If you want the short answer first, here it is. In San Antonio, professional roof washing is priced by the square foot of roof surface. Shingle roofs run about $0.25 per square foot, tile roofs about $0.35, and metal roofs $0.50 or more at companies willing to touch them. Most of the roof cleaning jobs we do land between $600 and $2,000 total.
The rest of this post breaks down what that means for your home, what moves the price up or down, and why Guardian Pressure Washing turns down metal roof jobs entirely.
Roof Cleaning Prices by Roof Type
Shingle roofs: $0.25 per square foot. Asphalt shingle is the most common roof in San Antonio and the least expensive to clean. The dark streaks you see on shingle roofs are algae, and they come off with a low pressure soft wash.
Tile roofs: $0.35 per square foot. Tile is everywhere in neighborhoods like Stone Oak and Shavano Park, and it costs more to clean for a simple reason: you cannot walk on it carelessly. Tile cracks under foot traffic, so cleaning it takes more time, more care, and the right technique.
Metal roofs: $0.50 per square foot or more, but not from us. More on this below, because it deserves its own section.
What a Typical San Antonio Home Costs
One thing that trips people up: roof square footage is bigger than the floor plan of your house. A roof slopes, overhangs the walls, and often covers a porch or garage, so a 2,000 square foot home usually carries well over 2,000 square feet of actual roof surface.
When we quote a roof, we measure it from a top-down view using Google Earth, then account for the pitch. That last part matters. A steep roof holds more real surface area than the aerial view shows, so two houses with the same footprint can carry very different amounts of roof.
Using our rates, here is roughly where common roof sizes land:
- 2,400 sq ft of roof: about $600 shingle, $840 tile
- 3,200 sq ft of roof: about $800 shingle, $1,120 tile
- 4,000 sq ft of roof: about $1,000 shingle, $1,400 tile
These are ballpark figures to help you budget, not a quote. Every roof is different, which is why we measure yours before giving you a real number. A free quote takes about a minute to request.
Why We Do Not Wash Metal Roofs
Metal roofs are usually cleaned with the same alkaline and hypochlorite based solutions used on other roof surfaces, and on metal those chemicals are risky. If the mix sits too long, dries in the sun, or hits the wrong coating, it can chemically flash burn the finish. The damage shows up as permanent staining or a dulled, etched surface, and it is especially likely on galvalume, the aluminum zinc coating used on a large share of metal roofs in the Hill Country.
A flash burned roof cannot be buffed out. The fix is recoating or replacing panels, which turns a few hundred dollar cleaning into a five figure mistake.
Plenty of companies will take the job anyway, and charge $0.50 per square foot or more for it. Some do it well. Many find out about galvalume the hard way, on someone else's roof. We decided the risk lands on the homeowner no matter who holds the wand, so Guardian Pressure Washing does not wash metal roofs, period. If you have a metal roof, our honest advice is to contact the roof manufacturer and ask what cleaning method they will stand behind before you let anyone spray it. Some metal roofs can handle a careful water only pressure wash; the manufacturer can tell you whether yours is one of them.
What Moves the Price Up or Down
Within those per foot rates, a few things affect where your roof lands:
- Pitch. A steeper roof means more actual square footage than the top-down measurement shows, and the price follows the true surface area.
- How bad the growth is. Light algae streaking rinses off faster than years of built up moss and lichen, and heavy organic growth takes more time and product.
- Access. If a roof cannot be reached safely by normal means and the job requires lift equipment, that can add $1,000 or more to the price.
Soft Washing First, Pressure When Tile Demands It
A shingle roof should never meet a pressure washer. High pressure strips away the protective granules and shortens the life of the roof you just paid to maintain, so shingle always gets a soft wash; the cleaning solution goes on at low pressure, kills the algae at the root, and rinses off gently. Because the growth dies instead of getting blasted off at the surface, the roof stays clean longer too.
Tile plays by different rules. Soft washing is still the starting point, but lichen grips tile so stubbornly that in some cases the only thing that removes it is a hot water pressure washer. Used carefully on tile, that is a legitimate tool, and we bring it out when a roof genuinely needs it. You can read more about the process on our roof cleaning service page.
The real value play is the full top-to-bottom bundle: roof, gutters, house wash, and windows in one visit. The same oak leaves sitting on your tile are sitting in your gutters, and the grime that washes off the roof ends up streaking the siding below it, so cleaning from the top down means everything gets done once, in the right order.
Get an Exact Price for Your Roof
Ballparks are useful, but your roof has an actual number. Send us your address through the quote form or call (210) 560-5966 and we will get you a firm price, usually within 24 hours. No pushy follow up, no obligation, just the number.
