Install A Bench - SFBA Bench Collective

If you put your bench in public, you’ll want to anchor it to the ground to ensure it is stable and to prevent it from walking away. This guide will show you how to add mounting brackets to your bench’s feet and anchor them to concrete (or soil).

Tools

Impact driver with nut drivers/hex sockets (9/16 in. and 1/4 in.)

Grey hex nut driver with 9/16 inscribed.

SDS+ rotary hammer (or hammer drill) with 3/8 in. masonry bit

The rotary hammer is only needed for anchoring in pavement.

Materials

L-bracket with hole for 3/8 in. bolt

L-shaped bracket with small screw holes and larger bolt holes.

#9 x 1-1/2 in. connector screw

3/8 in. x 1-3/4 in. or longer concrete screw anchor

Masonry anchors come in several forms, but screw anchors are the simpliest to use. Brands include Tapcon, CONFAST, and Simpson Titen HD. If you use a wedge or sleeve anchor, you will also need a hammer. Concrete needs 1.75” long anchors, while asphalt is less solid and needs longer 2.5” or 3” long anchors.

Long galvanized or stainless steel lag screws may be used for anchoring in soil. Altho they’re intended for wood-to-wood connections, here they can act as drillable stakes.

3/8 in. x 12 in. lag screw

Mounting Brackets

We use L-brackets as the connection between each wooden leg and the anchoring hardware. One side has small holes for the screws that attach to the bench, and the other side has a larger hole for the anchor.

If you want to shield the feet of your bench, do so before attaching the brackets.

For each bench foot, align the bracket with the template markings. Raise the bracket slightly off the ground to allow the anchor to pull the bench down.

Attach the bracket to the bench foot using two connector screws. Drive the screws using the impact driver with 1/4” socket. Avoid holes near the wood edge to prevent splitting. Stop tightening once the screw is snug against the bracket and wood; do not over-tighten.

Repeat for the other three feet.

Positioning

First, position the bench where you want to install it. Ideally there should be at least 5 feet of clearance for the sidewalk. The absolute minimum allowable clearance is 36 inches, according to the ADA, but it is best to avoid even approaching that minimum.

At bus stops, ensure there is adequate space for a wheelchair ramp to deploy from the front door. Ideally there should be at least 6 ft. of curb by 8 ft. of sidewalk clear, although many official bus stops fail to meet these guidelines.


AC Transit’s Accessible Landing Zone and Rear Clear Zone diagram from page 18 of their 2018 Multimodal Corridor Guidelines (full image).

On wide sidewalks, it is preferable to install the bench in the “verge” area between the curb and the sidewalk. Ensure there is enough space in front of the bench to walk and sit on it without entering the roadway, and adequate space behind for pedestrians and wheelchair users to pass by.

On narrower sidewalks, it may be preferable to install the back of the bench up against a building. Ideally get property owner permission before installing, and ensure no doors, shutters, gates, etc. are blocked.

Another option on narrow sidewalks it to install the bench with the back facing the curb, which allows access to the bench without using up additional sidewalk width. However this means people will sit with their backs to the roadway, which may feel unsafe and/or make it difficult to spot approaching buses.

Try to avoid blocking utility access covers and maintenance holes, noting that utility workers can move the bench for access if absolutely necessary.

Anchoring

Concrete Anchoring

Once positioned, hold the bench in place and use the rotary hammer to chip a small marking in the pavement where each anchor will go. Move the bench aside and drill the holes to the depth of the anchor plus 1/2” for dust (or as recommended by the anchor manufacturer). Then reposition the bench above the holes.

For screw anchors, use your impact driver with 9/16” socket to drive each anchor thru the bracket and into the hole. Stop once the anchor is securely pressed down against the bracket; do not over-tighten.

For wedge and sleeve anchors, with a nut shielding the top of the threads hammer the anchor thru the bracket and into the hole. Then tighten the nut to the recommended torque.

Give the bench a good shake to ensure it is secure.

Soil Anchoring

Soil anchoring is simpler than concrete anchoring. First position the bench on firm, level ground. Then simply use your impact driver to drive each lag screw thru the bracket and into the ground. Stop once the bench feet are securely against the ground; do not over-tighten.

Give the bench a good shake to ensure it is secure.