Got a fair bit of moss on one side of roof tiles, when the weather is a bit better I intend going on roof and using a power washer to remove moss and clean tiles. Should I seal the tiles after this and with what?
When dry I would brush off the moss (which is basically harmless and leave it). Power washing may erode the surface.
In message , Geoff Pearson writes
I suffer from the same problem. My tiles are (I believe) concrete, faced with coloured sand. They seem particularly prone to promoting the growth of moss (the sort which grows in large clumps).
On several occasions I have painstakingly gone along each row of tiles, and carefully prised off the clumps of moss with a hoe (where necessary, extending it by strapping it to a long 1" dia bamboo cane). [This is pretty dodgy work when you're up a 16" ladder.] Inevitably, the moss takes with it some of the sand facing. Afterwards, to wash away the remaining loose moss and sand, I've blocked the tops of the downspouts, and given the roof a good hosing down (starting at the top and working my way down). To try to kill off the moss which inevitably remains, and to discourage the next generation, on a calm day I've then used a carefully-aimed pump-up garden spray to give the roof a good spraying with a solution of ferrous sulphate (just ferrous sulphate - not a concoction of various other weedkillers and fertilisers). [You used to be able to buy 25kg bags of Fe2O3 for around £8, but the EC stepped in, and the most you're likely to find (if you can find any) is 1kg for £10 (H&S, y'know).] Finally, the guttering needs to be cleaned out, and the downspouts unblocked.
However, I have to admit that this is essentially a losing battle. I have toyed with getting the job done properly by one of the 'professional' companies. They claim that they remove all traces of moss, repair any defects they find, and finally give the roof a long-lasting waterproof coating, which they normally guarantee for 10 years. The problem is that, without getting them to come to do a survey, and give a proper quotation, it seems impossible to get any idea of a simple ball-park price for such work. In the meantime I continue let the moss grow, and have to rely on the services of the local blackbirds and magpies who, while searching in the gutters for tasty things to eat, do a pretty good job of throwing out a lot of the lumps of moss which inevitably land up there.
Might be an idea to kill the moss by chemical means as a first move. Dead moss just falls off.
If you power wash do it from above so you don't disturb the tiles.
Bill
Leave the moss in place. Fix a bare copper wire parallel to the ridge and as high up as you can manage on each facet of the roof. Within a year the copper salts will wash down the roof with the very slightly acidic rainfall, and the moss will die and be blown off. It does not need to be thick wire -
2.5 mm stripped out of mains cable is sufficient.AWEM
ss pretended :
As per the wet loft thread.....
You can prevent the moss growing by running some bare copper wire along highest part, so the copper sulphate which forms can be washed all over the roof. Copper sulphate kills the moss off and prevents its return.
I had a constant moss growth problem on my flat garage roof. Last year I ran some bared 2.5mm 2x copper wire across the highest part. It killed off the existing moss and there has been no more growth since then.
Andrew Mawson has brought this to us :
Snap !
Thanks for the copper wire tip, I had heard of this and I was aware of using the salts for lawns as the active ingredient for moss. Nice to read about some who have tried this and it works.
No, no and no. Power washing a roof will jet lots of water under it. Depending on construction this can be a thoroughly bad thing. It can also damage weak finishes. And 'waterproofing' sound building materials is generally cowboy practice
NT
My wife's got one of those - she calls it a kick-step ... ;-)
Ian Jackson explained :
All of the above are a really bad thing to do, as is pressure washing.
I tried copper wire along our ridge but it did not make any noticeable difference even after having been on for 4 years. I then had the tiles cleaned professionally 3 years ago and have not seen a hint of moss growth since. The company pressure washed the roof, sprayed on an antifungacide and then applied 2 coats of roofing paint - looks great. Across the road we have a friend who had his done but omitted the antifungacide and moss is now appearing again after 6 years.
What we moss sufferers really need is access to Weapons of Moss Destruction. ;o))
I am sure I recall a coal-tar based product with integral measuring spout used to kill weevils but also kills moss on roofs, not just for one season but some time. You just dilute and apply with a non- pressure method. Couple of days later when it is windy you get a "moss- ball storm".
Copper wire does work.
From using pressure washing on low grade cement paving and watching it erode down to the aggregate, I would not want to use it on a roof. I have a perhaps unfounded suspicion it could turn a 70yr roof covering into 40-50yr, potentially giving a very unnecessary bill. Equally, blasting high pressure water into a roof could well damage any marginal sarking felt - which if prevailing wind facing could create damp insulation at times of the year when you least want it.
Stuff the roof painting, copper or coal-tar based product. The copper is probably somewhat odour free... :-)
In message , Jim K writes
Well, for starters:
But it's a green insulation layer. B-)
But often it's a WET green insulation layer - and usually full of bugs and other nasties.
Bugs and things to feed the local wild life, excellent.
In article , js.b1 writes
The coal tar based product is armillatox, it has been withdrawn as a pesticide/fungicide due to licensing problems. It is still allowed for moss killing but I've not found it to be as effective as ferrous sulphate.
People still use it for the old uses but it is frequently sold as a "Soap Based Cleaner" by retailers wishing to avoid coshh issues. It is nasty stuff though, not something you want to get on skin.
Can't say I've had much luck with the copper wire trick.
That sounds like it... stunk too.
I have a strong feeling it used to be a broad copper braid, lots of surface area and water permeability.
Geographic location is probably a significant factor on moss growth, as well as surface finish of the tiles (rough or smooth).
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