Car park expansion joints: choosing covers for traffic, water and noise

A car park expansion joint is crossed by cars all day, washed with water, salt and oil, baked on the top deck and, on a multi-storey structure, sits directly above someone else’s parked car. The cover on it has to carry the traffic, follow the movement of the decks, stay quiet under wheels and, where the level below must stay dry, keep water out. This guide goes through those four demands and the Genotek systems that answer each one, using the facts in their datasheets.

Why car park joints are hard

Parking structures are long, exposed concrete frames. Their decks expand and contract with the temperature more than an air-conditioned floor does, ramps and decks meet at changes of level, and in seismic regions the joints between structural blocks also have to take multi-directional movement. A cover that suits a lobby floor can fail quickly here, for four reasons:

• Wheel traffic. Tyres turn, brake and accelerate on the cover, and some vehicles are much heavier than a car.
• Movement. Thermal movement every day, settlement over time and, where specified, seismic movement in every direction.
• Noise. A loose plate clatters each time a wheel crosses it, which matters in a residential or hotel car park.
• Water. Rain on the top deck, wash-down water and water dripping from cars all run towards the joint.

The parking floor joints range on genotek.net lists the systems used in car parks. The sections below explain how to narrow it down.

1. Traffic: read the datasheet’s traffic line

Every Genotek datasheet states the traffic the system is meant for. In a car park, read that line before anything else, and ask us when a joint will see something the label does not name.

• The Z4100 (PROFLOOR RM) datasheet lists heavy pedestrian and medium vehicular traffic, and states that it is not recommended where forklifts or other heavy concentrated wheel loads may cross it.
• The Z8000 (ULTRAPARK) datasheet recommends it for parking garages and warehouses and for areas with regular passage of forklifts, trucks and other heavy vehicles.
• The Z7100A (LUXPARK) datasheet lists heavy vehicular loads, for wider joint gaps.
• The Z4050 (PROFLEX RMS) datasheet names car parks among its uses, for wider joint openings exposed to heavy traffic, and its cover plate is supplied in aluminium or stainless steel in a thickness chosen for the job. Tell us which vehicles will cross it, for example service trucks or fire appliances.
• The GEN1000 (PROPARK 3P) and GEN1000B (PROPARK) datasheets list heavy pedestrian and heavy vehicular traffic and recommend them for parking structures, multi-level car parks and emergency and service vehicle areas.

The heavy duty range groups the systems meant for the heaviest traffic.

2. Movement: thermal, settlement and seismic

Most car park joints are thermal joints, and their covers list thermal and settlement movement. Where the structural engineer specifies seismic or multi-directional movement, choose a system whose datasheet lists seismic movement as well:

• The Z8000 uses a steel spring and allows vertical displacement between the two slabs. Its max/min drawing for a 200 mm joint shows the joint closing fully and opening by half its width (−200 mm / +100 mm, −100 % / +50 %) with ±50 mm of vertical movement.
• In the Z7100A, the Z4100A (SUPERFLOOR) and the Z4100, the top plate stays flush with the deck during thermal movement and, during seismic movement, temporarily displaces and slides over the finishing surface. The Z7100A can be supplied with PTFE tape so that the plate slides with little friction.
• The Z4050 is a heavy-duty centre bar system: a steel turnbar assembly under the cover plate takes multi-directional movement.

Compare the movement drawing for the exact size with the engineer’s figures in each direction. Our guide to seismic expansion joint covers explains how to read those drawings.

3. Noise: stop the clunk

A metal plate that can rattle will rattle under car wheels. Two design features in the range deal with this. The Z8000 has a damper system that stops the cover from clunking from side to side under moving traffic. The GEN1000 and GEN1000B are made of elastomeric rubber moulded around independent steel plates; their datasheets note the sound-absorbing property of the rubber and a smooth, slip-resistant transition over the joint that reduces the risk of tripping. The GEN1000B is a surface-mounted version.

4. Water: top decks, ramps and the level below

On a covered intermediate deck, water from cars and washing is the main concern; on the top deck and ramps, rain and sun as well. Where the space below must stay dry, the joint needs a watertight system, not only a cover:

• The WTZ4100 (PROFLOOR WT) is a watertight version for external floors with high water use where multi-directional movement is required. Like the Z4100, its datasheet lists medium vehicular traffic and states that it is not recommended for forklifts or other heavy concentrated wheel loads.
• The GENFOAM is a preformed compressible foam seal. Its datasheet recommends it for parking garage expansion joints, plaza decks and below-grade connections, and it is installed without drilling or other invasive anchoring.
• The Z8000 drawings show a water barrier below the cover as an option where the joint requires one.

A water barrier only works when it is continuous through every length and junction and connected to the deck waterproofing on both sides. Our guide to watertight joint covers explains the two lines of defence and where they usually fail.

Recessed or surface mounted

In a new car park, recessed covers sit in a blockout in the slab and finish flush with the deck coating. The datasheets ask for enough clearance from the reinforcement for the anchors, a deck surface level to within ±2 mm and a gap level to within ±5 mm, with the largest gap along the run matching the size ordered. The blockout has to be on the structural drawings before the slab is poured.

In an existing car park, a surface-mounted cover avoids cutting the slab:

• The CFH (PROHINGE) is a full metal hinged cover for surface-mount installation in areas with heavy loads. Its cover is serrated for slip resistance, its interlocking hinged anchor frames keep the cover aligned, it can accommodate a slab offset between the two sides, and its datasheet recommends it for retrofit as well as new work.
• The OF4000 (PROFLEX SM) is a surface-mounted centre bar cover that its datasheet recommends for renovation and retrofit work, with heavy pedestrian and light vehicular traffic.
• The GEN1000B is the surface-mounted rubber and steel option for heavy vehicles.

Before you order

Metal covers such as the Z8000 are supplied in standard lengths of 3.00 m, so plan the joints between lengths and the junctions at ramps and kerbs, and give the installer the model’s installation instructions, which are part of its document pack, before the blockouts are formed. Then send us the deck plans with the joint runs, the nominal joint widths, the movement figures from the structural engineer and the heaviest vehicle that will use each level through the contact page or at support@genotek.global. We will propose a system for each joint, including the ramps and transitions.

Frequently asked questions

What is a car park expansion joint?

It is the deliberate gap between two parts of a parking structure that lets the decks expand, contract, settle and, in seismic regions, move in every direction without cracking. A car park expansion joint cover closes that gap so that vehicles and people can cross it, and a watertight system also keeps water from reaching the level below.

Which Genotek covers are made for heavy vehicles in car parks?

Read the traffic line of each datasheet. The Z8000 (ULTRAPARK) is recommended for regular passage of forklifts, trucks and other heavy vehicles; the Z7100A (LUXPARK) lists heavy vehicular loads; the GEN1000 and GEN1000B (PROPARK) list heavy vehicular traffic and are recommended for multi-level car parks and emergency and service vehicle areas. The Z4100 and WTZ4100 list medium vehicular traffic and are not recommended for forklifts or other heavy concentrated wheel loads.

How do I stop a car park joint cover from making noise?

Choose a system designed against it. The Z8000 has a damper system that stops the cover from clunking from side to side under moving traffic, and the GEN1000 and GEN1000B are elastomeric rubber moulded around steel plates, which absorbs sound.

Can a car park expansion joint be made watertight?

Yes. The WTZ4100 (PROFLOOR WT) is a watertight system for external floors with high water use, the GENFOAM compressible foam seal is recommended for parking garage expansion joints, and the Z8000 can be supplied with a water barrier below the cover. The barrier must be continuous and connected to the deck waterproofing on both sides.

Can I replace a joint cover in an existing car park without cutting the slab?

Yes, with a surface-mounted cover. The CFH (PROHINGE) and OF4000 (PROFLEX SM) datasheets recommend them for retrofit work, and the GEN1000B is a surface-mounted rubber and steel system for heavy vehicles.

What information do you need to propose car park joint covers?

The deck plans with the joint runs, the nominal joint widths, the movement figures from the structural engineer, the heaviest vehicle on each level, and which joints must be watertight. Send them through the contact page or to support@genotek.global.