Truncated Domes
Replaceable vs Permanent Truncated Dome (2026)
Cojo
May 7, 2026
7 min read
A replaceable truncated dome panel is a tactile warning surface mounted in a frame so the dome plate can be unbolted and swapped after wear, while a permanent truncated dome is set or cast into the walking surface and cannot be removed without demolishing the substrate. Both meet ADA Standards 705.1 dome geometry when properly specified, but they diverge sharply on lifecycle cost, snowplow tolerance, and how a property owner replaces a damaged section ten years out.
This guide compares the two product families on the spec lines that actually drive a purchase decision: substrate compatibility, ADA 705 contrast and placement performance, replacement labor, and total cost of ownership across a 20-year horizon.
A replaceable truncated dome is a two-piece system. A permanent base frame is anchored into the concrete or asphalt substrate, and a removable dome plate (cast iron, polymer, or composite) bolts into the frame. When the dome plate wears out, oxidizes, or suffers plow damage, a crew loosens the bolts, lifts the old plate, and drops in a replacement. The frame stays in place for the life of the substrate.
Cast-iron replaceable systems are the dominant variant. Federal-yellow powder-coated iron resists snowplow strikes that destroy composite domes within a season. Manufacturers including East Jordan Iron Works and Neenah publish AASHTO M306 load ratings for the frame and ADA 705.1 dome geometry on the plate.
Replaceable frames anchor with stainless-steel mechanical fasteners into cured concrete or with cast-in flanges set into wet concrete during pour. The frame profile sits flush with the walking surface so the dome plate, when bolted in, rises 0.2 inches per ADA 705.1 height spec.
A permanent truncated dome is a one-piece panel that cannot be removed without breaking the surrounding substrate. The two main families are cast-in-place panels (set into wet concrete during a new pour) and surface-applied panels (epoxy-and-anchor bonded to cured concrete). Once installed, the panel and the substrate are mechanically and chemically joined.
Permanent panels are typically composite (fiber-reinforced polymer), polymer concrete, or precast concrete. They cost less per panel than a replaceable cast-iron system but cannot be selectively replaced. When a permanent panel fails, the contractor saw-cuts around it, demolishes a section of the surrounding concrete, and rebuilds the substrate before installing the new panel.
Yes. Both replaceable and permanent systems meet ADA Standards 705 when correctly specified. The federal regulation does not prefer one product family — it specifies dome geometry (705.1), 70 percent visual contrast (705.2), and placement at the curb edge (705.3). Both system types can be ordered in compliant configurations.
| Spec | Replaceable (cast iron) | Permanent (cast-in-place) | Permanent (surface-applied) |
|---|---|---|---|
| Service life of dome surface | 15 to 25 years (plate replaceable) | 15 to 30 years | 7 to 15 years |
| Replacement labor (per panel) | 30 to 60 minutes | 4 to 8 hours plus concrete cure | 2 to 4 hours plus epoxy cure |
| Snowplow tolerance | Excellent | Good | Fair to good |
| ADA 705.1 geometry compliance | Yes | Yes | Yes |
| ADA 705.2 contrast | 70 percent achievable, color-fast | 70 percent achievable | 70 percent achievable, fade risk |
| Substrate fit | New or retrofit | New construction only | Retrofit-first |
| Initial material cost per square foot | Highest | Mid | Lowest |
| Lifecycle cost (20 years) | Lowest | Mid to high | Highest in high-traffic |
Replaceable truncated domes are the right call when at least one of these conditions applies.
Bend, La Grande, Pendleton, and Hood River curb cuts see annual plow blade impact. Cast-iron replaceable plates absorb the strike and stay in place, while composite permanent panels often crack at the leading edge. Cojo retrofitted four Bend transit-stop curb ramps with replaceable cast-iron systems in February 2026 after composite panels failed in two seasons.
Replaceable systems shine on properties with 6 or more curb cuts where one or two will inevitably take a hit (forklifts, plows, vehicle strikes). Stocking two spare dome plates and rotating them in beats demolishing concrete on a per-incident basis.
Owners who hold property for 15 plus years amortize the replaceable premium across 2 or 3 dome-plate replacement cycles. Short-hold property (5 to 7 years) rarely captures the lifecycle savings.
Permanent truncated domes are the better fit when these factors line up.
A standalone retail entrance with one curb cut and no snowplow exposure does not need a replaceable frame. A surface-applied composite panel costs less up-front and meets ADA 705 for the building's likely useful life.
Cast-in-place panels deliver the lowest lifecycle cost on new pours because the panel and the surrounding concrete cure as one unit. There is no retrofit overhead, no epoxy bonding step, and the embedded edge resists peel-up better than any surface-applied product.
Surface-applied permanent panels cost the least to install and remain ADA-compliant for 7 to 15 years. If the structure itself is on a 10-year horizon, the permanent panel will outlast the building.
The replaceable premium is real. The break-even calculation depends on how often the dome surface is damaged or worn beyond the ADA 705.5 wear threshold.
Industry Baseline Range
| Cost element | Replaceable cast iron | Surface-applied composite |
|---|---|---|
| Initial material per square foot | $55 to $95 | $32 to $60 |
| Initial install labor per square foot | $18 to $35 | $14 to $30 |
| Replacement at year 8 to 15 | $14 to $28 (plate only) | $46 to $90 (full demo and reinstall) |
| 20-year total per square foot | $87 to $158 | $92 to $180 |
Cast-iron prices climbed 18 to 24 percent in 2025 on raw-iron and powder-coat surcharges. Composite panel pricing rose less but is being squeezed on epoxy adhesives certified to ASTM C881. Labor for both systems is up because ADA 705 inspection rigor is climbing under the U.S. Access Board's 2024 guidance refresh, and crews need extra layout time to verify dome geometry on every job.
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. Replaceable and permanent product family selection does not, on its own, satisfy ADA compliance — installation geometry and contrast verification are equally controlling.
On a Salem state-government parking lot in March 2026, we replaced 12 surface-applied composite panels that had reached ADA 705.5 wear failure at the 9-year mark. The owner authorized us to spec replaceable cast-iron systems for the rebuild. The frames anchor into the existing curb-ramp concrete and the property now has a 25-year horizon on the substrate with 5-year inspection intervals and a $200 per-plate swap budget. That is the lifecycle math in practice.
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