What needs replacing and when?

There are two aspects to a thatched roof:

The coatwork (the main part of the roof) in Combed Wheat Reed, Water Reed or Longstraw.

The ridge (the bit at the top) generally in straw, but can be sedge.

If you know when the roof was last thatched and what material has been used it will give you a good idea when to expect the need for further works.

General guide to life expectancy

N.B. This can only be a guide as there are numerous factors that have an impact on thatch longevity for example: pitch of roof, vicinity of trees, level of rainfall, quality of materials, quality of workmanship etc. For example: a flatter pitched water reed roof in a Devon valley will last maybe 40-45 years where as a steeper pitched water reed roof on a Norfolk hill may last 70 years.

Indicators for a roof in need of repair

A thatched roof only needs replacing because the surface of the roof has rotted away over the years.

Eventually the fixings that hold the thatch on beome visible. Once fixings are visible it tells us that the ‘serviceable’ part of the thatch, once covering the fixings by 8-9” has done its job and is now in need of replacement.

With fixings visible it is possible for water to ingress further into the roof. If action is not taken and the roof left in a poor state of repair it is possible in extreem cases that work is necessary on the timber structure.

You will see two types of fixings. Either metal rod or hazel sticks (known as spars). If either are apparant over a fair proportion of the coatwork it would be reasonable to expect it is in need of a complete re-thatch.

The photo above shows hazel fixings which run horizontally (as would metal rod) with spars skicking into the thatch. It is also possible to just see the ends of spars without a horizontal one. in all cases these would have originally been 8-9" below the surface.

You will also see a vertical gully nearer the ladder where water gets chanelled and wears out the thatch prematurely.

If the remainder of the roof is reasonable it is possible just to patch the gully to give the roof extra life.