“How much to do my roof” is usually the first question, and it’s a reasonable one to want answered before a crew is on site. The honest answer is that roof area is only one of several things that set the price — and on its own it’s not even the biggest one.
Roof area is the starting point, not the answer
Square footage sets a baseline, but two roofs the same size can be very different jobs. What actually moves the number from there is pitch, material, how established the growth is, and access — in roughly that order of impact.
Pitch changes the method, not just the time
A low-slope roof is walked and treated much like flat ground. A steep pitch needs fall protection, tie-off points and a crew moving more carefully and more slowly across the same square footage. That’s not an upsell — it’s the difference between a job that takes an afternoon and one that needs harness anchors set first.
Material sets the whole approach
- Asphalt shingle is always soft washed, never pressure washed — pressure strips the protective granules, which shortens the roof’s life rather than cleaning it.
- Cedar shake needs an even gentler touch; it’s a softer material that splits and lifts under aggressive treatment.
- Tile can usually take a light, controlled pressure as part of the method, depending on condition.
The product and dwell time are matched to the material, and that decision is made on site rather than assumed from a phone call — see our guide to roof washing for how we tell the materials apart.
How established the growth is
A roof with light surface algae and a roof with thick, raised moss that’s been building for three seasons are not the same visit, even at the identical square footage. Heavy, established growth needs to be cleared by hand in places so the treatment actually reaches the surface underneath, which adds real time. Does roof moss actually damage your roof covers how to tell which one you’re looking at.
Access is the quiet factor
A detached house with clear ground access around every elevation is the simplest case. A roof backing onto a property line with no truck access, or a strata roofline reached only through a locked amenity room, adds time before the crew touches a single shingle. Multi-building strata roof programs are scoped around this rather than quoted per building in isolation, because the access planning is often the same across the whole property.
What doesn’t move the price
Tree cover near the property affects how often a roof needs treating, not what a single visit costs — a roof under heavy cedar or fir will likely need attention again sooner, but that’s a scheduling question, not a pricing one for the job in front of you.
Getting an accurate number
Send us the address and, where you can, a photo of the roof — ideally the worst-looking slope, since that’s the one that sets the method. We’ll confirm pitch, material and access from there and put a price in writing before anything is booked. Our pricing page covers how we price every job this way rather than off a square-foot rate card, because the factors above are exactly the kind a flat rate can’t see.
Every treatment carries our moss-free guarantee, with the term confirmed in your written quote.