How To Replace A Shed Roof: A Step-By-Step Guide

A leaking shed roof is one of those jobs that’s easy to ignore, right until you discover a damp lawnmower, rusty tools or a suspicious puddle forming next to the garden chairs. 

The good news is that replacing a shed roof is much easier than you might think. In many cases, you won’t need to replace the entire roof structure at all. If the timber underneath is still sound, the job might simply involve stripping off the old roofing felt, checking the roof boards for damage and fitting a fresh, weatherproof covering. 

In this guide, we’ll explain how to replace a shed roof step by step, from removing the old felt and inspecting the timber underneath to measuring, fitting and securing the new roofing material. We’ll also share advice on when a simple repair might be enough and when your shed roof needs replacing. 

Whether you’ve got a traditional apex shed, a pent-roof garden building or a shed that’s simply seen a few too many British winters, here’s what you need to know before getting started. 

Quick answer: How do you replace a shed roof? 

To replace a shed roof, remove the old roofing material, inspect the timber underneath and replace any rotten or damaged boards. Once the roof is clean, dry and structurally sound, fit the new roofing felt or covering, secure it correctly and finish the edges and ridge to keep the shed watertight. 

Should you repair or replace your shed roof?

 

Signs your shed roof needs replacing 

A small tear in your shed roof doesn’t always mean it’s time for a complete replacement. But once problems start appearing across several areas of the roof, another quick roof patch is often only delaying the inevitable. 

Some of the most common signs that your shed roof needs replacing include: 

• Leaks or damp patches inside the shed, particularly after heavy rain. 

• Cracked, torn or brittle roofing felt that is starting to break down in several places. 

• Felt lifting around the edges or ridge, allowing wind and rain to get underneath. 

• Soft or spongy roof boards, which can indicate that water has reached the timber below. 

• Sagging sections of roof, which might be down to damaged roof boards or supporting timbers. 

• Visible rot, mould or staining on the underside of the roof. 

• Repeated leaks despite previous repairs usually means the roof covering has reached the end of its life. 

Do you need to replace the felt or the whole roof? 

When people talk about replacing a shed roof, they don’t always mean replacing the entire timber structure. 

If the roof boards underneath are dry, firm and flat, you may only need to replace the shed roof felt or other waterproof covering. This is the simplest scenario and is a job many confident DIYers can tackle themselves. 

Things become a little more involved if water has reached the timber below. Soft boards, dark patches, crumbling edges or areas that flex when pressed can all indicate rot or water damage. Replace any affected roof boards before fitting new felt. 

You should also check the supporting timbers beneath the roof. If the roof is noticeably sagging, twisted or unstable, the problem may go beyond the roof covering and boards. Damaged structural timber needs proper repair before you make the shed watertight again. 

Don’t cover up a problem simply because you can’t see it once the new felt goes on. A new waterproof layer will only perform as well as the roof underneath it. 

If the roof, walls, and floor are all suffering from widespread rot, is repairing the shed the most economical option? 

What is the best material for replacing a shed roof? 

For most traditional timber garden sheds, mineral roof felt remains one of the best materials for replacing a shed roof. It’s affordable, easily available and straightforward to install. 

It’s not the only option, though. 

EPDM rubber roofing is an alternative; it’s a great choice for pent and lower-pitched shed roofs. The waterproof cover has fewer joins compared to felt and gives you a long-lasting finish, even though it does cost more. 

Bitumen shingles are another option for apex roofs. They give a more decorative finish than felt and work best on summerhouses and bigger garden buildings. These are a little more time-consuming to install, but the finished look is worth it. 

For larger sheds and workshops, corrugated bitumen or metal roofing sheets might be the best material for a long-lasting shed roof. But the structure needs to be able to hold these materials. 

For a typical timber shed where you’re simply replacing worn-out roofing, good-quality shed roofing felt is the easiest and most cost-effective choice. 

For the step-by-step instructions, we’ll concentrate on how to replace a shed roof using roofing felt, as this is the most common roof covering found on traditional garden sheds. 

What you’ll need 

Before you start replacing your shed roof, it helps to have everything ready. Once the old roof covering comes off, you don’t want to leave the timber exposed to a potential downpour. 

For a typical felt shed roof replacement, you’ll usually need: 

• New roofing felt 

• Roofing felt adhesive 

• Galvanised clout nails 

• Hammer 

• Pry bar or claw hammer to remove old felt and fixings 

• Pliers 

• Tape measure 

• Straight edge 

• Sharp utility knife 

• Broom or stiff brush 

• Stepladder 

• Work gloves and eye protection 

• Replacement roof boards of timber for damaged sections (if there are any)

Check the instructions for the felt you’ve bought. Different products use different fixing methods, so read the instructions before you start. 

And, of course, choose a dry, calm day for the job. Roofing felt and gusty winds aren’t the best combination. 

How much roofing felt do you need?

The easiest way to work out how much roofing felt you need is to measure the actual roof rather than relying on the advertised size of your shed. 

For a pent roof, measure: 

• The full length of the roof 

• The distance from the highest edge to the lowest edge 

For an apex roof, measure: 

• The full length of the roof 

• The distance from the eave to the ridge, on one side 

• Repeat for the opposite side if the roof isn’t symmetrical 

You’ll need extra material for the roof edges, overlaps between pieces and the ridge of an apex roof. 

As a simple guide: 

Roof area = roof length x roof slope 

For an apex roof, calculate each side separately and add the two figures together. 

For example, if one side of your roof measures 2.4m long by 1.2m from the eave to the ridge: 

2.4m × 1.2m = 2.88m²

If both sides are the same size:

2.88m² × 2 = 5.76m²

That gives you the basic roof area, but don't buy exactly 5.76m² of felt. You'll need additional material for overlaps, edge overhangs and cutting. 

How to replace a shed roof step by step

The following steps explain how to replace a shed roof using roofing felt, which is one of the most common roofing materials used on traditional timber garden sheds. 

Step 1: Remove the fascia and barge boards 

Start by removing any fascia or barge boards that cover the edges of the existing roofing felt. Work carefully so you can reuse them if they’re still in good condition. 

If the boards are rotten, split or badly weathered, it’s best to put new ones back on. 

Step 2: Remove the old roofing felt 

Next, begin stripping away the old felt. Use a pry bar, claw hammer or pliers to carefully remove the existing roofing nails or fixings. Work your way across the roof rather than simply pulling large sections of felt away, as this can damage the timber boards underneath. 

If the felt has been glued down, you’ll have to work more slowly to lift without tearing pieces of the roof deck away with it. 

Step 3: Inspect the roofboards 

With the covering removed, you can finally see what’s been happening underneath, and this is one of the most important stages of a shed roof replacement. 

Check the entire roof surface for: 

• Soft or spongy timber 

• Dark staining 

• Crumbling edges 

• Mould or fungal growth 

• Split or warped boards 

• Sagging areas 

• Loose fixings 

Pay particular attention to the edges of the roof and anywhere the old covering was damaged, as these are common places for water to get in. 

If the roof boards are dry, solid and flat, you can move on to preparing the surface. 

Step 4: Replace any rotten or damaged timber 

Don’t fit new roofing felt over damaged roof boards. They should be removed and replaced before you continue. The new boards should sit securely and level with the surrounding roof so that the felt has a smooth, stable surface to sit on. 

It’s also worth checking the supporting roof timbers while the roof covering is off. If the roof is sagging or you discover widespread structural rot, the repair will be a lot bigger than just replacing the felt. 

Step 5: Clean and prepare the roof 

Once you’re happy with the structure, remove any remaining nails, staples, adhesive, dirt or loose material from the surface, and give the boards a good brush. 

Your roof should be clean, dry and as smooth as possible before the new felt goes on. Anything sticking up beneath the felt could eventually rub against and cause wear or punctures. 

Step 6: Measure and cut the roofing felt 

Measure the roof again before cutting your felt. 

Make sure there’s enough material for the overlap between sections and enough overhang around the roof edges. Roll the felt out on a clean, flat surface and use a straight edge and sharp utility knife to make neat cuts. 

Step 7: Position the first section of felt 

Start at the lowest edge of the roof and work upwards.

Position the first piece of felt so it lies straight, flat and with enough material extending beyond the roof edge. 

Take your time getting this first section right; if it goes on crooked, every piece will likely follow the same way. 

Smooth out edges, folds and bubbles before you secure it in place. 

Step 8: Fix the felt in place 

Secure the roofing felt with the fixings recommended by your specific instructions. You’ll often see it being galvanised clout nails, although some will use adhesive. 

Work methodically across the sheet, keeping the felt smooth as you go. Don’t overdrive the nails, as it’ll cut into the felt and weaken the waterproof covering. But don’t let them sit proud where they could snag or allow movement either. 

Step 9: Fit the remaining sections 

Continue working from the bottom of the roof towards the top, overlapping each new section over the one below it. 

This direction is important because it allows rainwater to flow naturally over the joins rather than underneath them. 

Keep checking that the felt is straight and smooth as you work, rather than waiting until you reach the ridge to find that everything has gradually wandered off line. 

Step 10: Finish the ridge on an apex shed 

If you’re replacing the roof on an apex shed, you’ll need to waterproof the ridge where the two slopes meet. 

Depending on the roofing system you’re using, this might involve fitting a separate strip of felt over the ridge or arranging the main sheets so that the top section provides the overlap needed. 

Whichever method you use, the ridge needs to be securely covered with no exposed gaps where wind-driven rain can get underneath. 

Again, follow the instructions supplied with your roofing felt for the recommended ridge detail. 

Step 11: Secure the roof edges 

Once the main roof covering is fitted, you can secure the felt around the edges. Make sure it sits neatly over the roof boards without excessive folds or loose sections. 

The edges are vulnerable to wind, so it’s important that they’re properly secured before the fascia or barge boards go back on. 

Trim away any unnecessary excess with a sharp utility knife, taking care not to cut the felt too short. 

Step 12: Refit the fascia and check your work 

Finally, refit the fascia or barge boards around the roof edges. 

These help protect the edges of the roofing felt while also giving the shed a much neater finished appearance. 

Before you pack your tools away, walk around the shed and give the new roof a final inspection. Check that: 

• The felt lies flat 

• All overlaps are secure 

• There are no exposed gaps 

• The edges are firmly fixed 

• The ridge is completely covered 

• No fixings are sticking up 

• The fascia boards are secure 

And that’s it; your newly replaced shed roof should now be ready to face the British weather once again. 

Replacing an apex shed roof vs a pent shed roof

The basic process of replacing a shed roof is much the same whether you’ve got an apex or pent roof. But there are some differences worth knowing before you start. 

An apex shed roof has two sloping sides that meet at a central ridge. When replacing the roofing felt, you’ll need to cover both sides of the roof and pay particular attention to the ridge. This is one of the most exposed parts of the roof, so it needs to be properly overlapped and waterproofed to prevent wind-driven rain from finding its way underneath. 

A pent shed roof has a single slope, with one side higher than the other. This generally makes fitting roofing felt a little simpler as there is no central ridge to deal with. The important thing is to work from the lowest edge upwards, positioning overlaps so that the rainwater runs over them rather than underneath. 

Whichever style of shed you have, don’t rely solely on its advertised dimensions when ordering roofing felt. Measure the actual roof slopes first and allow enough extra material for overlaps and overhangs. 

How to make your new shed roof last longer

Once you’ve gone to the effort of replacing your shed roof, a little maintenance can help you get as much life from the new covering as possible. 

Start by checking the roof a couple of times a year and after particularly bad weather. Look for lifted edges, damaged felt, loose fixings and any signs that water is beginning to get underneath the covering. Small problems are usually much easier to deal with before they turn into leaks. 

Keep leaves, moss, branches and other debris from building up on the roof. Apart from holding moisture against the roofing material, debris can prevent rainwater from draining away properly. 

Keep an eye on nearby trees too. Overhanging branches can scrape against roofing felt in windy conditions or drop heavier branches onto the shed during a storm. 

Don’t neglect the rest of the shed either. Treat exposed timber where necessary, repair damaged fascia boards and make sure rainwater isn’t repeatedly running onto vulnerable roof edges. 

Don’t ignore a leak either. If you spot water getting inside your shed, investigate it sooner rather than later. What starts as a small problem could result in rotten roofboards, which is a much bigger job to fix. 

FAQs

Can you put new felt over old shed felt?

Sometimes, but it is usually best to remove the old felt. Laying new over the old might just hide the problems rather than fixing them. We cover this in more detail in our guide to whether you can felt over old felt on a shed.  

How long does it take to replace a shed roof? 

Typically, for a small or medium-sized shed, it won’t take longer than a day, around three to seven hours, to complete it. But it’ll take longer if you need to replace roof boards. 

How much does it cost to replace a shed roof? 

Typically you’ll pay roughly £320 to replace a shed roof, but this varies depending on the size and the condition of the roof. This is paying someone to do the job too, which accounts for materials and labour costs. If you’re doing it DIY, then you’ll only need your time and materials. 

When is the shed itself beyond repair? 

Extensive rot in the walls, floor and structural framing; serious movement in the building, or multiple areas that have already failed; these are signs that repair is the less economical choice. 

Can I replace a shed roof felt myself? 

Re-fitting felt on a small timber shed roof is a manageable DIY job if you’re comfortable using basic tools. The job gets more complicated if the roof boards or supporting timbers are rotten. 

Can you replace shed roof felt in the rain? 

It’s best not to. Choose a dry, calm day when replacing shed roof felt. The exposed roof boards should be dry before you fit a new covering, and wet or windy conditions can make handling large sheets of roofing felt much harder than it needs to be. 

How often should shed roof felt be replaced? 

There isn’t a fixed replacement schedule, because it depends on the quality, installation, and how exposed it's been to sun, wind, and rain. It’s best to check your shed roof and see whether it’s time for a replacement. 

Do I need to replace the roofboard when re-felting a shed?

Not if they’re still in good condition. Once you’ve removed the felt, check that the roof boards are dry, firm, flat, and securely fixed. If they are, they can likely remain in place. 

Should shed roof felt be nailed or glued? 

It depends on the roofing felt you’re using. Galvanised clout nails are the most common way to secure felt, but some will use adhesive as well as fixings. 

Is your shed beyond repair?

Sometimes a new roof is all your shed needs. But if rot, leaks or structural damage have spread beyond the roof, it might be time for a fresh start. 

Explore the range at Atlas Sheds and find a durable, practical garden building that suits your space, storage needs and garden.