Roof cleaning

Over last decade or so, level of moss has got much higher (could be lack of sulphur from coal burning, or other factors?) and emptying gutters of moss has become practically an annual job, to avoid overflow during downpours.

The problem with moss and some roofing materials is that the moss doesn't necessarily die off in the summer, it depends on location, location, location :) The moss gets in all the small cracks and acts like a sponge. In winter the water held by the moss expands and starts spalling of parts of the tile.

While some of the cleaning may be to impress I've seen a few youtube videos where the amount of moss removed from a small(ish) roof has been massive.

I did see one video where someone new to the game of cleaning roofs managed to get a lot of water in the loft space :( It's not just using turning on a pressure washer full pelt but also the technique and understanding what is being cleaned :)

On the back of my house I have sections of the roof which doesn't get very much direct sunlight and is in shade all winter and most of the day in summer. I do get a problem with quite a lot of moss growing on my concrete tiles in this area. My solution is a garden sprayer, diluted BAC50 and soaking the roof every two to three years. This kills off the moss and a few heavy rain storms in the following months will wash the dead moss from te roof. The diluted BAC50 seems to keep the growth of moss at bay for 2/3 years.

What dilution do you use for the BAC?

I have an area prone to moss, and I’d like it killed off…

We had ours done a few years ago. The people who did it had prevously done a good job of replacing the timbers and lead in a leaking gulley in the roof here (the original work didn't include provision for the lead expanding in summer, so after 20 years, the lead cracked and started leaking).

The roof was cleaned with a high-pressure spray, a number of ridge tiles were re-cemented into place, and all the roof timbers checked for rot. In addition, two coats of some moss repellent were applied all over.

Roof looks much nicer now, too.

The other half of our semi had their roof cleaned 4.5 years ago while ours was untouched. Until late last year they looked obviously different but now they are indistinguishable. Is that about the right interval?

nib

I use approx 10:1, Water:BAC50. Spray and let it dry. Don't tread in it and walk it to other areas until its dry. I tend to wait for a dry sunny day with no wind to spray.

The moss will die and turn brown within a day and then turn into a powdery like substance over a few weeks but may take a month or two of natural weathering before you get a clean surface

Thinking about it wasn’t there a contributor to this group around 20 years ago who ran a business supplying ridge tile shaped sheets of copper that were intended to produce a run off when it rained that inhibited moss growth . I think she was based in Scotland.

GH

I thought it only needed a bare copper wire, not a whole sheet?

I wish I'd done it 10 or 20 years ago when I was happy enough to scrabble about on the roof, now I'd probably do a Rod Hull.

It's a d@mn sight more often that "annual" here. Every time we have a major downpour, a fresh lot of moss is dislodged and ends up in the guttering.

Yuk. Benzalkonium Chloride, used as a preservative in a variety of ocular-use medications like COSOPT and Latanoprost.

You don't want to get that stuff in your eyes in case you sensitize yourself to it and ever need to use ocular eye drops in future.

Two houses opposite me had this done about 8 years ago and they still look clean compared to neighbours. Maybe it helps that both houses have east-west roofs so plenty of sunlight on both sides.

Mine is North-South, great for solar PV but the North flank gets very little sun and inside the loft it suffers from condensation when the weather turns from mild/muggy to below zero as we go from late autumn to winter.

My problem is the gang of Rooks who peck away at the moss looking for insects every morning. Then the wind blows the dislodged lumps of moss off.

It is noticeable how much grit is now being lost from these Marley Modern flat files (1976), after every gale and a couple of houses have been re-roofed

Another reason why I had it done.

I've fitted a "hatch" similar to this in my downpipe and should be able to get some drain rods (or at least electricians fishing rods) up to poke moss out of the gooseneck it usually blocks in.

Maybe a wire doesn’t produce enough of the Copper Sulphate run off which is what kills the moss. I don’t have enough knowledge on the subject to say. There seem to be a number of suppliers of Copper roof components to combat the problem .

GH