Is moss harmful to roofs? 4 December 2022 at 11:39PM in In my home (includes DIY) MoneySaving 20 replies 1.1K views

sevenhills

I have a small amount of moss on my flat roof. I noticed someone on Facebook asking for someone to remove the moss on their house roof.
I assume moss is harmless, just that it may need removing before I repaint my flat roof.

diystarter7

Hi

It can be but rarely is unless it takes over flat roofs.

Don't pressure the washer
it off but use a brush. stiff brush but try not to remove the shingles on the roof but some will come off by just walking on it.

I've noted on a rental we have that has a small section of a detached garage in a shaded area moss grows - we brush it off every 2 years or so - usually in a dampy area. and easier to remove when damp.

where glove, eye cover and  face mass especially if it is very dry.

Thanks

FreeBear

Moss is only a problem if/when it blocks the gutter. As long as the growth isn't excessive, just leave it - That's what I do..

MoreProbs

I've no idea, so asking - what would happen if you used a moss killer? Would it die off and erode away, or would the deed stuff remain?

Keep_pedalling

MoreProbs said:

I've no idea, so asking - what would happen if you used a moss killer? Would it die off and erode away, or would the deed stuff remain?

The dead stuff would remain, especially on a flat roof, and new moss will spring up. No need to spray poison on your roof.

Section62

sevenhills said:

I have a small amount of moss on my flat roof. I noticed someone on Facebook asking for someone to remove the moss on their house roof.
I assume moss is harmless, just that it may need removing before I repaint my flat roof.

Most of the time there is more risk of damaging the roof from trying to remove the moss than there is from the moss itself.

E.g. using a "stiff brush" on a felted roof risks tearing the felt.  Walking around on a roof to brush it, or pressure wash it, risks puncturing felt or cracking tiles/slates.

If the roof isn't leaking and has no significant defects then usually the best thing to do is to leave it alone.  Ignore the horror stories and claimed remedies.

Mutton_Geoff

I've used Smart Seal's roof cleaner with very good results. Works on patios and other dark shaded areas that tend to encourage moss. Within a few weeks, the moss died back and was easy to sweep off with a broom on the end of a pole. No connection to the firm, just a happy customer.

https://www.smartseal.co.uk/roof/green-remover-and-sprayers/

propertyrental

Mutton_Geoff said:

..... easy to sweep off with a broom on the end of a pole. No connection to the firm, just a happy customer.

and the shingle....?

Mutton_Geoff

propertyrental said:

Mutton_Geoff said:

..... easy to sweep off with a broom on the end of a pole. No connection to the firm, just a happy customer.

and the shingle....?

Mostly used on pitched tile roof in shaded valley and on flat roofs that are EDPM and fibreglass (imitation lead finish) so didn't have the problem with shingle. I guess a soft broom would be fine since most of the shingle should be embedded in the felt.

diystarter7

MoreProbs said:

I've no idea, so asking - what would happen if you used a moss killer? Would it die off and erode away, or would the deed stuff remain?

Hiya

If possible, clean it off every so often as it keeps hold of water/rain for longer and cycle repats itself and over the years could cause an early deterioration in the felt than otherwise would have happened.

Thanks

Section62

diystarter7 said:

MoreProbs said:

I've no idea, so asking - what would happen if you used a moss killer? Would it die off and erode away, or would the deed stuff remain?

If possible, clean it off every so often as it keeps hold of water/rain for longer and cycle repats itself and over the years could cause an early deterioration in the felt than otherwise would have happened.

What is the precise mechanism which causes the retained water/rain in the moss to cause "early deterioration" of the felt?

Or is that just one of the horror stories put about by roof cleaning companies?