Thatch

I heard that good thatch can last upwards of 60 years as a roofing material. It can look pretty cool in the right environment. I wonder how it works. Anybody have any thoughts on the thatch?

(I'm so tempted to post another stupid pic....)

They can work well, physically and visually, but they are labor intensive to construct as well as to maintain further down the road.

You also have to be aware that traditionally there is always a fire inside the structure that is always drying out the thatch from the inside out. So unless you either live in a desert or plan on having a daily fire for cooking/heating as well as moisture control for the thatch, your roof is likely to have mildew/mold problems and a shorter lifespan.

Cool stuff, but probably only practical in traditional applications.

Hey Mo,

I took a framing class a while back at Fox Maple in Maine. They have classes with a thatcher from the UK, but more importantly Steve Chappelle dispelled a few of my own myths. If I remember right the method that Scottish? fellow used wasn't so prone to mold, was very long lasting, and proved to be as fire resistant as just about any other roof. Think there is limitted info on the Fox Maple site, and I may remember something in Joiners Quarterly. I'll take a look soon if I can convince my short term memory to work.

One other thing I remember Steve saying. Just about everywhere on Earth has something you can make a fairly durable thatch roof from, be it coconut fronds, reeds, grass, etc.

Best,

Zach

MO....MY MAIN CONCERN WOULD BE GETTING INSURANCE.A FIRE CLOSE BY WOULD HAVE ME WORRIED FOR SURE.I HAVE A BOOK ON IT AND THEY HAVE
SLATS,THEN ITS COVERED WITH SOD THEN THE THATCH.I`D WORRY ABOUT THE EARTHY SMELL FROM THE SOD AS WELL.
I`VE SEEN THEM IN BRITAIN BUT THEY DON`T HAVE SNOW LOADS EITHER AS FAR AS I KNOW.

CORDWOODGUY

Hi Zach,

The Scottish guy that you have made reference too is probably me. I was at Steve's in Brownville, Maine a few years back and do recall meeting some French Canadians however the thatcher to whom you refer is Jason Morley and he is from Kingsclere in Hampshire, England.

I spend a lot of my time examining old thatched buildings and they can indeed be pretty mouldy and damp but generally this is not the fault of the thatch but more to do with lack of dampcourses and of course the inability to fit rainwater gutters to a thatched roof which does tend to result in localised dampness in the ground surrounding the foundation line (eves dropping).

It is a good policy to maintain a temperature gradient across any old building especially those that are thatch covered and wattle and daub wall panel infilled. Generally aborbent materials can be brought back from the damp and mouldy state through heat and good ventilation provided of course that the source of any water ingress is resolved e.g. a leak in the roof.

Reed thatch (fragmytes) can and does last up to 60 years but as with any thatch it will slowly wear down and thus multiple coats tend to be built up over the centuries as the top or wearing coat is raked down to remove badly deteriorated thatch and then recoated. Oft times the layers in an old roof can be seen like the rings in a tree and very infrequently smoke blackened thatch on the underside can be found. This thatch would be about 450 years old. John Letts (a Canadian resident in England) has researched the types of straw being used in medieval times by examining the seed heads still present on some of this old smoke blackened thatch and he has a number of trial plots where is he growing strains of old fashioned thatching straw. Present day long straw or combed wheat read would be lucky to survive much beyond 25 years today before needing to be recoated with the ridge needing to be done every 12 - 15 years.

I did write and article for Thatch magazine a while back which can be downloaded from my website at :-

http://www.kfhume.freeserve.co.uk/pages/publicationspages/eavesdroppingpages/eavesdroppingframe.htm

The marriage of thatch and oak timber framing (Chene & Chaume) is one made in heaven.

Regards

Ken Hume - Master in Timber Building Conservation