Moss build up on the Thatch

[leonlb]

Hi All

We are new to this site as we have just moved in to our Thatched Cottage in Bishops Stortford, Hertfordshire. The previous owner allowed the trees to grow too high and subsequently there has been a build up of moss on one side of the roof. Tree specialist plan to reduce the trees in February, however, we wondered if anyone could provide us with some advice or share experiences with regard to the moss. Does it cause damage to the Thatch? should we have it removed? will it disappear once the roof is free of the over hanging branches? Any advice will be greatly appreciated. Many thanks

 

[livias]

I am not an expert on thatched roofs but I shall pronounce on this topic anyway.

Do nothing

The moss will stop flourishing when the trees are cut back. I expect that in the summer dead moss will tumble off the roof. I can't see that moss will be doing any harm to the roof and realistically, what could you do to remove it?

 

[88v8]

If the growing conditions are right for moss, ie sufficiently damp, it will flourish.

After rain, moss holds the damp and conduces to the rotting of the roof. It is particularly harmful in valleys, which tend to rot anyway.
On the whole it tends to colonise the north side of the roof, trees or not.
If you physically remove moss, it will pick up with it parts of the rotted thatch, leaving holes which will then rot faster, so that does more harm than good.

You can kill moss on the roof by spraying it with Jeyes Fluid (concentration per label) applied with a pump-up sprayer. One or twice a year should be sufficient. The dead moss will not fall off, but it will be dead and will no longer act as a sponge.

Lichen on the other hand, does no harm at all.

If you are new to thatch, you may not know, but valleys will routinely need redoing after 8+ years, and ridges after 8-10 years, depending on the straw that was used and how damp the area.
Thatch. Warm in winter, cool in summer, but a rich man's roof.

Ivor

 

[xanthe]

You might find this place helpful - it was recommended to my parents who have recently bought a house with hair.

http://www.thatched-group.com/

 

[88v8]

....a house with hair.

Pictures!!
We want pictures

 

[xanthe]

One hairy cob cottage...

http://s1144.photobucket.com/user/helenmayer/media/CGC/HousewithHair.jpg.html

 

[tobydog]

We have a reed thatched cottage with a north / south aspect. Without the help of overhanging trees, we managed to accumulate a vast spongy moss covering the north side to a deep of 2" in places. Due to the nature of the moss, it significantly inhibited the natural run-off process and kept the reed wet for several months of the year. As such we called in the thatcher who did the ridge a few years earlier and he suggested we remove it.

The moss was removed with a modified hedge trimmer. Whilst it did remove a certain amount of reed, most of this was just the dead ends. The roof was sprayed with Roundup which held back new growth although it has started to return after two years.

Some would suggest that this shortens the life of the thatch and, technically, that has to be true because we physically removed some of it. However, this needs to be weighed up with the fact that we found several areas of deep rot that would have gone unnoticed had we not removed the moss.

Unfortunately our thatch sits on a felt liner. Whilst there is air movement between the battens, the thatch probably doesn't breath as well as it might do with a permeable membrane.

I read recently that it's not the north side you normally need to worry about. The south suffers much more from greater temperature fluctuations and damage caused by regular wetting and drying. This is the side that tends to go first, presuming no overly aggresive moss growth.

 

[Penners]

leonlb - I've just responded on your duplicate post. Please don't post twice on the same subject. You only confuse and fragment the advice that you receive.

 

[leonlb]

Many thanks for all the helpful information and advice. As a result of which I made contact with a Thatcher and today. We have organised a time for him to come over and carry out an inspection of the roof. I will update you all with his findings!

Many thanks again