Water accumulation

Preventive inspection & advice

Water accumulation is a high risk for commercial buildings with flat steel roofs that are supported by a structure with a large span.

Calculation of emergency overflows 

If a lot of rainwater falls on the roof in a short period of time, there is a risk that the roof will bend, or even collapse under the ever-increasing water load. The drainage of excess water can be regulated by means of emergency overflows.

Our constructors calculate exactly what type of emergency overflow is required and where it should be placed.

NEN standard calculation and on-site measurement

The calculation of the amount of rainwater that a roof structure must be able to carry is laid down in NEN standard 6702. Before the calculation is made, we always start with measuring on location, so that we can check on site whether and which emergency overflows are already present. The slope of the roof is also inspected.

Archive research and advice

The rigidness of the structure is determined by means of archive research. Based on the results of the calculations that result from this, we issue a recommendation. It contains all the information about the type, number and size of the required emergency overflows.

Risk analysis and prioritisation

For one of our clients, we prioritised the advice by making a risk analysis for each location. Steel roofs without emergency overflows, and therefore with a very high risk, were the first to be modified, thus preventing major damage.

We work for large (retail) companies such as Ahold and Sligro. We also calculate the water accumulation for contractors and roofing companies such as Patina.

Solar panels on roofs result in extra weight

The Netherlands is becoming more sustainable. As a result, there is a demand for large areas for solar panels. What better place to do this than on the roofs of companies that consume a lot of electricity? We always advise on this subject with a water accumulation calculation. This way we can be sure that the roof construction is adequate and that the roof will not collapse under the extra weight of the solar panels.

Jasper Wiersma  

"Every roof is different. That is why we think it is important to measure the roof in question on site and not just rely on existing drawings or standard benchmarks. We look at the slope of the roof, but also at the possible drainage of adjacent roofs and the presence of solar panels. So we always provide complete advice!"

Other water accumulation projects


Solar panels

Solar panels calculation & advice