Other roof issues

Welsh slate was at its most popular during the Victorian period, and houses may still retain the original slate tile roof. The higher-quality, thicker tiles can easily survive 100 years and more. These will need careful attention, but they are a good sign that the roof, as a whole, is of a high standard. Slates of a lower standard are thinner and may be in a much worse general condition because impurities and cheaper cutting techniques lead to delamination or splitting. Because slate tiles are overlapped by a large degree, it is difficult to remove one from the roof without disturbing others.

Cheaper repairs for cracked or loose slates seek to hold the tile back on the roof by the use of a metal (usually copper or lead) strip, called a tingle. This remedy has been used for a long time and appears to work well, but can look a little untidy if too many tiles are held in in this way. If more that 15% of tiles are held in by tingles, you might suspect that there may be problems with ferrous nails corroding (nail sickness), and that it is time to refurbish the roof.

Slate roofs rely on the pitch of the roof to keep water out. If the pitch is less than about 20 degrees, the roof is likely to struggle. Joints between the tiles can allow water to seep by capillary action to the nails; steeper pitches help reduce this. At 20 degrees, the roof detailing would need to be very good and the roof would be better placed in a sheltered area.

Many slate tiles can be reused when a roof is refurbished, and as many of the original tiles as possible should be kept and re-fixed (following inspection).

Older tile battens may be untreated, and if they become too saturated and start to decay they can sag.