Tiger Stripes: Why Your Gutters Still Look Dirty After the House Is Washed

It is the call we get a week after a house wash. The siding looks great, the driveway looks great, and the gutters still have grey vertical stripes running down them. Nothing went wrong. Those stripes are a different problem with a different fix.

What tiger striping actually is

The streaks are not loose dirt sitting on the paint. They are a bonded film.

Rain running off the edge carries airborne grime, pollen and the oxidised binder out of the gutter's own factory finish. That mixture runs down the face of the gutter, and surface tension holds it in narrow vertical bands rather than an even sheet. The sun then bakes it on. Over a few seasons it stops being a deposit and starts being a layer chemically stuck to the aluminum.

That is why it follows the same lines every time, and why it is worst on the side that gets the most sun and the least rain volume.

Why a house wash will not touch it

A soft wash mix is built to kill organic growth. Algae, mildew, the green and black film on your siding. It is very good at that, and it rinses straight off.

Tiger striping is not alive. There is nothing to kill. The detergent runs over a bonded film and takes almost none of it, so the gutters come out looking exactly as they went in. Turning the pressure up does not help either. The film is harder than you think and the finish underneath is softer than you think, so pressure strips the coating before it strips the stripe.

What does remove it

It needs a dedicated gutter cleaner, applied to the face of the gutter, given time to dwell, agitated by hand with a soft brush, then rinsed. The agitation is the part people skip and it is the part that does the work. There is no spray-and-walk-away version of this.

It is slower than washing the house, it is charged separately for that reason, and it is worth asking for by name when you book, because a standard house wash quote does not include it.

What to expect honestly

• Most gutters come back to near new. Especially if the striping is a few years old rather than fifteen.
• Some do not come all the way back. If the factory finish has already chalked and failed underneath, removing the film exposes a dull, uneven surface. We can get it clean, but clean is not the same as glossy. At that point the honest answer is paint or replacement, and we will tell you that rather than keep scrubbing.
• It will come back. It is a weathering process, not contamination. Expect to do it every two or three years.

The thing worth knowing

Streaked gutters read as neglect from the street even when everything else is spotless. If you are selling, photographing, or just tired of the house looking half done, this is usually the single highest impact item left after the siding is clean, and it is one of the cheapest.

We clean gutter exteriors across St. Johns County and the Jacksonville area, as an add on to a house wash or on its own. Ask for gutter brightening when you call and we will quote it with the rest.