De-Watering Vacuum (DWV®)

RAM’s De-Watering Vacuum (DWV®) service offers a technically viable solution and cost saving alternative to roof replacement.


De-watering can be used on most roof constructions to quickly extract entrapped water from pre-determined pump locations. Our unique service, removes entrapped water from within a roof construction, before it causes irreversible degradation of the roof.


De-Watering Vacuum (DWV®) negates the need to strip large areas or the complete roof, providing a saving of up to 95% of replacing the wet insulation.


This is just one of our cost-efficient leak investigation services, so whether you’re looking to certify a new roof or simply looking to discover how watertight your existing roof is, our specialist engineers can help.


De-Watering Vacuum (DWV®) Service Benefits

  • Extracting entrapped water can extend Reliable Service Life
  • Enables cost savings of up to 95% compared to stripping and replacing roof
  • Can restore 90% of Thermal Performance of Insulation layers
  • Effective equipment, portable and highly Efficient


De-Watering Vacuum (DWV®) is the process of removing entrapped moisture from within a roofing membrane. Utilising specially designed vacuum pumps at pre-determined intervals allows moisture to be removed from within the building envelope, avoiding the often-expensive process of stripping back a roof or carrying out re-roofing works.

Water can be trapped within the roof insulation, roof screed or between layers of waterproofing. If this water can effectively be removed these key components can be salvaged and remain in place. RAM has developed a targeted approach to achieving precisely that through the utilization of our (DWV®) service.
De-Watering Vacuum (DWV®) removes entrapped water by creating a consistent period of vacuum across areas of the building envelope. Often used following a period of Moisture Mapping & repair works, either using Electrical Capacitance Testing (ECT®) or Thermal Imaging, the targeted use of De-Watering Vacuum (DWV®) can remove the entrapped water with limited invasive action.

We use Electrical Capacitance Testing (ECT®) to carry out a detailed moisture map of the waterproofing membrane. Electrical Capacitance Testing (ECT®) uses the conductive properties of water to allow our Engineers to accurately pin-point areas of entrapped moisture that wouldn’t otherwise represent themselves; for example, via visual inspection.

Once testing & repairs have been carried out & the appropriate positions for pumps decided upon; pump points are fitted to your roof. Each pump position is marked and numbered on a roof plan. Daily record sheets are completed by the on-site RAM Engineer, who monitors the level of water drawn, uses his experience to identify patterns and makes sure each pump is working with maximum efficiency. Nothing is left to guess work. De-Watering Pumps are never hired out in isolation, RAM firmly believes that only the combination of a proven mechanical extract system and an experienced engineer can the building owner be assured of the optimum results.

In almost all cases, yes. Provided the water saturation is within tolerable / economical levels, the appropriate repair works have been carried out beforehand and the target areas effectively identified; in most cases it can work out considerably cheaper to utilise our De-Watering Vacuum service. Our expert consultants will be able to provide you with the appropriate advice for your particular circumstances.

Unfortunately, De-Watering doesn’t work for all roofs and isn’t a suitable option for all of our clients; it is also difficult to ascertain whether Vacuum De-Watering will be effective until further testing and consultancy has taken place. Our advice, would be to get in touch and one of our expert consultants will discuss the appropriate process for your individual circumstances.