Re-Using Old Welsh Slate
Good quality Welsh Slate can often be re-used after 60-80 years on a roof. The percentage of salvageable slate will be dependent on a number of factors:
- Slates need to be carefully removed, ideally with a slate ripper, avoiding damage to the nail holes.
- Slates for re-use need an initial visual examination of the fabric of the slate. Particular attention should be paid to ensure that there is no excessive spalling to the nail holes and that there is no sign of delamination to the slate.
- The slate should still "ring true" when struck, if there is a dull thud then the slate is no good.
- Check that the existing holes are at the correct gauge to maintain the specified headlap. If the existing holes are enlarged then re-holing will be necessary and will only be possible if the new holes can be positioned no more than 30mm from the edge of the slate. In some cases the slates will have been re-fixed already during their lifetime and there may be multiple nail holes in the slate which would make its re-use almost impossible.
- If re-holing of the slates is necessary the existing holes should never be below the new holes as this could compromise the weather tightness of the roof.
- Sort re-usable slates into batches of slate of the same thickness laying the thickest slates at the eave and the thinnest up to the ridge.