How to Build a Garden Shed

Building you own garden shed can be quite a rewarding experience. Pre-built sheds very often are made as cheaply as possible, using the minimal amount of materials to hold everything together. Constructing your own ensures you know exactly what is going into it, as well as eliminating the hidden labor costs. If you are comfortable with using basic hand and power tools, creating your own backyard shed is not hard.

In the below steps, we will be building a 5' x 8', shed roof storage structure.  Through this example shed plan, the stage by stage and individual steps can be applied to the entire allotment of our shed designs, as well as most other ones found on the net.

Throughout the steps, details in enlarging and altering the example shed will be explained.  Screws are recommended for all parts of construction as they don't easily pry out and are more secure than nails.  Also always make sure to check our local building codes before starting any backyard woodworking project.

Step 1: Choosing a Foundation

The purpose of the foundation is to provide a stable and level starting place to support the rest of the structure. When it comes to picking a foundation, no matter what size shed you plan on building, there are several options to pick from.

4x4 / 6x6 Wood Rails & Concrete Blocks

Wood Rails and concrete blocks are the easiest and cheapest solution for a shed foundation. Not only can they be placed directly on the ground, they don't require digging holes, using gravel for drainage and don't require the shed's joists to be pressure treated, resulting in a lower material costs. The only real downside is that the grade needs to be close to level for this option to work.

If you choose to use wood rails, a minimum of two need to be used directly under the two band joists. We recommend using an additional rail for every 8' of depth for 2x6 joists. Because our example 5x8 shed is 5' in depth, the third wood rail in the middle was not necessary, but was installed to further reduce deflection.

If you choose to use concrete blocks, the same span principle applies when using 2x6 joists.  Checking to see if the rails and blocks are square is necessary for the rest of the platform to be square as well.  Use a 4' level and a straight 2x to make sure everything is sitting on a level plane.  It is usually necessary for some excavating to be done to achieve this.

Gravel Bed Foundation

Another option is to lay the shed joists directly on top of of a bed of gravel.  Excavate a level, 4-8" deep opening in the ground approximately 1' larger then each side of the shed.  In our 5x8 example, a 7' x 10', 6" deep rectangle shaped hole has been dug out and filled with stone.

Gravel is a great option for those who want excellent water drainage  and a clean look.  It's also easy to level the floor joists after the gravel has been raked.  It's downside is that it allows for strong winds to potentially move or topple a shed because of it's lack of anchorage.  4x4 lumber can be used to line the edges of the hole in order to keep the gravel from spreading and providing a even nicer ascetic.

Posts & Beams

For hillsides, slopping yards and elevated platforms, digging holes and installing posts and beams is recommended.  Start with the dimensions of your shed and reduce the width and depth by 18".  If you were to center these new dimensions inside the current shed footprint, these would be the center of the holes you must dig.  Using our 5x8 shed example, we should center a 42" by 78" rectangle.

If there are any dimensions over 8', and using 2x6 joists, a third set of holes must be dug.  Check your local building codes to see how deep the holes must be dug and what span you sized joists can handle.  Once the holes have been marked, checked for square and dug out, the posts can be installed.

The beams that support the shed's joists will run perpendicularly to them.  Because of this, the two opposite side posts will need to be parallel.  Brace and plumb the posts in the holes, as well as screw on a 2x to both of the in-line posts to insure they are parallel. Generally, leaving about 2' of the post above the grade is sufficient, except for intensely slopped landscaping.  Before the concrete is poured, double check to make sure everything is plumb, parallel and positioned where it should be.

After the concrete is dry, the beams can be marked and the notches cut.  Using a level and a straight 2x, mark where the bottom of the beam will start for all of the posts.  From these marks, cut a 1 1/2" deep notch that is the equal height of the beam.

In the 5x8 shed example, a 2x8 beam is resting in a 1 1/2" x 7 1/2"  notch approximately 1" above grade.  Install two, skewed 1/2" carriage bolts into each post and beam intersection.  For larger spans, a doubled 2x8 or 2x10 may be required, in which case 6x6 posts should be used, with a 3" deep notch.

Step 2: Framing the Joists

Most square shed platforms are made up of two rim/band joists and common joists.  The rim joists are what all the other joists are connected to and what holds everything together.  Most joist systems use 16" on center layouts, meaning the center of every joist is exactly 16 inches apart from the next one.  This layout is so common, most professional measure tapes have these numbers already marked out.

When you pull the measuring tape from the end of the rim joist, mark 3/4" behind every 16", resulting in the first open bay being 13 3/4" wide and the rest being 14 1/2" wide.  Doing this allows 4' by 8' plywood sheets to line up in the middle of the joists.  To make installing the common joists to the rims easier, use a speed square to draw visible plumb lines on the 16" O.C. marks.  It's fine if the last joist bay is less than 16" O.C.

In the 5x8 shed example, the two rim joists are 8' in length, resulting in seven common joists in total.  Use three #10 x 3" screws to secure 2x6 joists together, and four screws for 2x8s.  Check for square by cross measuring the platform corners to see if they are the same distance apart.  Once the joist box has been constructed, install it to your chosen foundation.

Step 3: Floor Sheeting

Shed flooring is usually made of 3/4" plywood sheets to adequately support substantial dead and live loads.  The plywood wood grain should always run perpendicular to the joists to maximize strength. 

Begin by dry fitting the first sheet in a corner, checking to make sure both the end joist and rim joist line up exactly with the plywood.  When the joists line up perfectly, screw down this sheet using 2 1/2" decking screws every 6" along the perimeter when possible, and every 12" in the field.  Offset the next row of plywood, usually by 4', to prevent seams from lining up on the same joist.  Applying construction adhesive right before the plywood is screwed down is recommended to reduce future creaking.

The left illustration shows what a 8x12 shed platform would look like during this process.  Notice that the 2nd row of plywood has been staggered by 4' to prevent long, single joist seams, but also using the material in the most efficient manner.  In the 5x8 shed example, two sheets of 3/4" plywood have been used, one being a whole piece while the other has been ripped to 1" wide.

Step 4: Framing the Walls

Shed walls are in many ways just vertical joists.  Instead of rim joists, walls have a bottom and top plate.  Instead of common joists, walls have studs.  Just like the joist system, wall studs should be laid out exactly the same, 16" O.C., and marked 3/4" behind.  For sheds with a lean-to roof, three walls will be one height, with the fourth wall being taller.  The 5x8 shed example will have this type of design.

Use the same #10 3" screws for framing the walls.  Connect the 2x4s together using two screws at each intersection.

The 5x8 example shed's tall wall will be 8' in height.  All four of this shed's walls will have a doubled top plate, resulting in 4 1/2" of plates taking up the overall wall height.  Because of this, the back wall will have three 8' plates and seven 7' 7 1/2" studs.  No windows are required for the back wall.  The left, right and front shed walls will be just 7 1 1/2" in total height, resulting in a 6' 9" common stud height.

The most common window size used by our plans is 2' x 3', with a rough opening size of 24 1/2" x 36 1/2".  Windows are framed using king studs, jack studs, cripple studs, headers and sills.  The header is made of two 2x4 or 2x6s, turned on edge and 3" wider than the rough window opening.  This is so that two jack studs can be placed underneath on both sides to support the header.  Two king studs, which are the same as common studs, are placed next to the two jack studs.  Two sills, cut to the width of the rough window openings will be installed between the jack studs.  Cripple studs just continue the 16" O.C. in the window framing layout.

Framing the door out is usually the same as the window, just without the lower sill.  For the 5x8 example shed, a header is not necessary because of the lack of roof load.  The rough opening for this shed door is 36 1/2" by 6' 9".

Because the left and right side walls are designed to sit between the back and front walls, they will measure 7" less than 5', or 4' 5" in width.  Be sure to compensate the 16" O.C. layout because of this.  The 2nd top plate of these walls will also stretch over onto the 1st top plate of the front wall as well.  This helps lock the walls together.

The front wall will use two 2' x 3' windows one foot from the wall edges.  Use the same principles from before to frame out these two windows.  The 2nd top plate should be 3 1/2" short on each side to allow room for the left and right side walls.