Truncated Domes
How to Install Surface-Applied Truncated Dome 2026
Cojo
May 7, 2026
6 min read
A surface-applied truncated dome installs on cured concrete with ASTM C881 epoxy adhesive plus stainless-steel countersunk anchors at 6-inch on-center perimeter spacing, completed in 90 to 180 minutes per curb cut by a two-person crew. The install must satisfy ADA Standards 705.1 dome geometry, 705.2 visual contrast, and 705.3 placement at completion or the panel has to come out. This guide walks through the full procedure step by step.
The procedure assumes a single 24-inch by 48-inch dome panel on a sound, cured-concrete curb-ramp landing. Variations for damaged substrate, multi-panel cuts, and alternate adhesive systems are covered in the variations section.
Inspect the curb-ramp landing. Look for cracks wider than 0.25 inches, spalls deeper than 0.5 inches, or out-of-plane variation greater than 0.25 inches across the panel footprint. Damage exceeding these thresholds requires repair before the panel goes down. Mark any damage and note repair cost in the project record.
Grind the substrate within the panel footprint to remove curing compound, sealer, surface laitance, oil, paint, or contamination. Diamond-cup grinding to a uniform clean concrete surface takes 10 to 20 minutes. Vacuum the dust thoroughly. Wipe the surface with manufacturer-specified solvent. The substrate must be dry, clean, and free of all foreign material before adhesive goes down.
Position the panel dry on the substrate at the back-of-curb. Verify with a tape measure that the leading edge sits at the back-of-curb (0-inch setback for sidewalk applications) and the panel extends 24 inches up the ramp at full ramp width. Mark the panel perimeter on the substrate with a pencil or chalk line. Mark anchor positions at the perimeter at 6-inch on-center spacing.
Lift the panel off the substrate. Drill pilot holes at the marked anchor positions to the manufacturer-specified depth and diameter. Vacuum dust from each hole. Test-fit each anchor to confirm depth.
Mix the ASTM C881 Type IV epoxy according to manufacturer instructions. Working time is typically 30 to 45 minutes at 70 degrees F. Apply adhesive with a notched trowel to the back of the panel, the substrate, or both per the manufacturer's instructions. Coverage rate is typically 1 gallon per 32 to 40 square feet, but check the data sheet.
Lower the panel onto the adhesive bed with the leading edge at the back-of-curb. Press firmly to seat the panel into the adhesive. Confirm the panel is flush with the surrounding walking surface (no rocking, no edge lift). Excess adhesive that squeezes out at the perimeter should be wiped or scraped clean before it cures.
Drive each anchor through the panel into the pilot hole. Torque to manufacturer specification (typically 8 to 15 foot-pounds for stainless steel). The anchor head should sit flush or just below the dome surface elevation, not protruding above. Visible anchor heads should not deform when torqued; if they do, the pilot hole or the anchor type was wrong.
Apply polyurethane edge sealant continuously around the panel perimeter. The bead should be roughly 0.25 inches wide, tooled smooth with a wet finger or tooling stick. Sealant prevents water from working under the panel and breaking the adhesive bond.
Block traffic from the panel for the manufacturer-specified cure time, typically 4 to 24 hours depending on temperature and adhesive type. ASTM C881 Type IV cures faster at higher temperatures. Use cones or tape to keep pedestrians and vehicles off the surface during cure.
Once cured, verify with a caliper that 6 randomly selected domes meet ADA 705.1 geometry (base 0.9 to 1.4 inches, top 0.45 to 0.9 inches and 50 to 65 percent of base, height 0.2 inches, center-to-center 1.6 to 2.4 inches). Verify with an LRV meter that the dome surface has at least 70-point differential against the adjacent walking surface (ADA 705.2). Verify with a tape measure that the panel is 24-inch minimum depth, full ramp width, leading edge at back-of-curb (ADA 705.3). Document the readings.
ASTM C881 epoxy will not bond to wet or contaminated concrete. The panel will lift inside 6 to 24 months. Solvent-wipe the surface and verify dry conditions before applying adhesive.
Over-torqued anchors deform the panel surface and can crack composite material. Under-torqued anchors back out under traffic. Use a torque wrench, not a impact driver.
Installing the panel before tape-measuring the placement risks setting the leading edge 4 to 8 inches behind the back-of-curb, failing ADA 705.3. Always verify before applying adhesive.
A panel that visually looks compliant can fall below 70-point LRV differential against a weathered concrete surface. Always verify with a meter at completion.
ASTM C881 has a working temperature range, typically 50 to 90 degrees F. Installs outside the window require heated tents in cold conditions or schedule shift in hot conditions. Adhesive that sets too fast or too slow does not achieve full bond strength.
A curb-ramp landing with cracks, spalls, or out-of-plane areas needs repair before the panel goes down. Crack injection with ASTM C881 Type I epoxy, spall patching with rapid-set polymer concrete, and grinding to bring the surface within plane are typical pre-install steps. Add 1 to 2 hours of crew time per cut.
Curb cuts wider than 60 inches typically require 2 or more panels set side-by-side. Each panel is installed by the same procedure. The seam between panels gets a continuous polyurethane sealant bead to prevent water intrusion.
Most surface-applied dome systems are warranted for concrete only. If the curb-ramp landing is asphalt, the recommended path is to remove a 24-inch by 48-inch section of asphalt, pour a small concrete landing, cure 7 days, then install the dome panel by the standard procedure.
This article reflects ADA Standards for Accessible Design as of 2026-05-07 and product spec sheets current at publication. Always verify current dimensions, contrast thresholds, and placement requirements with your local jurisdiction and the U.S. Access Board before issuing a final spec. Federal guidance under 36 CFR Part 1191 controls when state or local rules conflict. Manufacturer installation instructions take precedence over generic step-by-step guides for the specific product purchased.
On a Hillsboro retail center retrofit in April 2026 we installed 8 polymer-concrete panels in a single day with a two-person crew. Substrate prep ran 35 minutes per cut on the 12-year-old cured concrete. Layout and dry-fit took 18 minutes. Adhesive mix and panel set took 45 minutes. Edge sealant and anchor torque took 15 minutes. ADA 705 verification took 22 minutes. Total per-cut crew time landed at 2 hours 15 minutes. The standard procedure works on standard substrates. Damaged or asphalt substrates need additional prep time before the standard procedure runs.
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