Find a Roofer you can trust in Enfield.

How Often Do Flat Roofs Need Replacing?

When a flat roof needs to be replaced is determined by a number of factors which includes the roof’s exposure to the weather, the condition and age of the roofing materials as well as the construction of the roof. However, with proper maintenance and regular inspection, they should be used for nothing less than 50 years. There are some commonly used types of flat roofs which includes Felt flat roof as well as a GRP flat roof.

Felt Flat Roof

The lifespan of a felt flat roof also varies depending on the quality and grade of the felt roof incorporated. This can make the roof last within the range of 2 to 20 years. More often than not, felt flat roofs are usually installed in such a way to keep the costs down which implies the grades of felts that are mostly used are the economical ones implying a very short lifespan.

In the event whereby a premium grade of felt is incorporated in constructing a roof by professional contractors, will be guaranteed by the manufacturer to last between 10 to 20 years.

One of the major causes of a short lifespan in felts is leaks which should be regularly inspected and repaired once identified. If not, the roof will gradually deteriorate and become a lot weaker due to the action of the sun. However, when a felt roof starts to leak, it’s usually a sign that’s approaching the end of its lifespan and a replacement should be taken into account.

GRP Flat Roof

The GRP flat roof or fibreglass flat roof usually comes with a manufacturer’s guarantee of 20 years and is expected to have a lifespan of a minimum of an additional 10 years.

Unlike felt roofs, they’re more resistant to leaks. However, they should also be regularly inspected for leaks which are caused mostly as a result of installation error rather than the GRP roofing approaching the end of its useful life. If the GRP roof repair does not totally resolve the leak, you should start considering a replacement.

Blisters are most common on membrane roofing systems. Lots of contractors will tell you that if there are no signs of further damage, there might not be any need to repair flat roof blisters. They form when pockets of air or water get trapped between layers of the roof’s membrane or between the membrane and the frame. When the sun is out and it heats the pockets expand and stretch the membrane. If you do want to repair your flat roof blisters, there are a few ways to go about it.

If you have a membrane flat roof, cut away the membrane until you reach a place where the membrane is still stuck tightly to the roof. Reapply as many new membrane layers as you cut away over the blistered area. You might even need to do more. To make sure your patch remains watertight, you’ll need to leave at least 6 inches around the edges of the blister.

If you’ve got a felt roof, you can cut an X shape through the blister. Peel back the triangles that you’ve made and let the timber frame dry for a while (so don’t do this when rain is forecast!). Then, coat the area with lots of bitumen adhesive and leave it to dry until it feels tacky. Then press down the triangles of felt firmly into the adhesive.

After that, you’ll need to add more bitumen adhesive to the cuts you made. If you’ve got any spare roofing felt, cut a square that’s about 100mm bigger than the cuts then lay this over the adhesive. If you’ve not got any felt, it’s cheaper to use a self-adhesive flashing strip. Once you’ve laid the strip or patch over, seal the edges with more bitumen adhesive.

It’s relatively simple to remove a Velux window, whether it’s Velux-branded or is another brand of roof window. Here is a breakdown of the steps you’ll need to take to remove a roof window:

1. Remove the sash (opening part) from the roof window frame. Usually there are screws in the hinges to loosen or a button to press and lift out.
2. Next, remove the tiles or slates from around the window frame along with the flashing.
3. Unscrew all the brackets around the window frame and lift out the frame.

It’s that simple! You can do all of this from inside your home – there's no need to climb on the roof. Removing the glass pane from a Velux window, for example if it has blown, is a more difficult job and should be left to a professional. It involves removing the sash from the roof window frame and then removing the surrounding parts of the sash to lift out the sealed unit. They will then place the new glazed unit into the sash frame before securing all the parts back onto the sash and fitting it back into the roof window frame.

Fitting a Velux window into a slate roof is very similar to the way you’d install it in other roof types. All roof windows, whether a Velux-branded one or not, will come with detailed instructions for you to follow if you want to have a go at fitting it yourself. But here are some brief instructions to give you an idea of what’s involved in installing a Velux window into a slate roof:

1. After you’ve removed the Velux window from its packaging, remove the sash (the part that opens) from the frame, according to the manufacturer’s instructions.
2. Next, you need to prepare the opening for the window. You can often cut through the felt, remove one of the battens from under a slate, then slide all the slate tiles into the roof space. You should then make the cut 40-60mm wider than the window, cutting away roof timbers then replacing them with more around the opening to strengthen it.
3. The roof window’s bottom brackets need to be installed on one of the existing battens for the slate roof. One of the slate courses should line up 105mm below the top edge of the batten you use.
4. Then, measure from the top edge of the batten upwards to the height of the window plus 45mm. This is where the top installation batten should be installed, with an overhang of 100mm on each side.
5. Remove the course of slates below the window, trim any excess felt and fold it over the surrounding timber. This helps with waterproofing.
6. Add the insulation collar according to the Velux window manufacturer’s instructions.
7. Place the frame in the opening, adding the brackets according to the instructions. You’ll find that lots of roof windows have pre-drilled holes to make it easy for you.
8. Replace the sash and line up the hinges. Take a look at the opening at the bottom between the sash and the frame – it should be even along the entire width. Remove the sash again to fix the upper brackets according to instructions.
9. Add the underfelt collar for your roof window as instructed by the manufacturer, then replace any slates at the bottom. You might need to cut them to size.
10. Next, add the flashing according to the instructions, along with any parts that are not yet attached, including the hood section and top flashing piece.
11. Replace all the slates around the window, allowing 60-100mm of space between the course of slates above the window and the top of the window to allow for rainwater drainage. Then replace the sash into the frame again.
12. Add the vapour barrier on the inside of the window using the screws provided, then tape it to the existing vapour barrier to prevent moisture from reaching your roof structure.

And that’s it! If you think that sounds a bit complicated, ask a roofer or window installer to fit your roof window into a slate roof for you. You’ll get a better finish and you can be sure that you won’t get any leaks from a botched installation.

The feasibility of this will depend on the roof’s strength, in particular its load bearing capabilities. This is simply because tiles are heavier than the metal sheeting. Normally a tiled roof will need to take a load capacity of 60kg per square metre. You will need a trusted roofing company to advise on this.

What Is The Average Cost To Replace A Flat Roof?

Are you interested in knowing how much it costs to replace a flat roof? Here, you’ll discover a price breakdown for replacing flat roof. This includes a number of price determining factors such as materials costs as well as cost of labour and cost per square metre. All these enables you to make easy calculations so that you can determine a flat roof replacement estimate for your own project.

The type of flat roof that is the most common type is the garage roof and for the replacement of a single garage roof, the cost will fall between the range of £700 to £1000. Meanwhile for a double garage, you should expect a price increase of about 40 percent to 50 percent. The main price determinant that’s affecting the price of a new flat roof is the material incorporated in making it. For instance, lead or fibreglass are much more expensive when compared to felt roofs.

Generally, the cost of a flat roof replacement will fall within the range of £700 to £1300 varying largely due to the type of materials to be used by the roofer, the roof’s size as well as whether or not scaffolding would be used. Multiple flat roof applications also comes with different costs which includes:

• Felt roof ( £40 to £60 per square metre).

• Fibreglass roof ( £70to £90 per square metre ).

• Rubber roof ( £80 to £85 per square metre ).

• Lead bay roof ( £90 to £105 per square metre ).

• Fibreglass bay roof ( £40 to £60 per square metre ).

Several professional roofers work in pairs and to hire them you’re likely to be charged between £200 to £300 per day. The project can be completed with just a day’s work, but the installer should be back to make sure there are no leaks.

How you install commercial rubber roofing is similar to fitting it on a residential property, except that the area that’s covered is likely to be bigger. With commercial properties, you should always leave any maintenance and repair works to the professionals – whether you own or lease the property, you could invalidate any insurance if you try to install rubber roofing yourself. We’ll outline the steps roofers will take when installing rubber roofing on a commercial property.

Firstly, the installers will remove any existing coverings and clean and dry the surface thoroughly. This is vital in ensuring that the rubber will stick. They will then unwrap the EDPM rubber membrane and leave it to rest until it’s fully expanded. On a warm day this may take around half an hour.

Next, the roofers will work with half a sheet of rubber at a time and adhere it to the roof surface. They may use a water-based adhesive which they will spread onto the roof in sections, then roll the membrane onto the surface before moving onto the next section. If they’re using a bonded adhesive, they will apply it to both the roof and the rubber and leave it to dry until it’s tacky before extending the membrane.

Once the EDPM rubber is rolled out, the installers will brush the surface with a large broom to get rid of bubbles and provide a stronger bond. Then they will work of the edges, applying adhesive to roof and walls edges, sealing corners and creating watertight seals. They’ll also tidy up any excess membrane and seal all the trims.

As long as it’s installed correctly, your commercial rubber roofing should last you decades without any repairs needed. It’s always best to inspect your roof regularly to spot any damage before it becomes a bigger problem.

Velux installers offer the Velux Active home kit. This provides an automated system to enhance your indoor living. With its sensor-based ventilation apparatus, the Velux active home kit’s smart sensors repeatedly monitor your home’s temperature, humidity and CO2 levels for its optimum healthy living standards.

Sensor-based ventilation
Velux Active tracks temperature, humidity and CO2-levels, and ventilates to keep your indoor climate nice and healthy.

Automatic heat protection
Velux Active automatically protects your home from excessive heat by closing your Velux Integra blinds, awnings and shutters on hot days.

Set personal preferences
Want to swap your alarm clock for a sunrise or air out while you’re at work? Customise your indoor climate with Velux Active.

Voice-control and smart speaker integration come standard with VELUX ACTIVE with NETATMO, enabling you to draw the shades or open the windows just by asking.