How Much Does a Fibreglass Roof Cost?
Fibreglass roofing has become a popular choice for owners of residential and commercial properties. It's a low-maintenance, durable option that's affordable and long-lasting.
The average cost of a fibreglass flat roof is £3,000.
A fibreglass roof is also known as a glass-reinforced plastic roof (GRP). It is made from layers of glass fibres and resin, which make it very strong but lightweight. You can buy two types of fibreglass roofing:
The cheapest type is standard fibreglass roofing, which costs on average between £30 and £40 per m2. But you can also buy insulated fibreglass roofing. This is more expensive, but it does mean that the space below your roof will be more energy-efficient.
Keeping heat inside. If your flat roof is part of a house extension, then you'll want to make energy savings and keep your new room warm during the winter months. The cost of an insulated fibreglass roof is, on average, between £80 and £145 per m2.
If you're wondering how many square metres your roof might be, take a look at these average sizes:
- Shed: 5m2
- Single Garage: 18m2
- Double Garage: 36m2
- Home extension to create a new room: Between 20m2 and 40m2
- How Much Does a Fibreglass Roof Cost?
- What are the Supply Costs for a Fibreglass Roof?
- Additional Costs
- Tradesperson Costs for Installing a Fibreglass Roof
- How Long Does It Take to Install a Fibreglass Roof?
- Types of Fibreglass Roof Finishes
- Planning Permission and Building Regulations
- Benefits of Fibreglass Roofing
- How Much Does It Cost to Remove a Fibreglass Roof?
- FAQs
Fibreglass Roof Prices
These charts include the average costs for standard GRP (£30 to £40 per m2) and insulated GRP materials (£80 to £145 per m2) plus labour costs at between £50 and £60 per m2. On most roofing projects, the work is almost always carried out by two contractors.
If the job is complex, for example, you have skylights or multiple angles to cover, then it might take longer to install, and this should be reflected in any quotes you receive.
Fibreglass Flat Roof Cost – Standard Fibreglass
| Flat Roof | Size | Cost Of Fibreglass Roofing | Timescales | Labour Costs Calculated Per m2 | Total Costs |
|---|---|---|---|---|---|
| Standard Fibreglass | 5m2 | £150 - £200 | Half a Day | £200 - £240 | £350 - £440 |
| Standard Fibreglass | 8m2 | £240 - £320 | Half a Day | £200 - £240 | £440 - £560 |
| Standard Fibreglass | 18m2 | £540 - £720 | 1 Day | £900 - £1,080 | £1,440 - £1,800 |
| Standard Fibreglass | 33m2 | £990 - £1,320 | 2 Days | £1,650 - £1,980 | £2,640 - £3,300 |
| Standard Fibreglass | 20m2 | £600 - £800 | 1 Day | £1,000 - £1,200 | £1,600 - £2,000 |
| Standard Fibreglass | 25m2 | £750 - £1,000 | 1.5 Days | £1,250 - £1,500 | £2,000 - £2,500 |
| Standard Fibreglass | 30m2 | £900 - £1,200 | 2 Days | £1,500 - £1,800 | £2,400 - £3,000 |
| Standard Fibreglass | 35m2 | £1,050 - £1,400 | 3 Days | £1,750 - £2,100 | £2,800 - £3,500 |
| Standard Fibreglass | 40m2 | £1,200 - £1,600 | 4 Days | £2,000 - £2,400 | £3,200 - £4,000 |
Fibreglass Flat Roof Cost – Insulated Fibreglass
| Flat Roof | Size | Cost Of Fibreglass Roofing | Timescales | Labour Costs Calculated Per m2 | Total Costs |
|---|---|---|---|---|---|
| Insulated Fibreglass | 5m2 | £400 - £725 | Half a Day | £200 - £240 | £600 - £965 |
| Insulated Fibreglass | 8m2 | £640 - £1,160 | Half a Day | £200 - £240 | £840 - £1,400 |
| Insulated Fibreglass | 18m2 | £1,440 - £2,610 | 1 Day | £900 - £1,080 | £2,340 - £3,690 |
| Insulated Fibreglass | 33m2 | £2,640 - £4,785 | 2 Days | £1,650 - £1,980 | £4,290 - £6,765 |
| Insulated Fibreglass | 20m2 | £1,600 - £2,900 | 1 Day | £1,000 - £1,200 | £2,600 - £4,100 |
| Insulated Fibreglass | 25m2 | £2,000-£3,625 | 1.5 Days | £1,250 - £1,500 | £3,250 - £5,125 |
| Insulated Fibreglass | 30m2 | £2,400 - £4,350 | 2 Days | £1,500 - £1,800 | £3,900 - £6,150 |
| Insulated Fibreglass | 35m2 | £2,800 - £5,075 | 3 Days | £1,750 - £2,100 | £4,550 - £7,175 |
| Insulated Fibreglass | 40m2 | £3,200 - £5,800 | 4 Days | £2,000 - £2,400 | £5,200 - £8,200 |
What are the Supply Costs for a Fibreglass Roof?
The materials you will need to install a fibreglass roof, and the costs involved are:
- OSB Boards (if insulating the roof) £10 - £20 per m2
- Fibreglass Matting - £1.50 - £2.50 per m2
- Polyester Resin - £4.50 - £8.50 per kilo (the average amount is around 1.5 kilos per m2)
- Hardener (catalyst) - £15 - £23 (Between 1 and 3 litre bottles cover between 9m2 and 40m2)
- Topcoat - £5 - £10 per kilo (Topcoat averages around 0.5 kilos per m2)
- Acetone - £5 - £10 per tin (1 litre should cover 10m2)
- Edge Trim - £8 - £16 (typically 1 edge trim will cover 3m2)
- Primer for preparation - £25 - £32 per kilo (0.25 to 0.50 kilos per m2)
- Optional roof colouring - £5 - £20 per tin
Fibreglass Roof Prices - Materials Standard and Insulated GRP
| Project | Materials Per m2 | Total Average Price |
|---|---|---|
| Shed 5m2 | £30 - £145 | £150 - £725 |
| Dormer 8m2 | £30 - £145 | £240 - £1,160 |
| Garage 18m2 | £30 - £145 | £540 - £2,610 |
| Double Garage 33m2 | £30 - £145 | £990 - £4,785 |
| Home Extension 20m2 | £30 - £145 | £600 - £2,900 |
| Home Extension 25m2 | £30 - £145 | £750 - £3,625 |
| Home Extension 30m2 | £30 - £145 | £900 - £4,350 |
| Home Extension 35m2 | £30 - £145 | £1,050 - £5,075 |
| Home Extension 40m2 | £30 - £145 | £1,200 - £5,800 |
Additional Costs
Installing a fibreglass roof will also have additional costs, which you will need to add to your budget. Some of these costs may include:
Removal of Old Roofing Materials
If you are replacing your roof, then you will need to remove the old roof before a new fibreglass roof can be installed. Many contractors will include the removal in the project cost, but if, for some reason, it isn't included, then you should expect to pay around £80 to £100 per m2.
Disposal
Getting rid of the old roofing material might mean you will need to hire a skip. Depending on the skip size, the cost will be between £60 and £375 for skips between 2 and 8 yards. A 2-yard skip will take approximately 20 to 30 bin bags. An 8-yard skip will hold between 75 and 85 bin bags.
Roof Deck Replacement
Flat roof decks are often made from Oriented Strand Board (OSB), and these cost on average between £10 and £20 per m2. That means if you were covering a single garage of 18m2, you would spend between £180 and £360.
Insulation
Roofing without insulation is a cold roofing system, and with insulation, it is known as a warm roofing system.
Costs are higher for insulated fibreglass roofing. For example, standard fibreglass for an 18m2 garage will cost on average £540 and £720 for materials. Insulated fibreglass, on the other hand, will cost you between £1,440 and £2,610, which is a difference of between £900 and £1,890.
Edge Detailing and Trims
Edge detailing and trims not only look attractive, but they also serve to protect the roof from water penetration and other damage caused by the weather. Detailing and trims also reinforce the edges of the roof and reduce the risks of cracking.
The cost of edge trimming and detailing is on average between £8 and £16, with 1 edge trim covering around 3 metres. Therefore, an 18m2 garage would need 6 edge trims at a cost of between £48 and £96.
Scaffold or Roof Access
If access to your roof is difficult or at height, then the contractor may need to use scaffolding or a platform. Depending on the type of scaffolding or platform you need, prices range from £50 to £400.
Guttering or Fascia Upgrades
While you have a roofing contractor working on your property, you might want to upgrade your guttering and/or facias at the same time, especially if you need to hire scaffolding, as this will save you money by only hiring scaffolding once.
The costs for replacing guttering depend on the size of your property. For example, uPVC guttering installed on an average-sized three-bedroom property will cost around £500. To repair a gutter joint, you will be looking at between £50 and £125. Replacement fascias cost on average between £100 and £125 per metre.
Tradesperson Costs for Installing a Fibreglass Roof
A fibreglass roof will generally be installed by a roofer who will also have someone to help them. Roofers typically charge between £168 and £312 a day, with a labourer costing between £80 and £160 a day.
However, most contractors will charge on a per m2 basis. The labour costs for installing a fibreglass roof will depend on various factors:
The Location
If you live in London or the South East of England, then it is likely you will pay more for a tradesperson than if you live in another part of the UK.
Ease of Access
If the access to your roof isn't straightforward, then this could mean the job will take longer and the labour costs will be higher.
Size
A small roof, for example, on a shed will take a lot less time than a roof on a home extension of 40m2. If you are paying a contractor a day rate, then the size will be a consideration, as it will take longer to install a large roof.
Complexity
A complex job will take more time and require more skill, so it is likely that you will pay more for the installation. Working around skylights or with complicated angles is the type of situation that could result in higher labour costs.
Per Project or Day Rate
Most contractors will charge per m2 for a fibreglass roofing project between £50 and £60 per m2. But small jobs like a shed might only take half a day and could be charged at the roofer's hourly rate.
The average hourly rate for a roofer to install a fibreglass roof is between £21 and £39 per hour or £168 and £312 a day. On top of that, you will need to add the materials as well as the preparation, the application of a base and top coat and finishes.
As an example, a roofer installing a fibreglass roof on a small shed of 5 m2 might charge an hourly rate of between £21 and £39 an hour, rather than a m2 rate of between £200 and £240.
How Long Does It Take to Install a Fibreglass Roof?
The time it takes to fit a fibreglass roof will depend on the size and the complexity. A straightforward installation of around 18m2 will take around 1 day to complete. But larger areas will take longer.
For example, a double garage of 33m2 will take on average, 1.5 days. A 30m2 roof on a home extension will take around 2 days, and a larger installation of around 40m2 can take 4 days or more. These timescales include drying times between layers, which can take a few hours. The installation might also be delayed by the weather.
Types of Fibreglass Roof Finishes
There are three common types of fibreglass roofing, and they are:
- Standard Gloss Finish - This is a commonly used finish, which is popular because it is durable and gives an attractive gloss finish. Cost: £5 - £10 per kilo.
- Non-Slip Surface - Standard fibreglass can get slippery when it's wet, so if you have a surface that is going to be walked on, then a non-slip surface is the safest option. A typical application for a non-slip surface would be when a home or garage extension roof is also used as a balcony. Cost: £7.50 and £10 per kilo.
- Coloured Topcoats - A coloured topcoat creates an attractive finish. They often contain a hardener (catalyst), which means one less layer to install. Cost: £15 and £23 per kilo.
Planning Permission and Building Regulations
Normally, planning permission is not required to install a fibreglass roof unless you live in a conservation area or a listed building. Planning permission will also apply if you are making changes to the insulation or the building's structure.
But you will have to comply with building regulations, which state:
- The roof must slope to a minimum fall of 1:80
- There must be waterproofing extending up to the adjacent walls at least 150mm from the surface of the roof
- All cold roofs need to have adequate ventilation
- All warm roofs should have an adequate vapour control layer
- The roof must be built with sufficient strength to step on and resist strong winds
- There must be one or two edges to provide water drainage
Building regulations don't apply if you are repairing or re-covering 50% of an existing flat roof, and less than 25% of the outer shell is affected.
Benefits of Fibreglass Roofing
Fibreglass roofing has a wide range of benefits, which include:
- A long lifespan. Generally, fibreglass roofing lasts for between 20 and 30 years or more
- Resistance to harmful UV rays and other weather conditions
- Waterproof
- Lightweight but strong and durable
- Low maintenance
- Modern, attractive appearance
How Much Does It Cost to Remove a Fibreglass Roof?
The cost to remove a fibreglass flat roof depends on the size of the roof and how easy it is to access. The straightforward removal of a garage roof of 18m2, for example, will cost between £600 and £1,200, which equates to between £33 and £66 per m2.
FAQs
Q: Is fibreglass better than felt roofing?
A: Both materials are popular. Whether you choose to fit felt or fibreglass depends on your budget and how long you want your roof to last. Felt is cheaper to install. The cost of fitting a felt roof on a single garage is on average between £700 and £800, compared with fitting fibreglass, which will cost you between £1,440 and £3,690. Felt is also less durable. It will last around 10 years, whereas fibreglass will last between 20 and 30 years or more.
Q: How long does a fibreglass roof last?
A: Fibreglass roofs are long-lasting. You shouldn't need to replace a fibreglass roof for between 20 and 30 years. It is one of the most durable materials you can choose, second only to EPDM (rubber roofing), which should last between 30 and 50 years.
Q: Can you install a fibreglass roof during the winter?
A: Yes, it is possible to fit a fibreglass roof during the winter as long as the temperature isn’t below 5 °C because then the resin won’t cure. Also, make sure the weather is dry, so the decking doesn’t get wet. If it doesn`t stick properly, you`ll have problems in the future. Water in the resin will also mean the roof isn`t fully waterproof.
Q: Can I walk on a fibreglass roof?
A: Yes. Fibreglass roofs are often installed on balconies. A non-slip resin will ensure the floor doesn’t get slippery when it is wet, so that it is safe to walk on.
Q: Is a fibreglass roof easy to maintain?
A: Yes. Your roof will need a regular clean to remove dust and debris. Using a garden hose or a mop and bucket is recommended. Avoid power hoses as they can damage the roof's surface. Inspect the roof for damage. If you find a crack or a leak, buy a fibreglass roofing repair kit; they cost between £45 and £70 online or from local DIY stores.
You can also have your roof recoated using a gel coat or acrylic paint. The cost will depend on the size of your roof. 1kg of gel or topcoat will cost in the region of £5 to £20 per kilo.
