Flagstone Cleaning in Boerne, Texas — Our 3-Step System

People ask us all the time if we can clean flagstone. Yes — and here is exactly how we do it without blowing out the mortar joints.

We get this call constantly: "Can you clean my flagstone?" The stone is dark, mossy, mildewed, and the homeowner has usually already tried a pressure washer from the hardware store — which either did nothing or chewed the mortar joints apart. Flagstone is one of those surfaces that punishes the wrong approach.

Here is the good news: we have an excellent system for it, refined over years of cleaning stone patios across the San Antonio and Hill Country area. Here is a flagstone patio and fire-pit area we recently cleaned in Boerne, Texas.

Our 3-Step Flagstone Cleaning System

### 1. Pre-treatment to loosen the mold

Before any water touches the stone, we apply a chemical treatment that soaks in and breaks down the mold, mildew, algae, and biological staining that has built up in the pores of the flagstone and along the mortar lines. This is the step that does most of the actual cleaning. Skip it and you end up trying to muscle the dirt out with pressure — which is exactly how mortar joints get destroyed.

### 2. Hot water power wash — measured, not maxed out

Next we come in with a hot water pressure wash. Heat matters here. Hot water lifts the loosened growth off the stone in a way cold water simply cannot. But — and this is the part most operators get wrong — we do not crank the pressure to the top. Too much pressure blows the concrete grout right out from between the stones. Our crew is trained to read the surface and dial the wand in so the stone comes clean and the joints stay intact.

### 3. Post-treatment to keep it clean longer

Once the patio is rinsed, we apply a post-treatment chemical that kills anything the wash missed and slows regrowth. Flagstone lives outside under trees and morning dew — mold wants to come back. The post-treatment is what buys you the long clean stretch between services.

The Boerne Patio — Before and After

You can see it in the photos. The stone came in dark, blotchy, and green in the low spots. After the three-step treatment, the natural color of the flagstone is back — the tans, reds, golds, and greys the homeowner paid for when the patio was built. Fire pit, seating wall, stepping stones, and the main patio all cleaned the same way.

Got a Flagstone Patio That Needs Help?

If you have flagstone anywhere in Boerne, Fair Oaks Ranch, San Antonio, or the surrounding Hill Country, we can bring it back. We will not blast your mortar out and we will not leave you with a patio that looks clean for two weeks and green again by month three. Our system is dialed in for Texas stone.

Learn more about our pressure cleaning service or request a quote.