Smithers Purslow was established in 1977 as a Consulting Civil and Structural Engineering Practice, but in the 1980’s expanded into Building Surveying and Project Management growing to four offices throughout the UK.
At present it has three offices, the head office being in Glaston, Rutland and then offices in Lincoln and Newcastle. The Company has directly employed staff and suppliers based throughout the UK providing Nationwide coverage to its clients.
The business has four main compartments. Civil and Structural Engineering remains a core part of the business dealing with new-build, design alterations, drainage and infrastructure and defect diagnosis. The Building Surveying Department has a vast array of services ranging from acquisition and defect surveys through to project design and contract administration, including the likes of party wall and boundary disputes, health and safety consultation and specialisms in Listed Buildings and Expert Witness services. In the 1980’s the company became heavily involved in Insurances Claims assisting Insurance Companies, Loss Adjusters and Policyholders in resolving the likes of subsidence, heave and landslip damage and also fires, floods, escape of water and unusual perils such as explosion and impact damage. This has enabled the Company to develop a department dedicated to dealing with insurance claims, handling initial damage diagnosis and emergency works through to overseeing repairs. Involvement in insurance claims has also led to the creation of a fourth department in Technician Services that provides lower grade auditing and validation services to Insurers and Contractors.
Smithers Purslow has two associated companies in Property Assure which is an innovative company providing streamlined solutions for the likes of insurance companies and lending institutions and also Rutland Monitoring which specialises in pioneering structural monitoring of buildings remotely from site. Smithers Purslow staff have built up a considerable knowledge of dealing with properties that have suffered from water damage and how to correctly assess them and make sure they are made watertight and correctly stripped out and dried and then repaired to ensure problems do not recur in the future. This presentation attempts to share some of the vital lessons that have been learnt.
The presentation is by Andrew Bussey, a Chartered Building Surveyor who fronts Smithers Purslow’s Surveying and Insurance Departments. Andrew’s team typically handle in the region of £30m worth of insurance related repairs to buildings per annum. In the 2007 flood crisis in South Yorkshire and Gloucestershire, the team handled 600 major loss insurance claims passed to them in less than a two month period.
The list of water and moisture in buildings is pretty endless but the presentation will run through a handful of the most common from which stripping out, drying and repair can then be considered. Ground borne moisture is a fairly typical concern due to the absence of failure of damp-proof courses and damp-proof membranes. Failure or absence of basement level of waterproofing is also a problem. It is well established that pore structures of masonry and concrete will allow ground borne moisture to pass up through them via capillary action resulting in low level dampness in buildings. Modern construction dictates the use of damp-proof courses and damp-proof membranes, but of course these were not present in older building constructions and where remedial systems have been installed these are not always effective and long lasting.
Penetrating damp frequently occurs in the basement level of buildings and is largely dependent on ground water levels which often fluctuate meaning penetrating damp problems can be variable and seasonal. Water leakage from service pipes is also a common problem ranging from mains water feeds into buildings, internal hot and cold water pipework and concealed heating pipes. Internal and external waste and drainage pipework are also sources of moisture if not kept watertight. The most common issues Smithers Purslow sees as part of insurance claims are projects such as burst pipes in uninsulated roof spaces and voids enabling pipes to freeze and fracture causing widespread damage.
Regional drilling incidents seem to be more commonplace over the last decade and Smithers Purslow has assessed cases involving rivers bursting their banks, drainage systems, culverts and dykes not being able to cope with the deluge of surface water and incidents of flash flooding with land surrounding the properties acting as a vehicle to carry rainfall and debris into properties.
Major fire damage to property also causes water damage. In many instances, roofs and the weather-tight envelope of buildings are destroyed exposing the building to the elements meaning internal components are affected. In addition, fire service water will saturate materials causing widespread problems.
An obvious cause of penetrating dampness to buildings is lack of maintenance to the weather-tight envelope. There are many instances where the weather tightness of buildings has been affected by storm damage and snow loading, causing components to fail and let moisture in.
Many property owners have simply an occurrence of mould growth and mildew on internal surfaces and believe this is a direct result of a penetrating damp problem or the likes of burst pipes and defects described above. This is not the case and more often than not, problems relate to condensation due to occupancy issues. Revisions are often necessary to the insulation, heating and ventilation of the properties together with the occupants understanding how condensation occurs.
More unusual sources of moisture in buildings are vandalism damage. Smithers Purslow has looked at many cases where properties have been converted into drugs factories and where water has been poured into properties for plant growth and germination. This directly affects building materials and components and also causes widespread condensation issues.
The foregoing outlines a number of typical sources of moisture and water in buildings and it is important for Surveyors and Engineers reviewing such properties to understand the possible effects of moisture on construction materials and components. Not all professional and contracting companies involved in reviewing water damaged properties understand this and Smithers Purslow knows from its experience of major flood damaged properties in 2007 and subsequent incidents and also from recent spates of burst pipes, that many companies are over zealous in stripping out properties as they don’t understand how wet construction materials will perform.
Starting with metals, most of those used in building construction will not be completely resilient of moisture and many will display signs of corrosion to varying degrees if left in a moist environment. Surveyors and Engineers will need to make a judgement on their condition and whether or not drying the building and restoring it to its earlier conditions will preserve the metals involved. Most masonry will perform well in moist conditions and if it has become saturated or wet, should dry out if impervious finishes are removed to allow it to breathe. Lime mortars and plasters are not designed to be moisture resisting and hence moderate levels of moisture within them should not effect their integrity and wholesale removal of such materials in moist environments should not be required. In certain situations where large-scale saturation has occurred, lime materials will soften and deteriorate and replacement may be needed.
Gypsum based plasters do not perform well in moist conditions and will soften, blow and delaminate. They will also hamper drying of materials onto which they are applied, ie: brick and blockwork and wholesale removal is usually required due to direct damage to the plaster and to assist breathing and drying out. The same is true of plasterboards and where ceilings and dry lining components have been affected by moisture, and its usual they delaminate and soften and removal and replacement is usually the only option.
Sand:cement renders also perform robustly in most conditions and there should be no direct need for components to be removed as they should dry out satisfactorily and remain in good order. Some renders may contain water proofing additives which may hamper drying of materials to which they are applied, ie: brick and blockwork and hence removal of some renders may be required to assist drying of components.
In wet and moist environments, hard and softwood timbers will rot and decay and there is a possibility of dry rot and beetle infestation occurring. If materials are left in prolonged moist conditions, the integrity of the timber will disintegrate resulting in replacement being required. However, if the moist conditions are identified early, most timber components can be carefully stripped and dried and re-used. Depending on the quality of components used, there may be some distortion, warping and cupping of components meaning replacement may ultimately be required or adjustment and refitting. The likes of plastic and porcelain sanitary fitments and the suchlike will all resist moisture well and whilst some may need removing to promote drying of concealed surfaces, most should be able to remain following water damage.
Modern reconstituted timber components do not react well to moisture. The likes of chipboard and MDF now commonplace in internal joinery components, kitchen units and stairs all expand and delaminate if moist or wet, meaning removal and replacement is often the only course of action.
Like masonry, concrete will retain its structural integrity in moist and damp conditions and if a breathable environment can be created it will dry out satisfactorily. Insulation products react differently. Mineral wool relies on its insulation through the volume that is created through the quilt retaining air to insulate the property. If this becomes wet, the structure flattens and the insulation qualities are lost and hence replacement is necessary. However, modern insulation boards are not affected by moisture and should dry out adequately following water damage.
STRIPPING OUT AND DRYING
It is important for surveyors and engineers assessing water and moisture damage to properties to understand the passage of moisture that has occurred from the source and how this is then affected the construction and materials. This may involve some basic investigations to learn exactly how the building has been put together and the likely effects of moisture on the building. Many companies and contractors do not adopt this approach and instead, following the likes of flood and burst pipe damage, opt to strip the entire interior. Smithers Purslow have seen many examples where perfectly robust lime and sand:cement renders have all been removed from properties unnecessarily causing vast expense to property owners and/or Insurers. If earlier investigations have been completed, materials could have been left in-situ without hampering the drying process saving expense and time. So surveyors and engineers should look to achieve an optimum level of stripping out in buildings to ensure all concealed areas are appropriately exposed if wet and allow them to dry out but equally, not gutting a building’s interior unnecessarily.
As already explained, it is important to initially understand the source of moisture and plot any water movements through the building. From this, it is important that moisture content readings are taken using appropriate equipment for the materials involved to establish any concentrations and moist areas. From this, investigations into the construction and materials employed is essential and a precise schedule of strip out works can then be compiled. In compiling this it is important to consider the integrity of the building’s services and whether or not any asbestos containing materials may be affected. It is also vital that appropriate parties arrange the removal of any water damage contents from the building which will be harbouring moisture and hamper any subsequent drying.
Once contents and strip out has been completed, this is the optimum time for drying equipment to be installed in properties, including the likes of air movers, dehumidifiers and in some cases, background heating to create good drying conditions. With saturated contents and materials remaining in the building there is little merit in installing expensive drying equipment. Drying periods vary but the Building Research Establishment have suggested that around 25mm of masonry will take one month to dry out in unaided conditions. This means a solid 9”/225mm thick brickwork wall will take around four and half months to dry out if ventilated and exposed from both sides. Obviously, with air movers installed, dehumidifiers and background heating, the drying process can be speeded up and typical drying periods during the 2007 flood period were 6-8 weeks for properties that had been submerged in water throughout their ground floors.
There are also means to dry properties in a matter of hours and days for specialist situations such as commercial buildings where financial losses may be significant. Such systems involve introducing dry arid air to extract moisture from components but the supporting plant and equipment to provide this is relatively expensive hence it is not the norm. Introducing such unusual conditions to a building’s interior often has adverse effects causing materials to crack and shrink so the system needs to be well controlled by operatives.
It is important before final repair works to properties are allowed to commence that the building is declared dry and suitable for repair. The onus for this usually lies with drying companies who have genuine expertise in this field but Smithers Purslow has seen weaknesses in the documentation that is often prepared resulting in recurring damp problems to buildings. Moisture content readings after drying are often taken within minutes of drying equipment being removed. This often means that equilibrium conditions have not been restored to a building’s interior. Whilst readings being taken immediately after equipment has been removed is useful, it is also important that secondary readings are taken 2-3 weeks after the equipment has been removed to ensure lingering problems are not apparent. It is also important to ensure drying companies are using appropriate equipment to take readings of materials. Most moisture meters provide wood moisture equivalent readings (WME) and hence are only providing reliable readings in timber. There are devices to take readings in homogeneous materials such as plaster, brickwork and concrete and these should obviously be used in such materials to provide reliable data.
Concluding documentation from drying companies often only states that they have restored the building to pre-loss conditions and this may mean that any inherent pre-water damage problems may still be apparent which could cause problems in the future. For example, drying companies may have declared they have removed all flood moisture from buildings following such an incident but there may be a failed or absent damp proof course which will allow minor low level damp problems to manifest themselves in the future. It is therefore essential that surveyors and engineers appreciate the content of drying certificates and they may therefore wish to also assess buildings to see if there is scope for other inherent problems that a drying company may not have identified. Typical inherent problems are failed and absent damp proof courses and lack of subfloor ventilation which will cause problems in the future.
So following stripping and drying, a certificate should be available declaring the building suitable for repair and, if inherent problems have been identified, these can be considered alongside the repair exercise. Most Insurers will authorise repairs on a ‘like-for-like’ basis allowing for certain upgrades to comply with Building Regulations requirements of the present day. However, repairing a building also provides an opportunity to make it more robust for the future and even insurance companies are willing to accept this as it may limit their expense in the future. For example, if walls can be re-plastered using a more resilient sand/cement render this adds little cost to the overall project and in the event that a building is flooded or burst pipes occur again in the future, then this material should be able to remain on the walls and the building then repaired and dried out. This is a far more forward thinking approach than simply going back with dot and dab plasterboard that would not survive in the event of a future incident.
Likewise, electrical sockets can be raised above levels of potential flooding and suspended timber floors possibly replaced with solid concrete which will be more robust in the event of water damage in the future. Building Control are likely to request the likes of insulation and services upgrades depending on the extent of repair works being completed to properties.
SUMMARY AND CONCLUSION
Dealing with water damage in buildings is a vast subject and the foregoing provides a brief summary of some cases that Smithers Purslow has handled and typical methods of assessing damage, stripping, drying and then repairing. The presentation should serve little more as a prompt for surveyors and engineers going back to basic principles if dealing with water damage in buildings to ensure all possibilities have been considered and optimum levels of work are completed. The presentation will conclude by running through a number of examples of good and bad practice that have been seen over recent years and the effects of failing to deal with water damage correctly.
Andrew Bussey BSc DipArchCons FRICS MBEng
Director of Smithers Purslow
Glaston Hall, Spring Lane, Glaston, Rutland LE15 9BZ
Telephone: 01572 822000. Mobile: 07971 266 403
Fax: 01572 820022. Email: firstname.lastname@example.org