Double lapped concrete tile
Double lapped concrete tile
The double lapped concrete tile, is commonly seen on roofing along the coast and generally from the 1930’s onward. These have a suggested lifespan of 80-100 years. These do offer a roof with very long lifespans.
There are more common clay double lapped tiles, on single storey bays and these will last up to 70-90 years. As this was such a labour-intensive method of roofing. It was no seen on main roofs in the Victorian era as much.
The double lapped tile is the much smaller rectangular tile, that are completely overlapped. So in essence you have two completely layers of tiling. As opposed to more common half lapped tiles. These are not half lapped and tend to only be lapped by 75mm or 100mm. So really these should be called a 5th lapped tile!
Bristol
The double lapped plain concrete tile roofs are common on the 1930’s era estates. Such as Patchway in South Gloucester. Some of these roofs that are present do not have felt beneath them. This is as the double lapped tiles offered great weather proofing. Without the need for felts. Unlike the much more common half lapped tile. We often see the lack of felt being cited by other surveyors as reason enough to replace the coverings.
Reactive Vs proactive
Lots of these are still performing well. However as with most things on the assumption they are well maintained. If they are not a value argument can then be made for replacing the entire roof covering.
However, when there is no felt present. There is greater ventilation to help dry the timber battens on to which the tiles are hung. These battens can also be seen throughout the roof covering. Hence, they can easily and regularly be inspected.
The trades perspective
These tiles can last a very long time. Repair to individual failed tiles is relatively easy. Timber wedges placed either side of a broken tile. Lifts the surrounding tiles so a damaged one can easily be removed and replaced. When replacing a double lapped roof. We often see them being replaced with half lapped tiles. This is simply due to cost. Double lapped tiles require more battens, more labour. Hence are much more expensive than half lapped roofs so they are falling out of favour.