Everything you need to know about pitched roof extensions

Adding extra space with a pitched roof extension will enable your existing home to properly function for your family and lifestyle. Pitched roofs can be adapted to suit the particular location's tradition or put a new style spin on an existing structure — be it contemporary or period-style. Plus, they look great when used during a large two-storey addition, as well as a petite extension.

There's a lot that goes into building an extension, so having a basic grasp of the shape, size and style of your dream new space will help to create a brief for your architect at the design stage of a project.

Take a look below as we explore the pros and cons of a pitched roof extension, what to consider in terms of materials and budget, and, of course, loads of real-project inspiration.

Pitched roof extensions explained

Simply put, a pitched roof extension is an addition to an existing house with a roof structure in the shape of a triangle. The roof design therefore enables rain, snow and ice to slide off and into the gutters.

Pitched roofs can refer to any style of roof with a ridge or apex – pretty much anything other than flat roof extensions – although generally when they are being referred to, a classic pitch with a gable end is intended.

Pros of a Pitched Roof Extension

"Pitched roof extensions offer many benefits and are quite often a popular way to extend," begins George Allen, regional design consultant from Oakwrights, including:

• More insulation can be installed in the roof, providing better energy efficiency.
• Can suit contemporary and traditional house extension styles. "Pitched roofs are more traditional, but they can appear contemporary if a modern material is used and can be vaulted internally to provide drama," advises Lydia Robinson, founder of Design Storey Architects.
• "The vaulted ceiling roof space offers an airy feeling to the room, linking a room with lower ceilings for high ridge lines and lots of light!" says George Allen.
• "Pitched roof extensions are also very versatile, with multiple roof material options from clay, slate, shingles and zinc, there is an aesthetic to suit any property," adds George Allen.
• "There is also a benefit that pitched roofs can also help you overcome planning constraints," adds Yaniv Peer, director at Iguana Architects. "Traditional extensions under a householder application will normally be allowed to a depth of 3.5 under the planners discretion. However, if you intend on extending further than this then you will need a little ace up your sleeve and that comes in the form of pitching the roof eaves height down to 2m at neighbours boundary. Permitted Development (PD) Rights allow you to build up a fence up to a height of 2m and as such the position made to planning officers is that there is no further impact to outlook from the neighbours side then a garden fence."
• In a similar way to hipped roof extensions, pitched roofs are more stable than flat roofs when dealing with snow or heavy rain.

George Allen

George Allen has worked for Oakwrights for 7 years. He is the regional design consultant for Outbuildings and Extensions.

Cons of a pitched roof extension

Negatives of Choosing a Pitched Roof Design

However, there are some aspects in which pitched roof extension might not be suitable for every project:

• Can cost more than a flat roof , although not always (see below for more details).
• The design, roof slope and angle, and materials are key to a successful pitched roof extension — get any wrong and the finished product will look inappropriate to the existing house.
• The composition of the structure means there is increased burden placed on the foundations which may impact the depth of the required footings for the extension.
• Personal taste — flat roofs generally offer a more contemporary look which appeals to different homeowners.
• Some planning permission departments might prefer a completely different style of extension to that of an existing house to clearly demarcate the old and new structures.
• Can't have a green roof on a pitched extension.

Pitched roof extension costs

"Estimating jobs like pitched roof extension in the current market has its difficulties," explains Brian Berry, Chief Executive of the Federation of Master Builders (FMB). "We are seeing material costs at all-time highs. This increase is driven by a range of issues such as inflation, export duties, the war in Ukraine and energy costs.

"This is putting immense pressure on the bottom lines of small, local builders. 98% of small builders reported higher material costs on Q1 2022, with 83% of builders putting up their prices. This rise in cost, may understandably push customers to look for cheap and quick solutions. However, I urge extreme caution when looking for quotes, a good builder is a busy builder and may not come cheap. We would recommend collecting at least 3 quotes and using a service like the FMB’s ‘Find a Builder’ tool to ensure you are getting a quality builder.

"Consumers may also find that builders are using flexible contracts, this is to cope with the volatility of material costs, which ensures builders aren’t left out of pocket and keep jobs viable. The last thing you want half-way through a job is a builder going bust. Therefore, in the current market, you need to factor into your budget that the initial quote may end up being higher”.

For a quick estimate, use our extension cost calculator.

FAQs

Is a pitched roof extension more expensive?

"It would depend on the method of structure and the roof finish. A conventional trussed roof structure with a tiled finish might be a similar cost to a flat roof, but like anything, as soon as you go more specialist or alternative, it will cost more money," says architect Scott Donald.

We do a lot of metal clad (zinc) pitched roofs, which look great, but do come at a higher cost,"

"Technically there is more consideration that needs to be given by the contractor to the works and as such it demands a contractor with good carpentry skills," explains Iguana Architects' Yaniv Peer. "You must also balance out the type of glazing you intend on using i.e. is it to follow the form of the geometry or will you keep it rectilinear for the sake of costs? The same logic and also apply when considering external cladding on a angled facades, it is easier for external bricks to be applied to a flat surface then to cut bricks to an angle."

"Pitched roof extensions can turn out to be a cheaper alternative," says Oakwrights' George Allen. "This is primarily due to the cost of tiling compared to flat roof membrane roofing and the lantern cost.

"Tiling is also a much more common building practice, therefore not carrying as much of a premium. The wall space available on the existing exterior can govern your ridge height. If first floor windows are at a low level then a flat roof with lantern may be the best option."

"Pitched garden rooms can be in the similar region cost wise, however most clients go for a flat roof with lantern if they don’t have the height from ground to first floor for the pitched roof. So it is more of a personal preference or for practical reasons than cost," adds Oakrights' regional design consultant Zoe Grey.

Can you Add a Pitched Roof to an Existing Extension?

"Changing a flat roof to a pitched roof shouldn't change the structural loading on the existing extension foundations (but this should be confirmed by construction professions)" says FMB.

"This is subject to the detail of the host building, local planning constraints and structural survey."