How to build a garden shed

Video by Wickes. This guide draws on the popular "How to Build a Garden Shed Onto a Wooden Shed Base with Wickes", which takes you through the full assembly from base frame to finished door. The section on fixing the wall panels in sequence is particularly clear — it is one of those jobs where the order you work in matters more than most people expect.

1. Choose the right site

Pick a spot that is reasonably level and has good access around at least three sides — you will need to work around the shed during the build and for maintenance afterwards. Avoid sitting it directly beneath a tree if you can; falling leaves block gutters and retained moisture rots timber faster than almost anything else.

Check whether you need planning permission. Most sheds under 2.5 m in height fall within permitted development in England, but a shed close to a boundary or in a conservation area can change things. Five minutes on the Planning Portal is time well spent.

2. Lay a solid, level base

The base is everything. A shed built on an unlevel or soft base will rack, the door will bind, and the panels will distort within a season or two. You have three main options: a concrete slab, concrete paving slabs on a compacted sub-base, or a pressure-treated timber frame on concrete blocks.

For most garden sheds, a timber frame base on concrete blocks is perfectly adequate and easier to achieve level than a full concrete pour. Sit the frame on blocks at each corner and at intermediate points, packing with slate or plastic packers until the whole thing is level in all directions. Check with a long spirit level and take your time — the base needs to be right before any panels go up.

3. Read the instructions fully before you start

Modern panel sheds come with instruction booklets that are usually quite clear, but they repay a full read before you pick up a hammer. Know which panels are which, understand how the corners fix together, and check that all the parts and fixings are in the pack before you begin.

Missing fixings are always easier to deal with before the shed is half built. Trust experience on this one.

4. Assemble the wall panels in order

Stand the back panel first, braced against something solid or held by a second person. Fix the side panels to the back panel at the corners — most panel sheds use T&G (tongue-and-groove) boards that slot together and are secured with screws. Keep the panels plumb as you go, checking with a spirit level on each wall.

Fix the front panel last, incorporating the door frame. Do not fix the door itself until the frame is fully square — hang the frame first, check the opening is plumb and square, then hang the door.

5. Fit the roof

Roof panels lift onto the wall frames and overhang the sides slightly to throw water clear. Most apex shed roofs use two panels meeting at a ridge board. Fix the ridge board first, then lift each roof panel into place and fix down. Get a second pair of hands for this step — roof panels are large and awkward to manoeuvre alone at height.

Check the roof sits evenly and that there are no gaps where the panels meet at the ridge.

6. Felt the roof and seal the edges

Standard mineral felt is the most common shed roofing material and is perfectly adequate for a garden shed with a reasonable pitch. Lay it in horizontal strips starting from the eaves and working up, lapping each strip by at least 75 mm over the one below.

Fix the felt with clout nails and fold the edges down neatly at the eaves. Apply roofing felt adhesive at the ridge overlap. A well-felted roof should last eight to ten years before it needs replacing — longer with a quality breathable felt.

7. Hang the door and treat the timber

Hang the door on its hinges and check it opens and closes freely with an even gap around the frame. Most shed doors need the top hinge slightly forward of the bottom to compensate for the natural sag of a timber door — adjust the hinges until the gap is even.

Treat all external timber with a good quality fence or shed preservative as soon as the build is finished. Pay particular attention to the base frame and any end grain. A couple of coats on a dry day will protect the timber through the first winter and significantly extend the life of the shed.

When to call a handyman

Call Richard if the ground needs significant levelling first, if the shed is larger and needs two people for the roof panels, or if you simply want it built neatly and correctly without the weekend taken up. Shed assembly is very manageable as a DIY job; the base preparation is where most people would benefit from an extra pair of hands.