How to Felt a Shed Roof

So how do you felt a shed roof?

Felting a shed roof is an important part of protecting any garden shed from harsh weather. It also ensures that your shed looks great, all year round. It may seem like a tedious task, but felting a shed roof is actually pretty straightforward if you know what you’re doing.

Our step by step guide includes everything you need to know about what you will need, removing old roofing felt and adding new felt to your shed roof. We recommend replacing your shed roofing felt every few years if it is exposed to harsh weather. You won’t need to do this so regularly if it’s in a more sheltered spot.

What you will need:

  • Craft knife
  • Tape measure
  • Hammer
  • Roofing Felt
  • Felt and wood nails
  • Paintbrush
  • Felt Adhesive

Step 1: Removing Old Roofing Felt

Dismantle any existing timber fascia boards and put them to one side. Then use a claw hammer to remove any nails holding down the old roofing felt. Make sure the surface is clear of any nails which are sticking out and any debris lying about. If you see any obvious hazards, remove or flatten these first.

Step 2: Measure the Amount of Felt You Will Need

Before you felt your shed roof, you’re going to want to measure the dimensions of the roof itself to know how much felt you’ll need. Start with the width – measure from the eaves on one side, up and over the apex (if necessary) and down to the other edge. Make a note of this measurement, and then add 10cm to the figure. This is because you’ll want your felt to overhang by 5cm on each side, so that you can tuck it underneath the purlins.

Rolls of felt can vary in width, but usually they’ll be about 100cm wide. Most shed roofs have three strips of felt covering it length ways – one on the right hand side of the roof, one on the left and one spanning the ridge of the apex in the centre. You’ll want to allow for the strip in the centre to overlap the strips either side by approximately 10 cm.

Next, measure the roof from front to back, gable to gable. Add 15cm onto this number to allow for tucking the felt under the fascia boards (this equates to 7.5cm on each side).

Step 3: Cutting Your Felt

Generally, your width measurements will determine how many rolls of felt you need, and your length measurements where you need to cut each strip. Cut the felt roll length ways at the designated point (ensuring you’ve accounted for the extra overhang) using a craft knife or a Stanley knife.

Step 4: Applying The New Roofing Felt to the Shed

After you’ve cut the right sized felt, roll it up again and place it on the roof. You’ll want to start with one of the edge rolls. Roll it out again across the roof and make sure it overhangs by 5cm beyond the eaves. You may want to mark a pencil line across the length of the roof so you know exactly where the felt should go. Make sure the felt is rolled out in a straight line, and then nail it in at 10cm intervals across the length of the roof.

Once it’s nailed in on the inner side, pull it tight so that it lies flat along the length of the shed roof and nail along the eaves – on the side of the shed, rather than the top. The intervals between these nails can be wider – use one every 30cm.

Repeat this exact procedure for the other side of the shed.

Step 5: Felting the middle

Once the side panels are secured in place, lay the final felt strip over the ridge at the apex and make sure it overlaps the two felt strips on either side. 

Our best tip for ensuring security between the middle strip and the two outer strips is to use felt adhesive. You can find this at any local hardware shop. Lay it on thick with a paintbrush on top of the two outer strips (rather than the middle strip), covering solely the area that the middle strip will overlap them. Stick the middle down and give it a good press down to make sure it’s in place.

Then finish it off, using nails again at 5cm intervals, at the point where the edge of the middle strip meets the outer strips.

Step 6: Tidy the Corners of the Overhangs

Fold the excess felt at each corner of the roof outwards to make a flap, and then fold it back along the eaves and nail it into place. Where the overhang creases at the apex, at the front and back of the building, use  your knife to cut a slit in the felt at the centre point. Nail either side into the wood, and then flap the other side over, covering it, and nail this in too.

Along the gables, we recommend nailing the overhang in at 10 cm intervals.

Once you’ve nailed it down securely, you can re-attach the fascia boards to keep your shed looking tidy by hiding the folded roofing felt at each gable end. Use wood nails to secure it all in place and then trim off any excess material.