When should I repair my Thatch roof and when should I re-thatch it?


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There comes a time when decisions have to be made about the future up-keep of any thatched roof. Can it be repaired or should it be re-thatched?

At one extreme this decision is made easier if the roof has been leaking or shedding thatch over a period of time and despite the best efforts of your Thatcher the problems remain. In these circumstances it would almost certainly be best to re-thatch.

But what about those roofs that just ‘look tired’? They may appear thin and untidy, the fixings are starting to show and there is an abundance of moss. There is no doubt these sorts of roofs will need work but when will this be, what will the scope of it be and how much will it cost?

This is not a decision a Thatch Owner should take lightly without first gathering as much information as he/she can about the roofs history. In the same way that someone will record the service intervals of their car, most thatched roofs will have a history of being worked on – unless they are newly thatched.

As a starting point, three key pieces of information about your roof need to be tracked down. These are. . .

1. Knowing when the roof was completely re-thatched?

It’s important not confuse re-ridging work with re-thatching work and also your roof may have been partially re-thatched. If you are buying a house and the householder cannot get their hands on any old invoices from the Thatcher, ask them who thatched it. If they don’t know, make enquiries of a
few local Thatchers. They don’t have to visit the property (so shouldn’t charge you) and they may be able to shed some light on who did the work.

2. Knowing when was the roof re-ridged?

Because the time intervals for re-ridging work are more frequent (approximately 10-15years) it should be easier using the above methods to trace the Thatcher.

3. You should be aware of the life-spans of the different thatching materials and what material(s) your roof is thatched with?

It has to be said that not all Thatchers will agree on exact life-spans for the 3 main thatching materials which are Water Reed, Combed Wheat Straw and Long Straw but it is almost universally accepted that Reed is the longest lasting and Long Straw the least.
Please see my blog – What is the Lifespan of a Thatched Roof?

Once you have this essential information, it will enable you to start making some judgements about your roof. The roof might have been thatched 40 years ago in water reed and re-ridged 10 years ago. It might have a 20 year old coat of Long straw. Your ridge may be only 4 years old. The key here is matching the age of the roof with how long the material is supposed to last.

This will go a long way towards telling you how many years life the roof should have left in it and therefore what future work should be considered.

So far so good. The difficulty now is that not all roofs last as we think they should. How do we explain why a 15 year old roof looks a lot older and has hollows in it? Why does that 25 year old ridge still seem in relatively good condition? Going back to the car analogy why do some cars seem more reliable than others and seem to need less work doing to them?

Unfortunately this is where things become a bit more complicated. It is now important to be aware of other less tangible factors.

I have listed these below – all of which will have a direct impact on your roofs present condition and its ‘performance’ going forward.

 The Skill of the Thatcher will play a very great part.
 The decisions the Thatcher took when thatching the roof are crucial. Thatching is a craft so
Thatchers will all work differently!
 The quality of the materials are obviously important
 The pitch of the roof; a slacker pitch will wear more quickly.
 The aspect of the roof (is part or all of it in shade for most of the day as this will encourage moss and damp)?
 Does the roof have overhanging trees or shrubs? These may keep the roof in the shade, which will in turn keep the roof damper and encourage the build up of moss.

When you step outside and look up at your roof, try to identify what YOU consider to be the exact problem(s)? To what extent are they of an aesthetic nature or are they more serious? Just as the odd broken tile can be replaced, a thatched roof can also be selectively repaired. A badly worn valley on its own does not necessitate a re-thatch! That hole that seems to be shedding masses of thatch is probably no bigger than your fist. Why remove 2-3mm of moss if it grows back within a year?

I have included this photo as an example of how difficult it is to make judgements about parts of a roof. Is the dark water staining to the under eave of this roof a sign that water is penetrating the thatch or is it just running down the top of the thatch and along the under surface of the eave? Maybe it’s a combination of the two.

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Clearly you cannot make decisions about matters such as this without first speaking to a Thatcher and discussing the exact specification he is recommending for your roof. Why is he suggesting fitting wire netting to the whole roof if it’s never had it before and you have never been troubled by birds pecking at it? Why does one Thatcher say all of the existing thatch should be removed and another that a new layer is put on top of the old? Remember – the decisions a Thatcher makes on your behalf will affect its final appearance and also its future wearing qualities. However these judgements should not be confused with the Thatcher’s intrinsic thatching skill.

Many thatched properties are very old and will have been worked on many times. Unfortunately you may have inherited a property where previous work has not been done in the best interests of the roof or planned over the medium to long term. Just as you will be having to make decisions about your roof, previous owners will have gone through the same process.

The Thatch on your roof is just a part of your property (albeit it an important part!) and at the end of the day you will make decisions about the roof based on your personal circumstances. Cost will be a prime factor. It might be the case that you just want it to keep the weather out and are not too concerned with its appearance. Alternatively you may want to sell your property and put it on the market in prime condition with a new thatch. Finally you may simply want the work done so you can enjoy it – after all for most people the whole point of having a thatch is for it to look good.