Damp - what's the latest thinking?
Discussion
I recently had some "damp consultants" do a survey at my Mum's house and their proposal was something I've not heard of before, so I was wondering if anyone on here has any experience of this, or similar methods.
What they were proposing was (some of the details below may be slightly inaccurate, but hopefully the overall method is clear):
Leave the plaster intact on the problem wall (ground floor)
Fit battens directly to the wall and then attach a special plastic membrane a bit like bubble wrap to the battens using special fixings.
Attach more battens to the special fixings and then plasterboard onto the fixings.
dig out a channel at floor level - quite where this goes, I have no idea.
The idea being that the damp is already in the wall and there's no getting rid of it, so it condenses on to the "bubble wrap" and then drips to the floor. Keeping the moisture in the wall and out of the room.
It sounded fairly logical to me, but I would have thought that taking the plaster off first would mean losing less of the room. Also, having just had a brand new floor laid, the channel at floor level sounded quite drastic.
What they were proposing was (some of the details below may be slightly inaccurate, but hopefully the overall method is clear):
Leave the plaster intact on the problem wall (ground floor)
Fit battens directly to the wall and then attach a special plastic membrane a bit like bubble wrap to the battens using special fixings.
Attach more battens to the special fixings and then plasterboard onto the fixings.
dig out a channel at floor level - quite where this goes, I have no idea.
The idea being that the damp is already in the wall and there's no getting rid of it, so it condenses on to the "bubble wrap" and then drips to the floor. Keeping the moisture in the wall and out of the room.
It sounded fairly logical to me, but I would have thought that taking the plaster off first would mean losing less of the room. Also, having just had a brand new floor laid, the channel at floor level sounded quite drastic.
Wouldn’t the enclosed damp wall end up covered in mould as there is no airflow? Where is the channel going to drain to?
I’m not a damp expert but shouldn’t they be addressing why the wall is getting damp and looking at a French drain on the exterior side of the wall to take moisture away or a ventilation system rather than covering the wall up?
I’m not a damp expert but shouldn’t they be addressing why the wall is getting damp and looking at a French drain on the exterior side of the wall to take moisture away or a ventilation system rather than covering the wall up?
What they’re proposing is a type-C waterproofing detail which more commonly would be used in existing basements suffering from high water penetration.
In the first instance they should be investigating why the wall is saturated to the extent that they are prosing this as the solution since all it will do is mask the problem rather than cure it.
In the first instance they should be investigating why the wall is saturated to the extent that they are prosing this as the solution since all it will do is mask the problem rather than cure it.
About 40 years ago, I had a c1900 terraced house with solid brock walls, no proper damp course.
There were 'Damp Consultants' then, flogging various miracle cures.
It seemed to largely be about getting a piece of paper which kept mortgage lenders happy.
I eventually learned something from an old builder.
You spend a lot of effort keeping water out of where you don't want it, but you need to understand that some will always get there, and it needs a way out.
With my second house, I had some problem areas and ended up doing a lot of reading about the management of water and water vapour in buildings.
I got to know some building technology chaps at the local 'former polytechnic'.
But it comes down to where and how it's going from somewhere to somewhere and what acceptable levels are.
Don't forget, there is generally a significant outward flow of water from human activity, breathing, cooking washing etc producing water vapour.
Heating and ventilation are usually high on the list of things to look at.
I would say start by stepping back to look at the whole problem.
There were 'Damp Consultants' then, flogging various miracle cures.
It seemed to largely be about getting a piece of paper which kept mortgage lenders happy.
I eventually learned something from an old builder.
You spend a lot of effort keeping water out of where you don't want it, but you need to understand that some will always get there, and it needs a way out.
With my second house, I had some problem areas and ended up doing a lot of reading about the management of water and water vapour in buildings.
I got to know some building technology chaps at the local 'former polytechnic'.
But it comes down to where and how it's going from somewhere to somewhere and what acceptable levels are.
Don't forget, there is generally a significant outward flow of water from human activity, breathing, cooking washing etc producing water vapour.
Heating and ventilation are usually high on the list of things to look at.
I would say start by stepping back to look at the whole problem.
I have no idea what the best practice is as there seems to be a million and one different opinions and thoughts on the matter. Modern life is different to 200 years ago so it’s all well and good saying it should be lime plaster and breathable while at the same time fitting central heating and double glazing and effectively eliminating all airflow.
In any case, it sounds like what we have on a wall that sits about a foot below exterior ground level. It’s like a giant bubble wrap that’s mechanically fixed to the wall with plastic fixings and sealant. Then the plasterboard is dabbed onto the bubble wrap.
All I care about is whether the wall is dry and that nothing is falling apart - it’s all perfectly dry and solid. So, for me, it seems a perfectly acceptable way of doing things. Probably got some photos somewhere if interested.
In any case, it sounds like what we have on a wall that sits about a foot below exterior ground level. It’s like a giant bubble wrap that’s mechanically fixed to the wall with plastic fixings and sealant. Then the plasterboard is dabbed onto the bubble wrap.
All I care about is whether the wall is dry and that nothing is falling apart - it’s all perfectly dry and solid. So, for me, it seems a perfectly acceptable way of doing things. Probably got some photos somewhere if interested.
Like the reply above, I’ve seen this a lot, but only in basements, it does work in those applications, but they’ve got concrete floors and it’s against ground water so under a bit of pressure.
Does the wall maybe have gypsum rather than lime plaster on it, so just needs to breathe and get damp and dry out in turn?
I’m not a builder, but get involved with services in buildings so often work alongside schemes like these.
Does the wall maybe have gypsum rather than lime plaster on it, so just needs to breathe and get damp and dry out in turn?
I’m not a builder, but get involved with services in buildings so often work alongside schemes like these.
OutInTheShed said:
About 40 years ago, I had a c1900 terraced house with solid brock walls, no proper damp course.
There were 'Damp Consultants' then, flogging various miracle cures.
It seemed to largely be about getting a piece of paper which kept mortgage lenders happy.
I eventually learned something from an old builder.
You spend a lot of effort keeping water out of where you don't want it, but you need to understand that some will always get there, and it needs a way out.
With my second house, I had some problem areas and ended up doing a lot of reading about the management of water and water vapour in buildings.
I got to know some building technology chaps at the local 'former polytechnic'.
But it comes down to where and how it's going from somewhere to somewhere and what acceptable levels are.
Don't forget, there is generally a significant outward flow of water from human activity, breathing, cooking washing etc producing water vapour.
Heating and ventilation are usually high on the list of things to look at.
I would say start by stepping back to look at the whole problem.
I don't disagree with this, but how would I go about doing it. The "Damp Consultants" were people who were recommended to me - but I very definitely wasn't impressed. Google just produces pages and pages of people pushing their own solutions. How do I find someone decent and believable to help me figure out what to do?There were 'Damp Consultants' then, flogging various miracle cures.
It seemed to largely be about getting a piece of paper which kept mortgage lenders happy.
I eventually learned something from an old builder.
You spend a lot of effort keeping water out of where you don't want it, but you need to understand that some will always get there, and it needs a way out.
With my second house, I had some problem areas and ended up doing a lot of reading about the management of water and water vapour in buildings.
I got to know some building technology chaps at the local 'former polytechnic'.
But it comes down to where and how it's going from somewhere to somewhere and what acceptable levels are.
Don't forget, there is generally a significant outward flow of water from human activity, breathing, cooking washing etc producing water vapour.
Heating and ventilation are usually high on the list of things to look at.
I would say start by stepping back to look at the whole problem.
I'd suggest trying to understand where the water is coming from.
If you know you've got rising damp from having no dampcourse, you can look at local drainage to reduce the water at the foot of the wall
if you know it's primarily rain penetration you can look at breathable waterproof coatings
If it's coming down from the roof you can look at that.
IMHO it's worth looking at the 'normal' sources of moisture, like cooking and drying washing etc, because they all add moisture. which makes a problem more severe.
Also I think quite often you don't have to 'cure' the source of damp, it's enough to reduce it to a level the building can cope with.
There's water everywhere, in materials, in the air, moving around in a state of equilibrium or not.
I think aiming for 'zero' is a mugs game with some old houses.
Airflow and heating increase the amount of water your house can 'cope with'. If you've got x grammes of water coming through the wall each day, heating and ventilation might get rid of y grammes. If x>y you have a problem.
People to get advice from are old blokes with small building firms, people who own similar houses, people who do maintenance on similar properties like holiday cottages perhaps?
My neighbour would tell you about his Mum's house. It was fine while she was living in it, heating on and all that. Soon as it's empty for a winter, damp is a problem.
OTOH, some of the worst houses with 'damp' problems are relatively modern places where renters create a lot of moisture, don't open the windows and don't heat the place properly.
If you know you've got rising damp from having no dampcourse, you can look at local drainage to reduce the water at the foot of the wall
if you know it's primarily rain penetration you can look at breathable waterproof coatings
If it's coming down from the roof you can look at that.
IMHO it's worth looking at the 'normal' sources of moisture, like cooking and drying washing etc, because they all add moisture. which makes a problem more severe.
Also I think quite often you don't have to 'cure' the source of damp, it's enough to reduce it to a level the building can cope with.
There's water everywhere, in materials, in the air, moving around in a state of equilibrium or not.
I think aiming for 'zero' is a mugs game with some old houses.
Airflow and heating increase the amount of water your house can 'cope with'. If you've got x grammes of water coming through the wall each day, heating and ventilation might get rid of y grammes. If x>y you have a problem.
People to get advice from are old blokes with small building firms, people who own similar houses, people who do maintenance on similar properties like holiday cottages perhaps?
My neighbour would tell you about his Mum's house. It was fine while she was living in it, heating on and all that. Soon as it's empty for a winter, damp is a problem.
OTOH, some of the worst houses with 'damp' problems are relatively modern places where renters create a lot of moisture, don't open the windows and don't heat the place properly.
OutInTheShed said:
I'd suggest trying to understand where the water is coming from.
If you know you've got rising damp from having no dampcourse, you can look at local drainage to reduce the water at the foot of the wall
if you know it's primarily rain penetration you can look at breathable waterproof coatings
If it's coming down from the roof you can look at that.
IMHO it's worth looking at the 'normal' sources of moisture, like cooking and drying washing etc, because they all add moisture. which makes a problem more severe.
Also I think quite often you don't have to 'cure' the source of damp, it's enough to reduce it to a level the building can cope with.
There's water everywhere, in materials, in the air, moving around in a state of equilibrium or not.
I think aiming for 'zero' is a mugs game with some old houses.
Airflow and heating increase the amount of water your house can 'cope with'. If you've got x grammes of water coming through the wall each day, heating and ventilation might get rid of y grammes. If x>y you have a problem.
People to get advice from are old blokes with small building firms, people who own similar houses, people who do maintenance on similar properties like holiday cottages perhaps?
My neighbour would tell you about his Mum's house. It was fine while she was living in it, heating on and all that. Soon as it's empty for a winter, damp is a problem.
OTOH, some of the worst houses with 'damp' problems are relatively modern places where renters create a lot of moisture, don't open the windows and don't heat the place properly.
Great - many thanks for writing all of that, it's very useful.If you know you've got rising damp from having no dampcourse, you can look at local drainage to reduce the water at the foot of the wall
if you know it's primarily rain penetration you can look at breathable waterproof coatings
If it's coming down from the roof you can look at that.
IMHO it's worth looking at the 'normal' sources of moisture, like cooking and drying washing etc, because they all add moisture. which makes a problem more severe.
Also I think quite often you don't have to 'cure' the source of damp, it's enough to reduce it to a level the building can cope with.
There's water everywhere, in materials, in the air, moving around in a state of equilibrium or not.
I think aiming for 'zero' is a mugs game with some old houses.
Airflow and heating increase the amount of water your house can 'cope with'. If you've got x grammes of water coming through the wall each day, heating and ventilation might get rid of y grammes. If x>y you have a problem.
People to get advice from are old blokes with small building firms, people who own similar houses, people who do maintenance on similar properties like holiday cottages perhaps?
My neighbour would tell you about his Mum's house. It was fine while she was living in it, heating on and all that. Soon as it's empty for a winter, damp is a problem.
OTOH, some of the worst houses with 'damp' problems are relatively modern places where renters create a lot of moisture, don't open the windows and don't heat the place properly.
I've just put in underfloor heating in the impacted room, which should help. I'm also getting some blown render fixed at the roof level and also some other roof issues fixed. It could well be that a lack of maintenance over the years has made a manageable problem less manageable, but I think only time will tell.
Obviously nothing like the problems your mom is experiencing but we had issues with heavy condensation inside our windows. Large Victorian house extensively extended and we had done everything to modernise it including very nice aluminium double glazed windows with a thermal break. We realised that a house needs to breathe so after reading the thread on here fitted a Nuaire PIV (Positive Input Ventilation) system. It ticks along very quietly and keeps the air moving throughout the house. Guess what no more condensation.
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