The roof is one of a building’s most critical parts, serving as the main element that shields it from external factors. The roof’s slope is one of the most essential aspects in determining its quality and efficiency.
We often think that roof pitch is purely a matter of aesthetics. However, nothing could be further from the truth. The slope is a key architectural and structural consideration that directly affects the quality and durability of the roof. When talking about high-quality roofs, we must account for factors such as slope, the number of drainage areas, the permeability of the roofing material, and surface uniformity.
Why Are These Factors Important When Evaluating Roofs?
Slope is essential because it dictates the natural flow of rainwater, allowing for quick and adequate drainage. A properly sloped roof will protect the building from rain, snow, and ice accumulation, ensuring these elements don’t collect on top of the roof.
Calculating drainage surface is crucial, especially for roofs in areas with high rainfall. The general guideline is that for every 100 square meters of surface, 300 square centimeters of free, unobstructed drainage surface is needed to ensure optimal water flow.
Permeability also plays a crucial role in roofing. To prevent leaks, the surface must be as non-porous as possible. The water-to-cement ratio is critical for minimizing porosity and ensuring waterproofing in concrete or mortar roofs.
The uniformity of the roof is also critical. Any deformities can interrupt the flow of rainwater, leading to water stagnation and potential leaks. This underscores the need for a thorough roof inspection and correction of any irregularities before installing asphalt membranes or other waterproofing systems.
What Slope Should a Roof Have?
The slope of a roof is measured in either percentage or degrees. A roof with less than a 5% slope is considered flat. However, roofing specialists recommend a minimum slope of 5% to allow for proper drainage of water and snow. Without this minimum, water can accumulate, causing leaks, stagnation, bacteria growth, and increased maintenance costs. This highlights the urgency of meeting the recommended slopes to avoid these risks.
Minimum Slope
Flat roofs have less than a 5% slope, but a minimum slope of 1% is required for smooth waterproofing materials and 2% for granulated or aluminum finishes. On the other hand, asphalt shingle roofs need a minimum slope of 10% to ensure functionality and showcase their aesthetic qualities. To avoid leaks, a smooth asphalt membrane base is recommended for slopes between 10% and 25%
Maximum Slope
The maximum slope for a pitched roof is 45%. Beyond this, any structural element is considered a facade. However, recommended inclines also depend on the materials used, such as the minimum slope. The best waterproofing solutions for roofs with such inclines are asphalt shingles or granulated membranes, which offer protection and serve as decorative elements due to their texture and color.
