How Is Concrete Pumped for a Floor Infill Inside an Existing Building?

By PumpX Team · 17 October 2026

Pouring a floor infill inside an existing building is a different job from a new slab on open ground. There may be no access for a truck, no space for a boom and plenty of finished surfaces to protect. This is where a pump earns its keep, and where planning matters more than horsepower.

Why use a pump here

Wheelbarrowing concrete through a building is slow, tiring and often impossible over long distances. A pump delivers concrete through a pipeline and hose from a machine parked outside, so the concrete truck and pump stay at the kerb while the pour happens inside.

Which pump suits the job?

The key question is how the pipeline travels from the pump to the pour. Every extra metre of line, every bend and every reduction adds friction and increases the chance of blockage.

Planning the line

1. Walk the route from where the concrete truck and pump will sit to the pour. Note doorways, windows, stairs and any narrow points.
2. Choose the entry point. An existing doorway, a window opening or a purpose-cut opening. Protect frames and glass.
3. Lay rigid pipe where possible and use a flexible end hose only for the final placing section, as hoses wear and kink.
4. Support the line. The pipe moves when it pumps. Use stands, brackets or planks so it cannot damage floors or walls.
5. Keep bends gentle. Sharp bends increase blockage risk.

Mix and slump

Interior infill often needs a mix that flows to fill gaps around services and reinforcement. That might mean a mid-range slump or a pumpable self-compacting mix, but the design depends on the structural engineer's specification. Talk to your concrete supplier and the pump operator before ordering.

Protecting the existing building

• Cover floors, walls and finished surfaces along the route.
• Plan where washout and cleaning will occur, outside, in a designated area.
• Consider vibration and noise, especially in occupied buildings.
• Check the existing structure can carry the loads of formwork, fresh concrete and equipment. This is an engineering question, not a pump-operator question.

Common problems

• Underestimating hose length and finding the pump cannot deliver the distance.
• Not allowing for hose reach inside, so the placer cannot get to the corners.
• Poor communication between the person at the placing end and the person at the pump. Use clear signals or radio.
• Wet floors from washout water running into the building.

Safety

• Keep people clear of the end hose; it whips and moves with each pump stroke.
• Treat blocked lines as pressurised. Do not open couplings until pressure is relieved.
• Mind the dust, noise and carbon monoxide if engines run indoors or near openings.
• Use a competent supervisor for confined or enclosed spaces.

Practical tips

Ask the operator to visit the site before the day. A ten-minute walk-through often finds problems that photos hide, such as a narrow stair turn, a low lintel or a locked gate. Allow extra time for setting up and packing down the line, because interior jobs are slower than open pours. Keep a spare length of hose and a few extra couplings on hand, and make sure the people finishing the floor know the order of the pour so the hose is never dragged across fresh concrete.

Key takeaways

• A line pump parked outside with a pipeline through an opening is the typical solution.
• Route planning, line support and bends determine success.
• The mix must suit both pumping and the structural design.
• Protect the building and plan washout before the first load arrives.
• Follow the engineer's specification for the pour itself.

Check capacities in our machine specs library or find an experienced crew in the concrete pumping directory. Find pumps and operators on PumpX at pumpxchange.com.

Original question on Reddit: r/Construction: Concrete pump used for a floor infill in an existing building