Building Surveys of thatched houses and cottages need particular awareness of the characteristics of the different type of thatch, their life-expectancies and what to expect in terms of maintenance. There are three main types of thatch in common use and available in England,:-
A life-expectancy depends on the quality of work and materials and on routine patching. It also depends on the micro-climate of location, including proximity of trees and shrubs, and whether any damage is caused by rodents (mainly squirrels and rats). However, there are some thatchers who claim that their work will last longer than these examples, particularly if they work in areas where annual rainfall is less than average. A rough guide is to say that the further westwards one goes (to Devon and Cornwall, for example), the shorter will be the probable life-expectancy.
[A fourth type of thatch of Veldte Grass from South Africa is gradually being introduced, due to the shortage of the traditional materials grown in the United Kingdom. This is a modern, extreme variation of thatching-practice down the years, where thatchers have traditionally used what was locally available, which gave rise to the many variations of thatch and thatching across the regions of the United Kingdom. The life-expectancy of imported Veldte Grass in the British climate is an unknown quantity.]
All thatched ‘coats’ have a separate ridge-covering along the apex of the roof, which can be one of many types, all being variations of the following two types :-
As with the thatched coat itself, life-expectancy depends on the quality of work and materials and the micro-climate of location, including proximity of trees and shrubs, and whether any damage is caused by rodents. Renewal of fixing-spars can often be required between total renewals of ridges, but such work will not extend the life of the ridge-covering.
Normally, re-thatching in Long Straw or Combed Wheat Reed involves stripping the spar-coat (top-layer) of thatch until the under-coat is found to be a suitable base on which to build up the spar-coat. It is not uncommon to find that existing thatch must be stripped to bare rafters in some places (or everywhere) because the under-coat has been found to be decayed by water-penetration, rodents, or other cause.
Retention of the under-coat usually means that the timber components of the raftered framework under Long Straw or Combed Wheat Reed rarely see the light of day after being built and, therefore carry a greater risk of severe deterioration. However, it is sometimes possible to see something of the raftered framework in the upstairs rooms or in a small roof-space, but often no timber components are accessible.
However, when re-thatching in Water Reed (the most expensive and long-lasting), it is normal for the entire coat is stripped to expose the whole of the raftered framework and its supporting timbers, which means that the timber components of a Water Reed roof can be inspected every 50-70 years for on-going serviceability and repair, if appropriate. Water Reed is now widely imported from Eastern Europe, but it is still grown in Norfolk and other areas.
A thatched coat of about 12ins thickness ( 300mm) will usually provide good insulation against heat-loss.
Similarly, some thatched buildings have walls of brick, and/or brick-and-flint, and/or classic-timber-framing and/or cob (earth), all of which cannot be treated with the same broad-brush approach as brickwork. Many thatched buildings have more than one type of wall under their roof-structures, particularly where today’s building was one or more cottages, or a cottage and attached barn, or other permutation.
When the occasion demands, we are able to call on expert advice for second opinions from those with many years’ experience of practical thatching, and we are able to direct owners (or lessees) to very competitive rates for Buildings’ Insurance and Contents’ Insurance through leading Underwriters with specialist schemes.
For insurance quotations, click here for links to the NFU (Hungerford) and Thatched Owners’ Group