Here’s your 5 minute guide to specifying and designing a low pitched roof. Follow all of the steps below and you will be able to design and specify a low pitched roof correctly.

If you do not have the time to do this, delegate this to us for free and Richard Cook, the slate industry’s longest serving slate technical expert, will turn everything around within 48 hours.

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Step 1

Ensure the exact pitch of your roof.

Step 2

Make sure that you know the site’s exposure rating. This can be determined from page 6 of SSQ’s Slate Design and Fixing guide found here.

Step 3

Find out the size of the slate. Typically slates will need to be as least as wide as 30cm, with a minimum length of 50cm. The rule of thumb is the lower the pitch the larger the slate required. But the exact size can only be determined once you know everything related to the roof.

Step 4

Find out the type of the slate. It needs to be a premium (or “Ultra”) selection as consistency is particularly important for pitches that are low to ensure water tightness and maximise lifespan.

Step 5

Ensure that the headlap is a minimum of 4”

Step 6

Depending on how low the pitch is, you need to be using the right fixing system. Pitches that are particularly low should be using the hook fixing method.

Step 7

Contact your supplier for a bespoke NBS specification which should include all of the above best practice and conform to the guidelines set out in BS 5534:2003.

As mentioned at the top, Richard Cook, the industry’s longest serving technical manager, provides this free of charge with a turnaround time of 48 hours for your convenience.

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Still not convinced? These two case studies show low pitched slate roofs that work…

Case Study 1

Download the PDF to find out more about how a 20 degree pitch roof became the feature of the multi level roof on the banks of the River Thames.

Case Study 2

In this example, a complex, low-pitch, multi-slope roof crowns a luxury mansion set in the hills outside Istanbul overlooking the Bosphorus, the narrow strait that separates Europe and Asia. Download the PDF here for more information.

WARNING AND DISCLAIMER: Failure to comply with any of the above can result in your roof needing to be stripped off and reslated. It is that serious.

Every one of these steps needs to be strictly observed to keep water from penetrating the roof and helping the slates perform as well as possible.

If in doubt refer to BS 5534: 2003 or email us at and we will be happy to help.