building type notes
Car Wash Roofing Built For The Wash Environment In Columbia
A car wash punishes its roof from two directions at once, and most of the damage happens where nobody is looking. Hot water and detergent mist rise through the tunnel and condense on the underside of the deck. Chlorinated wax, tire-shine solvent, and rust-inhibitor vapor ride that same warm air column and settle on the steel deck, the fasteners, and the insulation facers above the bays. We build and service car wash roofs across Columbia with that interior chemistry in mind, because a membrane that looks perfect from the parking lot can be quietly losing its deck and its fastener pullout to corrosion you cannot see from the top side.
Express tunnels have multiplied along the high-traffic retail spines here, from the Harbison Boulevard corridor near Columbiana Centre out to the Two Notch Road and Decker Boulevard commercial strips, the Garners Ferry Road approach to Fort Jackson, and the newer pads going in around the Lexington side of the river on Sunset Boulevard. These are seven-day operations sitting in a humid Midlands climate, where summer dew points climb into the low 70s for weeks at a time. The outside humidity and the inside humidity stack on top of each other, and the roof never really gets a chance to dry out.
Why Standard Single-Ply Specs Fail On A Tunnel
The membrane manufacturers do not warranty their standard products against the chemistry a wash generates. That fact alone changes how we approach the tunnel bay. The vapor coming off the wash arches is alkaline from the detergents and aggressive from the wax and protectant carriers, and over a few seasons it embrittles seams and attacks the membrane at the curb welds first.
The Tunnel Bay Is Its Own Roof
We treat the roof directly over the wash equipment as a separate scope from the rest of the building. PVC is usually the right call there. Its chemistry holds up to the alkaline detergent and wax exposure far better than TPO or EPDM, and a fully adhered installation eliminates the membrane flutter that tunnel air pressure creates and removes the fastener field that vapor loves to corrode. Before we commit to a system we ask the operator what chemical program they run, because a soft-touch wax menu and a no-touch high-pH detergent line are not the same exposure.
The Underside Tells The Real Story
On any existing tunnel we pull the membrane back at a test area and look at the deck and the insulation facer from below. If the steel deck is showing white rust or the facer is delaminating, the roof is failing from condensation regardless of what the surface looks like. That finding drives whether we recover or fully replace, and whether we need a vapor retarder and venting strategy that a normal commercial building would never require.
