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Technical briefing 4 – The science of drying


Property restoration is a combination of science and stakeholder management. Technicians rely on a mix of psychrometry, construction knowledge, and even microbiology, to design appropriate drying regimes, set expectations for customers and clients and minimise disruption and costs.

Drying is complicated. Technicians use a combination of resistance meters, hygrometers, psychrometric calculations, experience and training to design a drying regime that has the right types and capacity of drying equipment to support the drying of the structure of the building at the correct rate. Having the right balance between heat, air flow and drying equipment is the key to quick, efficient and effective drying.

Historically the industry has relied on the “art” of drying rather than the science. Restoration companies have heavily relied on the experience and knowledge of technicians, trusting that their chosen approach is the best without any scientific checks or balances to verify that the chosen drying regime is the most effective, or is even needed at all.

This paper explains the drying process, addresses the many misconceptions that insurers have about drying and explains what “good” looks like. It then proposes some changes that the industry needs and introduces the technological developments that Revival and MA Group have put in place.

Popular misconceptions

There are several misconceptions about drying and restoration held by policyholder customers and many claims professionals within the insurance industry:

Drying equipment

The term “drying equipment” is misleading as it implies that the equipment installed in buildings during the drying process are there exclusively to dry the property out. However, air movers and dehumidifiers are exactly that – they move the air and take the humidity out of the air to support the natural drying process that individual materials within a building go through.

Materials and construction techniques

It is often assumed that the different materials in a building dry out at the same rate and there is a pre-defined length of time during which any property will dry out. Unfortunately, this is not true. The type of construction and the materials used will influence the length of the drying process and the chosen regime – cement dries out at a completely different rate to wood and plasterboard and a wooden framed building will require a completely different drying regime and duration to a traditional brick and block-built building.

Drying standards

It is often assumed that there is a “textbook” for drying, that the science is laid out clearly in manuals that can be followed with clear rules that need to be implemented. This is not the case. There are published standards and guidance such as PAS 64:2013 (Mitigation and recovery of water damaged buildings Code of Practice) which is guidance developed in collaboration with the British Standards Institution (BSI), and BDMA Standards 2011 designed to provide guidance and recommended best practice for those who work in the damage management sector and the wider related insurance industry. These publications are general guidance, and generally lack detailed information about drying times, the science and how to design an appropriate drying regime.

The technician knows best

There are many incredibly experienced and effective drying technicians employed in this industry, but the industry is very poor at demonstrating this with facts and data, so it is difficult to demonstrate that the technician is doing a good, efficient job. There are also many technicians who make the wrong decisions about drying regimes and the monitoring of them – for example, by using incorrect reading measurements for a material the drying can progress poorly resulting in delays and unnecessary costs.

The drying process – what “good” looks like

Materials and construction

Before a technician starts drying a property he or she should ensure that they have a clear understanding of the incident and the implications of the damage it has caused. They also need to look at the construction of the building and the materials used and should apply their training and experience to understand how the different materials will react to the damage and subsequent decontamination, drying and restoration techniques. When planning the drying regime the technician should also consider any pre-existing building defects and complete a robust and comprehensive damage investigation (which should be clearly documented).

Strip-outs are regularly carried out before drying takes place but often this is not necessary. A good technician will evaluate alternative options (such as cavity drying) and will consider the costs, overall claim lifecycle and customer impact associated with the various options (strip-out, reinstatement and alternative accommodation). No published guidance or standards help the technicians with this sort of detail.

The drying methodology and equipment used must be appropriate for the incident and the property’s construction – even if that means no equipment is required because opening a window will be just as effective. Restoration companies should ensure that their technicians have a wide variety of approaches and equipment available to them.

The science

Comprehensive moisture measurement techniques should be used at the start of the process and at appropriate intervals during the drying process. A technician must always have a target moisture reading for each type of building material in the building, which can be ascertained by doing readings in unaffected parts of the building. Multiple devices and differing tests will often be needed.

Psychrometry is the science and technology that relates to the thermodynamics (the movement of energy between materials) of gas-vapor mixtures. Psychrometric charts are used for calculating the values of relative humidity, absolute humidity, and dew points from psychrometer readings. They cut out the tedious mathematical formulas – as long as you have any two parameters where the lines will cross each other, you can determine all other parameters.

Technicians use psychrometric charts to determine the level of moisture in the air – by measuring relative humidity and the air temperature (using thermo-hygrometers) they can use the charts to determine the moisture in the air (weight of water vapour in grams per kg of air). When done at the start of the drying process it provides a guide as to whether a drying regime is needed at all.

Over-seeing the chosen drying regime

Excessive moisture in the air creates the risk of secondary damage so dehumidifiers and air moving equipment are installed to manage the moisture content of the air as the building materials dry out. The technician should take regular moisture readings of the various materials to ensure they are drying as expected and should regularly measure the temperature and relative humidity throughout the drying regime to ensure the drying parameters are promoting efficient drying – where there is a disparity there is something wrong with the drying regime and adjustments are required. Accurate documentation and analysis of moisture readings is critical to deliver the best possible outcome.

Once the materials have reached their target moisture level the property is deemed to be “dry”. The aim of the drying programme should be to return all building materials to their pre-incident condition. However, the target moisture level for the materials needs to take into account the activities that will take place after the drying has finished – for example, if reinstatement works will require replastering the first thing a plasterer will do is make the wall wet so that the plaster sticks!

A period of time (dependent on a number of factors) should be allowed to ensure the building materials reach a normal equilibrium once drying goals appear to have been achieved.

Challenges in the restoration industry

As floods and escapes of water become more and more common there is a greater need for the restoration industry to become more efficient and proactive. Floods usually create surge events which put a strain on available capacity and create stress for customers and higher indemnity costs for insurers, and burst pipes are increasingly common in modern houses, creating more demand for restoration services.

Specialist drying technicians are not always needed on smaller drying projects and many insurers are now using building contractors for these (with varying degrees of success). MA Group has run its successful MA Dry training course for several years now – contractors on our BRN become MA Dry accredited through a mandatory three-day training course. The course trains them to use the most efficient and intelligent drying method and ensures that they do not use, or charge for, unnecessary drying equipment. If the most efficient way of drying the affected area involves securing the property and then merely opening the doors and windows, that is the method they use.

The industry has invested heavily in technology for drying equipment – dehumidifiers, air movement equipment, air exchange and heat drying machines are all becoming increasingly sophisticated and efficient. As a result, restoration companies are having to invest more and more in the latest equipment, which puts pressure on cash flow. In the event of a surge there is usually not enough of the newer equipment available so the restoration companies either rent more equipment (which can be expensive) or resort to using older, less efficient machines.

There is a dearth of data analysis in the industry. When you consider how many bits of data are collected on each drying regime (moisture readings of individual materials, relative humidities, dew points, air temperatures, types of equipment used etc), it seems incredible that the industry has not made efforts to collate this data and analyse it to fine tune best practices. We still have general standards and guidelines with little detailed guidance on, for example, how quickly individual building materials take to dry under different conditions.

One of the challenges with data analysis is ensuring that the data is collected consistently and accurately so it can be compared and the right conclusions drawn. In this industry data is generally collected in too many different formats and at inconsistent points with varying bits of equipment, so comprehensive and accurate data analysis is probably not possible. To date, the insurance industry has had no way of knowing if restoration companies and their technicians are applying the science correctly and designing the most efficient drying regimes. Some less reputable restoration companies may have taken advantage of this and charged for unnecessary work – this is not a sustainable situation and the industry needs to wake up to this. The reinstatement industry is well-understood and measured – insurers want to achieve the same level of control over the restoration industry as well.

Challenges in the insurance industry

On the whole, the insurance industry does not have an in-depth understanding of restoration, and the rates and processes it has created over the years are encouraging the wrong behaviours in the restoration industry.

Mechanical drying is very effective when used correctly, for example flooding and larger escape of water claims. But often it is used when it’s not needed, adding extra unnecessary costs to an escape of water claim. Not only do these extra costs include the costs of the drying equipment, but they also include unnecessary strip out costs such as removing and replacing plaster that would not be needed with more appropriate and targeted drying approaches. In many escape of water cases simply opening the window and letting a room dry naturally is the most effective approach. To find out more read MA Group’s case study called Plugging the Leaks – Part 1

The insurance industry also loves to manage its supply chains in silos. A typical insurer gives the drying to a restoration company and the reinstatement works to a BRN. Not only does this create operational friction and delays in handovers, but there is no incentive for the different suppliers to work together to deliver the best outcome. If the BRN isn’t allowed to start work until the drying certificate is issued by the restoration company, then the claims durations become unnecessarily long, which is further exacerbated in times of surge when average lead time from instruction to start will often more than double. And as the restoration company is being paid on a per day or per room basis, it has no incentive to either identify the material as already dry, or to speed up the handover to the BRN. At MA Group we offer a one-stop shop for restoration and reinstatement to create that incentive to the benefit of insurers and policyholders alike.

Restoration jobs are often awarded to restoration companies without any understanding of the technical performance of that restoration company and its technicians. If the loss adjuster or insurer was able to analyse the data being collected on a claim, or across several claims, he or she would soon be able to see if the appropriate drying regimes were being used.

Similarly, if an insurer was able to analyse the data on drying regimes and restoration companies they may reconsider the terms of some of their supplier contracts. They would also see that strip outs are often unnecessary and simply add to the reinstatement costs (when innovative drying techniques would have been much better for costs and durations) and that reinstatement works can run alongside restoration works, again reducing claim durations and costs.

Introducing TREVOR

Revival is using Technology to REVOlutionise Restoration.

Using data, algorithms, mobile technology and Artificial Intelligence tools, TREVOR applies the science to predict outcomes, create confidence and deliver excellence in drying. This digital solution supports trained technicians to deliver certainty around drying by accurately predicting how long a drying regime will take and to alert technicians and Revival when the regime is not working as it should.

Using the data collected by our Revival technicians we have created mathematical models showing how long it takes, on average, for each type of building material to dry. We are using this data to monitor and manage drying regimes across the UK, eliminating the challenges and uncertainty our industry faces when drying properties. Fundamentally, by creating TREVOR we are reducing claim lifecycles through this combination of optimal restoration regime and being able to plan and commence reinstatement earlier.

This approach deals with the challenges facing the restoration and insurance industries by:

When combined with our integrated solution that includes our own BRN and disaster recovery capabilities, TREVOR helps us ensure that we deliver the most efficient claims management service and happier customers.

On average, TREVOR reduces claim durations by 21 days and average claim costs by £600.


Using TREVOR we can analyse the data of any insurer or intermediary to see how effective their historic drying regimes have been. If you would to take advantage of this offer of complimentary analysis please get in touch.

The technical solution

Here at Revival we are addressing the technical challenges head on by collecting the right data at the right time, analysing it and using it to monitor the performance of our branches and technicians.

At the start of a job Revival technicians use our mobile app, Scoper, to record moisture readings in the air and in each of the structural materials of the property, and the equipment being deployed. Scoper identifies the reading required for the material to help ensure accuracy. This data automatically feeds into our claims management system, Pulse, where it is analysed using TREVOR. Immediately we can compare these readings with our mathematical models to determine whether a drying regime is needed. If it is not needed an alert is raised by the system and we notify the Revival branch immediately.

As the drying regime progresses the technician records moisture readings at regular intervals through the Scoper app. TREVOR assesses these readings and alerts the technician and MA Group staff if the readings fall outside of the expected parameters. When this happens, the drying regime can be quickly reassessed and adjusted to get the drying back within the expected time scales.

Collecting the data at the appropriate times also means we can generate a Moisture Reading report from Pulse that we can send to clients and intermediaries, clearly showing the progression of the drying regime and all the collected data.

To find out more please get in touch:

Revival Divisional Director: Paul Sharkey

mobile: 07903 292029 email:

MA Group Chief Commercial Officer: James Bush   

mobile: 07896 011475 email: