House extensions are now seen as a cheaper alternative to moving home in the UK. This has led to a rise in low pitch roofing to accommodate these changes. Generally, 17.5⁰ and below is considered a low pitch roof. However, this can vary depending on the manufacturer, architect and installation company. It can seem confusing working out whether to go with a low pitch roof and what this could mean in the long run. Read on for advice whether you are thinking about building an extension, or if you need to re-tile a low pitch roof.
What are the Advantages of a Low Pitched Roof?
Whether you are thinking of building a single story extension to the rear of your home or simply re-tiling an existing low-pitched roof, it is helpful to be reminded of why the style is so effective.
First of all, the cost for a low pitched roof is reduced because there are fewer materials used in its construction. This leads to lower associated labour costs due to there being less time spent actually installing it. Not only will you spend less money on a low pitched roof but the turnaround time is much faster.
The tiles and slates used for low pitched roofs are very low maintenance and will always come with a manufacturers guarantee for at least a few decades. If the tiles are installed in an area where weather conditions aren’t too severe and damaged tiles and slates are quickly repaired, the roof will pretty much take care of itself. Low pitch tiles are also easier to walk on than other types and there are options that also come with screws to secure them into place.
Lastly, the overlapping system used with low pitch tiles and slates allows some roofs to be built as low as 10⁰. This offers more architectural freedom in the design stage allowing homeowners, developers and architects more creative license.
Why is Pitch Important?
The shape and pitch of a roof will also have an effect on the volume of the internal space in the building. This is usually one of the first considerations in the design stage. Determining the pitch for the roof of the property will impact on a number of other key decisions. These include the roofing system to be installed and the materials most suited to the architecture of the building.
The pitch is crucial in minimising the amount of time it takes for water and debris to clear from the roof. Getting the right pitch for the roof will also play a big role in it performs long term.
What is the Minimum Pitch for a Tiled Roof?
There are some general rules that can be applied to different types of tiles. However, these limitations were accepted before the advancement of modern technology helped to broaden the scope of their use.
There are now more options available to consumers and building companies. This means many of the tiles previously used on low pitched roofs for purely aesthetic reasons have improved in functionality.
Types of Tile & Recommended Pitch
- Plain Tiles: Previously it was accepted that 35° was the lowest recommended pitch for both concrete and clay variants of the tile. With the introduction of machine-made clay tiles, this has now dropped slightly to 30°, similar to the Marley Hawkins Single Camber tile. The limit for plain concrete tiles remains at the same level as you can see with the Sandtoft Plain Concrete tile which is set at a minimum of 35°.
- Interlocking Concrete and Clay Tiles: The benefits of interlocking tiles allow for faster installation and lower purchasing and labour costs. They can also be used on low pitched roofs, such as the Sandtoft 20/20 tile which is a highly popular clay option that can be installed on pitches of 15°.
- Clay Pantiles: Where the minimum pitch for clay pantiles used to be 30°, tiles like the Redland Cathedral pantile can be pitched as low as 22.5°. The interlocking technology used on the Koramic 401 Flemish pantile allows it to go a fraction lower at 22⁰.
- Concrete Pantiles: Where concrete pantiles previously had a recommended pitch of 20°, they can now be used on roofs at 15° if required. The Sandtoft Double Pantile Concrete tile uses its interlocking system to enable that added versatility.
- Double Roman Tiles: Similar to pantiles, the minimum level for double roman tiles was previously set at 30°. Newer versions such as the Redland 50 Double Roman Concrete tile are used on roofs at 17.5°, thanks in large to the integrated interlocking technology.
What is the Minimum Pitch for a Slate Roof?
It is generally accepted that the lower the pitch, the larger the headlap should be. When designing or altering the pitch of a slate roof, common weather conditions should be one of the first considerations.
Excessive rainfall will have a big impact on how fast the water is drained from the roofing system. Two other important areas to factor in are the height of the property and the length of the rafter.
- Natural Slate: The general recommendation for the minimum pitch for natural slate is 25°. There are some manufacturers that can go slightly lower, such as the SIGA 56M Natural slate, which can go down to 20° in some instances if used with slate hook systems.
- Fibre Cement Slate: The Marley Thrutone slate is a perfect example of a low roof pitch option. Economically priced and available in either blue or black, it can be pitched at 15⁰.
What are the Challenges of a Low Pitch Roof?
Many problems that arise from the installation of a low pitch roof derive from poor installation or lack of maintenance. Although this is also true of every other roof, low or steep.
Poor workmanship is a challenge you can minimise by taking the right precautions before work begins. You can ask to see examples of a contractor's work and request references from previous customers. Any reputable company should be happy to provide. You can also use the National Federation of Roofing Contractors, the largest trade body of its kind in the UK. They hold a database of recommended suppliers on their website.
- Leaks are one of the most common occurrences. This is usually caused by the contractor using an incorrect tile and not taking precautions to sufficiently protect the underlay. The damage caused by water ingress can be extremely damaging and expensive. The moment any leak is identified, it must be dealt with quickly to avoid it creating larger issues.
- Maintenance is another area that requires ongoing work. This means checking the roof for any cracks or broken tiles/slates from both the ground level and using a secure ladder. In isolation, minimal damage is fine as long as it is repaired quickly. This will prevent further problems elsewhere on the roof.
- Bad repairs can also serve to make problems worse, rather than actually solve the problem. Only experienced DIY experts should attempt to take on roof tile or slate repairs. Paying for a skilled contractor to fix the damage will be cheaper than costs incurred for issues caused by unskilled mistakes.