The Essential Guide to Thatched Roof Maintenance
The natural order of the world we live in dictates that just about anything will fall apart over time if it's not maintained. Your house is a good example. Whether you have a thatched roof or one made of slate tiles, the entire structure of your house must be maintained to prevent natural decay and dilapidation. As for thatched roof maintenance, it is part of the responsibility that comes with having this sort of roof.
One of the benefits of a thatched roof is its durability. Where slate and asphalt tiles may have a lifespan of 20 to 30 years, a high-quality thatched roof can last twice as long without the need for re-roofing. But the key to long life is maintenance. The more effort you put into maintaining a thatched roof, the longer it will last.
Thatched roof maintenance starts with routine inspections. According to the Conservation of Traditional Thatch Group (CTTG), regular inspections are necessary to identify any signs of deterioration as early as possible. As with any kind of home maintenance, maintaining a thatched roof is a lot easier when problems are identified as soon as possible.
What to Look for in Inspections
The CTTG offers an excellent inspection checklist that can be downloaded from their website free of charge. They list dozens of items to be checked in various categories broken down to make thorough inspections more manageable. Below is an abbreviated list of items on their checklist:
Main Thatch:
Thatch slippage
Loose stalks on the thatched surface
Presence of vegetation
Evidence of birds or rodents
The appearance of wet areas
The appearance of any decay
Ridge:
Unusual depressions
Evidence of birds or rodents
A visible base coat (it should not be visible under the ridge)
Erosion or slippage of thatch material
Gables/Verges:
Gable lines (should be straight when viewed from below)
Signs of verge erosion or material slippage
Underlying Structure:
Structural support beams (no signs of rot or decay)
The presence of mould or algae on underside of thatching
Unusual depressions in thatching material
Evidence of rodents
There are lots of other items on the checklist, but you get the idea. A routine inspection of a thatched roof should make it easy for property owners to identify problems as soon as they appear. Conversely, ignoring routine inspections makes identification much more challenging because the property owner doesn't know what the roof is supposed to look like.
General Maintenance Procedures
Even though a good thatched roof can go 50 to 60 years without re-roofing, ridges are different. The expected lifespan of a thatched roof ridge is about 15 to 20 years. In order to keep both the main coat and the ridge in good condition, the property owner should keep in mind the following:
Keep the area over the roof clear of anything that might block the sun or keep rain and snow from dispersing.
Immediate efforts should be taken to remove excessive moss as it tends to trap moisture. Small patches of moss are generally not a concerned.
Leaves and any other debris trapped in netting should be cleared so that moisture is not trapped underneath.
Tradesmen should never be allowed to walk directly on the roof surface. Any divots or depressions caused by falling objects should be addressed immediately.
Any isolated holes should be patched with the same kind of material. Patches can be held in place with spars or screws.
A general rule of thumb with thatched roofs is to disturb roofing materials as little as possible. For example, a tradesman who comes to work on the chimney should not walk directly on the thatch. He should run a ladder over the top of the roof and walk on it.
Making sure a thatched roof remains undisturbed suggests doing some other things as well. For example, television aerials or dishes should not be mounted on the roof. If they cannot be mounted indoors, a better option would be to mount to the side of the house or on a pole or stake in the garden.
More about Patching
Patching is one of the easiest parts of thatched roof maintenance but one of the most concerning as well. Should a hole appear in a thatched roof, the first thing the property owner must do is assess the cause. Is the hole a result of birds or rodents trying to nest in the roof? If so, patching alone may not be an effective solution.
Thatched Roofing in the Modern Era
If pests are a problem, the homeowner may have to install plastic netting to prevent future problems. Netting can be fitted across the entire roof or in key places only – like the ridge. Any installation of netting should be handled by a professional who knows how to do it right.
Perhaps a hole is not the result of birds or rodents. It could be that there is some damage to the underlying structure that has led to a loss of support underneath the roof. In a case like this, it would be necessary to repair the underlying structure before patching the hole. Otherwise, any damage to the underlying structure could spread and present a more serious problem in the future.
Re-Ridging the Roof
Replacing the ridge may not seem like routine thatched roof maintenance, but it actually is. Roof ridges take the most punishment from both the elements and animals. And because ridge lines reach an apex, they also represent the weakest link in the thatched roof. Therefore, ridges must be inspected more regularly and replaced more often.
Replacing a ridge generally requires removal of just the top layer only. If netting has been applied, that must be removed too. The thatcher will remove enough of the roofing material to create a flat surface onto which a new ridge can be built. This process can add years to the life of a roof.
Many thatchers take the occasion of replacing a ridge to 'dress up' the main coat at the same time. What is dressing up? Is the process of knocking down the existing thatch so that it is once again firmly anchored in its fixings. This is necessary due to the tendency of wind to pull up on thatching materials. After a roof has been dressed up, it is then brushed down. Brushing down removes loose material, moss, and any debris that might trap water and speed up decay.
The Question of Conservation
Property owners have one of two ways to look at thatched roof maintenance. The first is to look at it simply as a matter of preserving one's investment in the property by taking care of it. This mindset does not necessarily look at a thatched roof in any historical or emotional terms, but rather as a functional piece of the structure no different from siding or the foundation.
The other way of looking at maintenance is through the lens of conservation. This mindset sees the history behind thatched roofs and the importance of that history to the UK. A conservation mindset doesn't want to simply protect the monetary investment in the property; it wants to protect the historical significance as well.
How do these two mindsets play out in terms of practical thatched roof maintenance? In short, the conservation mindset generally leads a property owner to put more time, money, and effort into preserving a thatched roof rather than simply maintaining and eventually replacing it.
Conservation involves a minimum amount of intervention so as not to disturb the thatched roof. It advocates 'like-for-like' replacement of roofing materials whenever repairs have to be made. It involves hiring only skilled craftsmen capable of repairing and maintaining the roof according to its historical roots.
Extend the Life of Your Roof
You should now have a good idea of what is involved with thatched roof maintenance. If you have a thatched roof on your property, understand that addressing routine maintenance will extend the life of your roof indefinitely. It is like any other maintenance project on your property. Putting the time and effort into maintenance reduces decay and extends life.
Remember that thatched roof maintenance starts with routine inspections. You should be looking at your roof at least a couple of times a year, especially at the change of seasons. At the first sign of any maintenance requirement, it should be addressed immediately. When it comes time to re-ridge or add a new coat, only hire an experienced master thatcher willing to take the time to do the job right.
Sources
http://www.traditional-thatch.org.uk/content/caring-for-thatch/condition-assessment
http://www.traditional-thatch.org.uk/content/wp-content/uploads/2013/02/Thatch-Condition-Checklist.pdf
