Roofing Crossroads: Pitched Roof or Flat Roof for Your Home Extension?

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When it comes to extending your home, one of the most spoken topics with all our clients is ‘What works best for me, pitched or flat?’.  Your choice of the roof can significantly impact the look and feel of your home extension & design. Now since this is a crucial part of the design process, I thought best to write a short post to educate on the advantages and disadvantages of both roof types in order to help answer questions and make the process of choosing between the two, a little easier.

Pitched Roofs in Home Extensions


  • Pitched roofs are seen as the more durable roof type as they are great for allowing water and other debris to run off quickly, does not allow water to pool up and hence preventing leaks and damage to the roof as the erosion process is a lot slower.

  • Increased natural light due to the above point.

  • Pitched roofs are also seen to be better in insulation, making them more energy efficient as they have the ability to contain a lot more space internally compared to flat roofs to store an abundant amount of insulation if needed.

  • Better aesthetically (this one is debatable) but this is a general consensus.


    • Pitched roofs are generally more expensive than flat roofs, due to the complexity of the design, the materials used and the labour expertise needed.

    • They can take a lot longer to install than flat roofs to install

  • Pitched roofs can be less flexible when it comes to the design of your home extension. I.e. certain depths of extensions cannot have a pitched roof as the degree needed for installation of tiles will not be met. Get in touch with our consultants to figure if pitched roof is feasible for your build.

Flat Roofs in Home Extensions


    • Flat roofs are generally less expensive than pitched roofs, due to their simple design and the lower cost of materials

    • They can be quicker to install than pitched roofs

    • Flat roofs can be more flexible in terms of design, allowing for greater creativity and innovation. Flat roofs are used commonly in contemporary designs.

    • They can be durable with the right type of material and workmanship is used.

  • Flat roofs tend to provide much higher head heights overall compared to pitched roofs, this may be crucial to you and a deciding factor if you are looking for that extra volume-feeling.


    • Flat roofs are more prone to leaks than pitched roofs, especially if not installed correctly. There is usually a build-up of water and debris which exacerbates the corrosion process.  (Although with recent advances, this is not so much of a con as they are becoming more and more durable). Remember the Key here is to ensure proper installation!

  • They can be more difficult to maintain, as any debris or water can accumulate on the roof and cause damage over time, hence more frequent inspections are needed in comparison to pitched roofs.

There is a misconception I feel that you may have heard that ‘Flat roofs provide less insulation’. This is not entirely true. Yes, pitched roofs allows for a greater roof cavity that can accommodate more insulation as you naturally have more space compared to flat roofs. However, with proper design, good insulation material and proper workmanship, flat roofs can provide more than adequate insulation.


In simple terms, pitched roofs are generally more expensive than flat roofs, as they require more materials and time to construct. It is important to note that the cost will depend on a variety of factors, including the size of your home extension, the materials used, and the complexity of the design.

Flat roofs are generally less expensive than pitched roofs, but the cost will depend on the type of materials used. For example, GRP is more expensive than > EPDM which is more expensive than > PVC.

Design Considerations

When designing a home extension, it’s important to consider the type of roof that will work best with the overall design. For pitched roofs, the design will depend on the pitch of the roof and the materials used. Flat roofs can be more flexible, allowing for greater creativity and innovation in the design.

It is important to understand that in some situations, typical for Victorian properties with outriggers to the rear, you may need to use a combination of flat roof and pitched roof in order to solve other parameters like the impacts to light levels to adjoining owners. What exactly works best requires the experts to assess a number of options and then come up with one that would work best. Feel free to get in touch with us to find out which roof design may work best for your project, all information is provided for free!


Ultimately, the decision between a pitched roof and a flat roof will depend on your specific needs and preferences, site constraints and general planning laws. If you’re looking for a traditional, energy-efficient option and have a higher budget, a pitched roof might be the best choice. If you’re looking for a more modern and affordable option that offers greater.