.. Having a fairly level location is much easier to build a shed, having a slight slope to deal with isn’t a problem when using skids for your base. Try to avoid really steep slopes that will need to be secured with a retaining wall or bigger foundation to support the shed.
– Is The Area Well Drained?.. Choosing to set-up an outdoor building in a wet area is not a good choice; find a location that provides natural drainage for the area. It’s recommended to set your skids on compacted well drained crushed gravel to prevent moisture damage and rotting over time.
Building a Skid Foundation for a Shed
Ok. Now it’s time to actually look at building the skid foundation, I have broken this down into 6 steps to make it easier.
Step 1] Planning and The Design… Your sheds size is how you will determine what size of skids you will needing. You should be using material that has been pressure treated or another good choice is cedar. I personally prefer to use pressure treated material that’s been specially treated so it can sit on the ground or be buried.
You’ll want the skids to be the length of the shed, in our example of an 8’ x 12’ shed the skids would be 12 feet long. Some sheds with skids are made longer so it’s easier to hook up to them for moving. Most are just the length of the shed; I like to cut the skids about 1 ½ inches shorter on both ends.
This allows for skirting to be added if you need to keep critters from nesting under your shed. Also the ends of the skids are cut so they are angled to prevent them from digging into the ground when being moved.
If your shed is small, small size would be 6’x8’; 8’x8’ up to 8’x12’… you will need 6×6 pressure treated ties. A shed that’s bigger, 10’x10’, 10’x12’, up to 10’x16’ will need 8×8 pressure treated ties. A shed that is up to 8 feet wide will need 2 ties and a shed that’s 10 to 12 feet wide will need 3 ties.
I like to keep the ties 12 inches in from the outsides and where you need 3 ties put the extra tie in the center. I have added a drawing below showing the tie location. I also have shown how to cut the end of the tie so it will be easier to move. You can cut both ends of the ties if you want, just be sure to apply some “Cut and Seal” to any wood that has been cut.
Step 2] Getting The Site Ready… Having a shed with a skid foundation can have many benefits but only if you can access the site to set-up your shed. You’re going to want to have the site as level as possible to make moving the shed into place simple. If your going to be building the shed in place you’ll want to prepare the site so it can be moved later. Having the site on a high piece of ground for good drainage is also preferred.
Step 3] Installing The Gravel For The Base… Once you have found the location for the shed, it’s time to get rid of any grass and the top 4 to 6 inches of dirt. It’s also recommended that you place a layer of black plastic or landscape fabric so grass and other stuff doesn’t start to grow under the shed.
Now add 4 to 6 inches of 1 inch crushed rock and compact it really good, you can rent a plate tamper which will speed things up and give you a nice compact area to put your shed and it’s also nice to have a clean base for building a shed floor on the skids if you’re going to be building your shed in place.
Step 4] Prep The Skids… As I mentioned in the planning and design [step 1] choose the size for your skids and make sure you use pressure treated material.
– Cut your skids to the required length. If your planning on adding skirting around the bottom of your shed remember to cut the skids 3 inches shorter than the sheds base, this will give you 1 ½ inches at each end for the skirting to install. I will add the skirting detail in the “How to Build a Shed Floor on Skids” section below.
– Cut the notch on the ends of your skids as per the drawing above.
– Drill a 1 ½ diameter hole into the skids approximately 12 inches from the end and drill the hole in the center of the skid. This hole is to be used for attaching rope or chain that will be used to pull the shed when you decide to move it. Remember to apply the “Cut and Seal” wood sealer to any cuts and using an old toothbrush apply a generous amount into the holes you drilled.
– Measure and set your skids the correct distance apart and make sure they are square.
– Using a hand level and tamp the skids into the gravel base to get them level.
How to Build a Shed Floor on Skids
Now that you have prepared the site and have your skids in place it’s time to build the shed floor on top of the skids. The whole purpose of the skids is to provide a strong base to build a shed on; I’m going to go over the entire build in steps and will add drawings as needed. I will be using the same example for building an 8 foot by 12 foot shed.
Step 1] Get Your Material… You’re going to need treated 2×6 floor joists and box joist and for blocking to strengthen the floor. For the floor sheeting I’m going to be using ¾ inch tongue and grove plywood and ½ inch treated plywood for the sheds skirting. I will also include material needed for a step.
– 5 treated 2×6 @ 12 feet.
– 12 treated 2×6 @ 8 feet.
– 3 – 4×8 sheets of ¾ inch t/g plywood.
– 2 Pressure treated 2×4 @ 12’.
– 2 Pressure treated 2×4 @ 8’.
– 2 Treated 2x2s @ 12′.
– 2 Treated 2x2s @ 8′.
– 1 Treated 2×4 @ 10’ blocking.
– 1- 4×8 sheet of ½ inch treated plywood.
– 1 pressure treated 2×6 @ 12 feet.
– 1 treated 2×6 @ 12 feet.
You’re going to need some galvanized nails and or screws. I’m not going to give amounts needed, because you probably have nails and screws already. The amount will vary depending on the size of your shed, the store where you get your material can give you the correct amount of nails or screws you’ll need.
I have added 3 drawings below…
– Shed floor plan view.
– Skirting details, end view and side view.
Shed Floor Plan View
Skirting Details, End View and Side View
Here are the steps for building the shed floor.
Step 1] Pick the 2 best 12 foot 2x6s and check the ends for square and cut them to 12 feet long. Check the 8 foot 2x6s for square and cut them to 8 feet long.
Step 2] Layout your 2×6 box joists as per drawing. 15 ¼ inch to the first one and 16 inches to the end. We do this so the plywood will fit on the center of the joist.
Step 3] Nail the 2 end double 2x6s together, use 3 inch nails and put 2 nails every 16 inches and 2 nails at the ends, stay away about 2 inches from the ends so the boards won’t split or you can pre-drill the nails holes at the ends.
Step 4] Using a couple of the 2×6 12 foot pieces lay them across the skids about a foot in from the ends. This will give you a platform to assembly your floor.
Step 5] Nail into place the second floor joist in on both ends, use 3-3 inch nails on both ends.
Step 6] Remove the temporary 2x6s and let the floor sit on the skids, finish nailing the remaining floor joists into place.
Step 7] Position the floor onto the skids, setting the ends correctly so the double joists at the ends sits flush with the inside joist and the outside end of the skid.
Step 8] Toe nail the single joists into the skids using 3-3 inch nails, 2 on one side and one on the other side, alternate this on every joist. Carefully toe nail the double joist into the skids last.
Step 9] Using the 3 pieces of 2x6s treated cut and install blocking as per shed floor plan drawing. Nail with 3 – 3 inch nails on one side and toe nail the other side with 4 – 3 inch nails, 2 on each side. Be sure to follow plan and be certain the center row is center! Make sure the other rows are flush with the outside edge of the pressure treated ties.
Step 10] Install the 3 sheets of ¾ inch t/g plywood. Begin by cutting one sheet in half, that’s 4 foot by 4 foot. Lay the first sheet from the side you set the joist to 15 ¼, the sheet should fit on the center of the 8 foot floor joint. Line up the outside edges with the box joist and nail with 2 ¼ inch nails or 1 5/8 deck screws.
Using a straight edge draw lines where the center of the joists are and fasten down 8 inches apart and 6 inches apart on the joint. [Don’t nail are screw the edge that has the tongue on it]. Install the rest of the plywood and then nail or screw the entire floor down.
*** NOTE ***
If you’re going to be installing the skirting to your shed, install the skirting BEFORE you install the plywood floor. This is so you can attach the 2×2 skirting support with metal “l” brackets and install the skirting before completing the plywood floor.
Here are the steps for installing the skirting.
Step 1] Cut the 2 – 12 foot pressure treated 2x4s to 11’- 9” cut them on a 45 degrees.
Step 2] Cut the 2 – 8 foot pressure treated 2x4s to 7’- 9” cut them on a 45 degrees.
Step 3] Cut the 2 – 12 foot 2x2s to 11’- 9” cut them square.
Step 4] Cut the 2 – 8 foot 2x2s to 7’- 6” cut them square.
Step 5] Install the 2x2s that you cut to 11’- 9” to the long side of the shed and attach them to the floor joist using the “l” brackets. Make sure you set them back 1 ½ inches from the outside of the box joist.
Step 6] Install the 2x2s that you cut 7’- 6” to the inner box joist so it’s sitting back the 1 ½ inches, you will need to cut the pieces to fit between the pressure treated ties. If you want you can install these pieces onto the inner double joist before installing the floor.
Step 7] install the pressure treated 2x4s and using screws on the corners join them together. Make sure there set back 1 ½ inches from the outside of the box joints. Using the 10’ treated 2×4 cut pieces to fit on top of the 2x4s and attach one end to the 2×4 and the other end to the pressure treated ties. Do this on the long sides, the shorter sides won’t need any extra support.
Step 8] Cut the ½ sheet of treated plywood down to strips of 5 ½ inches, you should get 5 strips out of a 4×8 sheet of treated plywood. Install the strips onto the 2x2s and pressure treated 2x4s, use 1 5/8 deck screws.
Building the Step
Because the shed will be sitting up off the ground, you’re going to need a step to get into the shed. I have used a step of 4’ by 15 inches that should be wide enough for most doors. If you’re using a wider door or double door you will need to increase the 2x6s you’ll need.
Step 1] Cut 2 pieces of pressure treated 2x6s to 47 inches and cut 2 pieces to 13 3/8 inches.
Step 2] Assemble the pieces of pressure treated 2x6s as per drawing.
Step 3] Cut 3 pieces of treated 2x6s to 48 inches.
Step 4] Install 3 pieces of treated 2x6s as per drawing and leave ¼ inch gap between the 2x6s, there should also be a slight overhang on the 3 sides of the steps.
Attaching The Shed Floor to The Skids Securely
This is optional and should be done if you’re going to be moving your shed; it’s pretty easy to do and should be done BEFORE you do the skirting and plywood floor. If you don’t take this step when building a shed floor on skids it could mean causing a lot of damage to the shed when you move it.
If you have decided to not add the skirting you will still need to add the 3 rows of blocking as per Shed Floor Plan.
I have added a drawing below and will go over the materials needed and the steps.
Attaching Skids to Floor Detail
– 1 4×8 sheet of ¾ inch treated plywood.
– 1 5/8 inch deck screws.
Step 1] Cut the ¾ inch treated plywood into strips of 10 inches wide.
Step 2] Notch out the top of the plywood to fit between the joints.
Step 3] Attach the strips using the deck screws with 6 screws into each block between the joists and 2 screws every 8 inches into the skid, do this on both sides.
Install the strips so they are ½ inch down from the top and ½ inch up from the bottom.
I hope you have found this article on building a floor on a skid foundation helpful. I have used the example of an 8 x 12 storage shed. If you have any questions or need help with your shed, just leave a comment and I’ll do my best to help you. Thanks for reading.