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This document describes the types of building surveys and specialists reports which are available to, and often required by, homebuyers, mortgage lenders and relocation agents.
The UK housing stock is old and, despite an apparent boom in ‘home improvements’, the truth is that there are insufficient resources spent on maintenance and repair of older properties.  Before the ‘credit crunch’ the rate of new house building was low – some say it was at the lowest since the end of WW2.  Following the ‘credit crunch’ house building almost collapsed and recovery has slow and looks likely to remain so on account of difficulties in obtaining mortgages and changes to regional planning requirements.

It is a sad fact that 80% of homebuyers rely on their own (limited) viewing of the property and their mortgage valuation report, and take no other professional advice on the condition of their proposed purchase.  The result is that problems are often discovered with the property after it has been purchased, and the homeowner often looks for someone (else) to blame.
There has been an increasing readiness of homebuyers to complain about what they consider to be inadequate mortgage valuation reports and other surveys.  Serious complaints often lead to claims and legal action against surveyors.  This has led to the professional institutions tightening the guidelines and limitations on what is, and, more importantly, what is not, covered by surveys.  The result of this is that a surveyor may often be aware of, or suspect a problem (or potential problem), but is not allowed to investigate it further, or give a definitive opinion on the problem, within the limitations of the type of survey being carried out.  There is however a strict legal requirement overriding this, to the effect that a surveyor must ‘flag’ the problem or concern and recommend further investigation, usually by a specialist.  In most cases it is not fair to say that the surveyor is being overcautious, they are required to follow guidelines issued by their professional bodies, legal cases, and their professional indemnity insurers.
There is also an increasingly cautious stance being taken by lenders and insurers.  We see many reports where minor cracks or movement have been noted by a surveyor and have been dismissed as ‘not significant’.  Even so the lender or insurer has requested a structural engineers report before they would consider the property further.The result of this is that more and more specialist reports are required during the homebuying process.


The range of reports and surveys which are available can best be divided into three categories according to who normally carries them out.
Valuations and Surveys normally come first in the process and are carried out by Chartered Surveyors.  Typically they carry out Mortgage Valuations, Homebuyer Reports, and Building Surveys.  These usually address most, if not all aspects of the property, with an increasing degree of detail.
Structural Reports, by a Chartered Engineer (Civil or Structural), are usually requested when a surveyor has identified or suspects a particular structural problem such as subsidence or other structural movement.  Most lenders will not grant a mortgage on a property which has serious structural problems, often because they cannot insure the building.  Because structural problems can be very serious and expensive to remedy, there is a cautious approach to any suspected structural concerns.  In practise, many of the structural concerns are found to be not serious problems.
Specialists reports cover the remainder and include electrical, gas, plumbing, damp & timber, wall ties and other types of reports which are often requested.  These are generally carried out by small specialist contractors who have the knowledge and day to day expertise of these matters.  Electrical reports are invariably required to be carried out to BS7671, previously NICEIC registered electricians had a practical monopoly on these, but nowadays other approval bodies are able to register suitably qualified electricians.  The law requires that any tests and works on gas installations are carried out by Gas Sage registered gas engineers (previously the register was operated by CORGI, but this organisation no longer exists).  Other specialists do not have any demanding approval bodies or statutory requirements, it is therefore most important that they are ‘tried and tested’ and can be relied upon.
Statistics on the numbers of different types of reports and surveys on a national basis are pretty meaningless at present, given the vast reduction in property sales over the last few years, but as an example our own statistics for 2002 are as follows:-
Surveys 1000
Structural Reports 2000
Specialists Reports 1000
The high proportion of structural reports reflects our original specialisation.
Specialists reports are broken down according to type as follows:-
Electrical 300
Damp & Timber 400
Gas / plumbing 100
Drains / CCTV 200
Wall tie 60
Asbestos 20
Sulphate 10
Arboriculturalist 10


The three main types of surveys and valuations relevant to domestic properties are :-
MORTGAGE VALUATION - often called a survey, but it isn’t, and should never be taken as such.
HOMEBUYER SERVICE – This comprises a general inspection of the property with restricted investigation and reporting of problems and concerns – the Royal Institution of Chartered Surveyors (RICS) sets the rules. It also includes an open market valuation. A license is required from the RICS in order to carry out a Homebuyer Report. The Homebuyer Service is very similar to the Homebuyer Survey & Valuation which was withdrawn in April 2010.
BUILDING SURVEY – This comprises a comprehensive inspection and detailed report on the property.
The term ‘Structural Survey’ or ‘Full Structural Survey’ has been widely used in the past. To some people this would mean a Building Survey, whereas to others it would mean a Structural Engineers Report, perhaps even limited to a specific structural problem. This ambiguity has caused many problems in the past and has led to disappointed clients and embarrassed surveyors and engineers. The problem still persists today, even though the professional institutions have all agreed that the term should not be used.
Valuations are typically carried out by Chartered Surveyors of the General Practise Division of the RICS whereas Building Surveys are typically carried out by Chartered Surveyors of the Building Surveyors Division. Both types of surveyors may carry out Homebuyer Reports, or even all three types, but should only do so if they have the relevant experience. Chartered Surveyors are identified by the initials MRICS or FRICS after their name.
Chartered Surveyors are required by the RICS to carry professional indemnity insurance to cover any negligence in their work. It is important to check that the cover includes the type of survey or valuation requested – cover for mortgage valuations is typically more expensive and therefore may be excluded from a surveyor’s policy if the surveyor does not normally do them.
The previous government planned to introduce a compulsory Home Condition Report (HCR) as part of the compulsory Home Information Pack (HIP). In the event, the requirement for a Home Condition Report was dropped, leaving many surveyors somewhat annoyed at having spent several thousands of pounds on ‘re-training’, but relieved since they generally did not consider the HCR to be a sensible idea. Subsequently the Coalition Government has scrapped the HIP, but has retained the Energy Performance Certificate (EPC).


By far the most common type of valuation is the Mortgage Valuation, carried out on behalf of a lender. The valuation is carried out for their benefit, to enable them to decide whether or not a property offers suitable security, and if so, to what value.
IT IS NOT A SURVEY, but the surveyor must carry out a sufficient inspection of the property to be satisfied that there are no major defects which would affect the valuation.
Different lenders have their own forms and specific requirements but typically require YES/NO answers to questions such as ‘Is there any evidence of subsidence or other foundation movement?’ or ‘Are there any signs of damp within the property?’. Some may request comments on any items of concern whereas others may simply ask ‘Are there any of the following specialist reports recommended? Structural Engineer, Electrical, Gas, Damp, Timber, Wall Ties, Drains, Other_____(please specify)’.
The surveyor must therefore inspect the whole property, inside and out, including a ‘head & shoulders’ inspection of the roof void. However, the surveyor should not advise on solutions to problems or carry out any in-depth investigations of concerns – these should be ‘flagged’ for further action.
Typically, about 80% of buyers rely solely on the Mortgage Valuation report, which most lenders copy to the buyers. This is despite the fact that most Mortgage Valuation reports clearly state that it is not a survey and must not be relied upon as such and that the buyer is advised to obtain a survey on the condition of the property before committing themselves to purchase. It should always be remembered that the Mortgage Valuation is for the benefit of the lender and will only address matters which are of concern to them.
There are several types of valuation, the most common being the ‘open market valuation’. This is defined as the best price at which the property might reasonably be expected to be sold, at the date of valuation, assuming a reasonable period of marketing prior to sale, and that there is a willing buyer.
Mortgage Valuations also include a ‘reinstatement cost’. This is for insurance purposes and is derived from published tables dependent on the type and size of the property.


Relocation companies, and some other organisations who may be taking an interest in a property (other than providing a simple mortgage), usually require a valuation, plus an assessment of the property’s condition (with a view to future repairs and maintenance), its saleability and its mortgageability.
Typically this information is reported on forms defined by the particular organisation and is kept confidential, ie. it is not revealed to the sellers or prospective buyers.
Additional types of valuations may also be required, such as a ‘forced sale valuation’.  This is the best price which may reasonably be obtained if the property is to be sold within 90 days of being marketed.


The HBS is carried out to a standard format defined by the Royal Institution of Chartered Surveyors (RICS). The HBS is suitable for modern (from around 1900), domestic properties, of conventional construction, and which are in reasonable condition – if a property does not meet these conditions then a Building Survey should be requested.
The inspection is carried out to all visible and readily available parts but furniture is not moved and floor coverings are not lifted. Ladder access will be made to flat roofs and loft hatches up to 3 metres high, and binoculars will be used where appropriate to inspect area such as chimneys.
Services are inspected but the surveyor does not test or assess the efficiency of electrical, gas, plumbing, heating or drainage installations, or their compliance with current regulations. A damp meter is used to test for any damp to the structure.
The HBS briefly describes the property, its construction, features and location. The report details the findings of the inspection and summarises urgent matters which require repair or further investigation, and significant matters which require action or may affect the value of the property.


This is a comprehensive survey suitable for all types of properties, especially recommended for older properties, unusual properties, those which have been extended or altered, and those which are not in reasonable condition.
The inspection involves a detailed examination of all accessible parts, including lifting any loose floorboards and the like (subject to owners approval). Ladder access greater than 3 metres high is prohibited for health and safety reasons unless prior arrangements have been made to provide safe access.
Services are inspected but the surveyor does not test or assess the efficiency of electrical, gas, plumbing, heating or drainage installations, or their compliance with current regulations. A damp meter is used to test for any damp to the structure.
The report includes:-
A general description of the property, its construction, features and location.
The findings of the inspection.
Details of major and minor defects.
Budget costs for repairs.
Recommendations for further investigations by specialists


As we have seen, surveyors may well identify problems or concerns which they are unable to advise on. This may be due to the limitations of the survey or the surveyor may not have the necessary knowledge or expertise. When this happens the surveyor will recommend what further action is required.
Given that around 80% of buyers rely solely on the Mortgage Valuation, it is usually down to the lenders to ensure that further action takes place. Most mortgage lenders will advise their customers that a mortgage offer cannot be made until they receive a satisfactory report or the problem is rectified.
The need for further reports occurs after the valuation and/or survey so the conveyancing and mortgage applications are probably at an advanced stage. This usually results in an urgent need to obtain the specialists reports. A turn around of a week is usually requested and can usually be accomplished, although occasionally there may be only a few days available before contracts are exchanged – these circumstances would require special arrangements to be made to ensure that the deadline could be met.


Structural reports are often called an ‘Engineers Report’ or ‘Structural Engineers Report’, or might even be called a ‘Structural Survey’ by some clients. Very often the clients do not really know what it is that they need, so careful questioning is required to be determine what is needed.
Structural reports are usually carried out by a Chartered Engineer (CEng) who may be a Member or Fellow of the Institution of Structural Engineers (MIStructE / FIStructE), or the Institution of Civil Engineers (MICE / FICE). In either case it is essential that the engineer has knowledge of and expertise in subsidence and structural problems which affect domestic properties and their mortgageability. Some Chartered Surveyors (of the Building Surveyors Division) may also have the necessary knowledge and expertise to inspect and report on structural problems (or concerns).
With structural reports it is essential to understand what is being inspected and reported on, and what is not included. The various types of structural reports are described below:-


A Specific Structural Inspection is a visual inspection of a particular, structural problem or concern, and would include any related matters. Parts of the property not related to the specific problem may not be inspected and other problems may not be inspected. However, if the engineer were to note any other structural problems or concerns during the course of the inspection, these may be included in the inspection and dealt with in the report, but in any event would be brought to the client’s attention.
The report includes details of what was inspected and found. It will state whether or not there is a problem and if so, what needs to be done to rectify the problem or what further investigations may be necessary. Where repairs/remedial works, or further investigations are recommended, the report will give budget costs for these.


This is similar to a Specific Structural Inspection, except that the engineer will inspect and report on the structural condition and adequacy of all the readily accessible, load-bearing elements of the property, rather than a specific problem or concern.
The inspection includes the roof structure, floors, walls, lintels, and beams. It also includes the surrounding site in case there are any factors which could indicate a risk to the foundations.
The report will detail the structural condition and adequacy of all the loadbearing elements inspected. It will identify any structural problems or concerns and will recommend what needs to be done to rectify the problem or what further investigations may be necessary. Where repairs/remedial works, or further investigations are recommended, the report will give budget costs for these.


If the electrical wiring installation is old, or has been extensively altered or extended, or appears suspect, a surveyor is likely to recommend that it is inspected and tested by an electrician.


The Electrical Periodic Inspection Report is specified in BS7671. It is a detailed report, but summarises the condition of the various parts of the electrical installation with condition ratings.
The Periodic Inspection Report must be presented on special forms. Sample forms are shown below.


It is normal for a surveyor to use a damp-meter at random locations to check for any damp to the internal walls. The cause of any damp is usually fairly obvious, although not always so.
Typically, when a surveyor requests a damp report, it is to confirm that the cause is rising damp, to determine the extent of the problem, and to get an estimate for remedying it. A damp proofing specialist company is sufficient to provide this.
If the damp problem is other than rising damp it would be better investigated by a surveyor or engineer. Although this will cost more, you will get a far more detailed and accurate report on the problem, cause(s) and solutions and will probably save time and money in the long run
The most common type of damp is rising damp. Moisture from the ground rises, by capillary action, up the walls. The moisture often carries salts which are deposited on the face of the wall when the moisture evaporates. Internal decorations are stained and damaged, plaster can de-bond and become loose. Rising damp only extends up to 1 metre above ground level, the capillary forces cannot lift the moisture any higher. Normally walls are protected against rising damp by a damp proof course built into the wall. Very old properties did not have damp proof courses, and old properties may have damp proof courses which have become ineffective. Sometimes the outside ground levels are raised above the damp proof course, this is called ‘bridging’.
The solution to rising damp is usually to inject a chemical damp proof course, and to re-plaster the internal walls with a waterproof layer up to 1.2 metres high. This work usually comes with a 10, 20 or even 30 year guarantee.
Ground floor slabs are equally likely to be affected by rising damp. It is only modern properties which have proper damp proof membranes beneath the floor slabs. Older properties often relied on tile finishes to control damp. If there is a damp problem with a ground floor it is either controlled with an impermeable covering such as vinyl sheet flooring, or the slab must be replaced with a new one incorporating a damp proof membrane.
Penetrating damp is caused by moisture which penetrates through the roof or walls. Roof problems are usually evident. Damp penetrating through walls, which includes flashings at roof and chimney abutments, is usually quite evident, but it is usually very difficult to pinpoint and cure the precise cause of the problem and very often there is no quick or easy solution. Penetrating damp can sometimes be caused by gutter or roof problems which allow rainwater to spill onto and saturate areas of wall.
Condensation is the third type of damp. This is usually caused by the lifestyle of the occupants, rather than a defect with the property. Lack of ventilation and a tendency to use the radiators for drying clothes are common causes.
A typical damp report will identify those (readily accessible) areas where damp is present and will identify the cause, along with recommendations for any necessary repairs or remedial works.


Timber reports deal with fungal decay and wood boring insects, both of which can cause serious damage to both the structural timber and non-structural timber in buildings.
Typically, when a surveyor requests a timber report, it is to confirm the type of infestation, the extent of the problem, and to get an estimate for remedying it. Damp and timber reports are often carried out together, by the same specialist, as the problems are often related.


Fungal decay is more commonly known as ‘dry rot’ and ‘wet rot’. Dampness, combined with a lack of ventilation, creates ideal conditions for fungal attack.
Dry rot (Serpula lacrymans) requires a moisture content over 20% for the spores to develop. Fine grey strands (hyphae) of the fungus spread over and through wood and other materials. As it develops, fruiting bodies (sporophores) form and these give off spores which spread the fungus further. Timber attacked by dry rot becomes dry and brittle with cuboidal fractures, it is usually so weak that it can be broken up by hand.
Wet rot (Coniophora puteana) requires a very high moisture content of 40% to 50% and will become inactive if the moisture content is lowered. It does not usually spread over other materials. It leaves the timber a dark brown colour with small cuboidal splits or longitudinal cracks.
The first steps in treating fungal decay are to remove the sources of damp which are ‘feeding’ the outbreak and to carry out exposure works to determine the full extent of the attack. Repairs or replacement of badly affected timbers may be necessary. Following this it is usual to treat the timbers with an approved fungicide in order to prevent a future outbreak.


Wood boring insects, commonly, called ‘woodworm’, come in a number of varieties nad sizes from 3mm to 25mm long. They lay their eggs on or in the timber and the larvae that hatch from these feed on and bore through the timber causing the damage. It is not at all unusual to see woodworm holes which are old and the timber is no longer being attacked, activity is usually identified by looking for fine powder left by active larvae.
Treatment of active attack usually consists of brushing or spraying insecticides onto the timbers. Quite severe attack is required to cause a significant weakness to structural timbers so it is not unusual for timbers with woodworm holes present to be considered as structurally satisfactory. Badly weakened timbers may require repair or replacement.
A typical timber report will include an inspection of all readily accessible timbers and recommendations for any necessary further exploratory works, repairs and treatment.


Gas installations are potentially dangerous for a number of reasons. The most obvious reason is a gas leak resulting in an explosion. However, the biggest danger to life is poisoning from carbon monoxide gas and other fumes produced by a gas fire or boiler. Normally all the fumes will be vented safely away, but if the appliance’s flue is not properly installed, or if there is inadequate ventilation to a room, then they can build up in a room, and because they have no smell, the situation goes unnoticed, resulting in drowsiness and ultimately death. Problems can also occur with ‘balanced’ flues which terminate too close to windows, resulting in fumes finding their way back into a room.
The government has taken these dangers seriously. It is illegal for anyone to carry out work on gas installations unless they are registered with Gas Safe - previously this body was CORGI (Council of Registered Gas Installers, but this has now been disbanded. It is also a legal requirement that landlords have a gas safety check carried out every 12 months on let properties. If a potentially dangerous situation is discovered with a gas installation, the gas engineer is legally required to switch off the mains supply or disconnect/isolate the dangerous appliance – this can create friction with the homeowner, but is unavoidable.
A report on the gas installation for a homebuyer would normally involve a visual check on the installation to determine if there were any obvious faults. In particular the flues of the boiler and any fires would be closely examined to check if they were sealed from the room, and to check that they terminated sufficiently far away from any windows. Ventilation of rooms with cookers or gas fires is also an important requirement. A number of specific tests would normally be carried out, the main one being the ‘tightness’ (or soundness) test - this checks for any leakage of the installation. Subject to the above checks being satisfactory, an operation check would be carried out on each appliance.
The following form is typical of that used for gas reports.


Reports on the plumbing or central heating system are often requested in conjunction with gas reports and in the past there has been overlap between these with no clear instructions as to precisely what is required and why.  Sometimes the request is simply for providing a quotation for a necessary repair or upgrade (eg. replacing lead pipes).
There are no standard forms or formats for plumbing reports, and plumbing reports and therefore we have developed our own version which we believe addresses the points relevant to a homebuyer.
A (full) report on the plumbing system is includes a visual inspection of the installation and an operation check.
A plumbing report will check that the boiler works (but not if it is a solid fuel boiler which is not fired up), but will not include a detailed inspection or any tests on the boiler.

The plumbing system in a house in quite complicated:


Drainage (from the building, as opposed to within the building) is invariably underground and can only be seen at inspection chambers (manholes). Out of sight usually means out of mind and so it tends to be ignored until it misbehaves.


Often referred to as a ‘simple drains test’. This is often carried out by the surveyor at the same time as a HomeBuyer Service or Building Survey. It simply involves lifting manholes covers and running water through the drains runs from the taps within the property, whilst observing the flows throughout the drainage system. This allows the surveyor to check if the drains are running free, or if there are blockages, and will also indicate any severe leakage.


Leaking drains very often go undetected for years or decades, but if close to the building, the ground beneath the foundations can be weakened by the water, resulting in subsidence. It is for this reason that surveyors may request a drainage report when they have seen cracking or other indications of foundation movement.
In these cases, a water, or hydraulic, test is required. This involves plugging the drain at the lower end, filling it up with water, then waiting to see if it holds the water or if it leaks away. When the plug is removed, the water should flow away rapidly to indicate that the drain is not blocked. There may be several sections of the drainage, each of which will require testing separately.


CCTV surveys involve passing a small camera through the drains. The operator watches the picture as the camera progresses, so that any features can be closely examined and identified, and a video recording is usually made for later reference.
A CCTV survey will not determine that a drain is watertight, but it will show and locate areas of cracking, damage, open joints or blockage. A CCTV survey can also be useful in determining the layout of a drainage system and identifying unknown / abandoned branches.
Drains can be tested and surveyed quite easily if there are adequate inspection chambers, and if they are not blocked. However, especially with older properties, there may be few or no inspection chambers. In these cases, the only way to test and survey the drains is to dig holes and break into the pipes – this gets expensive! We often find drains are blocked, or are backing up from overfull cess pits or septic tanks. In these circumstances, there is little which can be done until the system has been unblocked, cleared or emptied – again an expensive operation.
A drainage report would normally include a plan showing the layout of the drains, along with details of pipe diameters, depths below ground, results of water tests, and findings of CCTV surveys.


Usually found at rural properties because they are located a long way from the nearest public sewer.
Cess pools are simply holding tanks for the waste water. They need to be emptied regularly, perhaps every month. Typically they were never designed for, and cannot cope with modern life which demands washing machines, dishwashers, and daily baths / showers. It is not unusual to find cess pools which leak – this may be due to age, or deliberate damage inflicted in order to reduce frequency (and cost) of emptying. A leaking cess pool which comes to the notice of the local authorities or Environment Agency will be subject to an order to be repaired or replaced.
Septic tanks provide simple, two stage treatment of waste water before it is discharged. Waste water passes into the first chamber where the solids settle and are digested by anaerobic (without oxygen) bacteria. The liquid passes to a second chamber where aerobic (with oxygen) bacteria clean up the water to a standard which is safe to discharge into the ground. The discharge is usually to a soakage system which comprises an array of buried, shallow, perforated pipes. With older septic tanks the soakage system may well be inadequate or choked. Septic tanks require de-sludging every few years to remove un-digestable solids.
Small treatment plants are unusual but may be found on larger rural properties or very small rural developments. They operate similar to septic tanks but have various means of mechanical assistance to mix the waste water and bacteria together and to oxygenate the aerobic part of the treatment.
With cess pools and septic tanks, other than a quick, visual inspection from the outside to gauge the age and likely condition, there is nothing which can be readily surveyed or tested without emptying the system and cleaning it out. This is of course an expensive operation and normally would only be undertaken if there were serious concerns regarding the adequacy or integrity of the system. A drainage report would not include this unless specifically instructed.


External walls to most buildings constructed after around 1920 are cavity walls. Typically there is an outer leaf of 100mm thick brickwork, a 50mm wide cavity, and an inner leaf of 100mm thick blockwork. The outer and inner leaves are tied together with wall ties. Wall ties are usually 900mm apart horizontally and 450mm vertically. They are usually galvanised steel, older ties having a relatively thin layer of galvanising which can allow the steel to corrode.
There are two problems with corroding wall ties. The ties can corrode in the cavity and break such that the outer and inner leaves are no longer tied together. If this occurs, there is a distinct risk of the outer leaf collapsing, especially under high winds which cause suction on the face of the wall. This is a rare problem, and this type of corrosion is most likely occur in certain areas of northern England where black ash was used in the mortar and which promotes aggressive corrosion.
The more common problem is when the part of the tie embedded in the outer leaf corrodes. This tends to occur on south and west facing elevations which are exposed to driving rain and which are often wet. Rust occupies a greater volume than the original steel and therefore the expansion of the tie in the bed joint forces it to crack. Cracks running along the bed joints, every 450mm up the wall, are a definite indication of wall tie corrosion. In severe cases we have seen the outer leaf being lifted by about 50mm at roof level.
A wall tie report comprises detecting the locations of wall ties using a metal detector and then either removing a brick or the mortar or drilling a small hole and using an endoscope to examine the condition of the tie. If ties are corroded or if there are insufficient ties, the report will recommend a suitable type of replacement tie. Corroded ties will need to be cut out of the outer leaf to prevent further cracking.


Asbestos was incorporated in the manufacture of all kinds of building materials and was used in construction from the 1950’s up until the mid-1980’s. Any building constructed or undergone extension or major refurbishment during that period will almost certainly contain asbestos.
Asbestos fibres are very small, and if inhaled they settle in the lungs where they may cause one of several asbestos related diseases after a period of 15 to 60 years.
There are three main types of asbestos and in most domestic situations they are embedded within the building materials where they are harmless. However, if the building material is sawn, drilled or the like, this can release the fibres into the dust so created. In most domestic situations it is safest to leave the building material in place and undisturbed.
An asbestos survey comprises a visual inspection to identify and building materials likely to contain asbestos and to advise on the level of risk and what action to take. Advice may be to leave the building materials undisturbed, but add a warning label for the attention of anyone who may do any work on the material (builders electricians, plumbers etc.), or to take samples for laboratory examination and further consideration, or removal of the material.


Sulphate attack on ground floor slabs is a very serious problem which can cause structural damage to the main walls of a building. The problem occurs when the fill material (hardcore) beneath the slab contains sulphates and these migrate into the slab. The sulphates react with the concrete causing it to expand, this results in heave of the slab and structural damage to the external walls as the slab pushes them out. Eventually the concrete may disintegrate. When the slab heaves, any internal walls built off the slab will be lifted and may cause damage to the structure above.
For the sulphates to migrate into the slab, there must be moisture present. Migration is encouraged if conditions allow the moisture to be drawn through the slab by evaporation from its surface. Migration is prohibited if there is an adequate damp-proof membrane between the fill and the slab. Although a high level of sulphate may be present, there may be no sulphate attack if the fill is dry and/or there is an effective damp-proof membrane. However, moisture contents can vary and increase to very high levels if an undetected water leak occurs, and damp-proof membranes can deteriorate with time. Whenever sulphates are present there is a potential problem for the future.
Hardcore containing sulphates is now banned from use below floor slabs, and in any case there is now a requirement for a damp proof membrane which would prevent sulphate attack.
Typically the problem properties are those built by local authorities in the 1950’s and 1960’s in mining areas. This is because colliery shale, which often contains sulphates, was often used for the hardcore. Sometimes the colliery shale would come from tips which had caught fire and this is where the names ‘red ash’ or ‘burnt shale’ come from and which alert the surveyor to a potential problem.
There are other sources of sulphates in hardcore, and there are other causes of heave to ground floor slabs, all of which must be understood and considered as possibilities when investigating such problems.
A sulphate report entails breaking one or more holes through the ground floor slab and digging down to determine the hardcore thickness and recover a sample for laboratory analysis. If a damp proof membrane is present it cannot be fully reinstated, and any surface finishes cannot be reinstated. It is therefore necessary for the owners to agree, in writing, to the investigations. The laboratory analysis will take about 2 weeks so at least 3 weeks is required to complete the report.
A sulphate report also includes observations on any movement, cracking or distortion to the external walls around damp proof course level, the internal ground floor walls (which may be built off the slab) and the slab itself. The condition of the concrete is examined, the presence or otherwise of any damp proof membrane is noted and the dampness of the hardcore is noted. These are all factors which either indicates a sulphate problem or which could affect the risk of sulphate attack.


An Arboricultural Report may be requested for two reasons. There may be concern regarding the health and condition of the tree, or there may be concern that the tree roots are, or could affect the property.
Concerns regarding the health and condition of the tree generally arise because it could pose a danger to the property or to people from branches breaking off or even the whole tree being blown over by high winds. This is definitely a job for an Arboriculturalist who will advise on the risks and what pruning or other measures are necessary.
Concerns regarding tree roots which may affect the foundations of a property occur when the underlying ground is clay. In order to assess the risks it is necessary to establish the tree species and its distance from the property, the depth of the foundations, and to recover soils samples for laboratory tests to determine the ‘Shrinkage Potential’ of the clay. From these factors it is possible to assess the risks with tables from the NHBC Standards. This type of report would best be carried out by an engineer.


We are often asked to obtain a Builders Report or a Roofers Report on a property or a particular aspect of it. In the past we have tried to satisfy these requests but with very disappointing results. Builders and roofers simply can’t do reports and it is not fair to ask them. They are not professionally trained, their experience is limited and their writing ability is generally very poor. Such reports are rarely satisfactory and we now refuse such requests in the interests of our clients. If a report, with observations, critical analysis and advice is required, then a surveyor or engineer should be instructed.
Very often these requests are in fact for an estimate of the cost to carry out some particular repair or remedial work on a problem which has already been identified by the surveyor. This is fine so long as the required work has been identified.


Estimates can be obtained for repairs or remedial works but it is essential that the required works are properly identified and specified. The more detailed the information, the more accurate will be the estimate. Ideally the surveyor who requests the estimate should specify the works but if this is not done then it may be necessary to instruct another surveyor or engineer to visit the property and prepare a ‘Schedule of Works’. Such a schedule is essential when the cost of the works exceeds more than say a couple of thousand pounds.
If we are provided with details of the required works and photographs of the property we are often able to prepare estimates ‘in-house’ without the need to visit the property. This ensures a quick turn-around. There will of course be cases where a site visit is essential to produce a meaningful estimate so we always need contact details of the owners / occupiers.
Although many builders will offer free estimates, this is not the case when dealing with homebuyers and the like. Builders are wise to the fact that such estimates rarely lead to a job so they do charge for them.
Estimates obtained in the above manner are fine for straightforward works of low value. When the cost of the works becomes more that say £2,000, it is recommended that several estimates are obtained, all based on the same ‘specification’ so that they are comparable. When the cost of the works becomes more than say, £5,000 we would recommend that formal tenders are invited based on drawings, specifications and schedules or work, using the JCT Minor Works Agreement as the basis for a written contract.


Mike Royall
WRD Engineers