IHW is the Dutch construction abbreviation for “in het werk”: work carried out on the building site itself, in place. The Dutch term corresponds to “on site / cast in situ” and stands in contrast to prefab, where elements are made in advance in the factory and only assembled on site.
Application
The classic example is “in het werk gestort beton”, or cast-in-situ concrete: concrete poured on site into the formwork instead of being delivered as a ready-made prefab element. The formwork defines the shape and is removed once the concrete has hardened.
Advantages of building on site:
- Seamless, monolithic structures with no joints between separate elements
- Custom work: shapes and dimensions are set on location
- No transport of large, heavy elements required
Disadvantages:
- Weather-dependent, as the work takes place in the open air
- Longer build time due to hardening and drying on site
- More labour and logistics on the building site itself
The choice between cast in situ and prefab depends on the design, the schedule, the budget and the conditions on site. The two are often combined within a single project.
Related terms
- In situ
- Cast-in-place construction
- Formwork
- Ready-mix concrete
- Concrete floor
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