Your choice of softwash system will depend on the nature and materials of a particular roof and the requirements of your customer.
This is the system we recommend for most softwash roof treatment contracts
For most roofing materials we recommend treating with Bio Cleanze – and prefer it even for non-porous natural and man-made slate because of the way the product gets deep under the laps and does not require rinsing.
Benz Lightning Cleanze can be used to give a more "rapidly clean" effect when needed. And it can work well on smooth, non-porous roof surfaces such as natural and man-made slate, especially if your customer wants a quick clean (before moving house, for example).
Quick Tip: Bear in mind that when Lightning Cleanze soaks into porous surfaces it can take considerable time to rinse. Rinsing is easy and quick on walls and horizontal surfaces but much more time-consuming on a roof. Remember to factor this time into your pricing if you use Lightning Cleanze on a roof.
Gently power (aka pressure or jet) wash the roof – using a low pressure setting if you have a variable pressure washer. And/or use a fan jet and keep the nozzle some distance from the surface if your power washer does not have a variable pressure control.
Do not use high pressure because this can damage the surface of the roof tiles and significantly reduce their life expectancy.
Work from the apex down (never from the gutters up because of the danger of the water spray getting under the tiles).
1) This is the opposite direction to when softwashing with Benz biocides because then we want the biocide to get under the laps and kill the spores that hide there.
2) When the roof looks clean from jet washing, remember that spores will not have been killed, so post-treating with Bio Cleanze will be essential.
The time a roof treated with Bio Cleanze stays clean will depend on multiple factors. For example, the severity of the colonisation, the prevailing weather, the type of surface and the local environment.
A reasonable general expectation for a porous roof surface would be around 18-36 months on average, and up to 5 years in optimum conditions.
Treat with Bio Cleanze at these dilutions:
If you use Lightning Cleanze to clean a roof, always thoroughly rinse it from the surface after allowing 30-60 minutes for the cleaning action to take effect. This ensures that the small quantity of salt left behind by the break down of chlorine is removed.
Also, we advise rinsing between applications of Lightning Cleanze to remove the debris cleared from the surface by the first treatment, allowing the next coat to penetrate the biofilm to an even greater depth.
On many jobs a single application will be sufficient. But if the colonisation is very heavy, two treatments – and exceptionally three – may be required.
We also recommend gently brushing each application of Lightning Cleanze into the surface, so that it penetrates the biological growth to the maximum depth and thus increases its effectiveness.
Yellow lichen on roof: It can take 7-12 months for yellow lichen to fully disappear from porous roof tiles. Althought depending on the local environment and how long the yellow lichen has been allowed to grow into the surface, the timescale may be shorter. On non-porous slate the time-scale time-scale could also be shorter.
Moss balls on a roof: Any moss balls over 10mm should be scraped if at all possible. Small moss balls will die after treatment with Bio Cleanze and fall into the gutter. Bigger than this and it’s down to the roof pitch – the steeper the pitch, the more likely the moss balls will fall off.
The above photo shows heavy moss being scraped from a man-made slate roof using a Benz roof scraper with nylon blade. Click here to learn about out roof moss scrapers
If the moss balls are heavy and/or on a shallow pitch roof, they may stay there and eventually recolonise. Allow up to a year for full results to be seen after treating with Bio Cleanze.
If the moss is still there after 12 months, re-evaluate what to do. If scraping is not an option then treat with Lightning Cleanze at 5:1 (two treatments one after the other can be particularly effective, as the product will soak in more deeply). The moss will turn to white mush after a few hours. The mush should be be sucked up and removed from the site.
Quick tip: This is not the best practice – as the mush can block gutters and downpipes after rinsing (downpipes must be sealed prior to treating) and may contain a certain amount of sodium hypochlorite. This is the reason for sucking up the mush and removing it from the site.
To get the near instant results claimed by some contractors requires the application of extremely strong sodium hypochlorite (ie bleach).
We generally recommend using Benz Lightning Cleanze at 5:1 dilution (2% available chlorine), or exceptionally, 4:1 (2.5% available chlorine).
At 5:1 dilution Lightning Cleanze is classified as non-corrosive to metal and rubber fittings. Even at 4:1 it is only mildly corrosive, which can be offset by pre and post rinsing of vulnerable fittings.
But contractors applying raw, industrial sodium hypochlorite at 3-6% available chlorine are spraying a highly corrosive chemical onto their customers roofs.
Unfortunately this means:
We are not sure of the impact to a contractors professional liability insurance policy in the event of an accident, or to their customer's household insurance policy, as this will likely vary from company to company. What we are certain of though is the the consequences will not be good ...
In contrast Benz Bio Cleanze and Benz Lightning Cleanze are fully legal and have been approved by the UK government (HSE) and Irish government (PRCD) for the cleaning of exterior hard surfaces.
So the best way to avoid serious negative consequences is to "Buy Benz and Be Safe".
Download the “Benz Professional Softwash Contractors Pricing Guide, which explains clearly and simply how to calculate the price per square metre for any given softwashing contract. (comes free with Benz Trade Tips)
Check to see if all elevations can be sprayed from the ground. If not, use a podium ladder, lightweight scaffold tower as in the above photo, cherry picker, or scissors lift.
Walking on roofs
This was standard practice for years before H&S came in. Nowadays best practice is to use a roofing ladder and scaffolding (a tower is often sufficient). If you don't, it is possible your insurance would be invalid in the event of an accident.
Also, using WFP it's often possible to treat the entire roof without stepping onto the roof at all. The exception can be the need to scrape moss and lichen before treating, although even for this a scraper attached to the end of a pole usually works fine.
Correct evaluation will help you work out the time the job will take and so price correctly.
The correct, and highly effective, method to treat roof slates and tiles with Benz Bio Cleanze:
If there’s any danger of serious spray drift, cover your customer’s plants with a lightweight sheet, ensuring that the plants remain undamaged by the covering.
Always spray all plants and lawns in the vincinity of the treatment area, or likely to receive spray drift, with copious quantities of fresh water immediately before and immediately after applying a softwash treatment.
Pre-drenching plant life helps dilute any biocide that may reach the leaves and soil. And post-drenching washes any spray drift from the leaves and further dilutes any that reached the soil.
Pre and post-drenching is a remarkably simple but highly effective way to care for your customer's plants, trees and lawns.
Quick tip: In our experience pre and post-drenching with fresh water, and minimising spray drift and run-off with skillful application techniques and Benz Softwash spray nozzles, works just fine.
We've found it to be the simplest, least time-consuming and most inexpensive way of protecting your customer's plants.
We've found absolutely no need to post-treat your customer's plants with any other product such as a liquid fertiliser (which in any case could be the wrong type of nutrition for your customer's particular plants and therefore could be harmful to them).
Choose an area of hard standing to set up your application equipment. If at all possible do not set up your equipment on your customer's grass. If the grass is the only viable option, cover it with a strong tarpaulin first.
Remove the worst of moss, lichen and liverworts with Benz Roof Moss Scrapers. It’s especially important to remove as much moss as possible from low-pitched roofs situated in sheltered or shady locations.
Watch the video below to learn about Benz roof moss scrapers for removing moss from roofs prior to softwashing with Benz Bio Cleanze
Begin spraying up from the eves, ensuring good penetration into the lap of the tile or slate. Pay particular attention to features such as a dormer back gutter, valleys, and so on as missed spots will start to show regrowth quite soon.
After spraying the whole roof up to the apex, follow with one final treatment down from the apex to ensure complete coverage of the roof.
It is important to protect our environment by minimising run-off into sewers and surface drains. Run-off can be kept to minimum or zero by using Benz softwash spray nozzles along with skillful spray and brush control techniques. If some run-off to drains is unavoidable, block the drains and/or gutter downpipes until application has been concluded.
Click here to read our Trade Tips post on working with run-off and drains
Notes on the video above: On this particular roof, with the ridge running down the hip, Ben wanted to make sure the biocide did not run down the roof tiles and into the gutters.
Obviously all the tiles have to be treated at some point, but if the biocide is running down the roof – and starting to overtake where you are spraying – it's better to stop, treat something else, then go back to where you were spraying and continue from where you left off.
On a standard ridge Ben first cuts in, then does a few courses of tile, then sprays the top of the ridge, then goes back down and sprays a few more courses of tile until it starts running down. Then he works from the bottom up for a few more courses, then back up to the top. (you'll see Ben doing this in the video)
On a roof that has long gutters this process of spray control may not be needed – as by the time you get to one end the other end will be starting to dry.
Spraying techniques like these help keep as much biocide on the roof as possible and prevent it just flowing into the gutters, which is wasteful.
Always wear full PPE (Personal Protective Equipment), including impermeable gloves, hair protection, chemical-resistant clothing and a full face shield.
Barrier off the working area and keep customers, the general public, children and animals away from chemicals and treated surfaces. Only allow them to re-enter when the area has been made safe.
On an area of hard standing, rinse your application and safety equipment with copious amounts of fresh water, being careful not to allow rinse water to flow into flower or vegetable beds, lawns, or surface drains.