Although a car wash may look like a simple structure, it is actually a very complex combination of systems, many of which are unseen, that in the end produce a clean car. This complexity can lead to longer build times than one might expect, and weather conditions can further complicate things. Typically a car wash will take 5-7 months from ground breaking to opening.
The first step in construction is bringing the site to grade and soil preparation work. This is critical because if the soil is not graded and prepared properly, water (and vehicles) can flow the wrong way. Additionally proper soil prep will reduce the risk of foundation and concrete problems later on.
Next underground work takes place. This includes trenching and placement of utilities, conduits and footers. Because the entire site will be overlaid with concrete, it is critical to ensure all underground work is completed during this phase, instead of later having to dig up or tunnel under concrete. Your general contractor is responsible for ensuring everything is done according to plan, but your equipment supplier will also be on site often, double checking that everything is being placed properly. This helps ensure proper equipment installation and operation later on down the road.
After footers have been poured, foundation walls and trenches are poured. Depending on the type of construction, block or prefabricated walls are laid followed by roofing. Some additional underground work may also happen at this time. Depending on the timing of the project and skills of the GC, some of these phases can happen concurrently.
Plumbers and electricians will then begin roughing in conduits and piping, especially main lines in the equipment room and bays. After all in-bay underground work is complete, the car wash equipment supplier can then lay the floor heat tubing in the bays, after which concrete is poured. In a tunnel wash, no floor heat is used inside the bay. In both self serve/automatic and tunnel washes, the concrete grade is important, however in tunnel washes it is critical that the concrete be within 1/8" tolerances to ensure proper vehicle tracking once the wash is in operation. The same goes for conveyor trenches in tunnels.
After concrete is in place, the equipment supplier will place, set and erect major pieces of equipment in the bays and equipment room. After they leave the plumbers and electricians plumb and connect their respective components. The car wash equipment provider then completes the installation and start up.
Of course this is a very simplified view of a very complex process.