How Much Does Roof Cleaning Cost in Kentucky? Real Numbers

You have a roof cleaning quote in one hand and a national average in the other, and the two do not match. That is normal. The national roof cleaning cost guides do not match each other either, and every one of them prices by a square foot that is not the one on your home’s listing.

What this post covers:

• What four national cost guides say roof cleaning costs, and why they disagree
• Why their rates mean square feet of roof, not square feet of house
• What our $400 roof minimum means for a small or simple roof
• Why humidity, shade and moss make some Kentucky roofs cost more to clean

The average cost to clean a roof, from four national guides

Here is what Today’s Homeowner, EcoWatch, This Old House and Fixr each publish for professional roof cleaning:

Cost guide	What it reports	Soft wash rate
Today’s Homeowner	$255 to $1,190 for a roof of about 1,700 sq ft	$0.30 to $0.75 per sq ft
EcoWatch	Around $400 on average, with most homeowners paying $250 to $650	$0.30 to $0.80 per sq ft
This Old House	$300 to $1,050 for a 1,500 sq ft roof, averaging $675	$0.30 to $0.75 per sq ft
Fixr	$450 to $700, with a national average of $612	$0.30 to $0.75 per sq ft

The totals disagree because the guides are not pricing the same job. They do not all assume the same size of roof, and most of their overall ranges cover several cleaning methods, not just soft washing.

The rate column is where they line up. Three of the four publish the identical soft wash range, and the fourth differs only slightly at the top. That rate, the soft wash roof cleaning cost per square foot, is the number that lets you check a quote. The catch is knowing what it gets multiplied by.

Roof cleaning cost per square foot: which square foot?

Every rate in that table is charged against the roof itself. Today’s Homeowner works from a typical American roof of about 1,700 square feet, which at its soft wash rate of $0.30 to $0.75 comes to roughly $510 to $1,275. This Old House adds that a roof measures slightly larger than a home’s square footage, because of the overhangs and the pitch.

That holds on a single story house. On a two story house, it does not.

The square footage on a listing or a tax record is living space, with every floor added together. A roof only covers the footprint, the outline the house makes on the ground. On a ranch those two numbers are close. Stack the same 2,400 square feet of living space on two floors, though, and the footprint shrinks to about 1,200 square feet. The roof shrinks with it, to roughly half the roof of a 2,400 square foot ranch.

The listing tells you how much house you have. It does not tell you how much roof.

That does not make a two story roof half the price. This Old House publishes per square foot figures that rise with each story: $0.05 to $0.75 for one story, $0.15 to $0.85 for two, and $0.25 to $0.95 for three. Less roof, but a higher rate for the height.

Neither number is the wrong one to start from, as long as you know which one a quote is built on. The quote tool on our contact page asks how big your house is and how many stories it has, then shows you an estimated range. Our pricing page lists typical Louisville area roof ranges alongside our minimum.

What our $400 minimum means for a small or simple roof

Per square foot pricing needs a floor, because some of the cost of any visit, like the drive and the setup, does not shrink when the roof does. A job minimum covers that part.

Our roof minimum is $400. Here is how a floor like that meets the national numbers. Today’s Homeowner puts soft washing at $0.30 to $0.75 per square foot of roof. At that national rate, which is not ours, an 800 square foot roof works out to $240 to $600, and a 500 square foot roof to $150 to $375. Put a $400 floor under both, and the 500 square foot roof costs the minimum wherever the rate falls, while the 800 square foot roof only meets the floor at the cheap end.

Worked the other way, those national rates put the break points at about 530 and 1,330 square feet of roof. Under 530, the minimum is the price at any rate in the range. Over 1,330, it never comes into play. In between, it comes down to where the rate lands.

So if an online calculator gives you a number under a company’s minimum, that gap alone is not a sign of padding: the calculator is multiplying your roof size, and the minimum is paying for the visit. And on a small or simple roof, ask for the minimum before anything else, because it is probably the whole quote. Simple counts as much as small here: the guides charge more per story (This Old House) and for heavier buildup (Fixr), so a low roof with light streaking sits toward the cheap end of the range.

If the roof is one job on a longer list, our breakdown of exterior cleaning costs around Louisville covers the house, the driveway and the deck.

Why Kentucky humidity and shade make algae streaks worse

The black streaks have a cause with a name. According to an algae bulletin from the Asphalt Roofing Manufacturers Association (ARMA), the trade association for asphalt roofing makers, Gloeocapsa magma is probably the most common of the several algae species behind them. All of those species travel through the air, growth shows up to some degree in every region of the U.S., and it is especially common where conditions are warm and humid. The algae’s natural pigments are what can gradually turn a light roof dark brown or black.

Kentucky summers fit that description. NOAA’s Kentucky State Climate Summary describes summers that run from warm to hot and humid, in a climate with abundant precipitation: about 38 inches a year on average in the northeast of the state, and around 58 inches in the southeast.

Shade is the other half, because the slope that stays wet longest is the one most likely to streak. ARMA’s cleaning guidance notes that algae can form where moisture tends to sit on a roof and, in its advice on moss, that north facing roof planes get less direct sun and stay damp longer than south facing ones. Overhanging branches add shade and drop debris that holds moisture. This Old House likewise flags moss, lichen and algae as showing up particularly in shaded areas.

Before you call anyone, look at your own roof. In Louisville or anywhere nearby, if one slope is streaked and the other is clean, note which way the streaked slope faces and what hangs over it. Fixr lists the level of buildup among the things that move the price. For telling algae from moss and lichen, see our guide to black streaks on Louisville roofs.

Roof moss removal cost, and why moss is a different problem

The national guides put a price on moss, but read the fine print. This Old House and Fixr both put moss removal at $0.20 to $0.70 per square foot, and both say most cleanings already take care of it, so it is usually not an extra charge. EcoWatch lists manual moss removal as its own method, the most expensive one, at $0.60 to $1.00 per square foot.

Moss earns its own line because it does something algae does not. ARMA’s guidance says moss can be detrimental to how asphalt shingles perform. It can lift or curl the leading edges of shingles, which raises the risk of them blowing off in high wind, and in severe cases it can move water sideways, causing moisture damage to the roof deck or even leaks. ARMA ties both moss and algae to moisture that lingers on a roof, so a damp, shaded roof can carry both at once.

So on a mossy roof, ask whether the moss is covered by the wash or handled as a separate manual job, because the national guides price those two very differently.

Why the cost to pressure wash a roof looks cheaper

The cost guides also list high pressure washing, and it comes in under soft washing. EcoWatch prices high pressure at $0.15 to $0.60 per square foot against $0.30 to $0.80 for a soft wash, and Today’s Homeowner lists $0.20 to $0.60 against $0.30 to $0.75.

That gap is not a bargain. The same ARMA guidance says never to use a pressure washer on an asphalt shingle roof, because it causes granule loss and very likely premature failure of the roof. The Consumer Reports guide to what you can safely pressure wash says no to roofs, warning that the spray can loosen shingles and strip asphalt shingles of their embedded granules.

What ARMA recommends instead is a soft wash in everything but name: a 50:50 mix of liquid chlorine bleach and water, left to dwell for 15 to 20 minutes, then rinsed thoroughly with low pressure water. Household bleach is sodium hypochlorite, the SH in the cleaning solution we use on roofs. A cheaper roof cleaning that costs you granules is not a saving. Our guide to soft washing vs pressure washing covers where each method belongs.

Is roof cleaning worth it?

Start with the honest part. ARMA’s guidance states that there is no scientific evidence algae damages asphalt shingles, though it certainly affects how a roof looks. The exception it names is a highly reflective “cool” roof, where algae hurts the long term effectiveness of the roof system.

So if all you have is streaking, you are paying for appearance, and that is a perfectly good reason to spend money. A streaked roof can make a sound house look tired from the street, and that is reason enough if you are about to sell or simply sick of looking at it. Know that it is not a one time fix: ARMA’s algae bulletin says cleaning with bleach works only temporarily and the discoloration may come back. If neither applies and there is no moss, waiting is a reasonable call. Moss is the part not to leave.

One add-on to think twice about: zinc or copper strips fitted to the roof you already have. ARMA’s guidance does not recommend them on an existing roof, because they go on either with exposed nails, which can cause leaks over time, or by breaking the shingles’ sealant bond, which can eventually lead to wind damage. It lists strips and algae resistant shingles as options for when a roof is being replaced.

How to check a roof cleaning quote

Five questions sort out most roof quotes:

1. What square footage is this priced on? Roof area and living area are different numbers, and on a two story house the gap is wide.
2. What is your minimum? On a small or simple roof, it is probably the price.
3. Soft wash or pressure wash? ARMA’s guidance says never to pressure wash an asphalt shingle roof, so there is one right answer.
4. Is moss included, or priced on top? This Old House and Fixr say most cleanings already cover it, while EcoWatch prices manual moss removal as its own, more expensive method.
5. Is the price fixed before any work starts? A number that can move once the work is underway is an estimate, not a quote.

Getting a real number for your roof

National figures get you into the right range. A real number needs your actual roof: its size, its height and pitch, and how heavy the growth is.

All in 1 Pressure Washing is a family business in Louisville, owned by twin brothers Chad and Cory Berger. We soft wash roofs with low pressure and a professional grade SH cleaning solution, we are insured, and the quote is free, with the price given before any work starts. See how our roof cleaning service works, or get a free roof quote for a home in Louisville, Prospect, Anchorage, Mount Washington, Shepherdsville, Taylorsville, Shelbyville, Bardstown, Elizabethtown, Frankfort or Lexington.