When it comes to roof washing, particularly in Southern California, it is very much done differently than in most other parts of the country. When I first started out in the pressure washing industry, like most, I attended the university of YouTube. There, one is bombarded with videos from different pressure washing YouTube stars that give their take on pressure washing. But most of these self-proclaimed experts are not particularly privy to your area since most are stationed in the South.

Pitfalls of Chemical Roof Washing

In the south and some parts of the Midwest, roof cleanings are done largely through the soft wash methods. Namely, they’ll say that in order to kill the algae you just need a good emulsifier and some sodium hypochlorite, let the chemicals dwell for 10 to 20 minutes, and presto, the organics are dead. From there the conversation to the customer goes something like this:

“Hello Mr. Customer, we’ve officially completed your shingle roof cleaning. What’s that you say? The algae is still on the roof? Well, Mr. Customer, in our industry we have a saying, ‘if it’s brown, it’s coming down’ so just give it a couple of months, and as soon as the rain comes mother nature will take care of the rest.”

It must be nice! That is not the case here in Southern California. Sure, we have shingle roofs, and, yes, soft washing is ideal in those situations, but we have, largely, tile roofs out here. Tile roofs in all their different varieties; for example, we have concrete tile roofs, clay tile roofs and all their variants.

When I first started, the last thing I wanted to do was destroy a customer’s precious roof, so I did research on cleaning methods for our roofs. But I couldn’t find anything on YouTube, and if you were to do a search on google, you’ll hear too many different opinions.

Forums from other companies that work in my area were the way to go. Companies that were actually in the trenches doing the work, here, where it counts, not in some Southern state where the organics are so gentle and weak that virtually any mix of sodium hypochlorite and surfactant would suffice.

Challenges in Humid Locations

In the South, the humidity makes it so that organics can thrive since the environment is ideal, for the very air itself has carries plenty of moisture. And, thus, easy come easy go—weak weeds grow out of such a gentle environment, and it does not take much to destroy them. However, in Southern California, the air is relatively dry, particularly in the inland empire, so much so that we hardly have organic growth on roofs. There is plenty of sunlight and heat and not so much moisture, so weeds really do have to be resilient to grow here. Hard environments with harsh conditions make for highly durable organic growth. The solution? Pressure.

A pressure washer with a turbo nozzle is needed here. The nozzle is adjustable, so the pressure can be somewhat regulated by changing the spray pattern. These nozzles work fabulously on concrete tile roofs. By the time the job is finished the roof looks like new, and, no, there is no, “You’ll have to wait for the rain to finish the job.” conversation.

What I would recommend is a house wash afterwards included with the roof wash, otherwise, you’ll likely stain the fascia boards of the home from the runoff of the roof wash, which would not be appreciated by your customer.

Cleaning Shingle Roofs

As mentioned, shingles do have to be soft washed, but you’ll need a much hotter mix here, since, again, the organics are much more resilient. And having a second hand at the bottom constantly watering the flowers and grass is absolutely mandatory since it means sure death for the landscape if the chemicals touch them. Clay tile roofs, are a mixture of both approaches.

Cleaning Clay & Tile Roofs

Clay tile roofs should first be wet and hit with light pressure. If that gets the job done, then stick with it. If not, you’ll have to soft wash the roof, and let your mix dwell for 10 minutes or so, assuming the heat doesn’t dry out your mix. Then you’ll have to rinse with light pressure.