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The survey methods we use are dictated primarily by three key expert guidance documents, which we use to guide and inform the damp survey process. Some key excerpts from these documents are below.
“Dampness should be fully investigated to identify its cause(s) and specify a solution. Where there is evidence of water ingress the source should be identified as soon as possible… sealing the fabric at one point can lead to damage elsewhere so advice from competent persons should be sought, particularly where modern treatments would change the nature of the fabric”
“Measurements of surface moisture are in themselves no indication that a genuine rising damp problem exists. Electrical meters [such as Protimeters or other capacitance meters] have a valuable role to play…and will identify areas where further investigation is required. They quite commonly give high readings on the walls of old properties where some accumulation of salts [over many years] usually occurs on internal surfaces. This does not mean, however, that the property necessarily has a dampness problem…”
This guidance document was put together as a joint effort by RICS, Historic England, Property Care Association (PCA), CADW and other expert bodies. It represents the first collaboration of its kind and is a great leap forward for the general damp industry to recognise that traditional, permeable, buildings (solid brick, timber, stone or cob) need to be treated in a more sympathetic way than modern buildings.
“Traditional construction absorbs moisture but readily allows it to evaporate when conditions become drier. This is in contrast to modern construction which relies on impermeable barriers to prevent moisture entering the fabric.”
We use FLIR thermal imaging cameras to find hot spots, cold spots and wet spots within a building. We like FLIR due to the MSX technology which overlays the thermal image onto a regular camera image provided fine detail of the actual scene, like in the image shown here. This makes it really easy to pick out areas of concern. These thermal imaging cameras are designed for building inspections and used by us primarily to pick out colder spots which may indicate a leak or a cold bridge. This technology is a really great tool that proves very useful in the right hands. Our long term experience diagnosing damp problems allows for intelligent interpretation of the image and further investigation as required.
Looking like something from a Steampunk fantasy novel the ‘Speedy’ Calcium Carbide Meter is an incredibly useful bit of kit. This allows us to take an accurate reading of the actual moisture content within a wall. No other bit of kit can give such an accurate reading and so quickly while on site. To use it we drill a 10mm diameter hole in the wall (not usually a problem since the wall in question is often in a poor state anyway) then put a weighed sample of the masonry dust into the ‘Speedy’ meter before giving it a good shake with some calcium carbide powder. This causes a fizzing in the chamber, pushes up the pressure gauge and gives an accurate % moisture content of the wall.
This is particularly useful if rising damp is suspected but the problem may also be down to condensation. Also a great tool to confirm a wall has dried out following the repair of external defects.
These familiar two pronged protimeters are useful on a survey to give an indication of areas which need further investigation. The Protimeter gives an accurate moisture content when used in timber which is very helpful to determine which timbers are at risk of fungal decay or insect attack.
The protimeter is not calibrated for masonry and does not give an absolute reading. It is also hopelessly thrown off the scent by any salts present in the wall – a big problem with older buildings which often accumulated salts from over the years.
As per the BRE245 guidance referenced above these protimeters cannot be used to diagnose rising damp.
Having said all of that the protimeter is great at finding dry areas of walls and this fact alone makes it very useful for damp surveys.
Eyes and experience are the most powerful survey methods for surveying damp problems. Damp Genius’s principle surveyor Tom Dear has worked on the tools carrying out damp works, managed a team of 17 damp experts for a large national firm and surveyed around 2,750 damp properties during his career.
The truth is that no tool invented can tell a surveyor what type of beetle has been attacking the floorboards and what this means. There is no magic survey tool which can appreciate how a building was made, what the history of the building is, if groundwater is likely present in an area, what type of render has been applied to the building, if the ground levels have changed and many other things experienced eyes will see.
All of these things take time and experience to develop and learn. If you have damp problem or need a survey for mortgage then please contact us to request a survey.
Sometimes it is very useful to be able to look within a cavity wall or behind some plasterboard. For these purposes we use a borescope or a snake camera. This enables to quickly determine if a cavity is blocked, if cavity wall ties have failed, if debris within a cavity is causing issues or even if interstitial condensation is present within a wall.
Looking within a wall is particularly useful if symptoms of rising damp are present but the house is of cavity construction. Cavities can become bridged by falling debris during any renovation work which has taken place above, such as new windows, new pipe penetrations or even roofing works.
On every survey we take humidity readings within the rooms, the bathrooms, the kitchen and outside for comparison. Humidity levels can cause a variety of problems within properties including moulds, paint flaking and plaster deterioration. In some circumstances the humidity can also be responsible for salt damage on walls as the high levels of condensation within the walls pores lead to existing salts becoming watery before accumulating on the wall surface.
Interstitial condensation is reasonably common and can be found within wall cavities or behind plasterboard walls.
Where rising damp is suspected we tend to carry out a salts analysis of the moisture within the wall plaster. This can quickly tell if salts commonly found in groundwater are present in the wall or not. If they are present then we know that the water is coming up from the ground (or has been in recent history) and the survey can then seek to explore the causes of this such as high ground, bridged cavities or damp proof course failures.
If the sample analysis shows no salts present then it is reasonable to assume that water is entering the walls from above, either failed render, pointing, roof or something else.