… and how much does it cost?

Interest in Dutch housebuilding techniques is prompted largely by their reputation for efficient, low-cost construction. As far as cost is concerned, two important questions need to be considered. First, why are building costs in The Netherlands lower than in surrounding countries, and what costs are we actually talking about? Second, could these low costs be achieved elsewhere, with or without using Dutch techniques?

The reason often given for the housing industry’s success is its use of prefabricated units and the supposedly Dutch tunnel-form system of casting concrete frames. But neither of these is significant as a cost-saving factor and the tunnel-form system is not even Dutch; it is a French invention. They are, however, the most visible features of Dutch housebuilding.

A comparison between Dutch, German and UK projects reveals that several factors contribute to lower costs in The Netherlands:

• Construction times These are very short, one reason being the time separation between the supporting structure (“tunnellable” frame) and the fit-out and fixings installation.

• Logistics and building management The building process is managed in a clear-cut way by a single overall contractor. The subcontractors are incorporated without disrupting the pace.

• Building and housing culture Efficiency comes above all else. Features that increase cost, such as basements and bay windows, are not included.

• A consensus society Major housing complexes are frequently developed jointly between a developer and a contractor. Major deviations in design and pricing are not accepted, as team members do not like to put themselves “outside the group”.

So, low costs in The Netherlands result from a mixture of construction techniques, knowledge and culture, making it difficult to capture the formula as a ready-made “export gimmick”.

My consultancy in Amsterdam has been involved in various projects in other countries involving the “Dutch model”. One recent scheme was at Thamesmead in south-east London. Although the project was abandoned because the developer was not able to acquire the site, it is possible to use it for cost comparison.

The stages of the project were costed in two ways: as if it were taking place in The Netherlands and as if it were being built in the UK. In both cases, the design was based on Dutch construction techniques. Contractor Ballast Wiltshier quoted a price on the basis of a provisional design. This was checked and negotiated by ourselves and British cost consultants. The results of the comparison, expressed in terms of average costs per 106 m2 dwelling, are shown in the bar chart (right).

After discussions with the contractor, the client set a target of £59 000/unit, which represented the provisional design as built in The Netherlands plus 15% and is shown as a red line on the chart.

It is significant that the developer was a joint venture between a Dutch housing association, Patrimonium, and a British one, the Peabody Trust. In addition, the contractor was a UK subsidiary of Dutch firm Ballast Nedam, which made it possible to use Dutch building methods to a great extent. These included:

• Tunnel-form frames and prefabricated roofing sheets

• Facing brickwork walls, with wooden frames front and rear

• Plaster or Ytong (plasterboard) interior wall elements

• Fittings as per the regulations and national requirements.

The difference between The Netherlands’ original budget and the UK’s, £27 400 or 65%, is because of the traditional building method used in the UK (brick shell, timber roof), the level of finish and the construction time.

The Dutch estimates are both based on the building taking place in The Netherlands. The difference of £9200 between the original budget and provisional design was mainly because of the client’s quality requirements (more expensive kitchen, second bathroom, and so on), whether or not as a result of UK regulations.

The difference between the Dutch and UK estimates on the provisional designs for building the houses using tunnel-form construction, £13 800 or 27%, was because of the differing floor, wall and ceiling finishes and installations, the construction time and the cost of transporting specialist equipment and materials to the UK. For example, in the UK, the rough concrete walls are not immediately sprayed or plastered but given a multilayer finish and/or additional boarding, and spray-on plaster is not used on concrete ceilings. The difference in the level of finish can account for as much as £3000-4000 per dwelling. In the UK, homes are traditionally fitted as standard and differ greatly in price and design from the Dutch standard.

If these differences are brought down, where possible, to the same level as Dutch construction and finishing methods, a price of about £58 000 is realistic. This analysis has been confirmed by Ballast Wiltshier’s tender and the negotiations held afterwards.

Based on the detailed cost analysis, it is clear that cost reductions can indeed be achieved outside The Netherlands using Dutch design principles and construction methods. In the Thamesmead example, there was a saving of about 15% compared with the traditional UK method. However, the design was along Dutch lines, with strict separation between supporting structure and completion works, and an Anglo-Dutch contractor was prepared to carry out the work. Experience, in Germany for example, has shown that it is difficult, if not impossible, to convert a traditional design to a Dutch concept. Nor is there any point in inviting Dutch companies to work abroad solely with the idea of saving on costs.

If cost reductions are to be achieved using Dutch techniques, the following conditions must be satisfied:

• Because of the speed of construction, there must be a strict separation in the design between the building shell and the completion works.

• The contractor must be familiar with the local market and trained in Dutch building and completion methods.

• The developer must have detailed knowledge of both the local and the Dutch market (including costs).

• There must be a long-term relationship (or one must be created) between the developer and contractor.

Experience shows that all the conditions contribute in equal measure to achieving the savings. In practice, this means that there will often need to be a collaboration between a local and a Dutch commissioning body and between an internationally active Dutch contractor and a local firm.