Cost of Repairing or Replacing a Roof Valley

Last updated 16th March 2021

All you need to know about having a roof valley repaired or replaced including costs of materials, costs of labour and time frames.

replace/repair roof valley

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How Much Does Replacing a Roof Valley Cost?

Roof valley repointing, or as it's more commonly known replacing, replaces cement only and re-use existing valley flashing, then you are looking at around £300 to £375, for a full replacement add on approximately £100-150.

This assumes typical replacement with cheap and easy to access roof tiles and easy access to both the house and the roof valley itself.

Most roofers work in pairs, and the average cost is around £250 per day between them. In terms of times frames, you're looking at around 4-6 hours to repair a roof valley or around 6-8 hours to fully replace.

Of course, these prices can differ depending on a variety of factors. If you live in a big city, like London or Manchester, you're likely to pay an increased price due to the cost of living. If you have had a conversion, extension, or simply just have a large home, the area of the roof will determine the overall cost associated with the job.

If the contractors working on your roof valley discover other aspects of your roof that requires repair in order for the valley repair work to be completed, this will be added to the initial quote.

Another cost defining factor depends on the type of roof valley you have installed on your home, which we will discuss later on in the article.

A big issue that some contractors come across that can further increase the price of the job is the ease of access to the roof. If there are several overhanging trees, or any other obstacle preventing easy access to the roof, then scaffolding may be required in order to complete the job. The cost of this scaffolding is added to the overall quote.

Replacing a Roof Valley Prices

Valley Type Type of Repair Duration Avg. Cost
Lead Lined Valley Small Repair – Replace shingles, seal leak etc. 2-3 Hours £75-£200
Lead Lined Valley Full Replacement 2 Days £500-£600
Preformed Valley Small Repair – Replace shingles, seal leak etc. 2-3 Hours £80-£150
Preformed Valley Full Replacement 2 Days £450-£550
GRP Valley Small Repair – Replace shingles, seal leak etc. 1-2 Hours £50-£100
GRP Valley Full Replacement 1 Day £350-£450
Preformed Mortar-Free Valley Small Repair – Replace shingles, seal leak etc. 2-3 Hours £75-£150
Preformed Mortar-Free Valley Full Replacement 1-2 Days £450-£550


Supply Costs

When you enlist a contractor to complete work for you on your home, you're paying for more than just the materials. However, if you were to purchase the materials yourself, you may be able to secure a better quote from a contractor by doing some of the work yourself.

Of course, the price of the materials depends on how long your roof is, or how many valleys you need. Valleys aren't supplied in long lengths; instead, they are bought in chunks of 3m, allowing you to purchase as much as you need for your home.

For a GRP roof valley, the average cost is around £10-£20 per 3m, depending on the material, shape and colour you require. They come in a variety of styles, so you should be able to pick one up that matches your roofing. Lead lined valleys are a little more costly and are tougher to purchase through a retailer.

For these valleys, you'd be better suited speaking to a lead roofing expert for advice and quotes.

Additional Costs

Whenever you have any surveying or repair work on your home, there is always the chance that further issues or defects are discovered in the process. For example, if you're having a roof valley repaired, the contractor may discover that there are some roof tiles that need replacing or repairing.

Often, there is no way to tell whether there are any necessary repairs on your roof until somebody has had the chance to get up there to look.

In some cases, the work on your roof valley can't be completed without repairing or replacing defects that have been found. In this case, you would have to repair them at the same time, incurring further costs on the overall job.

However, sometimes you can allow the roof valley work to be completed and then look toward the other repairs with more time. It all depends on the severity of the issues and whether the initial work can be completed.

We've written articles that cover the most common issues that are found on roofs, and you can find them here. Recementing ridge tiles, roof clean and treatments and full roof replacements.

Cost Breakdown Calculator

Individual costs for hiring a roofer to replace a single roof valley - Total Cost: £450

30%

Materials
£135

50%

Tradesmen
£225

20%

Scaffolding
£90

What is a Roof Valley?

The roof valley is that part of the roof where two sloping roofs meet together, where rainwater has to be channelled downwards into a gutter. These roof valleys have to deal with a lot of water during heavy rainfall and are prone to leaking.

Roof valleys are usually made from lead, concrete tiles or fibreglass. The method of repair will obviously depend on the materials used in the construction but could involve a minor repair or complete replacement.

Roof valley

The valleys ensure that no water is left standing on any part of your roof, increasing the probability of a leak. It provides a quick, clean and easy route for the water to exit the roof, which is incredibly important in the winter months where frozen ice on your roof can lift and move tiles, leading to far bigger issues down the road.

You only need a roof valley when you have two roofs on your house facing opposite directions.

Cost Affecting Factors of Replacing a Roof Valley

Nearly all of the jobs required on a home or building are affected by a number of factors and variables that change from job to job. Of course, the first defining factor is the location of your home, with big cities like London and locations in the south naturally incurring higher charges for all trade jobs.

Another big factor in the pricing of any job is the size or amount of work that is required. A semi-detached that requires only one valley will be considerably cheaper than a detached that needs 3 valleys, not just in the cost of materials, but in the manpower and time consumption.

Roof valley replace3ment

The type of work required can alter the price also, with certain valley and roof types producing more of a challenge to work with than others, especially if there are multiple components that require replacing or repairing. Another typical requirement is to repair the roof valley gutter, which directs the water to the drain once it's off of your roof.

For a tradesman or contractor to complete the work efficiently, safely and professionally, they will need certain tools and equipment. This ranges from scaffold hire, to waste removal and everything in between. You should always find out whether waste removal is required in the quote or not because if it isn’t, you'll need to investigate some skip hire options.

What Does Replacing a Roof Valley Entail?

Once it has been established that the roof valley is damaged, then the first step is to remove the tiles/shingles along the valley which will allow you to remove the valley flashing. Take care to only lift up as many tiles as you need to get the new flashing into the roof or roof gully.

Then carefully fit the new flashing over the connection between the roofs and fix in place using mechanical fixings or concrete depending on the type of valley. If using cement or a waterproof adhesive, then leave the flashing to dry completely before you start replacing/refitting the roof tiles, throwing away any damaged tiles and fitting new ones.

When any work is being carried out on a roof, a full inspection should be carried out on the roof tiles, flashing, chimneys, fascia/soffit and guttering. Labour is often the most expensive part of a quote for any roof related repairs, so it makes sense to get any roof repairs done at the same.

In addition, tiles will quite possible be disturbed/broken during a repair to the roof valley, so spare tiles should be on hand prior to starting the job.

In the majority of cases, a complete roof valley construction is required, and cement is the best option. However, sometimes the roof valley itself is in good condition, but the cement is in poor condition and crumbling, or the roof gully is at fault, so it can in some circumstances be possible to just re-bed the tiles onto new cement, leaving the existing valley in place.

Roof valley replacement

But if the base for the roof valley is concrete tiles, then they will almost certainly need to be replaced as it is almost impossible to repair concrete tiles and they are prone to leaking.

A full replacement of the valley or valley tiles will involve removing all the tiles, all the cement and also the under-felt (which is usually rotten anyway). If you have a bad water leak coming from a faulty roof valley, where water is staining the ceiling of the floor below, you need to replace your roof valley before serious damage is caused to the building structure.

Lead valleys can be repaired, which is handy as they are particularly difficult to dispose of being toxic.

With any job where roof tiles are removed, you will find that some are damaged, or you will actually break them in the process or removing/refitting - so always have spare tiles to hand. Though most tiles are not expensive, so this is not a major problem in terms of cost.

If the existing valley roof flashing is lead and this needs to be removed, then do not simply throw this away! Lead is toxic and needs to be disposed of correctly, but you may find your local scrap merchant will actually pay you for any lead flashing you have that is surplus to requirements!

DIY Replacing Valley

Working on roofs is not recommended unless you have the necessary qualifications, experience and equipment. Working on old roofs is not only dangerous to those doing the work, but extensive damage to the roof itself is also a real possibility which would make the DIY job far more expensive than hiring a competent roofing contractor in the first place!

DIY Roof valley replacement

Roofing is hard work, and the weather in the UK makes it not only dangerous but also pretty uncomfortable!

You also need to fit enough to work at height, often carrying heavy tools and materials. Roofing is definitely not for everyone, but if you are fit and comfortable working at heights, possess all the necessary tools and safety equipment required, it is possible to work on your own roof if you are determined!

Choosing a Roof Valley

Lead Lined Valley Cost

Lead lined valleys are quite literally valleys with a lead lining in them to expel water from the roof, to stop any standing water from damaging the roof and cause a leak. The biggest issue with lead lining is that it is technically a ferrous metal, which, when exposed to heavy sunlight, can eventually crack, leading to a breach in the valley.

The positives are that lead can be repaired and treated if it does have a crack, but this is only a temporary fix. Eventually, the lead lining will need to be completely replaced. It is unlikely that this damage will occur for many years after installing a new lead lined valley, so bear that in mind when selecting materials.

Preformed GRP Valley Cost

GRP stands for Glass-Reinforced Plastic and is seen as an excellent alternative to lead-lined valleys. GRP products take far less time to install than other options are generally much cheaper to buy and are extremely lightweight, putting less strain on your structures.

Preformed roof valley

The preforming increases the install time, with them being easy to handle and ready to attach the roof, they also don't streak or stain. These valleys shouldn't need replacing for many years, so they're certainly a good choice for most homes.

Preformed Mortarless Valley Cost

These roof valleys direct water to the guttering on your home without it discharging over the sides due to long upstands either side of the valet. They also have a variation available in which there is a central upstand for homes with two roof slopes that have uneven pitches.

They are very similar to GRP valleys, but with slight alterations. They benefit from the same advantages that GRP valleys do; however, they are slightly more expensive and take longer to accurately install.

Do I Need My Roof Valley Replacing?

There are tell-tale signs that your roof valley is close to needing a repair or replacement, usually centring around leaks, or the abnormal expelling of rainwater. The only way to confirm what aspect of your roofing requires repairing is for a trained professional to survey it themselves, most probably by getting atop the roof for closer inspections.

If you have any leaks inside your home, there will undoubtedly be something on that requires repairing, either the slates or the valley. If water is expelling from the roof in the wrong areas or in an unusual fashion, the valley is more likely to be at fault. Either way, surveys from roofing companies are often cheap or free when you use the company for repairs.

Costs of Roof Valley Repair

We mentioned earlier that when the survey or work has begun on your roof valley repair or replacement, other issues that may hamper the contractor's ability to complete the job can appear. Flashing and valleys can hide other problems with tiles or shingles, like crack, lifted or broken tiles and shrunken and damaged shingles.

In this case, it would be pointless to repair or replace the valley without also repairing the shingle or tile issues. Take a look at our article on repairing broken roof tiles to find out more about the costs associated with the job.

If you or the contractor discover that the valley is blocked with debris and other foreign objects, this will need to be cleared before any survey or work can be completed on it.

Roof valley repairs

If you have trees that overhang your roof, moss could even be an issue. This cleaning and debris removal aren’t too expensive, and it's integral to keep your roof in good shape. Again, check out this article on removing roof moss to discover more about the process and pricing of roof cleaning.

In short, these repairs, cleanings and replacements can range from £50 to £500 depending on the severity of the problem and how quickly it must be rectified. It all depends on your unique circumstances.

Cost of Removing a Roof Valley

To remove a roof valley, it would cost around £300 depending on the size and type of roof you have. People will remove a roof valley to repair the cement underneath, to repair a roof valley leak or simply to prepare for a full roof valley construction.

A roof valley may also be removed will new fibreglass valley gutters are installed, which are becoming more common in recent years, although you don't always have to remove the valley for this job.

People often question whether this can be done as a DIY job, as is becoming increasingly more common in the modern world. The problem with this is twofold, firstly, working at height is a lot more challenging than people realise, especially on certain types of roof, and it can get very windy up there even if it isn't down below.

Secondly, you can damage a roof very easily simply walking on it, and you can damage it even easier by removing roof valleys if you don't have any experience in this type of work.

We always encourage anyone to enlist the help of trained and licensed professionals for specialist work on roofs and homes. Of course, there are many tasks that can be done as a DIY project, but some are simply too advanced to be attempted.

FAQs

Flashing is added to the roof valley to ensure that the runoff water doesn't penetrate the actual roof valley, protecting it from the elements. It is another form of defence for your roof to prevent leaks and the need for further repairs.
Roof shingles are individually overlapping sheets typically made from wood, metal or composite materials like asphalt or fibre cement. The shingles provide a route for water to run off the roof, minimising the chances of a roof valley leak.
Assuming a typical size roof valley of up to 3 metres in length, standard roof tiles and no access problems, then it will usually take around half a day to replace the cement and simply re-bed the existing valley into place, but if you need the complete valley replaced then it will take a full day to complete the job.
Firstly, you will need to seek clarification from your local housing association or body, to understand what you can and can't do without planning permission. Secondly, working at height is challenging and dangerous, especially without professional equipment. On the ground, the wind is blocked by structures, trees, cars and many other things, but atop a roof, there is no cover or protection from the wind, making a slight breeze very unsteadying.

Trained professionals with have harnesses and safety equipment to protect themselves from any missteps or mistakes, something which you probably won't have. While it may be legal to work on your own roof, we would heavily suggest against it for your own safety; it just isn't worth the risk.
You can find many reputable scaffolding firms online and in the local listings, however, unless you're familiar with what type of scaffolding you need, it may be better to leave the scaffold hire to the contractor that will be working on your roof, as they will order precisely what they need to complete the job.

How to Find & Hire a Roof Valley Replacer

The roof over your head is one of the most important structures of your home, protecting you and your belongings from the elements. When you are considering any roofing work being carried out, using an NFRC (National Federation of Roofing Contractors) member contractor to carry out the work is a good start and will give you some peace of mind.

The National Federation of Roofing Contractors is the largest roofing trade association in the UK, and all members are rigorously vetted to ensure a satisfactory trading record, high-quality skills and technical competence, satisfactory insurance cover, full compliance and knowledge of current health and safety legislation, and full compliance with the Government-endorsed TrustMark scheme to help the public find reputable tradesmen to carry out work on their home.

But always gather at least three quotes and pay careful attention to the recommendations given - do not simply go for the best price, when it comes to roofing the quality of work is just as important.

Sources

https://en.wikipedia.org/wiki/Roof_shingle
https://www.roofinglines.co.uk/blog/what-are-roof-shingles
https://www.hambleside-danelaw.co.uk/pitched-roofing/products/grp-valley-trough/
https://www.renownroofingmanchester.co.uk/roof-terminology/the-roof-valley/
https://www.buildingsheriff.com/valley-repair-costs.php
https://www.thunderstruckrestorations.com/understanding-different-types-of-roofing-valleys/

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