Extension Roofing Guide

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product guide
Extension Roofing Guide

Building an extension is without doubt one of the best ways to gain extra space and add value to your home. There are countless benefits to building a visually appealing, well-planned extension, but getting it right can be a tricky process. One element many homeowners struggle with is deciding on the correct roof type and roofing material for their extension.

With so many options available, choosing between them all can be difficult. Below, we’re going to talk you through all the different extension roof types, discussing their pros and cons, and then we’ll explore the various roofing options best suited to both pitched and flat roof extensions.

Table of Contents

Extension Roof Types

As with all roofs, extension roofs fall into two main categories, pitched and flat roofs. There are a number of different styles of each, suited to different budgets and aesthetic tastes. Some roofs will offer more space, while others are designed to be more resilient against extreme weather.

Flat Roof Extensions

Flat roofs are favoured for their quick and easy construction, as the lack of a pitch means the building process is far more straightforward. Flat roof extensions are an excellent choice for homeowners looking to minimise project costs, as both building the roof and covering it will cost considerably less than a pitched roof extension.

What’s more, thanks to the flat design, you’ll be able to increase ceiling height further than a pitched roof extension without running into issues regarding planning permission. Two caveats of flat roofed extensions are aesthetics and weather resistance. Flat roofs are far more susceptible to issues such as roof leaks, due to their impaired ability to effectively shed water, and their nature limits the design options available when compared to pitched roofs.

The most popular materials for flat roofed extensions are EPDM membranes and roofing felt, both of which we’ll discuss further down.

Pitched Roof Extensions

Pitched roofs are far more varied in their design than flat roofs, with many options to consider for your extension.

Gable Roofs

A gable roof is perhaps *the* classic pitched roof design, featuring an inverted “V” shape for a simple, yet highly robust extension roof that will resist the elements yet offer a timeless appeal. Whilst gable roofs are very effective at withstanding most weather conditions, they can be susceptible to very high winds, so another roof type may be more suitable for properties in places such as the Highlands. Another thing to be aware of is the height added to your extension by a gable roof. Whilst this will naturally offer you more space and a more impressive appearance, you may run into difficulty regarding planning permission. So be sure to double-check first.

Popular roofing materials for gable roofed extensions include roof tiles, felt roof shingles, and roofing sheets.

Gambrel Roofs

Also known as “barn roofs”, gambrel roofs are iconic, offering an unmatched rural aesthetic found most often on barns and other agricultural buildings in the US. Here in the UK, gambrel roofs are very popular for larger residential properties. A gambrel roof extension will be extremely hardy and offer plenty of room in the loft space. This option also sports unmatched visual appeal, able to support a wide range of accessories and additional features.

Roof tiles and cedar wood shingles are the two most common materials used to protect a gambrel roof extension, thanks to their traditional, premium appeal.

Hipped Roofs

Often seen atop houses, hipped roofs feature slopes on all four sides rather than just two. Whilst this certainly adds to their visual appeal, be aware that a hipped roof will make your extension far trickier to construct, which will add to project costs. Hipped roofs are common in both square and rectangle building designs and deal well with poor weather conditions.

Many different materials are used on hipped roof extensions, but most commonly roof slates and shingles.

Single Slope Roofs

If you’re looking for a low-cost pitched roof option for your extension, then a single slope roof could be ideal. Extremely easy to construct, and highly effective at handling extreme weather and temperatures, these roofs are fantastic for smaller extensions. Ideal for anyone looking for an option that offers simplistic charm.

Roofing materials most commonly seen on single slope extensions are fibre cement slates, plastic roof tiles, and roofing sheets.

Mansard Roofs

Visually, a mansard roof is a cross between a traditional gable roof and a hipped roof. This French design combines the appeal and performance benefits of both, and with fantastic results. However, these can be rather difficult to construct, and therefore may require expert assistance if you’d like to build one for your extension.

Mansard roof extensions can be covered with a variety of roofing materials, including roof tiles, slate roofing, roof shingles, and more.

Choosing the Roof Pitch for Your Extension

Once you know what style of roof you’d like for your extension, it’s time to decide on the pitch. This decision depends on a lot of factors, including the style you’ve chosen, the size and structural strength of your main property, building regulations and planning permission, and your budget. Learn how to calculate roof pitch.

Roof pitches are usually split into three categories:

  • Flat roofs: A flat roof is any roof with a pitch lower than 2:12
  • Low-pitched roofs: A low-pitched roof is a roof with a very gradual slope, generally between 2:12 and 4:12.
  • Steep-pitched roofs: The most common, yet with the highest variance, any roof with a pitch greater than 4:12 but lower than 21:12 is classed as steep-pitched.

So Which Extension Roof Type is Best for Me?

As always, the best option for you depends on your budget, taste, and requirements. If you’re looking for a large extension that features plenty of ceiling and roof space, including stylish roof windows and more, then a pitched roof design such as the gable roof is what you require. However, for homeowners on a limited budget that just want a simple space to extend their property, a flat roof extension may be just the thing for you.

Extension Roofing Materials

Pitched Roofs

Roof Tiles

Roof tiles are by far the most widely used roofing material in Britain, both for the roof on your main property and extensions. Tiled roofs offer fantastic visual appeal, with an enormous array of styles, colours, and finishes available to buy. Roof tiles are most commonly made from concrete or clay, but synthetic options such as plastic roof tiles are also very popular due to their light weight and reliability. If your extension can support them, slate roof tiles are a fantastic choice that will lend your roof unrivalled premium aesthetics.

Roof tiles are however some of the more expensive roofing materials used for extensions, but for that investment you’ll get an extension roof that will look beautiful and truly stand the test of time. What’s more, thanks to continued innovation in the design and manufacture of roof tiles, everything from their durability to ease of installation has made rapid improvements in recent decades. When you buy roof tiles here at Roofing Megastore, you’ll also get the chance to buy specially made fixings to speed up and make the whole process of covering your extension roof far more straightforward.

Roof Shingles

Roof shingles are another common material used to cover pitched roof extensions. Their popularity has grown enormously in recent years, particularly for garden outbuildings. Shingles are available in a number of different materials, the most widely used being felt shingles. The best shingle to use on your extension roof depends on a few things, including roof pitch, budget, and more. If you’re looking for unparalleled rustic appeal, we’d highly recommend wood shingles made from real cedar.

Shingles are best known for their combination of aesthetics, cost-effectiveness, and ease of installation. We work with a number of top roof shingle manufacturers to offer homeowners a wonderful range of options, whether to roof their extension, shed, garage, or anything else.

Roofing Sheets

Another incredibly popular option, particularly for homeowners carrying out projects themselves are roofing sheets. Roofing sheets confer a number of advantages that materials such as tiles, slates, and shingles simply cannot. Their large size means that you need far fewer sheets to cover the same roof, drastically reducing project time and therefore labour costs. Plus, the range of roofing sheets available means you’re sure to find a material and style that suits your budget, needs, and taste.

The most popular roofing sheets for extensions are corrugated metal sheets, as these offer fantastic durability and decades of reliable protection for your property. Metal roofing sheets are also available in stylish tile effect profiles, which will allow your extension to seamlessly blend into your property and enjoy the many benefits offered by roofing sheets.

Flat Roofs

Roofing Felt

By far the most common flat roofing material used in Britain today, roofing felt will give your extension a weathertight covering that won’t break the bank. Available in a number of styles, finishes, and installation styles, felt roofing is a fantastic option for a homeowner looking to keep project costs low.

A felt roof will prove highly durable for a decade or more, significantly protecting against the elements and water ingress. While felt roofing is susceptible to damage over time, repairing a felt roof is extremely cheap and easy. Learn how to felt a roof yourself.

EPDM Membranes

EPDM rubber membranes are enjoying increasing popularity as more and more homeowners realise their many benefits. A simple way to cover and protect a flat roof for decades, EPDM membranes are reliable, strong, and require almost no maintenance.

What’s more, these membranes are highly affordable. A flat roof extension protected by an EPDM membrane will effectively resist UV rays, impacts, high winds, rain storms, and more. Completely waterproof, EPDM does not suffer from the nightmare leaks that often plague felt roofs, as roofing membranes are most often installed in single sheets with no seams for a clean, highly durable finish.


So there you have it. We hope our guide has been informative and helped you come closer to making a decision on the best extension roof for your project. Here at Roofing Megastore, we stock an enormous variety of materials suitable for extensions, sheds, garages, conservatories and more, all at fantastic prices delivered straight to your door. If you’ve still got any questions, be sure to get in touch with our customer service team. Call them on 01295 565 565, email [email protected], or use our handy online live chat.

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