Storage Units: Lean-to Shed (DIY Small Buildings)

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If there is an existing high wall, fence, or side of a house, you might wish to make a small building as a lean-to attached to it. This construction means you already have a rigid support that will hold the building in shape and protect it from the effect of high winds. If it's upright and straight, it gives you a datum for squaring the building you are adding. If you check and find it's not true, do not make the new building to conform to its errors. The added shed should be upright and square or it will look wrong. Where the new shed meets the untrue wall, you should fair it in. You might be able to cut covering boards to conform or you might have to attach shaped uprights to the wall, with their outer edges vertical. Treat the roof joint similarly. Obviously, the roof joint must be weathertight.

Consider the effect of the addition on its surroundings. Will you have to divert a path around it? Will it obstruct light or view through an existing window? When you put down foundations, of whatever type, make sure they can't cause rainwater to run back into the house foundation. If you are joining onto a fence, is it in suitable condition for your purpose? You might be giving yourself more work in the future if you will have to replace the fence because of rot or for other reasons.

If you want to walk into it, a lean-to building must have enough height for a door. Slope the roof away from the existing wall. You can have a flat roof, but you should give it a slight slope so it sheds water. A steeper slope is usually better, particularly if you get heavy snowfalls. For a gardener’s shed, the height at the outer wall might be less than 6 feet, if there is a worktop inside, so you do not walk right up to the wall. You might modify the sizes suggested to suit your situation.

The building shown in figr. 3-11 is covered with vertical, matched boarding. For horizontal boarding, arrange the framing upright. For a plywood skin, the framing is satisfactory as shown. All of the parts are prefabricated—two ends and a front, with a roof that you can make in position.

The ends settle the sizes of other parts. Make the door end first (figr. 3-12). It is shown 72 inches wide with a height sloping from 90 inches to 72 inches, but this stage is where you make your modifications, if required. Assemble the frame with 2-inch-square strips, notching them into each other, and jointing the corners or using gussets (figr. 2-5). The strip at the outer corner (figr. 3-12A) need only be 1 inch thick to fit inside the front piece.

At top and bottom of the high edge, notch the framing to take boards which you will use to screw the assembly to the supporting wall (figr. 3-12B,C). Cover the framing with tongue-and-groove boards which have about a ¾-inch- finished thickness and which are 6 inches wide. Allow for the overlap on the front (figr. 3-12E).

Fit strips around the door sides and top to cover the boards and framing (figr. 3-12D). Let these project forward with rounded edges. Leave the frame strip across the bottom of the door opening, either permanently or until after you have fastened down the walls.

Use this first end as a pattern for making the opposite end identical. Carry the rails right across. The boarding probably will provide adequate vertical stiffness, but if necessary, include some uprights between the rails. Cover that end with tongue-and-groove boards. If you wish, you can add another door or a window in the end, arrange it as described for the front.

Make the door with upright boards similar to the covering. Put three ledges across and one or two diagonals. Put a strip as a stop on the side of the opening the door will close against. Arrange three hinges, a handle, and a lock or other fastener.

Make the front (figr. 3-13) to match the height of the ends. You could bevel the top to match the slope of the roof, although you should get a close enough fit for most purposes by letting the roof rest on the front edge. Make all the framework with 2-inch-square strips, with joints similar to those in the ends. Corners fit inside the shed ends (figr. 3-12F). Cover the framing with upright boards in the same way as the ends.

figr. 3-12. Details of the door end of the lean-to shed.

figr. 3-11. This lean-to shed fits against a wall and has windows in its lower Side.

figr. 3-13. Wall and window details of the lean-to shed.

For the window openings, make a sill the full length, notch it around the intermediate uprights (F 3-13A). Put pieces of covering board over the two uprights and frame around the window openings in a similar way to the doorway (figr. 3-13B). Put strips around to make recesses for the glass (figr. 13-3C).

Postpone fitting the glass until you have erected the shed. When you do fit it, putty the glass into the recesses or use more wooden strips.

As you erect the ends and front to the wail, screw or bolt the horizontal strips into their recesses at the back and fasten through them into the wall, taking care that their lengths match the front, or you will be unable to square the assembly. If you do not expect to move the building, you can nail or screw the front corners. Otherwise, use bolts. Fit square strips to cover the board edges.

The roof could be ¾-inch plywood or tongue-and-groove boards laid with their smooth sides upwards. In both cases, use framing strips at about 18 inch intervals to fit inside the walls. Allow for an overlap of about 6 inches on the shed walls. At the supporting wall, bevel to make a close fit and fair the edges if necessary. Edge the outer limits of the roof (figr. 3-12G). More strips inside will help when locating places where other roof framing parts do not come.

Nail or screw on the roof. Cover it with tarred felt or other material. At the edges, wrap around the border pieces. At the top edge, the joint will depend on the material of the fence or wall. If possible, carry the covering material up so existing clapboards or other projections will shed water over the cover rather than under it. Screw strips through the covering to secure it. It might be necessary to use a jointing compound or mastic to ensure complete waterproofing.

For storing and preparing garden plants and equipment, it might be sufficient to paint the building and leave it as it's . For a neater inside and to provide some insulation, line the walls with hardboard or plywood. A broad shelf the full length under the windows will serve as a bench and also will brace the walls. Other shelves and storage arrangements attached to two or three walls also will provide stiffness.

Materials List for Lean-to Shed:

4 uprights

6 uprights

2 uprights

5 rails

2 rails

2 door rails

4 end rails



1 window sill

18 window frames

9 window frames

2 door frames

1 door frame

2 backs

4roof frames

3 roof edges


2 x 2 x 92

2 x 2 x 74

1 x 2 x 74

2 x 2 x 96

2 x 2 x 76

2 x 2 x 50

2 x 2 x 36

2 x 2 x 56

2 x 2 x 26

1 x 4 x 74

¾ x ¾ x 24

¾ x 3½ x 24

¾ x 3½ x 76

¾ x 3½ x 32

1 x 6 x 100

2 x 2 x 96

1 x 1 x 108

¾ x 6


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Updated: Thursday, December 9, 2010 4:17