Technical tips – clay plain tiles

Plain tiles made from clay have been used to cover roofs in Britain for over 800 years and they form much of the character of the roofs seen in the South East of England and the Midlands.

If you’re looking to add warmth and character to either a refurbishment or newbuild project, then clay plain tiles are a great choice. Although some roofers do have concerns about installation being time consuming or difficult, this doesn’t need to be the case, providing you plan carefully, pay attention to detail and have the right tools.

Here we take at look at some common technical queries:

1. Will I have to cut clay plain tiles?
Cutting is one of the most frequent things our technical team gets asked about clay plain tiles. Clay is a natural material and following the firing process, during manufacture, it becomes very hard. This is great from a long-term durability point of view, but it does mean the tiles are harder to cut than equivalent concrete tiles.

In order to reduce the amount of cutting required, planning is very important to ensure the best fit and largest width of tiles can be used, while also maintaining the broken bond laying pattern. Small pieces should be avoided. Experienced roofers will adapt to and account for these factors to ensure they can create a high-quality aesthetic finish.

However, regardless of planning and experience, you can’t avoid cutting clay plain tiles altogether. It is inevitable that cuts will be required during the installation process, for example, when completing hip and valley detailing, where raking cuts to roof tiles will be required.

2. How should I cut the tiles?
All cutting and drilling of tiles should be carried out in well ventilated areas to prevent the inhalation of dust, in accordance with Health and Safety recommendations. Wherever possible, avoid dust inhalation by using cutting equipment fitted with dust extraction or dust suppression. Always wear appropriate personal protective equipment (goggles, protective clothing, ear defenders and an approved respirator) when mechanically cutting tiles.

Avoid cutting tiles that are laid in situ, particularly open valleys, as this may cause damage to the valley lining and is also a health and safety hazard. After cutting or drilling tiles, brush off all dust from the surface to avoid staining.

3. What tools should I use?
Traditionally roofers would have used a scribe and hammer, or pincers and this method is still used today. However, these days most contractors will use power tools that are specifically designed for a hard material, such as a diamond tipped masonry disc cutter. These must be used with appropriate dust suppression. Further guidance can be sought from your tool supplier or Marley Eternit’s technical advisory service.

4. I’m creating a curved roof, what tiles should I use?
Double lap tiles are the only small element roofing materials that lend themselves to curved roofing. Single lap interlocking tiles are not suitable.

In particular, our Acme Double Camber range is ideal when you want to create a curved roof because of its latitudinal camber. However, all of our Hawkins and Acme Single Camber tiles can also be used to create curved roofs and you can get advice on how to do this from our technical team. As an advisory note, we do recommend that curved roofing projects are only undertaken by experienced roofers.

5. How do I cut Double Camber tiles?
Some taper cutting will be required subject to the radius of the curve. BS 5534 also states that the sidelap should be no less than 55mm.

6. What are the main things to consider when installing clay plain tiles?
Careful planning and attention to detail are crucial – don’t rush into fixing the tiles. Attention to detail will pay off with the end-result that you get.

Thoughtful specification of tiles will give you the best finish and take time to select the most appropriate fittings for each project. Fittings can make a big difference to the overall look of the finished roof, more so on clay roofs than with any other roofing material. For example, bonnet hips or arris hips will both give a different aesthetic on the finished roof, even though they serve the same function.

www.marleyeternit.co.uk/clay