You are claiming rising damp is only present in relation to the water table is incorrect. All buildings incorporate DPC in the uk as rising damp can occur for many reasons, not as you state regularly in your uploads.
Steve, Thank you very much for taking the time to comment on my video. Encouraging dialogue and collaboration among surveyors is crucial for ensuring that properties are accurately diagnosed and treated. My focus is primarily on long-lasting solutions that rely less on generic definitions and more on pinpointing the exact sources of water intrusion and addressing them directly, as this approach ensures the most durable outcomes. The root causes can generally be categorised as follows: 1) Groundwater - Consistently referred to by geologists as the water beneath the water table. 2) Rainwater - This includes water at any stage of its descent, from roof, gutters, drains, or percolating through soil. The difference between rainwater and groundwater is groundwater is bounded by the water table. 3) Leaks - Such as mains water, accidental spillages, and moisture from construction. 4a) Excess Vapour - Leading to condensation. 4b) Hygroscopic Salts - These are not a source moisture but cause deliquescence, a form of condensation at normal level of relative humidity. Groundwater Dynamics Geologists define the water beneath the water table as groundwater. Directly above the water table, the partially saturated area known as the capillary fringe typically extends about 1 to 2 meters. Bricks within this fringe can exhibit signs of partial rising damp. Above this zone, in the unsaturated area, rainwater is primarily influenced by gravity, pulling it downward. Moisture can rise up to about 10 cm here, compared to 1 - 2 meters if bricks are in contact with the saturated earth below the water table. Ironically, water found above a damp proof course (DPC), such as condensation on slate within the sub-floor void, can mimic symptoms of rising damp. This is not due to groundwater but because the DPC acts as a barrier, stopping the gravitational pull of water downwards. If condensation occurs in the sub-floor void, the initial steps should be to identify and eliminate the source, potentially a damaged drain, and improve sub-floor ventilation if required. Ignoring these steps can lead to issues like rot, woodworm, subsidence, and symptoms akin to rising damp. The Limitations of "Rising Damp" The term "rising damp" can often be misleading, as water from any source will be absorbed in all directions, including upwards. The standard definition is: "process of external ground water being drawn up through brickwork by what is known as capillary action". However, in my opinion, rising damp has often been the default diagnosis in the absence of other obvious explanations, rather than the result of actively seeking corroborating evidence. As a basic requirement, there should be confirmation that the dampness appears more or less horizontally across the entire property and extends to adjoining buildings, resembling dampness above floodwater rather than being confined to cold zones such as corners of wall. Additionally, it’s crucial to examine the ground for saturation within one meter of the base of the ground floor walls, and, if possible, around all four sides of the building. It’s important to confirm that if saturation is present, it does not display a higher concentration on one side than another, as this could indicate the presence of a leaking pipe rather than groundwater absorption. Thank you once again, the more we challenge each other and come to consensus based on facts, the better the public will be served. All the best, Simon Your comment reminds me of an exchange with a RICS surveyor see: dampsurveys.com/rising-damp-diagnosis/. For ease, I’d like to replicate that discussion here. Simon - - - - - - From Alan: BRE 245 advises that walls built of porous masonry can (only) have rising damp where they: 1) Stand in water or saturated ground, and 2) Have been built without a physical barrier to the upward movement of moisture. However you seem to be saying that only ground water can cause rising damp, (ie a high water table). Am I understanding you correctly? as it seems to me that soil saturation from any source could lead to RD and I think this is what the BRED is suggesting? I would grateful if you would be kind enough to clarify this please - as when in doubt I tend to follow BRE advice. [no need to edit this message exchange.] My responce to Alan: Alan, Thank you for reaching out with your query regarding the interpretation of BRE 245 and its application to identifying the causes of rising damp in buildings. Your understanding of the nuances of moisture absorption into porous masonry is critical, especially when considering the various sources of soil saturation and their impact on rising damp. BRE 245 indeed suggests that for rising damp to occur in walls built from porous materials, two conditions must be met: firstly, the walls must be in contact with water or saturated ground; and secondly, there must be an absence of a physical damp-proof barrier to prevent the upward movement of moisture. Your observation that soil saturation from any source could rise up a wall is astute and aligns with the broader interpretation of the guidance. I agree that groundwater (water beneath the water-table) is not the only definition of the source of water in rising damp. However, I choose to define rising damp as the upward rise of groundwater for many reasons: 1) Water from any source will rise up an absorbent material, such as kitchen paper dipped in tap water. The rise of moisture is a symptom of damp, not a source or root cause. 2) Sources of water other than groundwater, such as condensation, leaking pipes, overflow from rainwater goods, or high vapour levels in the sub-floor (often resulting from leaking drains), should and can be easily dealt with at their source. 3) There is a tendency to treat every unresolved source of dampness at the base of a wall as rising damp by default because no other source can be found, not because the source is groundwater or indeed a DPC has been breached. 4) Groundwater sufficiently in contact with a wall to cause rising damp, can be identified by drilling down about 1 metre on all four sides of a property (taking care not to damage wires or pipes) and leaving a tube to measure water levels. If the water levels are equal, then, and only then, there may be groundwater; otherwise, if one level is higher than another, it is probable that there is a leaking underground drain or similar source, which should be fixed to avoid the risk of rot or subsidence. 5) The common method of treating for rising damp is not just injecting absorption-reducing chemicals (which I am not totally against, occasionally recommending them), but also the replacement of plaster with an impermeable “slurry”. This is the main issue as it hides the damp, rather than dealing with the root cause, risking worse problems later. Clearly, if, for instance, a neighbour or the local water board refuses to fix their leaking drain, then you may have no choice. But you should be aware of the risks and mitigate those risks, such as by legal notification and by increasing sub-floor ventilation. 6) A common misinterpretation of rising damp is the presence of hygroscopic salts in a wall, which while they can on rare occasions come from groundwater, they normally results from burning coal or equine urine. Furthermore, hygroscopic salts are easy to remedy without replacing plaster. Overall, there is a tendency in UK to identify every damp issue at the base of a wall as rising damp, without evidence of groundwater. Testing to make sure the soil is saturated would be a good starting point, that would perhaps lead to more sub-floor leaks being detected and fewer insurance claims for subsidence - as well as fewer rising damp claims. Simon Alan's response 1: Thankyou very much for such a detailed and informative reply. I really cannot disagree with a single thing you have said. It really is a great pity that other surveyors do not adopt your objective approach. Hopefully one day sufficient research (perhaps by UKCMB) will be undertaken to fully clarify the rising damp debate once and for all. Alan's response 2: Thankyou for your detailed and informative reply. I think you have hit the nail on the head and I really appreciate you outlining how to test for groundwater. As you say there is a need for an authoritative and agreed guide which we can all rely on, but there are no signs of this on the horizon. In fact we dont even have an agreed definition for “rising damp.” I actually wrote to BRE suggesting they update the now old BRED 245 but they showed little interest and implied that they would only do this under government or other significant influence.
What are the implications for the building when a downpipe is depositing water directly into the ground like this? Would you create a drainage system?
You are claiming rising damp is only present in relation to the water table is incorrect. All buildings incorporate DPC in the uk as rising damp can occur for many reasons, not as you state regularly in your uploads.
Steve,
Thank you very much for taking the time to comment on my video. Encouraging dialogue and collaboration among surveyors is crucial for ensuring that properties are accurately diagnosed and treated.
My focus is primarily on long-lasting solutions that rely less on generic definitions and more on pinpointing the exact sources of water intrusion and addressing them directly, as this approach ensures the most durable outcomes. The root causes can generally be categorised as follows:
1) Groundwater - Consistently referred to by geologists as the water beneath the water table.
2) Rainwater - This includes water at any stage of its descent, from roof, gutters, drains, or percolating through soil. The difference between rainwater and groundwater is groundwater is bounded by the water table.
3) Leaks - Such as mains water, accidental spillages, and moisture from construction.
4a) Excess Vapour - Leading to condensation.
4b) Hygroscopic Salts - These are not a source moisture but cause deliquescence, a form of condensation at normal level of relative humidity.
Groundwater Dynamics
Geologists define the water beneath the water table as groundwater. Directly above the water table, the partially saturated area known as the capillary fringe typically extends about 1 to 2 meters. Bricks within this fringe can exhibit signs of partial rising damp. Above this zone, in the unsaturated area, rainwater is primarily influenced by gravity, pulling it downward. Moisture can rise up to about 10 cm here, compared to 1 - 2 meters if bricks are in contact with the saturated earth below the water table.
Ironically, water found above a damp proof course (DPC), such as condensation on slate within the sub-floor void, can mimic symptoms of rising damp. This is not due to groundwater but because the DPC acts as a barrier, stopping the gravitational pull of water downwards. If condensation occurs in the sub-floor void, the initial steps should be to identify and eliminate the source, potentially a damaged drain, and improve sub-floor ventilation if required. Ignoring these steps can lead to issues like rot, woodworm, subsidence, and symptoms akin to rising damp.
The Limitations of "Rising Damp"
The term "rising damp" can often be misleading, as water from any source will be absorbed in all directions, including upwards. The standard definition is:
"process of external ground water being drawn up through brickwork by what is known as capillary action".
However, in my opinion, rising damp has often been the default diagnosis in the absence of other obvious explanations, rather than the result of actively seeking corroborating evidence. As a basic requirement, there should be confirmation that the dampness appears more or less horizontally across the entire property and extends to adjoining buildings, resembling dampness above floodwater rather than being confined to cold zones such as corners of wall.
Additionally, it’s crucial to examine the ground for saturation within one meter of the base of the ground floor walls, and, if possible, around all four sides of the building. It’s important to confirm that if saturation is present, it does not display a higher concentration on one side than another, as this could indicate the presence of a leaking pipe rather than groundwater absorption.
Thank you once again, the more we challenge each other and come to consensus based on facts, the better the public will be served.
All the best,
Simon
Your comment reminds me of an exchange with a RICS surveyor see: dampsurveys.com/rising-damp-diagnosis/.
For ease, I’d like to replicate that discussion here.
Simon
- - - - - -
From Alan:
BRE 245 advises that walls built of porous masonry can (only) have rising damp where they:
1) Stand in water or saturated ground, and
2) Have been built without a physical barrier to the upward movement of moisture.
However you seem to be saying that only ground water can cause rising damp, (ie a high water table).
Am I understanding you correctly? as it seems to me that soil saturation from any source could lead to RD and I think this is what the BRED is suggesting?
I would grateful if you would be kind enough to clarify this please - as when in doubt I tend to follow BRE advice.
[no need to edit this message exchange.]
My responce to Alan:
Alan,
Thank you for reaching out with your query regarding the interpretation of BRE 245 and its application to identifying the causes of rising damp in buildings. Your understanding of the nuances of moisture absorption into porous masonry is critical, especially when considering the various sources of soil saturation and their impact on rising damp.
BRE 245 indeed suggests that for rising damp to occur in walls built from porous materials, two conditions must be met: firstly, the walls must be in contact with water or saturated ground; and secondly, there must be an absence of a physical damp-proof barrier to prevent the upward movement of moisture. Your observation that soil saturation from any source could rise up a wall is astute and aligns with the broader interpretation of the guidance.
I agree that groundwater (water beneath the water-table) is not the only definition of the source of water in rising damp. However, I choose to define rising damp as the upward rise of groundwater for many reasons:
1) Water from any source will rise up an absorbent material, such as kitchen paper dipped in tap water. The rise of moisture is a symptom of damp, not a source or root cause.
2) Sources of water other than groundwater, such as condensation, leaking pipes, overflow from rainwater goods, or high vapour levels in the sub-floor (often resulting from leaking drains), should and can be easily dealt with at their source.
3) There is a tendency to treat every unresolved source of dampness at the base of a wall as rising damp by default because no other source can be found, not because the source is groundwater or indeed a DPC has been breached.
4) Groundwater sufficiently in contact with a wall to cause rising damp, can be identified by drilling down about 1 metre on all four sides of a property (taking care not to damage wires or pipes) and leaving a tube to measure water levels. If the water levels are equal, then, and only then, there may be groundwater; otherwise, if one level is higher than another, it is probable that there is a leaking underground drain or similar source, which should be fixed to avoid the risk of rot or subsidence.
5) The common method of treating for rising damp is not just injecting absorption-reducing chemicals (which I am not totally against, occasionally recommending them), but also the replacement of plaster with an impermeable “slurry”. This is the main issue as it hides the damp, rather than dealing with the root cause, risking worse problems later. Clearly, if, for instance, a neighbour or the local water board refuses to fix their leaking drain, then you may have no choice. But you should be aware of the risks and mitigate those risks, such as by legal notification and by increasing sub-floor ventilation.
6) A common misinterpretation of rising damp is the presence of hygroscopic salts in a wall, which while they can on rare occasions come from groundwater, they normally results from burning coal or equine urine. Furthermore, hygroscopic salts are easy to remedy without replacing plaster.
Overall, there is a tendency in UK to identify every damp issue at the base of a wall as rising damp, without evidence of groundwater. Testing to make sure the soil is saturated would be a good starting point, that would perhaps lead to more sub-floor leaks being detected and fewer insurance claims for subsidence - as well as fewer rising damp claims.
Simon
Alan's response 1:
Thankyou very much for such a detailed and informative reply. I really cannot disagree with a single thing you have said. It really is a great pity that other surveyors do not
adopt your objective approach. Hopefully one day sufficient research (perhaps by UKCMB) will be undertaken to fully clarify the rising damp debate once and for all.
Alan's response 2:
Thankyou for your detailed and informative reply. I think you have hit the nail on the head and I really appreciate you outlining how to test for groundwater. As you say there is a need for an authoritative and agreed guide which we can all rely on, but there are no signs of this on the horizon. In fact we dont even have an agreed definition for “rising damp.” I actually wrote to BRE suggesting they update the now old BRED 245 but they showed little interest and implied that they would only do this under government or other significant influence.