How old is your property? Depending on the type of construction, can depend on the type of survey you need, as we will need to eliminate different potential damp issues to come to a conclusion.
Data is king when it comes to damp issues, along with building pathology. Another thing that is imperative is to have the correct diagnostic equipment; fortunately we have the latest equipment available to aid every survey. Specialist training and over 15 years experience, along with following the correct methodology in standards relating to damp issues is also very important.
Often you will find damp expert websites, and survey reports stating that they follow BS 65676: 2005, which is the British Standard for the Code of practice for diagnosis of rising damp in walls of buildings and installation of chemical damp proof courses. What typically happens is that a homeowner is tricked into booking the damp survey which will be non invasive damp survey. This means you will not get a comprehensive report with quantitative moisture analysis following the British Standards. Please read the below screenshot from the British Standard below.
This clearly states that to eliminate and confirm the diagnosis sampling is needed for the correct diagnosis. It also clearly states that chemical tests – a speedy meter which is often referred to as a carbide meter also only measures total moisture content on site. This clearly shows that the gravimetric method is the correct way for quantitative diagnosis, all of our surveys follow this methodology unless we can’t take plaster/mortar samples (eg pre-purchase surveys). If you haven’t been offered this service by the damp surveyor, you have to ask the question why they don’t want to carry out the survey as instructed in the British Standards.
If you require a damp survey for potential rising damp, you must state to the surveyor that you require the survey to follow the British Standard BS 6576, and diagnosis following BRE Digest 245. The survey will be invasive, as this is the only way to confirm the diagnosis of rising damp.
Below are some pictures showing some defects that have to be eliminated. If a property has a physical damp proof course it would be extremely unlikely that it has broken down, and need a new chemical damp proof course.
Below shows that a an external path is bridging the damp proof course. Lowering the ground levels to eliminate this issue, is a job we carry out on a regular basis.
Below shows bridging of the damp proof course by the external render. This render can be cut back carefully and a bell mouth formed to prevent bridging of the damp proof course. Normally some lime pointing is also needed at low level.
Below shows bridging of the damp proof course by the external pointing.
Below shows a picture of bridging of the damp proof course by debris in the cavity. This is such a common problem, and this type of work we carry out weekly. Unfortunately it is often not inspected because ideally you really need a camera to look in the cavity to inspect bridging issues.
Below shows bridging of the damp proof course by the internal plaster. This is another common problem, which can’t be inspected without removing some skirting board internally, hence again the need for an invasive damp survey to visually see this.
Below shows bridging by the flooring screed. Another common issue, that again needs an invasive survey to inspect this. Our cutting equipment can cut this joint out up to 120mm, so there is no need to remove big chunks of the solid floor.
If you require a damp survey for potential rising damp, you must state to the surveyor that you require the survey to follow the British Standard BS 6576, and diagnosis following BRE Digest 245. The survey will be invasive as this is the only way to confirm the diagnosis as you can see in the above pictures.
What is an invasive survey? Well this can be carried out without much damage, some of which can be carried out externally.
Externally we can check the cavity for debris either by removing a brick, or be drilling a 9mm hole and using our boroscope camera.
Internally normally a small amount of skirting would need to be removed, this is carried out with very a fine oscillating blade to make a small cut. This would then reveal floor and wall junction for inspection, a small amount of plaster/render is removed below skirting level (this can then be covered with the skirting board). Now we can check to see the height of the damp proof course in comparison to the floor to see if its bridging, and to see if the plaster is bridging the damp proof course.
A series of around 9mm holes are drilled vertically every 250mm, this will show in the laboratory analysis any free moisture/hygroscopic salt distribution if there has been a long term rising damp issue. This called a vertical gravimetric profile.
Along with the survey, and the gravimetric profile we now have the data needed on confirming the exact cause, and most importantly how to move forward with repairs.
BS 5250 is the British Standard for Condensation.
The condensation ‘season’ is normally around September to April, typically most houses that have condensation will see issues normally on windows internally or perhaps cold areas of the building where thermal bridges occur.
Most of our condensation and mould surveys are carried out for Housing Associations, Landlords and letting agents as well as private home owners.
First of all an internal atmospheric condensation survey is carried out, allowing sufficient time for all of the equipment to come to equilibrium. My choice of thermal hygrometer is the Flir MR77, this is because this links to my thermal imaging camera which is the FLIR T600. This is a fantastic piece of equipment as I have full control over the measurements. I can now carry out what I call a condensation risk assessment on the building.
One of the measurements we can check is the dew point, this is the temperature at which condensation occurs. Sometimes when looking at an issue, for whatever reason condensation isn’t occurring, however it can be very close to dew point condensation, this is where a thermal imaging isotherm paints the picture and gives the at risk areas that maybe be subject to further checking.
Ventilation is also a major factor to consider when evaluating an issue. I often find that ventilation isn’t always compliant following Approved Document F, and the Domestic Ventilation Guide. As a BPEC qualified ventilation specialist, I can also give the necessary advice on any ventilation issues, and possible subsequent condensation, mould, and indoor air quality.
Approved document F link below.
Domestic Ventilation Guide link below.
In order to evaluate ventilation, it has to be measured for air flow rates, my choice in equipment is the Observator Diff. Using this equipment I don’t need to use minimum bench mark figures, this also ensures that when we install we get the best out of the equipment specified for replacement.
Is the building fabric dry? This normally starts with an aerial survey especially if some parts of the building are not visible from ground level. Then the building is then surveyed from the chimney down to look for any obvious vesible defects that correlate with any internal issues.
Regarding the actual diagnosis of damp when we carry out the damp survey we would normally produce a graph for each profile drilled (BRE DIGEST 245) as per below that visually demonstrates the quantitative moisture measurements, and then armed with this data we can then offer the correct advice for you.
We also carry out leak detection surveys using specialist listening equipment, and CCTV drain surveys.
We also carry out CCTV drain surveys. As you can see in the below pictures the blocked drainage pipes were the cause of the rising damp in these properties.
Many damp surveyors don’t have all of the necessary equipment to carry out a comprehensive survey of damp issues, so the opinion is based on more of a visual survey. From many years of experience this just isn’t good enough.
We have all of the specialist equipment, and the laboratory equipment to follow the methodology in BRE DIGEST 245, to give you the answers to fix your problem.
If you need a damp survey give us a shout
What is condensation and why is it a problem now? One of the biggest points of confusion for homeowners...
What is condensation and why is it a problem now? One of the biggest points of confusion for homeowners...
What is condensation and why is it a problem now? One of the biggest points of confusion for homeowners...
What is condensation and why is it a problem now? One of the biggest points of confusion for homeowners...
What is condensation and why is it a problem now? One of the biggest points of confusion for homeowners...
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