Roofing Question

The moss on the roof is causing slates to lift

We have a grade 2 listed cottage and there is a lot of moss on the roof which has caused the slates to buckle at the edges. Been told to not remove the moss as it will let water in, but we have had 2 leaks in recent years and wondering if we need a new roof?

3 Answers

Best Answer

Natural slate roofs along with traditional clay plain tile roofs, although can get debris build up between the joints do not generally moss up as much as man made products.
Some have a natural camber, but I have not yet witnessed a natural slate curling at the edges over time.
The roof covering you are describing is a man made fibre cement slate, they used to contain asbestos, and an asbestos survey is usually carried out prior to any removal works.
We find them on a lot of old farm buildings.
Obviously as the building is listed, you will need to obtain consent to renew the roof coverings and the new roof will be specified accordingly.
Believe it or not they may specify a new slate to match the existing or if the roof originally had natural slate on, may want you to put on as original, however being grade 2 there is a lot more leniency.

If done correctly the moss can be cleaned off the roof which will definitely help, however if the roof is old and does contain asbestos you yourself cannot, nor can you instruct anyone else apart from a qualified asbestos company to do so.

I hope this helps
Bert
Donovan Contractors

Answered 8th Feb 2013

Donovan Contractors Limited

Member since 9 Jan 2013

It sounds like you have old asbestos or fibre cement type slates as these do tend to attract a lot of moss . I think the person who told you it would leak if the moss was removed may think the rain will get underneath the buckled slates . I think it may be worth employing a roofer to clean the roof initially as I don't think it will leak just because the moss has been removed . Get at least 3 quotes from good roofers off this site & ask their advice about the cleaning cost as opposed to new slates & then compare & make your decision.

Answered 7th Feb 2013

Norjan Properties Ltd

Member since 20 Jan 2010

iam presuming it is the original roof.
in which case it will not have any underfelt in place, as it was general practice to bed the tiles onto the roof batons using lime mortar this acted as a barrier against water ingress.
the lime mortar would catch any rainwater that penetrated the tiles hold it and allow it to expell natually thus allowing your roof remain watertight and to breathe.
overtime the lime mortar will have worn out and eroded alone with your slates thus allowing water ingress into the property, any damage to the slates will also allow increased water ingress as their is no underfelt in place to stop the water entering the propety.
underfelt is your secondary defence slates being your first

as it is a listed building their are three people you have to keep happy.
english heritage [ your local listings officer ]
planning, [ your local planning office ]
building regs [ who will sign off the job once completed ]

although it may sound daunting the person that is most important is the listings officer as planning will follow their lead and provided the roofer has done his job properly building regs will just rubber stamp it.
as it is a listed building you will not be able to replace the roof without getting full consent from the planning officer at your local council that would take approx 12weeks to achieve consent your roofer will have to supply samples of the new slates they wish to put on your roof.
as you will only be allowed to replace like for like
a chat with your roofer and your listings officerpreferable to-gether is your best way forward to achieve a trouble free project shouls you wish to go along this route.
should you require any further information feel free to ask.

good luck alex

Answered 7th Feb 2013

ADR Property Maintenance

Member since 1 Mar 2009

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