Can Shingles Be Used for Low-Pitched Roofs?
Timber roof shingles are suitable for use on roofs with pitches as low as 14 degrees and are a beautiful building material that brings the warmth and character of natural timber, as well as sustainability benefits, to a wide range of roofs.
While a low-pitch roof may not show off the aesthetic qualities of timber shingles as well as a steeper pitch would, roof shingles provide a lightweight, durable and environmentally friendly choice.
Why choose roof shingles for low pitch roofs?
Typically made from cedar wood, timber shingles have long been a popular roofing option, bringing a variety of advantages to projects ranging from family homes to commercial properties and leisure applications. These benefits include:
- Attractive appearance – Cedar shingles have a timeless charm that complements both traditional and modern homes. Over time, they develop a silvery patina that enhances their aesthetic appeal.
- Water resistant – Cedar contains natural oils that make it resistant to moisture.
- Natural durability – Cedar is naturally resistant to rot, insects and frost damage, making it incredibly tough. With proper installation, cedar shingles can last for over 50 years.
- Naturally renewable – For projects that are more sensitive regarding their environmental impact, cedar shingles offer a naturally renewable building material solution.
- Insulating – Cedar has good insulation properties, and the Western Red cedar used to manufacture Marley’s roof shingles is recognised as the best thermal insulator among the commonly available softwoods. Its insulation qualities are far superior to brick, concrete and steel, and it offers a high level of acoustic insulation.
Ensuring a weather-tight finish for low-pitch shingle roofs
Low-pitched roofs are typically defined as those with a pitch below 30 degrees. This shallow angle creates challenges for water drainage, increasing the chance of rainwater ingress, especially if the wrong roof coverings are installed or they are installed incorrectly.
Timber roof shingles, however, are an ideal choice for low-pitched roofs because they promote water runoff and are naturally resistant to moisture and rot.
To achieve a watertight roof finish using timber shingles, the gauge of the shingle (assuming the standard 5X or 400mm shingle) must be no greater than 125mm for roof pitches between 22 and 74 degrees (creating a ‘three-ply’ or ‘triple lap’ roof), and no greater than 95 mm (creating a ‘four-ply’ or ‘quadruple lap’ roof) for roof pitches between 14 and 21 degrees.
A vapour-permeable roofing underlay, or an non-vapour permeable roof underlay that meets the requirements of Annex A of BS 5534:2014+A2:2018 is also required. The underlay laps should be sealed using double-sided tape. The underlay acts as a second line of defence against rainwater ingress in extreme circumstances. Shingles should be classed as a close-fitting roof covering and ventilated in line with BS5250, normally eaves to eaves or eaves to ridge depending on the size of the roof and the roof pitch. In some circumstances, it may be necessary to install counter battens to achieve the ventilation requirements.
When installing shingles to, or close to minimum roof pitches (depending on the gauge), it is recommended that nail tape is used below the counter battens (if used) and/ or battens as this provides a seal around the nail fixings, providing additional protection from moisture ingress.
Kevin Taylor, training and technical support manager at Marley, notes that the detailing around roof features – such as valleys, abutments and roof windows – is essential to maintaining the waterproof integrity of a low-pitch shingle roof. “These can be vulnerable points on any type of roof because water can accumulate or flow in unintended directions, leading to leaks and water damage,” he explains. “Specialist products, such as Marley’s GRP dry valley and ventilated abutment system, can help to ensure that these critical roof areas are fully protected.”
Marley’s cedar roof shingles for low-pitch roofs
Cedar shingles are a versatile, reliable and sustainable roofing material that can be used effectively on low-pitched roofs when installed correctly. As part of Marley’s complete roof system, our Western Red Cedar Shingles and Shakes are fully compatible with our other roofing supplies, including our JB red timber battens, roofing underlays and ridge and eaves ventilation systems.
If you're considering cedar shingles for your next project and would like to learn more about their suitability for low-pitched roofs, download our product brochure or get in touch. Our team is happy to answer any questions about low-pitch roofs and provide guidance on roof shingle specification and installation.