Moss on flat roof

I have a garden room extension with a flat roof, the type of construction with the sticky top layer covered with loose small grit/gravel, pretty common. I think it's about 20+ years old, and is in good nick, you can walk on it no problem and is sound.

It does get a layer of moss which grows consistently. Most years in spring I have removed some of the thicker moss (it is easy to remove), but last year I didn't and the layer is now fairly spread across the roof. It's not a problem. But I was wondering if this is a good or bad thing. Looked on the net and and got different answers.

Should I just leave it to do its own thing? I quite like the look of it though you can only see it from the upstairs windows.

Cheers
GG

 

Roof gardening is all the rage now

Sorry, no sensible advice - if it's doing no harm ......

 

A few years ago I treated my with diluted bleach and it worked. Read on web of all the things you can buy which cost an arm & leg but came across the bleach method on some gardening web site.
It killed it off but came back about 2 years later but never been as bad.
It did not look nice to me even though could be only viewed from bedroom window.
When I do it again I will do as you,remove as much as I can then the diluted bleach.It was surprising how heavy it all was.To me personally it was not doing the roof any favours what with the weight of moss & dirt/earth + it holds the wet.

 

Ummm, still unsure. If I go the removal route, I'll just pick it off which has been easy in the past. @trogre I wonder if yours was much thicker coverage than mine as I can't imagine sopping wet this stuff would be that much weight. Just took a snap as an example.

 

GG, you may well find that birds (particularly starlings) will have a good go at tossing that off your roof in a few weeks time. So, if you feel you want to go the removal route, at least give them a chance to get in first

 

@Gay Gardener I'd be inclined to wait as ("M"said) the birds will have a good go at it in the spring I'm sure it's filled with lots of tasty bugs which they will enjoy! Then I'd remove it thoroughly. I'm not a fan of chemicals in the garden but I'd possibly use a diluted mixture of bleach or jeyes fluid to kill it off. Good luck & please let us know how you get on

 

I cleared our flat roof on new years day. The stuff weighs a ton when sopping wet and blocks your gutters in the process. I removed mine with a broom and stuck it all in the compost bin.

 

It wont do any harm..

Anything that holds moisture on a flat roof is generally considered a benefit but more so in the summer. Its the heat of the sun in summer that gubbers flat roofs as the expansion and contraction is what ruins flat roofs.
The grit is spread over the roof to do exactly what the moss is doing IE shielding the felt. The other way of deflecting the heat of the sun is to paint the roof with a silver bitumin based paint called silverflex. Silverflex is designed with one thing or one purpose and that is to reflect the heat away so as to reduce the expansion and contraction.

If you don't want the moss there then strands of copper wire will stop it from growing. Copper kills lichens and moss absolutely dead !

 

Yes I think it is a tricky decision. I'd read up about the the moss being a good UV protector especially with the type of roof I have which is the sticky type with the looseish grit covering which is intended to provide the same UV protection. And the downside of the wet and weighty moss in wintertime - luckily the roof faces ESE and gets a fair bit of sun and also being in the Fens a fair breeze which I think stops it from being sopping.

Thanks for all the input though. I shall have a good inspection once the weather warms up and see then.

GG

 

Hi gay Gardener. Sorry not been on forum for a while as trying to sort out all the bits I will need when I change bathroom suite and practicing soldering pipework.
No doubt you have sorted it out now but my moss was about the same thickness.But as Jungle Jane pointed out ,it weighs a ton.

Charlie 996. My next door neighbor will not agree with you about anything holding moisture on a flat roof being a benefit.
Last summer he had his front porch & attached garage resurfaced in grp glassfibre. Took a while before it rained and when it did ,oh dear. Not sure if they got the slope wrong but it looks like they have made a right c...k up. The porch has about 4" of water laying on it permanently until sun dries it out or evaporation.The garage is about 2" deep permanently.
Try as they have just cannot get hold of the roofers so either moved on or gone into liquidation!