Generally, you have two choices when it comes to planning the roof of your extension or construction project- flat roofing or pitched roofing. The roof structure is a key component to your build and which exact design you decide on will depend on multiple factors including the type of building, your budget and the planning laws at either a local or national level.

To help you decide, we have outlined the main advantages and disadvantages of both roof types.

Flat Roof

Advantages

  • This is usually the style chosen for smaller structures, for example garages and extensions. The base of a flat roof is horizontal and fixed to the ceiling joists underneath, with a waterproof membrane on top. It is common for the roof to be pitched just a few degrees to allow rainwater to drain away into a hopper
  • Most commonly, flat roofs are constructed from asphalt or three-ply modified bitumen (also known as felt flat roofing), topped with a layer of gravel to protect it from UV sunlight. This design can offer a lifespan of approximately 20 years. A new design that is becoming increasingly popular is Ethylene Propylene Diene Monomer (EPDM); a 3mm thick rubber membrane which is applied seamlessly in one piece and offers a lifespan of more than 40 years.
  • Flat roofing is usually the more affordable option at the point of construction as it involves less materials and labour than a pitched roof. It is possible to complete a full replacement of the roof in one single day.

Disadvantages

The main disadvantage to a flat roof is the maintenance it requires. With the most common design (felt flat roofing) offering a lifespan of 20 years, it can be a bit of a daunting prospect thinking about having to maintain and eventually replace this type of roof, especially if you are wanting to sell your home. Whilst EPDM is an improvement, offering another 20 years on felt flat roofing, some people believe it is an unsightly alternative and won’t match the style and traditions of the adjoining properties in the neighbourhood.

Pitched Roof

Advantages

  • If you have a lot of ‘things’ and a lack of space (as most people tend to accumulate), pitched roods are best for their loft space. They are built with at least two slopes that rise to meet at a peak and are constructed in such a way as to give plenty of usable space in the loft area. In the process of designing the roof, any planned usage of the loft can be incorporated into the plans, meaning this type of roof offers flexibility that a flat roof cannot
  • The pitched roof, if constructed properly, is almost certain to offer a longer lifespan than a flat roof as it is built with materials that are more durable and weather resistant. It also means the internal accommodation under the roof is more efficiently insulated, so it doesn’t suffer the temperature extremes that rooms under flat roofs tend to
  • A pitched roof allows the building to more effectively blend in to either the rest of the property (in the case of an extension) or to neighbouring buildings.

Disadvantages

  • The main disadvantage for pitched roofs is the expense, due to the more complex design, additional building materials and extra man-hours that are required for this style
  • Pitched roofs place a greater burden on the foundations of the building, which may result in implications for the depth of the footings. Therefore it is not always feasible to replace a flat roof with a pitched roof on an existing structure.

At Bedford Timber we sell everything you need for all sizes of roofing jobs. Contact us to find out more and see how we can help you with your roofing and all other building requirements.