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The flat-roofed design is a welcome addition to modern homes.
Do you like this style?
Let’s find out all you need to know about flat roofs, how to care for them and the materials they’re made of.
A flat roof… not really flat
Despite its name, a flat roof is not really flat.
In fact, its surface has a slight slope, generally between 1% and 15%, to allow rainwater to drain off.
A large area requires a steeper slope to prevent stagnant water.
Why choose a flat roof?
Here are the main advantages of a flat roof:
- This style suits most contemporary architecture;
- A flat roof provides additional usable space in your home;
- Installation is simple and more economical than with a pitched roof.
- Greening a flat roof is a great way to beautify your home and add a touch of greenery, especially if your garden is rather small.
The elements of a flat roof
A flat roof is made up of several components, including the framework, the floor, the insulation and the final coating.
Here’s what you need to know about the structure of a flat roof.
The framework
This is the roof structure that supports the entire roof.
This framework must be strong enough to absorb the weight of the other components, especially if you intend to use the roof.
The framework is generally made of wood.
Specialists recommend quality woods such as chestnut and oak.
The use of metal is becoming increasingly common.
Roof decking
Concrete is the best option if you want an accessible flat roof that can be used as a terrace.
Alternatively, you can use steel troughs with limited thermal insulation, or OSB panels that require regular maintenance.
Thermal performance
Insulation is essential for a flat roof.
Professionals can choose between three methods: warm roof, mixed roof and inverted roof.
Each method is characterized by the arrangement of the waterproofing membrane, the vapour barrier and the underroof (optional).
Final coating
The final coating is the visible part of the roof.
There are several types for a flat roof:
- Bitumen: frequently used for flat roofs, it is characterized by its thickness and adhesion;
- EPDM: this rubber blanket offers good durability and superior resistance;
- Multi-layer coating: multiple layers of consolidated bitumen superimposed on one another provide ideal waterproofing;
- PVC: an inexpensive option, but less reliable, less durable and less resistant;
- SEL: the Liquid Waterproofing System is made up of elastomers and resins.
It is suitable for frequent use (especially on flat roofs); - Vegetated cladding: an aesthetic composition of various plants that protects against the vagaries of the weather.
Its weak point is its considerable weight, which requires reinforcement of the roof structure.
