All you need to know about thatched roofs

So, you have seen your ideal cottage, but it has got a thatched roof and the fear of the unknown enters your purchasing decision. What are the key considerations when considering when purchasing or owning a thatched property?

Trevor Musk, company director and head of Durrants Building Consultancy explains.

It is costly to repair and replace a thatched roof?

The thatching cost usually is based on the area of roof to be thatched. Thatcher’s work on “square” 10 feet by 10 (100 square feet). The average roof is around 6 – 12 square although some properties are 4 square and some 80 square. The cost also depends on factors such as shape of the roof, type of material, design of the roof, ridge type and style whether wiring is required, the type of flashing required and more.

The thatcher may not know what work is required to the timbers before the original thatch is removed. This can sometimes create an additional cost.

Always get your thatching quotations in writing so it is clear what you are being offered and also so that the thatcher is not asked to do extra work which is not quoted for. As with all things, the most expensive quote may not be the best thatcher and similarly a cheap quote not the worst, but again you do get what you pay for. Ideally use a thatcher registered with the National Society of Master Thatchers (NSMT), although not all thatchers are members of this organisation.

What type of thatch is it?

There are three main thatching materials used on roofs, Water Reed, Combed Wheat Reed and Longstraw and there are other materials used. These vary in application, style and longevity. Thatch is an environmentally friendly building material.

Water Reed

This material is widely used throughout the UK. It is also known as Norfolk Reed and Continental Water Reed. This material is very hard and has the longest lifespan of all the thatching materials. There are always exceptions to the rule but Thatch Advice Centre knows of roofs which are over 60 years old. New properties are thatched in this material because it gives the most cost effective roof to customers. To change to this material on a listed building would require Listed Building Consent. Water Reed roofs are generally straighter and less rounded looking than the other materials

Wheat Reed

This may be called Wheat Reed, Combed Wheat Reed or Wheat Straw. Combed Wheat Straw has been used as a thatching material for decades. It was the by product from grain production. The advent of combine harvesters has meant that it is now a specialist product, only produced by those with the old fashioned machines. It is labour intensive by modern day standards. Combed Wheat Reed roofs generally have a more rounded appearance than Water Reed. This material has a lifespan of around 25 – 35 years.

Longstraw

This is the same material as Combed Wheat Reed but it is produced differently once it has been brought in from the field. A Longstraw roof is more shaggy in appearance as the straws are put on with both ears and butts of the material facing downwards.

How do I know if the thatched roof is in good condition?

Before the purchase of a thatched property we would always recommend to get an independent survey of the roof by a thatcher and again one that it is registered with the NSMT.

Indication of a worn roof – on the ridge, the wire netting may be left raised where the thatch has degraded and the fixings (spars) may well be showing sticking out. The ridge may well be perfectly serviceable even if the fixings are showing and it is looking a bit untidy.
Lines across the main roof coat work and dips also indicate wear. Moss and lichens often are associated with well decayed roofs and sometimes the roof has reached a stage in its life where moss is best left as to remove it will do more damage than good.
If you look at the eave and see a triangle of dark material it may indicate water ingressing and wear of the roof.
Lead and cement flashings coming away from chimneys and gaps where they meet the thatch should be checked and cement flashings which are cracked or broken may need looking at. Lead flashings are the best.

Does having a thatched roof affect my buildings insurance?

Firstly, it is very important that you have buildings insurance on your thatched property. It must be appropriate and have the correct rebuild cost included. Be aware of what is and what is not covered and if in doubt ask the question before taking out the insurance. Understand your property and that most insurers will ask specific questions about your property, its thatch and construction.

Everyone believes that thatch is more expensive but, as with all insurance, if you know what you want and shop around for a specialist who meets your needs you can get a good solution. Be aware that some insurers are cheaper for a reason, other offer certain covers as standard which some insurers have as additional features. Be sure that you compare ‘like for like’ when getting insurance for your thatched property.

If you are wrong with your rebuild cost, and you need to rebuild your property for any reason, your pay out can often be very disappointing. You will potentially be paid out less, by the % of the amount you were underinsured, which often means if you are for example 50% underinsured, you would only get say 50% of 50%, e.g. 25% of the sum you were expecting. Specialist insurers now ask for more checks and precautions to be taken in order for them to be able to give cover. Often insurers will carry out their own survey of a property within the first few weeks of setting up a policy. This is for their own risk assessment purposes.

How and when do I maintain a thatched roof?

The lifespan of a thatched roof and therefore its maintenance requirement is due to several factors. Because of the natural degradation of the material over time, it will eventually reach the stage where it requires completely rethatching. Repairs may extend the life of certain areas but it will reach a situation where there is no life left in the surrounding material and it is false economy.

Keep an eye on your roof and any changes especially before and after the winter period. Always get more than one quote for work which requires doing so that you avoid the ‘rogue thatchers’ touting for work. Unfortunately they exist in all trades and memberships and smart websites are no guarantees. Establish early on what condition the thatch is in, then any necessary work can be quoted for and planned into a schedule of maintenance.

If a listed property requires a total rethatch, the local council listed building department/conservation officer should be consulted. The owner and thatcher should both seek the relevant advice from the authorities if they are uncertain as to the requirements. Listed Buildings should always be maintained on a like for like basis
Generally the ridge of the thatch will require replacing every 10 -15 years. The coat work will vary depending on the material used and its associated lifespan.
To keep the roof in best condition:
Allow it to dry well, remove trees and plants which may hinder the sun and wind drying it or rain dispersing. If it is damp it will also increase the likelihood of moss and algae growth which in turn keeps the roof wet.

Do not allow other trades to damage the roof either with ladders or by walking on the thatch. Any divot created has potential to accelerate the wear of the thatch and on the ridge damage to fixings can be especially detrimental to the roof life.

Do not assume that because the roof looks neat (with a good- conditioned ridge pattern) that it is prime condition. Often sellers get a new ridge done on an old roof which is beyond its life just to sell it.