Flat roof Costs

How To Replace Flat Roof Felt

Also referred to as tar paper, roofing felt is installed underneath the roof’s shingles to help deny water access to your home. Installing the roofing felt in overlapping layers builds a water barrier in situations whereby the weather damages or blows away the shingles. Although the application of a roofing felt on a flat roof is relatively easier and safer than working on a peaked roof, it’s advisable to take enough care and precautions. If you lack proper training and experience for this task, we’d recommend you employ a reliable professional to guarantee the best results and save you from further headaches especially in cases whereby unfortunate errors are made. This step by step guide will give you a good insight into the flat roof felt replacement process.

• Take a measurement of the width and length of the roof.

• Calculate the square footage by multiplying the numbers.

• Multiply the square footage gotten by three (it’s advisable to install three layers of roofing felt to create a really strong weather barrier).

• Use a claw hammer to remove the existing roofing felt.

• Use utility knife to cut the new felt to fit the length of the roof.

• Place the first piece along the roof’s edge and use a hammer tacker to tack the felt in place with staples or galvanized nails and hammer.

• Put the staples or nails at every 6 inches along the side touching the roof’s edge as well as down the short sides.

• Repeat the same process for the second piece, laying it out beside the first row of felt.

• Cut a piece of felt to the appropriate length using a utility knife to begin the second layer of roofing felt, and cutting it in half, lengthwise.

• Apply construction adhesive along the first row using a trowel.

• Press the first piece for the second layer onto the adhesive. Repeat this process until the roof is covered with a second layer

• Apply construction adhesive over the second layer to install the third layer. Begin with a full piece of felt without cutting it in half.

• Overlap each piece by 2 inches until you’ve completely installed the third layer.

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.

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.

It depends on the material you use, but if your flat roof is installed correctly it should last for at least 10 years, and at least 20 if a material other than felt is used. Always question a roofing company when they quote to find out what materials they use and what guarantee's they offer.

Most material warranties come from the waterproofing layer manufacturers, and can last between 5 and 20 years. If your roofing contractor is on the manufacturer’s installer list, it might cover their work. It’s important that you always read through all the information given to you about your warranty so you know exactly what is included.

Ponding is where you see pools of water appearing on your flat roof. Unless your roof is leaking or showing other signs of damage, you don’t need to replace it. When you do have your flat roof replaced, tell the contractor so they can find out the cause of the ponding.

If your existing roof is still in good condition but the membrane is getting old, it’s often not worth exposing the structure to the weather whilst the contractor strips off the old membranes. The contractor will leave them in place to act as a base layer for a new roofing system. As long as there are no other problems with your roof, then overlaying is a good way to replace your flat roof.If you have any more questions about flat roofing that aren’t listed here, fill out our form to ask a contractor.

You should inspect your roof twice a year, ideally after rain or snow, to see if it’s draining properly. Also in the Spring to check for damage that may of been caused over the winter months that will need to be put right before the next winter. Have an inspection carried out if you are unsure.