Striping, Slopes and ADA Basics for Small Lots

A friend who rents a small storefront asked me to help turn the gravel behind it into concrete parking, because he knew I had poured my own driveway and figured that qualified me. My first sketch fit seven spaces. I was proud of that seventh space. It is also the one that would have caused a problem, because the moment parking is used by the public you are not building a driveway anymore and the rules stop being suggestions.

I am a homeowner who poured one patio and hired out one driveway. Nothing here is a code opinion or a substitute for what your building department says over the counter. It is the checklist I wish I had before I drew anything.

Start with the sizes, not the shape

Everyone starts by outlining the pavement. Draw one stall instead and see how many honestly fit.

Standard stall: commonly 9 feet wide by 18 feet deep, with 8.5 by 18 allowed in some places for compact spaces.
Drive aisle: about 24 feet for two-way traffic with 90 degree parking; angled parking at 60 degrees needs 12 to 18 feet one-way but loses spaces to the angle. A stall you cannot exit without a three-point turn will be used wrong forever.
Delivery vehicles: if a box truck or dumpster comes in, its path and resting spot drive the layout, and both need thicker concrete than the car stalls.

Once we drew a real 24 foot aisle, seven spaces became five.

The accessible space is a set of dimensions, not a paint color

This is the part I knew nothing about. The federal design standards are published at ada.gov, and they are readable, which surprised me. How they apply depends on the scope of work and how the local plan reviewer reads it, so treat these as the shape of the requirement, not a ruling on your lot:

Count: a lot with 1 to 25 spaces generally needs at least one accessible space, and at that size it should be van accessible.
Width: a car accessible space is 8 feet wide plus a 5 foot striped access aisle. A van space is 11 feet with a 5 foot aisle, or 8 feet with an 8 foot aisle.
The aisle is not a parking space. It is the room a ramp or lift deploys into, it must be marked, and two spaces can share one.
Clearance and signage: van routes want 98 inches of overhead clearance in and back out; the sign’s bottom edge sits at least 60 inches up so a parked vehicle cannot hide it.
Route to the door: continuous and at least 36 inches wide, with any curb ramp no steeper than 1:12 running and 1:48 across.

The slope is the trap

Here is the one that nearly got us. Accessible spaces and their access aisles must be close to flat — no more than 1:48, about 2.08 percent, in any direction. But a slab that does not drain ponds water, and the practical minimum for drainage is 1 percent, or 1/8 inch per foot.

So the whole allowable window there is roughly 1 to 2 percent — over a 24 foot run, a fall of three to six inches, hit consistently. My hand-graded patio is off by more than that across 12 feet, which tells you whether I should be setting grades. Where I live the window is tighter still: over a hundred freeze-thaw cycles a year means a flat spot holding meltwater is ice by morning and scaled by spring. Plan the drainage direction first, then check whether the accessible spaces fit inside it.

Concrete, then paint, in that order

The slab is a separate question from the layout, and where small lots get underbuilt:

Thickness and strength. Cars only, 5 inches at 4,000 psi. Where a delivery truck, trash truck or loaded dumpster sits, 6 to 8 inches with #4 rebar at 12 to 18 inches on center, held at mid-depth.
Base. 6 inches of compacted aggregate, verified to something like 95 percent Proctor, not eyeballed.
Joints. Cut 6 to 18 hours after the pour, spaced 24 to 30 times the slab thickness — 12 to 15 feet on a 6 inch slab.
Cure it. Seven days wet or covered. In dry, high-altitude air a slab can lose enough surface moisture in an afternoon to weaken the top layer.
Then stripe. Wait roughly 28 days for paint to bond. Lines are 4 inches wide. A rented striping machine is $60 to $130 per day, traffic paint $35 to $65 per gallon; hiring it out runs $6 to $15 per stall.

Wheel stops, bollards and curbs belong on the same drawing, not added later — the trade-offs are in curbs, wheel stops and bollards.

Frequently asked questions

How many accessible spaces does a five-space lot need? Under the federal design standards, a lot in the 1 to 25 range is generally expected to provide at least one, van accessible. How that lands on a property depends on the scope of work, so confirm at the permit counter before you set forms.

Can an accessible space be sloped for drainage? Only slightly. The limit is 1:48, about 2 percent, in all directions including the access aisle. That is a narrow band between draining and being too steep, which is why those spaces belong on the high, flat part of the lot.

How soon can I stripe a new concrete lot? About 28 days. Fresh concrete is alkaline and still releasing moisture, so paint applied early tends to lift or discolor. If markings are needed sooner, removable markers beat striping twice. Give the surface a proper wash before any of it goes down — an industrial cleaning contractor in Atlanta will get laitance and film off so the paint actually keys in.

Accessibility standard: ADA Standards.