Do I need to remove moss from Victorian tiled pitch roof?
Anonymous user 28/02/2024 - 3.56 PM
Dear all, I was wondering if you could shed some light. I have a mid-terrace 1877 Victorian stone property with a main roof being of timber construction and pitched design. It is continuous across the neighbouring roof and both roofs appear to have been re-tiled at the same time. However, moss growth is noted across the tiled surface to the front and the rear pitches. According to the surveyor, this is caused by the loss of the smooth surface to the tile surface and formation of indentations which has allowed moisture to be held encouraging moss growth. According to the surveyor, there is no evidence of the tiles having failed and no defects noted affecting the tiled surfaces. According to the surveyor, a bitumen felt membrane is fitted below the tiles.
According to the surveyor, the ridge is formed by concrete ridge tiles which are in fair condition. According to the surveyor, a single roof vent is visible to both pitches at low level but with no corresponding vent at high level so minimising the amount of airflow within the roof space. According to the surveyor, the roof vents are partially blocked by the moss growth which will limit even further the ability for moisture to evaporate from the roof space.
I was wondering if you can shed some light as there seems to be a difference in opinion. My surveyor has advised the following.
Remove the moss growth to both roof pitches (avoid pressure washing) and install a sacrificial zinc or copper strip to discourage future growth.
On the other hand, a local roofer is advising the following.
Avoid removing the moss as it will cause more damage to the roof tiles.
I look forward to your invaluable clarification. Cheers.
Adam
Are you a tradesperson and able to answer this question?
There are a couple of different things here it really depends on the age of the roof tiles if it will cause damage or not but as your surveyor has said the only issue the moss is causing is to the vented roof tile which is not really doing a great deal anyway
There is always a chance the moss covering the vented tile will allow water ingress into the loft space creating dampness and there is also the chance the moss covering the other tiles will allow water ingress under your tiles onto the under felt if the felt is ok it's not a problem if the felt has failed anywhere it can create dampness. The call is entirely yours. The old adage is if it's not broken don't fix it.
Both your roofer and surveyor are saying the same thing it's not causing an issue your surveyor is looking at potential future issues your roofer is looking at what's happening now not what may happen.
Good luck Alex
The moss growth will continue to get more widespread and more dense. Moss is an absorbent material and without getting to technical the moss can eventually become a problem in more ways than one, so its best to have it removed. Once the weather becomes milder and drier than a solution of moss/ weed killer can be sprayed on the surface of the roof. This should stop the moss from growing any further. After which you can then remove the remaining growth by means of brushing and scraping it away. But if the tiles are already splitting and in a bad condition you may have a bigger problem. Because moss is extremely absorbent, it has a lot of moisture and this freezes during the winter. This will eventually attack the integrity of the tiles and cause major damage. Removing the moss will eliminate this damage to a greater extent than simply leaving the moss to grow unchecked. I hope my advice has been helpful.
The simplest solution would be to have the moss removed by softwashing.
This is done without any high pressure. Or anyone going physically on to your roof.
The tradesperson would erect a small tower scaffold. Then using specialist poles with the appropriate scraper profile. Scrape the moss from your roof. Then apply a biocide. Which would kill of any remaining moss and spores.
This method is the gentlest method. And puts no pressure on your roof. And with the correct application of biocide. This will keep your roof clear of moss. For a minimum of three years.
After that period. If you feel it may be necessary to prevent the possibility of regrowth. You only need to have your roof treated with biocide. Without the need for it to be scraped.
