Other roof issues

Thatch is probably the most universal roof covering of all time and still remains popular today. The most common material for thatch was straw, as it was widely available. Reed is considered to be the best material for thatching, but it is not apparent that this was a universally used product for common domestic construction. No thatch will be original, but there is strong debate about the appropriate type of replacement material. Many local authorities have reed-only thatching policies so check local preferences. The demand for reed can often outstrip supply, so householders need to plan thatching work well in advance (possibly years), if reed is an absolute requirement.

The performance of a thatched roof is best assessed on the principle of form following function. That is: neatness, slope and durability. Thatched roofs work by taking the water off the roof as quickly as possible and dropping it to the ground to be absorbed. All of these factors need to be in place for the whole system to work, so it is imperative that the eaves are deep, the area around the building is porous and well-drained and the pitch is at least 45 degrees. (In the South West, thatch pitches tend to be shallower than elsewhere in the UK, which can shorten the life span).

It is not easy to quantify the lifespan of thatched roofs, as they can be added to (toppings) or easily repaired, but the ridge usually requires attention after 10 years or so, as it is the most vulnerable part of the roof in high winds. Ridges are defined as either flush (butt up) or cut (wrap over). A water reed thatch is expected to last upwards of 50 years, with wheat reed lasting between 25 and 30 years and straw between 15 and 25 years.

Thatched roofs are vulnerable to moss growth and vermin attack. Often, wire netting is added to roofs to prevent animals nesting, but moss growth is usually connected to weather conditions and roof exposure. Removing moss can cause parts of the roof to come off with it, and there are mixed views on the benefit of removing it.

Water penetration problems mainly occur at the junctions between the thatch, walls and chimneys. These areas can be repacked during regular maintenance.