The Cost of Replacing Felt Under Tiles

Tips & Advice
The Cost of Replacing Felt Under Tiles

Replacing the felt under your roof tiles is a process that needs to be carried out infrequently. Often, your sarking felt can last as long as your roof, up to 80 years or over, even if it shows signs of wear around the eaves. Other times, however, if your felt is of a lower quality* you may find that the damaged areas require more frequent replacement – around every 25 years or so. Only a qualified roofer, with a first-hand look, will be able to tell you for sure.

*This was more common for homes built in and around the 1950s due to a materials shortage at the time.

All of this can cost you, on average, between £3000 – £10,000. But why? Well, there are several factors that you’ll need to consider when it comes to calculating the overall price of roofing felt refurbishment of any kind, which we will explore below. Replacing your roofing felt is not a cheap process overall, but after reading this guide, you’ll hopefully understand why it’s so important, and why it is well worth the cost.


What Is Roofing Felt?

Roofing felt is a material designed to provide a waterproof barrier beneath your main roofing material (it is usually used with tiles). It’s the final defensive layer before the more vulnerable sections of your roof are exposed to the elements, so it is important to keep it in top condition.

When performing correctly, roofing felt will protect from rain, snow, ice, and the effects of extreme changes in temperature – all of which, without this defence, can lead to condensation, mould, mildew and leaks that could ruin your roof. Being both flexible and versatile, it can be used on various roofs of different shapes and sizes without issue and as such has been a staple of roof construction for decades.

Why Do I Need to Replace the Felt Under Tiles?

There are multiple reasons you may need to replace the felt under your tiles, but one, in particular, will depend on the type of gelt you have. Roofing felt originated in the 1930s and for the first couple of decades that saw its widespread use, it had issues with ‘breathability’ – in other words, it suffered from condensation issues.

Since then, newer felt materials have been produced emphasising breathability and thus the issue of condensation has been reduced massively across the country. However, some of this newer felt continues to lack long-term durability and is still prone to weakening as time goes by, becoming brittle to the point of disrepair. In these cases, unfortunately, repairing a small hole within a sheet is going to do little to delay the process of deterioration. 

roofer replacing felt under tiles

Eventually, you will start to spot water stains on and around your ceilings and upper walls. These patches of damp may allow mould to grow, or seriously (even dangerously) weaken the structural integrity of your roof and ceiling. Replacing your felt should be a priority the moment you notice these marks in your home and you cannot locate an alternative explanation for their presence.

How Do I Know My Felt Needs Replacing?

When your roofing felt needs replacing, there will be various signs. The most obvious is damp ceilings and walls, but this isn’t all. Particularly serious cases will lead to water destabilising or cracking your ceiling, which will result in leaks. You may also spot cracked tiles or exposed felt on your roof; signs that the situation at least requires an inspection either by you or, better yet, a roofer. 

damp and cracked walls

Keep in mind that it’s better if you act on replacing your felt before you let things escalate to the point of damp and leaks. Alternatively, if you have only just moved into the building (or are looking to buy), you may at some point want to hire a professional to inspect your roof's condition. Not only will this give you a clear idea of the felt’s condition but also any other warning signs that you’ll want to be aware of such as issues with your guttering, damaged flashing or missing tiles.

What Factors Affect the Cost of Replacing Roof Felt Under Tiles?

The job of replacing your roof felt can come with a fair few additional costs in addition to the felt and labour. Depending on the size and scope of the problem, you may also need to consider some of the below factors.

  • Roofing Felt
    • Can come in a variety of sizes and styles with different features
    • Be sure to shop around to find the product that is ideal for you
  • Scaffolding for Hire
    • Extremely important when it comes to any roofing work
    • Good quality scaffolding will be secure, reliable, and easily scalable
    • Can also be purchased rather than hired, but this will be considerably more expensive
  • Roof Tiles
    • The cost of tiles will depend on how many you need for your roof
    • Keep in mind that you should try to find like-for-like replacements
  • Ridge Tiles
    • It would be preferable to purchase these tiles under the same make and model as your other tiles
    • Remember to purchase a few spares in case your tiles crack or break during installation
  • Fixings
    • Required to secure your tiles as well as (potentially) your felt.
    • The number of fixings will depend on the number of tiles – it is usually two fixings per tile but can be either more or less
    • Please note that fixings are applied to ‘dry-fixed’ tiles, which are the most common tiles on the market today
  • Battens
    • Extremely important for roof stability
    • Placement is extremely important, as is the number of battens
    • Consult a professional if you are unsure of how to measure and place battens
  • Flashings
    • Protects any surrounding roof windows or features with flashings
    • Old flashings can potentially be removed and then added back to your roof, though this is not usually recommended
    • Can be made from a variety of materials, though the most common is lead

How Much Does Roofing Felt Replacement Cost?

There are many different expenses you may need to consider when replacing your roof felt, even without asking a professional tradesperson for help. However, when taking into account the difficulty of the task at hand and the steps required to do it right, we are going to factor labour into the cost.

With that said, let’s look at the different elements that go into the cost of replacing your roofing felt, and the rough estimates of the average cost of replacing roofing felt under tiles:


Approx. Cost (£)

Scaffolding for hire


Roof Tiles

800 – 1000

Ridge Tiles










Sarking Felt

100 – 150

As you can see, replacing roofing felt is no small feat, and even a relatively cheap job may set you back as much as £3,000. Prices of more than £7,300 and upwards of £10,000 are also not unheard of.

It’s understandable why many feel it would be better to cut out the middleman and avoid hiring traders to help them build their roof – after all, labour is a huge factor behind the cost of even a small project. However, we would never recommend it. Felt replacement and indeed many roofing jobs that involve the removal and replacement of tiles and other vital components on your roof are jobs best carried out by someone with considerable experience.

Remember to do your research when looking for builders, roofers, or other tradespeople, taking care to read reviews and customer comments to be sure that you’re working with a reputable group that will deliver the experience you deserve.

If you have any further questions about roof felt, tiles, or roofing projects in general, do not hesitate to get in touch with our award-winning team at 01295 565 565 or by using our handy live chat below. 

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