Fight Club – The Come Back


Although the smaller fighter in the ring, PSS are the no.1 contender and welcome the ‘friendly’ competition with our sister company SMD!

Designers wishing to specify a floor construction that avoids the use of RC formwork with props, or looking for a solution that will increase space between columns for greater capacity will sometimes consider both options and their various benefits.

Precast concrete floors are often selected for its long spanning capability, high acoustic properties, and the flat soffit. Hollowcore planks have a higher self-weight when compared to the sheet elements of a metal deck system, but not necessarily when considered with the composite system and concrete required.

Saving on material and labour costs is, understandably, a key consideration for designers and their clients on any construction project, but the programme and buildability impacts of the two options should not be ignored.

design stage precast concrete

Touch gloves!

A heavy blow to start with, metal decking systems can be lightweight in comparison with plank construction, potentially transmitting a reduced load to the foundations.

Precast wobbles but counters with;

  • Structural efficiency – Hollowcore offers an ideal structural section with a wide range of depths to independently maximise efficiency within the overall floor depth when compared with metal deck.
  • Support economy – With either masonry or steel frame. The spanning capabilities of hollowcore reduce the number of supports required. Composite steel beam design with precast floors can reduce the total tonnage of steel beams by up to 40%.
  • Reduced Deflections – Precast has a natural camber which offsets the imposed load deflections.

Acoustic Performance – Hollowcore satisfies Part E of the Building Regulations with construction details for attached dwellings.

construction stage pre cast concrete

Speed benefits the fighter but the timeframe of the overall construction stage is a split decision.

Bundles of metal deck sheets are craned into position, this is usually managed by the main contractor or steel frame contractor, taking up valuable supervision time whilst erecting the structure. Decking must be manually handled into position by operatives working on often narrow steel beams.

Precast does involve more crane time when compared to metal deck alone. The correct crane positioning and management are crucial to the installation process. This additional time is offset in the labour volume and overall duration required with metal decking.

PSS plan and manage the lifting of all precast units for the project, allowing our customers the freedom to concentrate on other phases of the build. Precast involves a lot of heavy goods movement, this should be a consideration if the project struggles with access.

Considering the add-ons with metal decking and subsequent fixings, stud welding, edge shuttering and concreting topping operations, results in a labour and time intensive construction phase. Potentially costing approximately 20% in programme when compared to installation of precast concrete planks.

Precast planks are manufactured off-site to suit the structure thus avoiding on-site cutting of metal deck sheets. With pre-formed features also cast off-site, laborious setting out, shuttering and in-situ details are minimised.

post construction pre cast

Precast dodges and counters!

Flat soffits of hollowcore planks allow fixings for finishes and services to be suspended easily, making them accessible for future maintenance. Alternatively, as produced on steel beds and when handled correctly, hollowcore planks provide a smooth soffit finish that can be directly painted or even left exposed.

Modifications such as holes can be drilled on site to incorporate additions of voids for new services or changes in use are relatively straightforward with adequate design coordination.

health and safety

Gum shield in and watch for the body shots!

There is no doubt, when installing planks careful consideration needs to be paid to health and safety with risks such as working at height and crane lifting operations etc. All of which, need to be properly assessed and managed.

Once installed, Hollowcore provides an immediate safe working platform without the need for additional fixings. This eradicates dangers from ‘slippage’ of metal decks off their supports and protects lower levels.

Manual handling is dramatically reduced with precast floors as all units are lifted into place mechanically. There are no hot works or HAVS from cutting, stud welding and shot fired fixings are involved.

For either option, it is critical to engage with competent and professional contractors at the earliest stage possible.

sustainable precast concrete

This one’s going the distance!

Both the British concrete and steel industries are admirably working towards improving carbon emissions.

The inherent performance of concrete means that it can contribute to reducing the carbon emissions of the built environment.

With the ever-changing scenery in this sector, it is impossible to find a clear winner in this round.

precast concrete winner

Winner by unanimous decision – Precast Concrete

Precast packs a punch and is a tough contender. With a proven record of versatility in design combined with structural performance. Speed of installation, strength in planning and cost-efficient options all whilst reducing risks. PSS would be happy to service your next project, please contact us for more info.

Composite steel deck construction has many advantages and if you need to specify metal decking, SMD can offer a comprehensive range of floor deck profiles in varying depths, steel grades and gauges to suit the design criteria.

I’m sure a rematch will be on the cards soon!