Forest Garden


The core range of Sheds from Forest Garden includes Overlap Clad Sheds, Shiplap Tongue & Groove Sheds and Tongue & Groove Sheds. Assembly of all these Sheds follows the same basic principles and can be summarised in the following six steps:

  • Prepare and assemble the floor; depending on the model this may involve nailing floor sheets to bearers and screwing floor sheets together.
  • Locate wall and door panels around the perimeter of the floor, screwing each panel to the next.
  • With all panels aligned correctly, screw panels to the floor.
  • Hang the door(s) and install the windows.
  • Assemble, position and screw roof panels to Shed panel framework.
  • Secure felt to the roof.

While these tasks can be carried out by an individual with competent DIY skills and experience, it is recommended that two people are employed in the assembly of a Shed as it is much easier to have one person to help lift, position and hold components in place while another fastens the screws and nails. Two people with moderate DIY skills, the right tools and the time and inclination to follow the instructions will be able to assemble a Forest Shed with ease.

Tools required for the job:

  • Powered drill and powered screw-driver (or combi drill-driver)
  • Pozidrive PZ2 screwdriver bit(s). Note that a few products come with some smaller screws with which a PZ1 bit should be used.
  • Flat head screwdriver
  • Metric drill bits (2mm, 3mm, 4mm, 5mm)
  • Metric tape measure
  • Spirit level
  • Claw hammer
  • Craft knife / scissors (for cutting roof felt)
  • Step ladder
  • Mastic sealant and applicator (optional)
Fully Asssembled Shed With Doors Open


As with any building, a timber Shed will need a suitable base or foundation on which to stand. Sheds should not be simply erected on grass or soil. They need a hard and level base to keep everything straight so that panels line up and doors will open and close properly.

Forest Garden can supply a timber Shed Base consisting of thick (70mm x 47mm) pressure treated bearers that are screwed together to create grid on which the Shed can stand. These Shed bases can be assembled onto hardcore/construction aggregate. Metal spike supplied with the Shed base kits can be used to get the Shed base level on uneven ground. Alternatively, a base can be made with concrete slabs laid on a levelled bed of sharp sand or a levelled concrete base laid on hardcore. All Forest Sheds come with pressure treated bearers for the floor which isolate the Shed and its floor from ground contact and can be laid directly onto the prepared base.

See our Base Preparation Guide for more information on suitable Shed bases.

Assembly – Floor

All Forest Sheds come with the floor pre-assembled to the bearers, saving the user the job of nailing all the bearers to the floor. Medium and larger models have more than one floor assembly and these have to be screwed together before positioning the fully assembled floor in the desired location of the Shed.

Assembly – Walls (see notes below of pre-drilling pilot holes).

The wall panels on Forest Sheds are made up of cladding boards nailed to a perimeter frame. All panels have a top and bottom. On apex panels the (pointed) top is clear. It is important than rectangular side-panels are placed on the base the right way up. The bottom is identified by the edge where the bottom cladding board overlaps the perimeter frame. This is so that when the frame is located directly on the edge the Shed floor, the lowest cladding board overlaps the floor on the outside of the Shed, covering the join between the frame and the floor to prevent rainwater ingress.

On most Forest Sheds, the front and back panels run the full length of the floor end they are assembled to. The side panels are then ‘sandwiched’ between the front and back panels. The first panel to be positioned onto the floor should be one that runs the full length of the floor to ensure that the frame of each panel is joined to the next in the right order and configuration. Position the first panel with the bottom frame resting on the edge of the floor. Line up the ends of the frame with the edge of the floor and hold in place. Offer up the next panel and once again rest the bottom frame on top of the edge of the floor. Slide the two panels together at the corner of the Shed and so that the frame of each panel butts up against each other from top to bottom. Using a spirit level, check the two panels are vertical. Drill pilot holes through the frame of one panel, into the frame of the other and screw together as described in the instructions.

Work your way around the Shed, locating each subsequent panel before screwing it to the frame of the one it goes next to.

Once all the wall panels are in place ensure they are all inline around the perimeter of the Shed floor and once everything is square and inline, screw through the bottom frame of each panel into the floor and underlying bearers.

TIP: where the bearers do not run along the edge of the floor, their location can be identified whilst inside the Shed by looking for the heads of the nails that have been used to secure the floor to them.

Assembly – Door and Windows

Using the hinges supplied with the Shed, hang the door to the Shed framing as per the instructions that come with your Shed.

Secure windows into frames by following the instructions. Most of the Forest Sheds are supplied with security screws for the windows. These can only be turned in (clockwise) and not removed (counter-clockwise) so ensure you have the assembly configuration right before screwing in. In the event that a security screw does have to be turned out you will need either bull nose pliers or mole grip pliers.

TIP: When mounting the door, ensure that there is adequate gap (3-5mm) between the top and sides of the door and the door opening. This is to allow for expansion of the door as the weather changes.

Assembly – Roof

Different Sheds have different roof configurations. Typically, on a Forest Shed you will need to nail two battens to each roof board. One batten will be the same length as the roof sheet and should be fixed so that it is flush with the edges of the roof board at both ends and along its length. This batten will form the eaves of the Shed roof and will be used for hammering the felt tacks into, along the side of the Shed. The batten on the other side of the roof board will be shorter than the rood board and should be fixed so that the roof board overlaps the end and length according to the instructions. This batten acts as a locater for the roof board as it slots down between the two apex frames at the top of the apex. Depending on the Shed, additional roof trusses or roof beams will be installed. These will often make use of metal “Z” brackets.

TIP: All the roof boards should be offered up and aligned correctly and equally to form the roof of the Shed before being fixed to the Shed frame using nails as per the instructions. If you secure the first roof board with all its nails before offering up the next you may find that it is no aligned correctly. This would be a problem as removal of the nails to allow re-alignment is difficult and likely to damage the timber components. If necessary, locate and secure each roof board with just one or two nails before aligning all roof boards and securing permanently with the rest of the nails.

Assembly – Felt

The roof of most Sheds is made watertight and waterproof with the use of roofing felt. Fixing the felt is probably the most challenging and critical part of the build. If it is not done correctly and with care, water will get in. So, take time and be careful with the felt – it is fairly delicate and can tear if not handled carefully. Also note that Shed felt can be rolled but avoid allowing it to fold as this will weaken it. The roll of Shed felt will normally have to be cut into lengths that fit the length of the Shed roof and allow for a 50mm overhang at each end and edge. Lay and locate the cut sheets of felt at the lowest points of the roof first, working up, with each subsequent sheet overlapping the one below it to ensure water run-off.

TIP: Felt tacks should not be tacked into single layers of felt on sections of roof that are sky-facing. This will risk rainwater getting under the head of the tack and running down the shank into the roof board. Felt tacks should be into the side of the battens at the bottom edge of the roof board (the eaves). The felt that is folded over the front and back apexes of the Shed can be secure in place with the barge boards. The felt tacks that secure the felt on the weather facing top of the Shed will be tack through the top overlapping layer of felt, through the underlying layer of felt and into the roof boards. This method of tacking through two sheets of felt prevents the problem of water ingress.


Follow instructions for finishing details including door hasp and staple, corner strips, barge boards and finial. If pilot holes are not drilled on these thinner timber components they will split.

TIP: for effective sealing of the corner joints a mastic sealant can be applied to the joint from the outside before fixing the corner strips.

Guide to Pilot Holes and Clearance Holes

  • Pilot holes should be 1 to 1.5mm smaller than the diameter of the screw thread being used. So for a screw with a 4mm diameter thread, the pilot hole should be 2.5mm to 3mm diameter.
  • While pilot holes are essential, it is best practice to also drill clearance holes. These are used when fastening two pieces of timber together by screwing through one and into another. The clearance hole should be drilled through the near-side (first) piece of timber only, to allow the screw to pass through freely; the screw thread does not need to engage in the first piece and the clamping is provided by the screw’s head. Clearance holes should be the same diameter as the screw’s thread or slightly bigger. Drill the clearance hole through the initial pilot hole. See example below which represents drilling through battens to secure Shed wall panels together.
Assembly Pilot And clearance Hole Diagram


While you may not have options for where to site your Shed in your garden there are a few factors to consider if you do.

If you build your Shed under a large tree then in the autumn leaves and twigs will fall on the roof of the Shed. Particularly if it is wet, these leaves may accumulate and stay on the Shed roof, as they rot and mulch down then can cause damage to the roof felt. Worse still, if birds such a pigeons perch on branches above the Shed their droppings will rot the felt.

Most apex Sheds that have a window can be built with the window panel on either the left or right side of the Shed. Don’t assume that if the instructions show the window on the left side of the Shed that is must be assembled on this side. On a Forest Apex Shed the window panel can be assembled on the left or right side so decide which side is best for the location of the Shed in the garden. Similarly, the door on Forest single-door Sheds is design so that it can be hung to open from the left or the right as preferred.

For more information, please see our How to Build a Shed video, our How to Build a Wooden Shed Base video, our How to Build a Shed Onto a Wooden Shed Base video, and our How to Felt a Shed Roof video.