GMB
Ground-Mounted Bench
The most versatile bench type in the system. The GMB works on an existing slab or embeds into a new footing, and the above-grade frame stays the same either way. That makes the installation method a site decision rather than a design decision. It is the default choice when site conditions do not include a seatwall or a wall to anchor to.
When to Specify the GMB
Specify the GMB when there is no seatwall and no structural wall available, or when the bench needs to sit out in the open. It suits plazas, campus quads, parks, streetscapes, and any location where seating is freestanding.
It is also the type to specify when the installation method is still undetermined. Because both mounting methods share the same above-grade assembly, the decision can be deferred to site documentation without affecting the bench design.
Two Installation Methods, One Bench
Method A · Surface Anchor
Bolts to an existing or new concrete slab with no separate footing. Contractor-supplied wedge anchors or equivalent, suggested minimum 1/2″ diameter with 4″ embedment into a 3,000 psi slab. Verify edge distance and embedment given base-plate thickness. Easier to install and easier to remove, which suits both new construction and retrofits.
Method B · Post Embed
Steel posts embedded into a new concrete footing. 20″ minimum embedment, minimum footing 12″ diameter by 24″ deep at 3,000 psi, sized per soil and load. Permanent, robust, and more resistant to vandalism. Best suited to new construction where long-term permanence is the priority.
Same above-grade assembly
Both methods use the same above-grade assembly. Wood, edge profiles, board count, and finished dimensions are identical. The above-grade assembly ships as one piece regardless of installation method.
Footings shown are a baseline for typical compacted soil. Final footing dimensions, depth, and reinforcement should be verified by the project’s engineer of record and/or geotechnical engineer based on actual site soil conditions, seismic design category, and applicable loading. Larger or deeper footings may be required for poor, sandy, expansive, or sloping soils, or for elevated installations.
Method A: Surface Anchor
Method B: Post Embed
Key Design Criteria
| Parameter | Limit |
|---|---|
| Seat depth | 17.5″ standard (backed); no limit (backless) |
| Seat length | No limit continuous; typical max 8′ per section |
| Seat height | 17.5″ default for most configurations; customizable on request |
| Radius | Backless curved per the radius limits below |
Two Forms
BB · Backless
Available straight and curved. The most versatile configuration in the system.
BE · Backed
Full bench with integrated backrest. Straight configurations only. If a curved, backed configuration is desired, please reach out directly to discuss.
Curved Configurations
The GMB curves in the backless form. Minimum radius depends on board pattern and orientation. All values below are minimums. Specify a radius equal to or greater than the value shown.
Curved, long-axis orientation (L)
Available in profiles 22, 23, 24, and 26. For a curved bench in profile 32, use an S-orientation pattern.
| Max bench length | 22L | 23L | 24L | 26L |
|---|---|---|---|---|
| ≤ 44.5″ | 5′ | 5′ | 6′ | 14′ |
| ≤ 58.5″ | 8′ | 8′ | 11′ | 22′ |
| ≤ 71.5″ | 10′ | 12′ | 16′ | N/A |
Curved, short-axis orientation (S), Method A · tapered gaps
Rectangular boards with tapered gaps, lengths measured on the inside radius edge. Often the best choice for gentle curves at larger radii.
| Profile | Minimum radius | Condition |
|---|---|---|
| 22S / 32S | 9′ | Seat depth ≤ 24″ |
| 23S | 11′ | Seat depth ≤ 24″ |
| 24S | 14′ | Seat depth ≤ 24″ |
| 26S | 20′ | Seat depth ≤ 24″ |
Curved, short-axis orientation (S), Method B · custom-milled
Trapezoidal boards with a uniform 1/2″ gap, lengths measured on the outside radius edge. Available in 24S and 26S. Often the best choice for tighter curves. Minimum outer radius equals seat depth plus one foot.
Materials and Finish
Surface anchor. Mild steel supports, sandblast cleaned, epoxy primer, then superdurable powder coat. Mounting plates at the concrete interface are 304 stainless. DM Braun uses stainless anywhere steel bears directly on concrete, since abrasion at that interface can wear through a coating and expose mild steel to rust. The plate isolates the mild steel supports from direct contact with the slab.
Post embed. Mild steel posts embedded into the concrete footing. Above-grade steel receives the same sandblast, epoxy primer, and powder coat system.
All assembly and anchoring hardware is stainless steel. Powder coat color is specified by name from the DM Braun standard color chart, with many RAL colors available as custom.
The same stainless-at-the-concrete-interface principle governs the SWB, which is all stainless because its whole frame bears on concrete, and the CWB.
Options
Armrests. Both types are available on the GMB. Type 1 is welded to the steel frame at the factory, fixed at frame support locations, and available on backed benches in L orientation. Type 2 mounts to the underside of the wood boards, can be located at almost any position, and is field-retrofittable.
Leg style. The GMB has a default leg style, but has multiple options available as a project-specific option, resolved on the detail at CD phase.
Edge profiles. Four standard radii: 1/8″, 1/4″, 1/2″, and 3/4″.
Skirting. Available. Wood skirting panels cover the front face, and in some cases the rear face, of straight configurations, in profiles 22, 23, 24, and 26.
Specifying the GMB
Use the five-part product code through SD and DD. Example: GMB-26S-CU-BB-I is a ground-mounted bench, 26S board pattern, curved, backless, in Ipe.
At CDs, send dimensions, substrate conditions, installation method, leg style, and detail options. DM Braun produces the project-specific detail sheet.
See the full two-stage specification process on the BraunMark hub ›
Frequently Asked Questions
Does the bench design change depending on how it is mounted?
No. Both the surface anchor and post embed methods use the same above-grade assembly. Wood, edge profiles, board count, and finished dimensions are identical, so the installation method can be decided later without revisiting the design.
Can the GMB be installed on an existing slab?
Yes. Method A surface-anchors to an existing or new slab with no separate footing required, provided the slab is 3,000 psi minimum and edge distance and embedment are verified.
What footing size does the post embed method require?
20″ minimum embedment into a minimum 12″ diameter by 24″ deep footing at 3,000 psi, sized per soil and load. Final footing design should be confirmed by the project’s engineer of record or geotechnical engineer.
Can the GMB be curved?
Yes, in the backless form. Minimum radius depends on board pattern and orientation. See the tables above.
A curved backed bench option is available, but falls outside of the limits of BraunMark. DM Braun can work through this with the design team as a full custom item.
What is the standard seat height?
17.5″ for most configurations, and it can be customized on request. Standard seat height for a 32 profile would be 18.5″.
Can a GMB be relocated later?
Surface-anchored benches can be unbolted and relocated. Post-embedded benches are permanent by design.
Configure your Ground-Mounted Bench.
Set the bench type, board pattern, wood and layout, and we will produce the project-specific detail at CDs.