Feeling frustrated because of a sagging or leaking shed roof? We're here to help with our top tips on how to repair it! 

No matter what you use your shed for, whether it’s purely for storage, as a hobby room or maybe even a garden bar, you’re likely to feel upset or even annoyed if its roof begins to sag or leak. If you’ve noticed your shed roof is sagging or leaking, it’s time to address the issue! Don’t leave it to rack and ruin, it’ll end up costing you more. Don’t go out and buy a whole new shed either, we guarantee the problem will be easier to fix than you think.

Let’s look at the issues first…

A sagging and leaking shed roof

Whether your shed is facing both of these issues or just one, the roof is likely to be feeling a little weak. If your shed roof is sagging, it’s likely you’ve noticed it bowing on the inside, if it’s leaking, you’ve probably noticed some water inside your shed.


What are the causes?


Sagging is mainly caused by too much weight on top of your shed roof and not enough support underneath so start by checking for and clearing any debris and pooling water. If pooling water is the cause of your shed roof’s sagging, you’re going to want to check for leaks too!

Although pooling water can cause leaks, leaks are more common than sagging as tears, cracks, missing pieces of your roofing material and general wear and tear can also be a cause of a leaking shed roof.

Remember...shed maintenance is hugely important and if you are not regularly clearing debris and water , you need to start making this part of your garden maintenance routine otherwise your shed roof is more at risk of becoming damaged.

How to repair a sagging roof

Once you’ve cleared the debris and water, you can start the repair. The best way to do this is to add additional support to your shed roof from the inside. Fit new rafters and don’t just focus on the affected area, fit them across the full shed roof to prevent sagging in other areas.

When should you replace a sagging shed roof?

Pastel pink shed with ONDULINE CLASSIC Black roofing sheets

How to repair a leaking roof

Depending on the existing material of your shed’s roof and how much damage the leak has caused, you may be able to repair your roof by simply replacing the section that is leaking. Torn or cracked roof felt is a good example of this.

To repair roof felt you’ll only need basic tools such as a hammer, utility knife, nails and a tape measure - the same ones you may have used to install your felt in the first instance.

  • Step one - You may need to remove your shed’s ridges, also known as fascia boards, to access the damaged felt
  • Step two - Remove the damaged felt by prying off the existing nails with a hammer (or flat head screwdriver). Be careful not to cause added rips and tears
  • Step three - Measure and cut your new piece of felt to the correct size in order to replace the existing piece you have just removed. Allow a two-inch overlap on all sides
  • Step four - Attach the new piece of felt with nails and make sure there are no lumps and bumps
  • Step five - Reattach your shed’s ridges (fascia boards)

When should you replace a leaking roof?

Dog in front of garden shed with Onduline's ONDUVILLA roofing sheets

Final tip

Before you go ahead with any repair or replacement make sure you have fully checked the condition of your timber structure. The last thing you want is to find this has been damaged too, especially if you have already made the effort to repair or replace your roof, as you’ll find yourself needing to undo all your hard work just to redo it all over again!

Hopefully you have found these quick tips on how to repair your leaking or sagging roof helpful. If you have since decided you’d rather replace your roof completely, our lightweight and easy-to-install roofing can be purchased via our eShop as well as select ranges available via The Range, Amazon, and Wickes.

Discover the full range at onduline.co.uk.

Discover all of our installation guides here.