How much are garage roof replacement costs?

With the average flat felt garage roof only offering a life expectancy of 10 - 15 years, you might find yourself wondering how much are garage roof replacement costs?

A short life span combined with extreme weather conditions can lead to early wear and tear on many garage roofs, meaning fixing or replacing it can end up being a job you have to take on - especially if you've purchased an older property. But what are garage roof replacement costs and what are your options? 

Here we look at types of roof that you might have on your garage as well as the costs involved for replacing each type.

How much are garage roof replacement costs?

Andy Simms, a building expert from MyBuilder.com, tells us that “ultimately the cost of replacing your garage roof comes down to three things. Does the roof covering need replacing, does the roof structure need replacing, and what materials are you going to use?"

Timing is everything when it comes to the cost of replacing a garage roof. If you spot early signs of cracking on felt, then this is when you should start investigating the issue. Leave it and you risk the water seeping into the supporting timbers below leaving you faced with a much longer and costlier repair.

There are a number of variables you will need to consider when replacing your garage roof. As well as choosing the right material to cover the roof, you need to consider the following:

• Location of your property and number of contractors available in the area
• How easy is the access to the garage roof?
• What is the size and detail of the roof?
• Is the roof flat or pitched?
• How much scaffolding will you need and how long for?
• How many skips will you need to remove the old roof?
• Will you require extra insulation?
• Labour costs
• Guttering and decking boards may be needed depending on the garage use

As costs tend to vary across the UK, each item will need checking with a local supplier using a network such as Mybuilder or Checkatrade. 

However, for essentials such as skips, you can expect to pay upwards of £120 for a midi-skip (4-5 yards) and around £22.50 per metre square for scaffolding. Labour costs will normally be quoted as part of the job if using a reputable builder or supplier.

1. Felt garage roof replacement costs

With garages often built purely for practical reasons, as somewhere to house cars, bikes, tools or as an overflow storage space, it's common for builders to construct them using a flat roof design covered with bitumen felt.

In broad terms, "to renew the felt on a single garage will likely set you back around £400 - £600 including materials," says Andy.  The good news is, you won't be paying for an excessive amount of labour if you choose to replace felt with the same material. A simple felt replacement could be completed in one day with two tradesmen on site.

As well as being fast, cheap and relatively simple to install, it's a lightweight method that can also reduce time and money spent on groundworks. According to the Roofing Association (RA), replacing the felt every 15 years still works out a more cost-effective solution to building thicker walls and deeper foundations.

Although it's commonly assumed issues arise because the roof is flat, it's not always the case. Every flat roof is still required to have a slight pitch to ensure rainwater drains off and the roof complies with BS 6229 and BS 8217. 

Subsequently any problems that do arise tend to be caused not just by rain pooling on the surface, but rather by the combination of water and sunlight causing the felt to become brittle and crack. 

This in turn can lead to leaks which may work their way into the supporting roof timbers causing additional and costly damage.

2. Replacing roof timbers cost

But, if you've not been able to establish if the timbers are damaged and the roofer peels back the felt to find they are, the sum will increase substantially. 

“Replacing the structure of the flat roof on a single garage is likely to cost between £2,000-£4,000," advises Andy. A cost that could rise to around £4,000-£6,000 for a pitched roof.

If you know or discover that the timbers have been damaged by water, the RA also advises you check the roof sheets (normally sheets of plywood). If these need replacing, you can expect to pay an additional £40 per 2.4m x 1.2m sheet.

3. Fibreglass and rubber garage roof replacement costs

Although felt has been the mainstay of flat roofs for many years, there are also a variety of other materials you can consider for your garage roof. The main decision you will need to make is whether the increased life span of an alternative covering outweighs the extra initial outlay.

"There’s a lot of choice when it comes to flat roof coverings," says Andy. "Another roof material that has seen growing popularity in recent years is glass reinforced plastic (GRP), also referred to as fibreglass. This can be two to three times more expensive, but usually comes with a guarantee of 20-25 years." 

If you're using GRP fibreglass to replace your roof, you can expect to pay upwards of around £70 - £100 per square metre for your garage roof replacement costs. This won't include extras such as insulation or replacement of timbers.

Another choice is Ethylene Propylene Diene Monomer (EPDM), a durable synthetic rubber that is hardwearing and offers an even longer life-span of 50 years. 

However, at around £45 per square metre it's more expensive to install than felt and some critics say it can be prone to shrinkage or damage from trees branches.

But, as GRP and EPDM suppliers also offer repair kits  you could potentially avoid a full replacement if damage occurs.

There's of course also an environmental upside to choosing an alternative material to felt. As well as lasting longer and potentially looking more aesthetically pleasing, the longer lifespan means they don't need to be replaced as often resulting in less waste disposal of bulk materials.

4. Pitched garage roof replacement costs

Although flat roof materials can be considered for pitched garage roofs, there are also additional options.

Iron metal corrugated sheets were once a common sight on pitched garage roofs, offering a hardwearing, long-lasting option that also dealt admirably with rain and extreme weather conditions. 

Now usually reserved to agriculatural or commercial buildings, the domestic range has expanded to include a variety of other metals, plastic, bitumen and fibre cement. Some are even designed to mimic tiles.

Costs for using corrugated sheets range range from £15-£40 for metal, £20-£25 for fibre cement or £30-£35 for tile-effect sheets. However, if tiles are your preference, be prepared to pay more.

"Replacing standard roof tiles could set you back around £1,500-£2,500," says Andy. Asphalt shingles are an economical alternative, saving a few hundred pounds."

Tile prices alone can range from £10-£35 for concrete tiles up to £40-£60 for slate.

FAQs

Can I replace my garage roof myself?

As replacing a garage roof may involve specialist tools, structural work and involves working at height, it's recommended that you always use a qualified tradesperson to carry out the work.

If the need to replace your garage roof has made you consider whether it's got the potential to be an extra room, check out our garage conversion ideas.

Andy Simms

With almost a decade of experience on the front line in construction as a multi-trader, Andy is uniquely placed in the construction industry to help bridge the gap between tradespeople and product managers with his role at MyBuilder.com.