Prefabricated Buildings Are Booming—Why Are Your Costs Still So High?

Looking at prefabricated buildings worldwide, low cost is an advantage of prefabricated concrete construction. In many countries and regions, social housing and affordable rental housing often use prefabrication precisely because costs are lower.

Globally it is rare for prefabricated buildings to cost more than cast-in-place concrete buildings, yet in China the cost of prefabricated concrete buildings is currently higher than cast-in-place work—in some regions or projects by more than 30%.

Most developers, focused on short-term cost, are reluctant to choose prefabrication actively, and contractors have little room to push back.

Below we analyze how cautious technical standards and aggressive development targets squeeze the industry from both sides—and why costs stay stubbornly high.

Example 1

Analysis: Although we also add supplementary rebar in cast-in-place structures, we do not use nearly as much as in prefabricated buildings.

Example 2

Analysis: Per clause 8.2.4, in practice we typically lap 100% of shear-wall rebar on site.

For cast-in-place shear-wall construction, practice is usually 50% lap splices.

In addition, horizontal bars above sleeves in prefabricated structures must be densified, while cast-in-place structures do not need densification at that location.

Example 3

Analysis: In technical references and component drawings you can see the densified rebar zones of prefabricated shear walls; seismic detailing directly increases rebar quantities.

The figure above shows densified rebar in a prefabricated shear wall—steel that cannot be saved. A cast-in-place structure would not need such dense reinforcement, but prefabricated buildings have no choice.

Example 4

Analysis: Composite slabs are at least 6 cm thick; adding a cast-in-place topping of no less than 6 cm brings the total to at least 12 cm. Cast-in-place floor slabs can be as thin as 10 cm—an implicit cost increase of about 20%.

Analysis: Prefabricated structures use truss composite slabs—the key word is "truss." Extra rebar is inevitable, because cast-in-place structures generally do not add trusses. (Truss-type composite slabs account for about 80% of current prefabricated buildings.)

As floor thickness and rebar quantity rise, self-weight rises too. To offset that self-weight, beams, columns, and other supports must grow in size... (costs naturally climb.)

Example 5

Analysis: The figure above is from a 2016 Fujian project: item 19 alone—truss rebar for composite slabs—added an extra 184 kg, while total rebar was only 230 kg. Direct cost impact is clear.

Example 6

Technical specification for prefabricated concrete structures, Article 6.1.4: For Category B (7-degree seismic fortification) integrally prefabricated structures, seismic measures shall be strengthened as if the local fortification intensity were raised by one degree; when the local intensity is 8 degrees and the seismic grade is Grade I, measures stricter than Grade I shall be taken.

Analysis: Raising the seismic grade by one level means more work on shear walls...

Through the above, the impact of technical rules on prefabricated building cost should be clear. Construction quotas and PC component costs also affect prefabrication costs.

We should recognize that high cost is a major constraint on prefabricated building growth today. High-cost prefabrication cannot stay competitive for long in a market where resources are allocated freely.

Address: No. 1777 Hualong Road, Shanghai Website: www.ourcompany.com Tel: 021-60760737 Mobile: 17721310336 Email: marketing@ourcompany.com 24H customer service: 400-716-6557