Slate roofing comes with several benefits. They last virtually a lifetime, are easy to maintain and repair, and offer excellent energy efficiency, helping you save money on your electricity bill. Moreover, if you are planning on extending the house roof, slate roofing can be used for house extensions, but you need to understand the ideal pitch for a slate roof.
What is slate roof pitch?
In housing construction, pitch refers to the slope of a roof and is essentially the measure of how steep the roof is. It is based on the height of the roof, the rafter length, and pitch. The higher the pitch angle, the steeper the roof. For instance, a flat roof will have a pitch angle of 0-degree, although it is impractical as pitch helps in water and snow drainage.
Usually, a low-pitch roof is when the pitch angle is lower than 20-degrees. However, this measure can vary among manufacturers and the installation contractor.
The importance of roof pitch
The pitch and shape of the roof have a direct impact on the internal volume of the building. When designing a new house or planning the extension of an existing one, the pitch is usually one of the first factors architects consider, as it impacts several key decisions, like the material to be used in construction and the type of roofing system to be installed.
Roofing pitch is also crucial in determining how fast water and debris will clear from the roof, and therefore significantly impact the longevity of the roofing system. In most homes, you will find a minimum pitch of 20° to 30°.
In snowy regions, roofs are steeper to assist in draining snow and preventing water build-up, which can affect the performance of the roof. Therefore, roof pitch is also an important factor to consider when looking at base flashing heights and gutter systems.
Minimum pitch of a slate roof
Generally, the steeper the roof, the better the service life of slate. Slate shingles last longer on steeper roofs, and they are more visible from the grade, allowing visitors to visualise the full glory and beauty of slate roofing.
Slate roofs typically need a minimum pitch of 17.5° to 20° depending on the construction of the slate and the area where the house is situated. This is because a shallow double lap roof uses a “headlap installation” technique, where multiple tiles are arranged in a manner to prevent rain from entering the house. However, this technique only works the best when there is a minimum 20° slope to the roof, facilitating water drainage.
If the roof is nearly flat, water will stagnate on the tiles instead of draining down the gutters, eventually finding its way to the small cracks between the tiles. This can lead to premature weathering and reduce the lifespan of the slate tiles significantly.
On the other hand, installing slate tiles on extremely steep roofs also requires additional precaution with additional fasteners due to the weight of naturally occurring slate. Even the most Victorian-style houses across the world will usually have a maximum slope of 45-50°, as it can be expensive to install slate on anything with more slope than that. If you have any questions about the minimum put of slate roofs or any other technical questions, we are happy to help! At The Slate Roofing Company, we are the experts at all things slate roofs and we’ll be able to confidently answer your questions provide you the best advice for your home or business. Contact us now to start the conversation!