A garage is a wonderful addition to any home. A garage not only allows you to store your car overnight, but you can also use it for storage or hobbies. Although most garages are built sturdily, they don’t meet the requirements to be habitable.
A lot of builders tend to use flat roofs on a garage rather than a pitched roof. The reason is simple. Cost. A flat garage roof replacement cost a lot less than a pitched roof. Unfortunately, flat roofs don’t last as long as a pitched roof with a slate or tile covering. The average life expectancy of a flat roof is between 10 – 15 years. The average life expectancy of a pitched roof for a garage is approximately 50 years.
A high percentage of homeowner’s budgets won’t stretch far enough to afford the cost of a pitched roof for a garage. In most cases, a cheaper alternative is more affordable. A bitumen felt garage roof costs roughly £900 -£1000 in total. That price includes labour and materials. It takes approximately one day for two men to complete a garage roof replacement.
There are many benefits to having a flat garage roof. For a start, they are easier to build. They cost a lot less. Their lightweight. They don’t need deep foundations. If you do the math, replacing the felt on a garage roof every 15 years or so is much cheaper than having to build thicker walls and stronger foundations to support a pitched roof covered with tiles. The cost of flat roof replacement will always win on price.
Although the name suggests that a flat garage roof is flat, this isn’t really true. Flat garage roofing has a slight pitch, which allows rainwater to run off and prevent pooling. The biggest problem with felt roofs is they are prone to becoming brittle and cracking. The cause of the cracking and brittleness is the combination of water and sunlight. Once the felt is brittle and cracking, it may begin to leak, causing damage to the timber below. However, it usually takes between 10 and 15 years before problems arise with a felt roof.
There’s no other way to tell if the roof structure is rotten apart from removing the felt. The easiest way to preserve your garage roof structure is to replace the felt as soon as you notice it’s turned brittle. Once the felt on a garage roof is brittle or cracking, you must replace it immediately.
How Much Does a New Garage Roof Cost?
The cost of a new garage roof will depend on the size of your garage. The condition of your roof structure and your choice of roof covering will also affect the cost. A garage roof replacement cost in the UK can vary anywhere between £750 and £3600.
A professional roofer will remove the old felt from a roof and ensure the timber structure is in good condition. If the timber is rotten, it will need replacing before re-felting the roof. If any of the garage roof sheets need replacing, the cost of garage roof sheets is approximately £40 each. Each plywood sheet measures around 2.4 m x 1.2 m. You will have to add that expense to the final cost.
Up to now, we've only spoken about standard roofing felt for garage roofs. Up to a decade ago, all flat roofs were made with bitumen felt and asphalt, but that is no longer the case. These days there are more options available. EPDM and GRP fibreglass have become very popular over recent years. Although EPDM garage roofs and GRP fibreglass garage roofs are superior compared to felt and asphalt roofs, it's worth noting that modern roofing felt has advanced a great deal. Modern roofing felt has a longer life expectancy thanks to modern technology.
New Garage Roof Costs
The table below gives you an idea about the cost of replacing a single or double garage roof. The final cost of replacing a garage roof will depend on your garage's size, your choice of roof covering, and the condition of the roof's structure. If you want to get a garage roof replacement estimate, measure your roof's area and multiply it by the cost per square metre in the table below.
Here are the Most Popular Types of Garage Roofing Materials
Let's make one thing clear before we go any further; there is no such thing as the “best” flat roofing covering. The best flat roof covering is the one that suits your garage and your budget. The detail, shape, and unique size should be considered before deciding what type of flat roof to get. Below you will find the most common types of roof coverings for garage roofs.
Bitumen felt is the cheapest covering for a flat roof, and it has stood the test of time. Although other flat roofing materials are available, felt is still the most cost-effective type of roof covering for flat roofs. You can use felt on almost any sized roof. It is not advisable to use felt on a DIY roof because it requires heat for its application.
It's a shame that the poor reputation of old roofing felt still plagues the reputation of modern felt. Modern felt is much more advanced than it's older counterpart and can last much longer.
GRP is a hard wearing and lightweight covering. The installation of GRP does not need heat, and there are no joints. Other benefits of a GRP flat roof are it has a long lifespan, vandal proof, and looks great. If you consider yourself to be a DIY enthusiast, it is possible to install a GRP flat roof yourself.
Although GRP has many positives, it's worth noting that the covering is not flexible. It is not recommended to try and install a GRP flat roof on a large area. A new GRP garage roof can be slippery after installation.
EPDM is a type of rubber covering that is hard wearing, lightweight and flexible. The installation process does not need heat, and the lifespan of an EPDM rubber roof is 50 years! But an EPDM rubber roof doesn't look as nice as a GRP roof. Also, there is a possibility that this type of roof might shrink with age.
These are the three main types of garage roof coverings. Each material has its own qualities. If the price is the most important factor for you, then felt would be your best choice. If your budget will stretch further, a GRP or EPDM roof would be much more hard wearing and will last a lot longer. The choice is yours!
Types of Garage Roofs
There are several different types of garage roofs. You might not be aware of some of them, so we will describe each type of garage roof below. We will begin with the flat roof because that is the most popular.
A flat roof's support structure can be made of different materials before the roof covering is installed. The majority of flat roofs have a timber support structure. The joists in the flat roof support structure measure approximately 150 mm x 75 mm. Each joist is set 450 mm apart.
A garage with a flat roof must have a slight angle to allow rainwater to run off. For a flat roof installation to be compliant with BS6229 and BS8217, the slope has to be a maximum of 1:80 and a minimum of 1:40. A flat roof installer will create a pitch by nailing wedge shaped pieces of wood (also known as furring pieces) onto each joist. The next step is to nail 25 mm thick plywood on top of the roof joists. The following step is to lay the bitumen felt on to the plywood.
Quite a few garages with flat roofs are made of concrete instead of timber. Concrete lintels or steel RSJ’s are used instead of timber to support a concrete roof. The gaps between the joists are filled with concrete blocks. The following step is to apply a layer of screed on top to make sure all the gaps and joints are sealed. Once the screed is set, it is now ready to have the waterproof covering installed.
Other popular choices of roof covering are corrugated plastic or metal sheets. A timber structure is still required to support a corrugated garage roof. Once the timber structure is in place, the corrugated plastic or metal sheets are fixed on top of the covering. Several decades ago, it was common to see a metal garage roof made of corrugated iron. These days, polycarbonate sheets and corrugated PVC are much more popular.
One last thing about pitched garage roofs, the majority of pitched garage roofs tend to be detached from the main property. Garages with a pitched roof have a roof structure just like a house. The roof tiles or slates are placed on top of the structure, exactly like a house. Most agricultural or commercial properties opt for a pitched metal garage roof. Although metal garage roofs aren’t as visually appealing, they cost a lot less and do the same job.
The majority of large garages do not have a pitched roof. For the garages with a pitched roof, the pitch usually matches the house's pitch. If the garage's width were similar to the house's width, then the garage roof would be of a similar height as the roof of the house. As long as there is a reasonable distance between the house and the garage, it should look okay. If the garage is too close to the house, it might be difficult for visitors to distinguish between the house and the garage. This is just an example of some of the pros and cons of having a flat roof.
· The cost of a flat garage roof is much lower than a pitched garage roof. The cost of materials for a flat roof is much lower, and they are quicker to build.
· It is much easier to carry out basic roof maintenance on a flat roof because they are much easier to walk on.
· The open space on the roof does not have to go to waste. You could turn it into a roof garden or a patio. You're only limited by your imagination. Check out Pinterest for some superb flat roof design ideas!
· Garages with flat roofs absorb the sun's rays all year round. This can be especially useful during the winter months. The warmth from the sun's rays will be transferred inside the building.
· A flat roof will need more maintenance than a pitched roof. Take this into account before deciding on which type of garage roof to choose.
· The average lifespan of a flat garage roof is between 10 – 15 years. The quality of materials plays a huge role in the lifespan of the roof.
· The choice of roof covering materials and styles are limited.
· The buildup of debris and the drainage of rainwater can cause problems for flat roofs. The roof will need to be kept clear of debris to allow rainwater to drain away freely. Failing to keep the roof clear of debris may result in a quicker deterioration.
Planning Permission & Roof Building Regulations
The local building regulations and planning permission vary when it comes to flat roofs.
In most cases, there is no need to follow the building regulations for a simple garage roof repair. However, if the roof is going to be replaced, you might want to upgrade the insulation at the same time to minimise heat loss. Upgrading the insulation might mean altering the height of the roof. Insulation can be quite thick. If the roof's shape or height isn't going to be altered, you should not have to apply for planning permission. Check with your local planning permission office before you proceed. You will want to make sure you're not breaking any rules.
The same advice applies if you are considering having solar panels installed on a flat roof. As long as the panels do not exceed the height of the roof on your home, you shouldn't need planning permission. Click on the link if would like to know more about solar panel costs.
If you wanted to replace a slate roof with a tiled roof, you would have to comply with the local building regulations. The building regulations for changing a roof covering are there to make sure the roof is structurally safe. In addition to following the local building regulations, you would have to comply with the energy efficiency and fire safety requirements. If you would like more information, you can get in touch with the building control office.
If you plan to make changes to your property's height, shape, or appearance, it is best to get in touch with the local planning department.
British Standards Codes of Practice
Flat garage roof installers have to follow specific codes of practice. The specific codes that need to be followed for the construction of a new flat roof are BS6229 and BS8217.
Professional garage roof installers have to make sure that there is a slight angle on the roof to allow rainwater to run away. The gradient is a minimum of 1:40 and a maximum of 1:80.
The installer should also use a vapour control membrane or another breathable membrane to allow water vapour to escape.
Here Are Some Questions to Ask a Roofer Before You Hire Them.
A garage refurbishment doesn’t come cheap. It makes sense to ask a few questions beforehand to make sure you are hiring a qualified tradesman. Here are four questions you should ask before hiring anyone.
1. How many year’s experience do you have? Replacing slates and tiles is one of the basic skills of a roofer. But, have they had any training and have the qualifications to install a new flat roof using new technologies?
2. Ask the roofer if they can provide you with a few references from recent jobs they have completed. Get in touch with the references and ask them about their experience hiring this roofer.
3. Make sure you ask each roofer for an accurate quote. You don’t want a “roundabout figure” over the phone. You want to get at least 3 accurate quotes from three different roofing companies.
4. Always keep in mind that the cheapest quote isn’t necessarily the best. If the quote is much lower than the others, it might be a sign of a lack of experience, or he missed a vital part of the job. Be aware of sneaky, underhanded sales tactics. One of the most common sales tactics is to give you a low estimate at first, then add more items to the bill at the end.
Sometimes there are genuine reasons for extra expenditures that are unforeseeable until the job has started. For example, removing the felt off a flat roof only to find water damaged plywood and rotten joists. A professional tradesman would have a good idea of what to expect and bring it to your attention right from the start.
Garage Roof FAQ
How Often does a Garage Roof Need to be Replaced?
The answer to this question depends on several different factors. These factors are the type of roofing materials used, how exposed the roof was to the elements, and if it was well maintained. The lifespan of a garage roof can be anywhere between 10 – 50 years. There are tell-tale signs that a garage roof might need replacing. Look for damp patches inside the garage or cracked, brittle felt covering.
How Can I tell if my Garage Roof Contains Asbestos?
If your roof is made of corrugated sheets that are grey in colour, there is a good chance your garage roof contains asbestos. The use of asbestos in construction materials was banned in the late 1980s. If your property was built before asbestos was banned, it is highly likely that your roof may contain asbestos.
Can I Remove my Asbestos Garage Roof Myself?
Although you can remove your asbestos garage roof, it is not advisable. Asbestos is a hazardous substance. It can cause respiratory diseases such as asbestosis, mesothelioma, and lung cancer. Only trained professionals should handle and dispose of asbestos. There are stringent rules to be followed for the removal and disposal of asbestos. It would not make sense for you to jeopardise your health by doing it yourself. Follow the link to learn more about the cost of removing asbestos from a garage roof.
How Much Will it Cost to Replace my Garage Roof?
The cost of replacing a garage roof will depend on the type of garage you have, its size, and the type of roof you would like to replace it with. The only way to get an accurate price to replace a garage roof would be to get a quote from a professional roofing company.
How Long will it take to Replace my Garage Roof?
The average time it takes to replace a garage roof is one day. If there is structural work involved, such as replacing rotten timbers or replacing plyboard, it may take longer.
What Type of Roof will Last the Longest?
The type of roof that will last the longest on a garage is a pitched roof. A pitched garage roof has a sturdy timber structure, and the roof covering is usually tiles or slate. A pitched roof on a garage will last much longer than any other type of roof.
Should I Insulate my Garage Roof?
Insulating your garage is entirely your choice. It’s worth keeping in mind that garages weren’t built to retain heat. Most garages have a door with gaps all around and under the door. If you wanted to insulate your garage, you would have to make sure it is airtight to keep the warmth inside.
What is the Best Material for a Garage Roof?
There are pros and cons for each type of roof covering. It would be best for you to seek advice from a professional roofer. If you want to know what is the longest lasting material to use on a flat roof, the answer would be EPDM rubber.
How Much Does it Cost to Replace an Asbestos Garage Roof?
The average cost to remove and dispose of asbestos from a garage roof is about £400 for a single garage and £800 for a double garage. Remember, these prices are approximate. The size of your garage and your location will determine the final cost. You mustn’t attempt to do this yourself. Only an HSE registered company is authorised to remove and dispose of asbestos. If you try to do it yourself, you will be seriously jeopardising your health. If you suspect your garage roof contains asbestos, visit asbestosadviser.co.uk for more information.
Find a trusted, local roofer near where you live
Garages are not only used for storing cars; they are often used as hobby rooms or somewhere to store valuable items. For this reason, you will want to make sure that you are hiring a skilled roofer who can replace the roof and make sure it weathertight.
If you would like to get a free no obligation quote for a garage roof replacement click here