A DIY Guide: Covering a Flat Roof Extension

Covering a flat roof extension is well within reach of a DIYer with confidence and skills these days. With innovative materials and DIY roof kits readily affordable and available, homeowners all over the UK are rethinking their roof extension projects.

Flat roof extensions have been making a major comeback across the country in recent years, as homeowners move towards improving their current homes in favour of moving house. It can often prove to be a more cost effective route to getting the additional space you need, particularly with rising moving costs, fees, stamp duty and more.

We’ve covered the fundamentals of extensions in a previous blog post, such as what they are and how perceptions have changed over the decades, planning permission and how to seek it and other planning tips. Today, PermaRoof UK takes a closer look at covering flat roof extensions and the best way forward so you can do-it-yourself.

Further reading (PDF opens in new window):

• What is a flat roof extension?
• What every homeowner should know about extensions

Choosing the right covering for your extension flat roof

Selecting a modern roof covering will simplify installation for a DIY project and this should be the first step in the planning stages. EPDM rubber roofing membrane is an excellent choice, whether you are working on a new build or recovering an old felt roof. It offers superior weatherability over an exceptional expected service life of more than 50 years and is fast and easy to install.

Because EPDM can be cut to large, custom sizes, it can typically be laid in a single sheet up to 15.24m x 30m. This is a big plus for DIY, avoiding historically vulnerable joins.

Liquid rubber roofing is also a good choice, especially if your flat roof on the extension has areas where membrane might be difficult to install. Application involves mixing liquid PU with an accelerator and uses fibre matting for structure and integrity. It can also be used to create anti-slip surfaces and is ideal for green roof projects where walkways or paths are needed.

You can find out more about liquid roofing here or download our comprehensive application guide.

Further reading:

• Why EPDM roofs are ideal for DIY

Getting the quantities right first time

Buying the right quantities for your flat roof extension is a priority. Getting it wrong can make a big difference to the project coming in on-time and on-budget.
Overbuying wastes both money and materials and underbuying can delay the project or compromise installation. It is important to ensure you:

• Measure the flat roof extension accurately
• Allow for membrane overhang when ordering
• Quantify the correct accessories – i.e. trim, fixings, caps and corners
• Ensure sufficient adhesive and sealant

Buying a flat roof kit for your extension project can remove all doubt about buying the correct quantities. A kit from PermaRoof UK includes membrane, adhesive, sealant and trim, fixings and accessories – and all you need to do is measure your roofing accurately and enter your size, we’ll do the rest.

If you’re looking for a different approach, try our free online EPDM Kit Builder App. Enter your project specifications and let that do the work, producing a kit list that we will quote for you.

Further reading:

• How to Measure Flat Roofing
• View all our roofing tips and planning information

Preparing the flat roof extension for rubber membrane

The way you begin your project will be determined by a number of factors, including whether it is a new build extension, or whether you need to replace the covering on an existing one. There will still be preparation to complete on a brand new substrate, but you will already have a good basis for applying your extension cover. Recovering an existing flat roof extension will require additional preparation work, such as potentially removing the worn covering and/or conducting any necessary repairs to the deck.

To find out more about how, where and when to prepare your flat roof for rubber roofing installation, please browse our free downloads.

• Preparing your flat roof extension
• Safety Tips

Installing extension flat roofing

Once correctly prepared, installing EPDM on your flat roof extension can be fast and straightforward. We provide full support to all our customers and have an extensive library of installation guides to walk you through every step of the way.

You will find a wealth of information in our video library, including step-by-step tutorials covering every aspect, from the fundamentals of applying your adhesive to installing EPDM around a skylight.

Visit the video library here.

Further Reading:

• How to Install a Rubber Roof Yourself
• Flat Roof Application Review
• Installing PermaRoof Plus Trim
• Forming an Internal Corner

View all our PDF installation guides.

Let us help

PermaRoof UK offers expert advice, high quality products and installation support to all our DIY and trade customers. Talk to our award winning sales and support teams today on 01773 608 839.

PermaGroup has established links with some of the biggest names in our industry thanks to our reputation of excellence. Read more about becoming a supplier or stockist here.