A stitch in time… Makes good sense and saves money
What to look for:
- Broken nibs
- Missing tiles
- Moss growth
Most of the comments above apply also to tiles.
Roofing tiles are made from fired clay in the same method as bricks and traditionally were produced by the same manufacturers from local clays generally for use in the areas immediate to the works. This has led to many regional variations in colour, size, thickness and profile of tiles.
As with slates, the durability of a well maintained tile roof should have a lifespan of well over a century.
Various fixing methods are used. Some clay tiles are nailed into place in the same method as slates whilst others have ‘nibs’ on the back which hook over the battens (nibs are common in profiled tiles). Peg tiles use an oak peg, or ‘drops’,(now commonly aluminium or nylon) to hook the tile onto the roof batten.
Inspect the roof as for slated roofs above. The most common defects are loose or broken tiles or damaged timber battens or boarded substrates. Tiles can become porous and weakened with age.
Replacement tiles should match the original tiles on the roof as closely as possible and should be laid in the same fashion. Plain tiles are usually double lapped (the end of a single tile overlapping the head of a tile two courses below), profiled tiles (such as s-shaped pantiles) are often single lapped.
If replacing a tiled roof new battens need to be spaced precisely to ensure the tiles maintain the appropriate lap over their underlying neighbour. If the roof is to be insulated then it may be necessary to introduce counter-battens to create adequate space for the insulation. However this thickening of the roof depth can be particularly noticeable at verges and eaves.
Original tiles should be reused whenever possible, as well as being the most economic option this will maintain the character of the roof. When reusing tiles it is important to remove surface soiling such as moss as this can promote the retention of water and speed up the decay of the tile. The use of chemicals for cleaning should be avoided as this may damage the tiles. The use of a hard bristled nylon brush, as with slates above, is the simplest method.
There is a big difference between hand-made and machine-made tiles in overall appearance and, in some cases, durability. The regularity of the shapes, sizes and colour of machine made tiles are often unsuitable for a historic roof. New tiles for replacement should match the colour of the existing tiles as they were when first laid as they will blend in after a few years of exposure to the weather.
If appropriate, during a full roof strip, replacement tiles can be positioned in unobtrusive areas to avoid the impact of new tiles against old with reused tiles relocated to the more prominent locations.
Handmade tiles produced in the traditional fashion are still commercially available and although more expensive than a modern tile their use should be considered.
Modern concrete plain tiles should not be used as a replacement for a clay tiled roof. Along with the detrimental visual aspect, concrete tiles are often heavier and thicker than clay tiles and the roof structure may not be sufficiently strong to accept the additional weight. Concrete tiles can also deteriorate much quicker and have a limited lifespan when compared to clay.