A Potted Guide To Installing A Flat Roof

Flat roofing offers several benefits to homes and businesses alike. They are cheap to construct. They last longer than a traditional pitched roof. And, thanks to their energy efficient design, they can offer reduced heating and electricity bills.

However, whether you are building a new system on a new property or having repairs made to an existing one, before you get started there are plenty of things to think about – from the structure and insulation through to the waterproofing and finishing.

By fully understanding these things you can prepare a surface that, in addition to the benefits mentioned above, also looks great and adds value to a property.

1. Flat roofs are not actually flat
First, it's important to know that flat roofs are not actually completely flat. They should always have a slope to allow for water run-off.

2. Access and usage
If the sole purpose of the surface is simply to protect the building and everything in it from the elements then the build is going to be relatively straightforward. However, one major benefit of a flat roof is that it can also be used as a raised terrace, patio or decking area but will require second floor access from the interior or an external stairway. Even if it the covering is simply going to be just that, a roof, then you'll still need to make sure you can access the roof easily for maintenance.

3. Weight load
If the roof is intended to be used for access or recreational purposes then find out exactly what additional weight the roof can support. A professional roofer, architect or surveyor will be able to help you with this.

4. Warm or cold
In a cold roof system, the insulation sits under the deck between the joists which means ventilation will need to be included to stop condensation forming. With this method there will be some heat loss. In a warm system the insulation sits above the deck but below the weather-proofing, meaning there's no risk of condensation and so there's no need for ventilation.

5. Waterproofing
Waterproofing your roof is probably the most important part of the whole project. For obvious reasons flat roofs are more prone to leaks than pitched ones. There are a number of products and materials you could use to keep your surface area dry including GRP (Glass Reinforced Plastic), liquid coatings, single ply, bitumen, asphalt and paint – all of which have varying degrees of cost and difficulty to install.

6. Compatibility
If you are applying new waterproofing over an existing membrane it is important to check the new product is compatible as you might need a primer. One final reminder – the roof must be thoroughly clean and completely dry before you begin.

Flat roofs may not be the simplest roofs to install but thanks to improved materials and installation techniques they are some of the most durable and easy to maintain and repair if something goes wrong.