The When, Why and How Guide to Thatched Roof Replacement
You may have heard that a good quality thatched roof can last as long as 60 years. That's true. A roof made of Norfolk reed and installed by an exceptionally skilled craftsman could very well outlive that craftsman. But nothing lasts forever. Thatch roof replacement is a normal part of owning a structure with one of these roofs.
Property owners can reduce the frequency of total replacements by adhering to standard maintenance procedures for thatched roofs. Those maintenance procedures include:
Routine roof inspections
Clearing of moss and debris
Addressing birds or rodents in the roof
Periodically replacing the ridge
Patching any holes with the same material.
A well-built ridge can last between 15 and 20 years, so only one or two replacements should be necessary before a thatched roof needs total replacement. When replacement time does come, it should be left to a master thatcher with plenty of experience.
How to Know When to Replace
Let's say a property owner purchases a home with a thatched roof and is told the roof has another 20 to 30 years of life left in it. How is the property owner to know this is true? After all, it's hard to tell much about a thatched roof from the ground. That's why routine inspections are recommended. Inspections identify small problems that can be addressed quickly, thus increasing the life of a roof.
Even with inspections, thatching material loosens and break down over time. So part of routine maintenance is dressing up and brushing down. Hiring a professional to handle this accomplishes a couple of things. First, the professional will know how to dress up and brush down without damaging the roof. Second, a professional will be able to tell when a total thatch roof replacement is necessary as opposed to adding a new coat.
If you're not aware, there is a significant difference between the two procedures. Adding a new coat does not involve removing the existing roofing materials save the ridge. The thatcher simply builds a new layer of roofing on top of the existing layer. However, you can only re-coat a thatched roof so many times.
A single coat is usually 10 to 12 inches thick. Therefore, re-coating more than twice could exceed building regulations in some restrictive areas; it might also make the roof so heavy that the underlying structure can no longer support the weight. The general rule of thumb is to re-coat when possible but replace when necessary.
Overcoating and Spar-Coating
The historical significance of thatched roofs makes it terribly difficult to recommend a complete strip and replacement. So thatcher's in the UK try to avoid complete thatch roof replacement if they can. One way to do so is to employ either an overcoating or spar-coating strategy.
Overcoating and spar-coating are procedures that involve removing just enough existing thatch to provide a firm base for a new coat. Older layers of thatch are left alone to preserve their history or simply to reduce costs. Overcoating and spar-coating have been practised for centuries, which is why some of the oldest buildings with thatched roofs still have some of their original layers intact.
Unfortunately, not all thatched roofs in need of replacement can be saved by overcoating or spar-coating. For example, some roofs consisting primarily of 40-year-old water reed must be stripped right down to the bare timbers when it comes time to replace. Only an experienced thatcher can decide the best course of action when it looks like replacement might be necessary.
Local Regulations Must Be Adhered To
The first thing most property owners think about when it comes time for thatched roof replacement is cost. That's not necessarily a bad thing, given that property owners don't want to spend more than they must on the upkeep of their homes. But there are other considerations to be accounted for, including local regulations that have to be adhered to.
Local authorities have enacted regulations over the years for the purposes of preserving thatched roofs. Take the county of Devon for example. Devon boasts the largest volume of thatched roofs1 in the world. There are literally thousands of thatched structures in the county. Almost all the residences are listed properties, meaning any repair or replacement of a thatched roof must be done in accordance with the county's official guidance.
A listed structure in Devon would be subject to roof replacement using either identical or similar materials. The roof would not be able to be altered to any extent that it would destroy the character of the existing structure or be significantly different from other structures with similar roofs. In other words, local regulations require property owners to meet historic standards whenever possible.
The last thing a property owner wants to do is hire a contractor to replace a thatched roof without seeking local permission and understanding local rules. A thatched roof that is replaced in violation of local regulations could mean significant penalties. In some cases, property owners could be forced to remove the roof and start over.
Thankfully, master thatchers take great pride in their work to the extent that they are reticent to make repairs or do replacements without being absolutely sure of local rules. It is the contractors who are not master thatchers that property owners need to be concerned about.
Hiring a Master Thatcher
When a thatched roof replacement is necessary, the property owner's choice of contractor will primarily determine the finished product. As with any other home maintenance or repair project, great care should be taken to properly vet contractors by way of estimates, references, and so on.
There are several questions property owners can ask when vetting contractors:
What materials do you use and from where do you source them?
What is the best material for my roof, and why?
What kind of maintenance will be necessary after replacement?
What kind of ridge are you planning to lay?
How long will the project take?
What kind of guarantees/warranties are offered with your work?
Do you have references I can contact?
Are you covered by insurance?
Do you do the work yourself, or do you sub-contract?
It's always good to get at least three or four estimates before starting a replacement project. Multiple estimates accomplish several things. First, they quickly identify contractors whose prices may be so low as to indicate poor craftsmanship. Second, having multiple contractors look at a property should result in a more thorough understanding of the condition of the roof. And third, getting multiple estimates prepares the homeowner so that there are no surprises at the end.
A master thatcher with a good reputation should offer a fair price for total replacement. His estimate should be itemised, which is to say he takes the time to list everything involved in the job along with its cost. One thing to remember, though: an estimate is just that. There may be additional costs involved once the replacement project begins.
Thatch Roof Replacement in Summary
To summarise our discussion on thatched roof replacement, it is a normal part of property ownership. A well-built roof constructed with high-quality materials should give you anywhere between 40 and 60 years before total replacement is needed. Should you suspect you may need replacement, contact several contractors and ask them to come by and take a look.
If overcoating or spar-coating is recommended, going that route is generally recommended over total replacement. But if your roof needs to be stripped back to the timbers and rebuilt from scratch, make sure your contractor is a master thatcher with plenty of experience and a commitment to do the job right.
Sources
http://www.devon.gov.uk/thatching.pdf
