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What slope for a pergola?

A pergola is one of the best solutions if you want to enjoy your exterior year-round. It is decorative and exists in all the possible styles you can imagine, from the most rustic to the most contemporary. If you are reading this article, it's because you already have an idea of the style of pergola that you would like to install. Now let's talk about the slope for a pergola. Among other things, the slope enables the evacuation of rainwater. But what is the most suitable inclination?

What criteria does the slope of a pergola roof depend on?quelle-pente-pergola

A slope prevents the stagnation of rainwater and improves sun protection. In addition to the aesthetic details, certain criteria must be taken into account for the slope of your pergola. 

First of all, the slope will not be the same if your pergola is wall-mounted or freestanding. The same applies if you choose to install a bioclimatic pergola with adjustable slats.

It is also essential to take into account the materials used for the construction of your pergola as well as the climate of the region where it will be installed. Once you are aware of these points, here are some indications that will help you choose the slope:

  • sloping pergolas are more common for lean-tos than for freestanding ones. This is explained by the fact that a freestanding pergola has four legs. To create a slope, the posts must be of different sizes (in parallel), which could destabilise the pergola;
  • whether the pergola is bioclimatic or classic, we recommend a minimum roof slope of 5% to efficiently evacuate rainwater; 
  • if you decide on a steeper slope for your pergola, the water will run off quicker and headroom will be reduced in the place where the ceiling is lowest;
  • concerning the materials used, stagnant water will tend to age wood prematurely. Therefore, choose a sloping pergola for this type of material. If you choose an aluminium pergola, other options are available if you prefer a flat roof.

A sloping or flat pergola: the differences

As we have seen, the slope of a pergola rood enables good rainwater runoff. It also gives another appearance to your new shelter. Nevertheless, flat roof pergolas also exist. Let's take a look at the differences between sloping and flat pergolas.

Sloping pergolas

The roof slope, generally 5%, prevents water from stagnating and forming puddles on the roof. Puddles will deteriorate your pergola more quickly. Moreover, the slope of a pergola roof protects against the sun's rays for a longer period during the day. Thus, your pergola will continue to protect you when the sun's rays are lower. Don't neglect the elegance of a sloping pergola. Leaning against the house, it harmoniously decorates the exterior space thanks to its attractive lines. The design must nonetheless be well thought out beforehand for it to blend in perfectly with the home. Good to know: you may wish to add solar panels. It is possible to build a photovoltaic pergola. For optimal electricity production, the slope of the solar panels must be between 30 and 35°, or choose a roof angle of at least 15 to 20%.

Flat pergolas

Flat pergolas are the most well known because they are the easiest to build oneself. They have a roof at a 90° angle, perfectly perpendicular to its posts. This particularity gives them a contemporary design. In addition, this enables you to close your pergola at a later date thanks to the addition of picture windows. As the roof is horizontal, rainwater is not evacuated. But don't worry! The builders have thought of everything! The addition of gutters enables the recuperation of water, which is then evacuated at the base of the posts. As modern pergolas are built of aluminium, they run no risk of mould or deterioration due to rainwater.

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