The surface cleaner being used in this video has a fixed rotating arm like a propellor with a pressure washing tip on either end.
Assuming the roof is in very good condition, the damage that occurs by pressure washing is not caused by the pressure washing itself but by the lack of skill or care taken by the person doing it. If a worker is using a wand rather than the surface cleaner, they could get too close to the shingles or aim the water coming out of the wand up the roof rather than straight down. Aiming up the roof can lift the shingles thus breaking the seal that adheres it to the shingle below it. If this were to happen, shingles could lift during high winds and potentially tear.
95% of the time, we remove moss by hand with specialized brushes. As seen in this video, some roofs have so much moss that removing it by hand would not only be extremely expensive, the amount of brushing needed to remove it could certainly hurt the roof.
The surface cleaner with its fixed rotary arm can only aim the water straight down with the tips being the same distance away from the shingles at all times, thus eliminating user error. The height of the tips (distance from the shingles) can be adjusted to suit the situation. Again, we only do this in extreme situations where the roof is in excellent condition and where moss growth is so extreme that any other method would not offer the homeowner satisfactory results.
After a job such as this, we put the customer on a regular spraying schedule to prevent moss from ever forming again. Click here if you want to be taken to the roof spraying page.
Moss Removal on Roofs
Moss is usually brushed off with stiff nylon brushes, depending on which is more effective. We only power wash in the rarest of occasions.
Workers work off of hook ladders and are tied of with a rope and harness system for their safety.
After all of the moss is brushed off, the roof gets blown off. The gutters are then vacuumed out. This moss removal process will remove almost all the moss. There will be tiny bits off moss here and there remaining but you will not be able to see the left over bits. All remaining bits of moss and algae will be killed off when we spray the roof.
Prices always include the gutter cleaning and all clean up on the ground.
Spraying the roof is always needed. This service is almost always done on a separate visit depending on the time of year the moss is removed. Spraying the roof to prevent the return of moss has to be done on a dry day with no rain for 12 hours afterwards.
You will need to have us spray your roof once or twice per year to keep the moss off. Once per year is the most common. The frequency of spraying mostly depends on the amount of shade around your home, the pitch of the roof and if we are in a year with an El Nino weather pattern with an unusually warm winter. We do not guarantee that moss will not return unless you are on a regular spraying cycle. We will assess the time it takes to spray your roof when removing the moss and give you a firm price for subsequent visits.
We never use Zinc Sulphate for spraying roofs as this product is toxic and very harmful for invertebrates and aquatic life. This is a direct quote from the World Health Organization…
“ The substance is very toxic to aquatic organisms. It is strongly advised not to let the chemical enter into the environment”
Some companies will use this so just be aware of its impact on the environment and the human health. Click here if you’d like to read where this quote came from.
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Whenever we’re removing moss on a roof near a power line, we call BC Hydro to send a crew to temporarily shut off the power. It’s called a Safety Shutoff. In this photo, we needed about an hour to complete the moss removal in this area. Once the work is done, the crew returns to turn the power back on. We take employee safety very seriously and Safety Shutoffs are standard practice when working within 10 feet of a power line.
