Moss problem – which is better zinc or copper?
Hello
I am new here.
We have a moss problem on an old north facing slate roof, in an area of high rainfall, not far from the sea in the West Highlands of Scotland.
There is no felt underneath the slates and the moss seems to be acting like a sponge sucking rain water back up onto the underlyling planks! The slates are held down with old steel nails. During the frequent storms quite a lot of salt spray seems to get to the house. In winter a lot of the wooden planking seems to be slightly to moderately damp (lots of buzzing when tested using a damp meter!), however it seems that the sea salt that has built up over time seems to be preserving the wood (!).
I have no idea why the nails are not corroding faster, but mostly they seem fine so far.
We are thinking of adding a copper wire (or copper or sink flashing) near the top/apex of the roof, to help kill off the moss, however we are concerned that this might corrode
a) The nails
b) The cast iron guttering & down pipes
c) The lead flashing
An alternative might be to poor some sort of chemicals along the top for the roof say once a year, however it is a pain in the ass to get onto the roof which is quite high and at a steep gradient.
Have any of you folks tried copper wires or strips, or zinc strips? If so
– How effective was it at killing moss
– How much do you need in order to be effective
– Did you have a problem with staining building up over the years?
With thanks
J
J
Replies
My impression has been that zinc works as well as or better than copper, and is cheaper.
A simple way to install zinc it to cut heavily galvanized steel sheet into strips and slide them under the front edges of shingles, attaching however you can manage.
The effectiveness of zinc is seen on many US homes where moss and algae do not grow "downhill" from galvanized flashing around dormers and plumbing vents.
Befrore you spend a lot of money on either do a small test area. The effects of zinc or copper don't extend very far so it will require a lot of either to keep your roof clean. Might be more effective to clean the roof every few years.
Where are you in West Scotland? We love it there in the summer and we've seen lots of mossy slate too!
J
i emailed Walter the Slateman, a former poster here. If you want to correspond with this Mainer, private message me (found in my profile) and I'll give you contact info. He is everything about slate. It's his profession, of which that isn't a big prolific bunch to choose from.
his initial response was you needed to manually remove the moss, perhaps redo some areas underneath to solve this problem.
lemme know
Doesn't much matter which metal,
but you'll need to add a strip about every 4'. You'll need 1" or so wide strips. Wire won't be adequate. Slide the strips under the slates and the water running down the trots between the slate will carry some metal. As mentioned, you'll need to remove the moss. The metal runoff will kill it, but not disolve it. I'd suspect the chimney might be the culprit in your active leak.
Lead Flashing...
... if you can find it on your side of the pond, works better than either copper or zinc for moss deterrence.
Had an asphalt-shingle (conventional stuff here in the US) roof put on a house I used to live in. Roofer commented on moss growing on shingles that were removed first, said that over time the stuff will eat the new shingles too, suggested lead as a remedy. At the top edge (this was a shed roof) he installed a pre-made lead sheet product under the first course. That new roof never had moss after that. Roof measured 40' x 24' at about 1:3 pitch w/overhanging maple tree over half (sap, twigs, seeds, leaves) that only added to the moss potential.
I'd use lead if authorities allow it. Proven moss deterrent, little to no corrosion potential with othet metals up there.
Modern asphalt shingles of decent quality have zinc or copper built into the mix, to prevent moss/algae growth.
No need to chose. Just use brass and get both. (ha, ha, for those who take me seriously)
Both zinc and copper are effective in addressing moss problems, but copper is typically considered slightly more potent. Copper sulfate or copper strips release copper ions that inhibit moss growth, while zinc sulfate releases zinc ions with similar effects. Ultimately, the choice may depend on factors such as cost and environmental considerations.
No need to chose. Just use brass and get both. (ha, ha, for those who take me seriously)
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