Managing Damp in Old Buildings
The Official Definition of an Old Building used to be "Built before 1919". That didn't really help anyone understand what made them different. It's now defined as:
"A solid walled structure, built using breathable materials, which needs to breathe"
It's inevitable that you will find dampness somewhere in an old house. Nothing lasts forever, but despite English weather, our old buildings stand the test of time better than any modern house. The worst enemy of old houses is we humans - it's what we do to them, or fail to understand about them, that causes problems and makes you think you have to 'Damp Proof'.
So called 'Rising Damp specialists', and building surveyors recommending damp treatment for 'Damp Walls' have caused massive, and irreparable damage to old buildings through their incompetence. Don't use them. Many of these idiots are churning out 'Homebuyer Survey' reports with a standard clause in them that recommends 'Specialist Timber and Damp Survey'. An entire industry has grown up on the back of it, and is thoroughly nasty and aggressive when its basis for existence is challenged. It is run by the Property Care Association - or PCA for short.
Did you know that in Holland, they don't even have damp courses? True... Even in new houses, damp proof courses are not required. They build their houses with their feet in the water, and they don't get damp walls. I teach Dutch architectural students at college, and they fall about laughing when we talk about what they call our 'Quaint English Custom' of damp courses and injection damp proofing. Sounds funny, but this is serious stuff - we are being defrauded to the tune of hundreds of millions a year, by chemical companies selling useless, fraudulent treatment.
In America they don't have a damp industry. Try walking the streets of New York. You won't see a single injection hole. When I describe what the damp industry does in this country, friends of mine in the States who are surveyors and conservation experts just howl with laughter.
This Google chart proves my case that the Rising Damp phenomenon is just that - a manufactured English fraud:
Don't stop walls breathing!
When a wall warms up after a cool night, air contained within its pores expands as it warms and a small proportion moves out of the wall via the connected pores. As the wall cools down the air within contracts and air moves back into the wall from the atmosphere. So masonry walls ‘breathe’ – out as they warm up, and in as they cool. Breathing occurs on a daily basis, or more frequently in periods of variable weather; breathing is shallow when there is little temperature variation and deepest when the daily range is greatest. Walls don’t actually breathe in the human sense: they sit there while changes in temperature (and air pressure) do the work. The ‘breathing’ analogy is a convenient way of understanding frequent exchanges of air from masonry to atmosphere and back again. If air drawn into the wall is humid, and the wall cools below dew point then water vapour in the humid air condenses as water droplets in the pores of the masonry, though the wall will still appear ‘dry’. During warmer and drier times, some of this water will evaporate and leaves the wall as it breathes out. Even walls which seem dry will contain water, the amount varying with changes in the season and climate. If there are salts or other hygroscopic (moisture-attracting) materials in the masonry, the amount of water drawn into (and retained in) the wall can be sufficient to make the wall visibly damp, even in dry weather. This is the same as happens when you leave a pot of salt on the kitchen table - it gets wet..
Anything that prevents a masonry wall from breathing will reduce its life expectancy. Coatings designed to seal the surface of masonry walls (and so ‘protect’ them) trap moisture behind the coating and cause a damp problem elsewhere, such as on the other side of the wall. If there are appreciable salts in the wall, damage caused by inappropriate use of coatings can be dramatic . Coatings themselves - cement renders, gypsum plasters, plastic emulsion paints - will eventually be forced off the wall.
Most problems of damp in pre-1920's buildings have been caused since the war, when cement and gypsum plaster became widely available - these two materials are responsible for over 90% of the damage that we see. They are impervious, they trap moisture and cause rot - they are death to an old house. Add silicone sealants to a timber frame, and you have instant rot of oak which is probably 400 years old. I have seen new timber frames start to rot in 2 or 3 years when incompetent framers seal the panels using mastic instead of oakum, which can breathe.
Homebuyer Surveys - the truth about them...
I am constantly inundated by people who are getting Homebuyer surveys, in which the 'Surveyor' recommends you get a 'specialist timber and damp survey from a PCA registered contractor'.
If a qualified surveyor - some members of RICS, some Fellows - tells you that an independent 'timber and damp' survey is required - I suggest you tell them you are not paying the bill. These people are incompetent. If they cannot diagnose the REAL reasons for damp in an old house - tell them to go survey a dolls house.
If they even MENTION Rising Damp - they are incompetent. Do NOT pay them.. Walk away from the survey, and get someone who knows about old buildings. Stephen Boniface, former chairman of the construction arm of the Royal Institution of Chartered Surveyors (RICS ), has told the institute’s 40,000 members that ‘true rising damp’ is a myth and chemically injected damp-proof courses (DPC) are ‘a complete waste of money’. Quite a number of my clients have sued surveyors - one just emailed me to say the surveyor that told him he had rising damp has just settled out of court for £5000 in compensation. Another client in Wales told the very highly qualified surveyor where to shove his bill - the surveyor wrote a lengthy reply in which he explained that he has a lifetime of experience in diagnosing rising damp in houses all over the area - unfortunately we found out he'd previously surveyed this particular house, and was recommending the same treatment the second time around in as many years. You can imagine the response to his request for payment!
Do NOT let any building society or bank force you have any form of damp treatment before they approve a loan. If they do, contact us and we will stop this rubbish. Be aware that times are changing, and more and more people are questioning this ridiculous practise - it is only a matter of time before banks drop this expensive and unneccesary habit - but we all need to put pressure on them to stop it.
There are GOOD surveyors out there - RICS does train people - but there is such an entrenched belief in rising damp that entire industries are fed by it. A surveyor is required by RICS to state clearly whether they consider themselves capable of surveying an old house. You must ensure that if your house was built before around 1930, you ask that they clearly state this, and sign their survey that they consider themselves capable of surveying your type of house. RICS actually run a conservation course which helps equip their surveyors for the job - it is a great pity more people don't do the course!
There is a MASSIVE problem of fraud, and incompetence in the Building Survey industry. If in doubt, do your research - you probably are... its why you are here...
This is the English Heritage Guidance document that covers almost all the points discussed here - hopefully, when you see the importance that EH gives the subject, you'll realise I am not just ranting on..!
There's another good article here:
Rising Damp is almost non-existent - it rarely occurs naturally , and it CERTAINLY doesnt move a metre up the walls as 'damp proofing' 'specialists' would have you believe. We have built experimental walls with old, porous bricks, jointed with lime mortar. When the base of the wall is placed in water, the bottom row will get wet. Water is wicked up the brick, reaches the first mortar joint and evaporates. It rarely if ever goes beyond the first joint unless it is 'bridged' by having cement render slapped over the top of it. It certainly doesnt go the magical metre high that every rising damp salesman will claim. Do you know that it has NEVER been reproduced in a laboratory, despite many attempts to do so - even by the industry itself.
- Injection Damp Proofing old houses is a WASTE of time and money - it doesnt work, and it causes irreparable damage to the fabric of your house
- Damp Courses are almost NEVER broken, bridged or damaged, as damp proofing companies will always tell you
- There is almost always a specific reason for damp, which is easily fixed
- Do NOT be talked into hacking old plaster off and re-plastering with gypsum, or worse still, waterproofing compounds, or so called 'waterproofing or renovating plaster'!
- Nearly every case of so called rising damp is just condensation - the bottom of the wall is coldest, so moisture condenses near the floor - it doesnt rise!
- If you have a rotten timber frame, its because of all the modern materials used to plug the gaps and cover it - sill beams covered with cement, wattle and daub covered with cement, silicone sealant around the panels and filling holes in the wood..
- NEVER use cement, tar, cement render, modern acrylic or silicone caulking on a timber frame - it will rot in front of your eyes
- Never use modern acrylic or emulsion paints - they are death to old walls - they are plastic - they trap moisture and cause damp!!
- Never use companies like Peter Cox unless they give you a full technical diagnosis of your problem using instruments OTHER than a damp meter.
The Ultimate Proof that Rising Damp Doesnt Happen!
Have a look at this photograph I took a while back. Water, running through a millrace - and the wall is dry!!
Understanding your Built Environment
Restoring an old home is all about understanding the environment, and how it affects materials it's built with. By understanding this, it becomes a relatively simple task to sort out and manage problems causing damp.
Remember - it is all about 'Breathability' - such a simple ethos - allow moisture to enter and leave the building fabric without hindrance and it will never build up. Moisture is just water that has condensed - allow water to move around freely as a gas, and it will never cause a problem. Put somethng in it's way, and you will regret. Just like putting a plastic sheet on the lawn - in the morning it is wet underneath.
We study the materials old houses are built with. We understand them. We work with clients to restore old homes to beautiful, warm and dry places. There is something very special about the look and feel of a lime plastered wall with clay paint - it is almost luminous in quality - very soft and welcoming. All the materials used in old homes are nice, friendly and green. By using them, not only will you FEEL good, but you will be DOING good - they are carbon friendly, and contain no toxic chemicals - lime mortars and plasters are carbon neutral, clay and linseed paints similarly - sheepswool and hemp fibre insulation are natural and nice (they are also just as good as chemical insulation), timber is a renewable resource...
We can ALWAYS find the cause of damp, whatever form it may take, and in our collective experience, we have NEVER had to drill hundreds of holes into brickwork, thereby destroying historic fabric. We NEVER inject chemicals which are supposed to stop water from 'rising' up the walls, which never did anyway.(and they are going to magically 'soak' into brick, stone, mortar and fill all the gaps... dream on!)
Avoid ANYTHING to do with the Property Care Association, or anyone claiming to be a 'Surveyor' who is using the CSRT and CSSW qualifications! They are a scam - they are not academic qualifications, and you will become another victim of the damp industry.
Common Examples of 'damp', and Rising Damp Solutions...
All about Condensation and how it relates to damp in old walls...
First - you need to understand there is no such thing as 'Rising Damp'
'Rising damp' usually shows itself as damp patches towards the bottom of a wall, in corners, at the bottom of chimneys, or as plaster falling off, or sounding hollow. Paintwork often goes flaky and powdery (damp??!) Building Surveyors or Timber and Damp Surveyors say its damp, because their silly little meter gives a high reading. This dampness reading is completely misleading - its NOT recording moisture. The reading can be high because of salts which have been drawn into the wall by the moisture. It only records conductivity, not dampness in whatever it is pushed onto - in most cases about a millimetre into the plaster on the surface of your wall. Salts are highly conductive, so even if the wall is dry, the meter will show a high reading. The surface of walls are often wet - covered in cold water that has condensed there. I can almost guarantee the wall underneath will be bone dry.
Rising Damp is a figment of building surveyors imagination - it doesnt exist!
The worst cases of seriously wet walls that we have to deal with are caused by the wall being encased in cement - external cement render, and internal 'damp proofing' plasters and renders underneath gypsum plaster. This combination is certain death to a stone or solid brick wall, and we have often removed internal plaster in cases like this to reveal crumbling brick and stone which you can poke a finger through. Left to dry out, with the offending render and plaster removed, the stone hardens and the wall dries out on its own.
Don't trust surveyors meter readings!
We often check surveyors meter readings by drilling a hole into the wall behind the plaster. We take a sample of the actual brickwork or stone - and not surprisingly when we do a proper test on the powder from the drillhole, its bone dry.
We also now have very sensitive and sophisticated equipment which we take on our surveys - this measures the relative humidity of the air in your house, the temperature, and 'dew point' - ie, the temperature at which condensation starts to take place. We measure the temperature of the walls themselves and relate this to the dew point, so you can see for yourself exactly where the problem starts, and why.
There are 3 standards which all state quite clearly that 'damp' meters can't be used to diagnose damp. If a surveyor uses a 'damp' or resistance meter and comes up with a diagnosis, or recommendation based on using one, you need to insist that they refer to these standards - BS5250 - code for the control of condensation, BS6576 - code for the installation of damp proofing and BS 7913 - conservation of historic buildings.
I find it hilarious that the Property Care Association have a 'code of practise' which is a direct crib of BS 6576, but it very conveniently omits paragraph 4 of the real code of practise, which states that damp meters cannot be used to diagnose damp - that chemical methods need to be used.
To read all about damp meters - check this out: Ping Prong meters - Guilty of Fraud
The 'Damp' is only surface deep - which makes sense. Humans breathe - when we do, moisture loads the air in the room, and condenses at the coldest spot - the bottom of the wall. That moisture is concentrated by things that retain it - plastic (acrylic paints, wallpaper, that lovely magnolia emulsion you just put on, ) or gypsum plaster, waterproof plasters, anything with cement in it... and the only way it can escape is to blow the plaster or bubble the paint.
Cement Render is Certain Death to an old house!
The same problem occurs with cement renders. There was a mistaken belief after the war (and there still is!) that damp houses were caused by water getting in through the outside walls - this rarely happens. That belief resulted in houses being covered with thick coats of cement render - which traps moisture in the fabric of the walls, and causes massive build up - which then blows out into the internal walls. The solution is to remove render and let the walls dry out. If brickwork is damaged and needs repair or replacement, it should be done with lime mortar. If it is proposed to re-render, you must always use lime render, which can breathe freely, and allows trapped moisture to escape.
Government grants to insulate - the most common cause of damp
Incredibly, one of the biggest causes of damp problems in homes nowadays is the huge push by the Government to insulate homes. I do dozens of surveys in which the complaint is mildew, mould, water running down walls and windows. When asked when the problem started, the answer is always the same - 'We had a grant to get insulation installed - it was after the insulation went in'. Insulation traps heat. Heat = warm air = more water held in the air as humidity. When all this humid air finds a cold wall (you insulated the roof, right? You didnt make the walls warmer... ) it condenses as mould, water, mildew on clothes and so on. Read the humidity pages to understand more about the problem... the solution - better ventilation and humidity extraction.
Common causes of damp...
- Modern paints
- Cement render
- Gypsum plaster
- Ground levels outside higher than inside
- Broken guttering or missing downpipes
- Vegetation growing near the wall
- Trees creating shade and moist air near a wall
- Lack of ventilation - double glazing, no vents
- Blocked chimneys - fireplace blocked up, no vents
- Furniture against walls creating cold, damp areas
Building Surveys... for the 'Timber and Damp' reports that the idiot surveyors always demand.
We inspect and prepare a survey and report on an old building, together with recommendations and solutions to any problems found. We will NEVER recommend injection damp proofing. If you are considering buying a property, contact us to arrange a survey before you commit to buy - our report will estimate how much money you may need to spend to bring it up to scratch - and give you more confidence in your purchase.
We travel all over the country. We can examine the entire house and come up with suggestions or solutions for other related problems - we are experienced in all aspects of building conservation.
Remember: 99% of so called qualified building surveyors DO NOT understand the way old houses work. They are beautifully qualified to tell you how a modern house works, but haven't a clue what to do with the sort of problems you see on these pages. If in doubt - get the survey - but when they recommend injection damp proofing, shoot them, throw them out, report them to the Building Society - anything - but get rid of them!!! Their report isnt worth the paper it's written on.
Our costs are typically around £800 plus travelling costs for the survey. This includes a report which is usually sufficient for most purposes. We spend the day on site with you, examining a potential purchase, explaining any problems we find, and how to overcome them, with estimated costs. This gives a clear picture of what you need to budget for if you are buying a property. In some recent cases, it has meant that the property was not worth buying.
On the other hand, buyers have used our reports to negotiate a discount to the purchase price which will cover the cost of work to be done - this has exceeded £20,000.
Additional costs are charged at a day rate for report writing, depending on the detail required - we can draw up plans and Listed Building Consent applications. If you doubt the value of this approach - Contact your local Conservation Officer, who works for the Council - or ask the IHBC (Institute of Historic Building Conservation) for a recommendation of someone in the area.
More about those 'Damp Meters' ...
Your silly surveyors meter - with the two little prongs on it that's like a mini cattle prod - is what we call a resistive moisture meter. Its designed to measure moisture in wood - ok - get that.... Wood - Timber - Bits of Trees.... It was NOT designed to measure moisture in stone, or brick, or plaster...
There are 3 separate British Standards which state that 'damp' meters or resistance meters are unsuitable for measuring damp. If you get a survey from ANYONE - whether a RICS surveyor or a con artist from the PCA - if they use a 'damp' meter - you must immediately, and clearly state that these standards say a damp meter cannot be used, and how have they diagnosed damp:
BS 6576 - Code of practise for installation of damp courses - the PCA bible that they use to convince you a damp course is needed. It clearly states that you can't use a 'damp' meter to diagnose damp.
BS 5250 states the following, on page 19 of the standard:
B 8: Measurement of dampness:
Accurate measurements of the moisture content of brick or mortar cannot be obtained by the use of electrical moisture meters because the presence of salts increases the electrical conductance of the water, giving falsely high readings. Gravimetric methods carried out on samples taken from the fabric give the most reliable results. The use of chemical absorption type moisture meters will give a result in a short space of time and be almost as reliable.
The moisture content of wood is very predictable - its similar in most varieties of wood, whereas stone and brick are incredibly variable in their water content and resistivity. Resistivity - big word - electrical resistance - in short, its hard for electricity to travel through wood, even when its wet. Wood is a really good insulator. The meter is calibrated for this.
Stone is the opposite - wet stone carries electricity very well thanks, as does wet brickwork. Old lime plaster thats made with ash does as well - funny how carbon is a good conductor.. That foil backed plasterboard does pretty well when they stick the cattle prod into it - goes off the scale! All those Victorian paints are full of metal oxides. So... whenever your jolly Building Surveyor sticks his little prongs into the wall, its odds-on that the silly little red light will go off the scale. He'll gleefully announce you have rising damp, penetrating damp, and a host of other problems that can only be resolved with the application of a lot of money, and re-plastering by his recommended 'Damp Contractor' buddy, who will squirt chemicals, and generally make a mess.
There are other pieces of equipment that tell us more about moisture in walls. They include Carbide Meters, and the kit that we use - the Thermo-Hygrometer. You get much more accurate readings which tell you a lot more about the problem. There is still a lot to be said though, for personal knowledge. A wet wall can still be very little problem if the reason it is wet is properly diagnosed. Diagnosing Damp is the key. Once we know the root cause, we can sort out a solution. As you can see on these pages - the root cause is almost always NOT rising damp - its a host of other things which in a lot of cases, you yourself can control.
A word about qualifications...
Have a look at the letters after your 'Timber and Damp Specialists' report. Research the qualifications, (Try investigating what you have to do to get CSRT or CSSW after your name - its a joke!) and see what they mean.. Have a look at the syllabus - its freely available on the internet.. mostly about injection damp proofing chemicals and how to use them.. These aren't qualifications - they are all about giving a veneer of respectability to people who are trained to commit fraud. Full academic qualifications take years to learn and acquire - these take a 2 day course with a tick box 'exam' which is mainly concerned with which chemical you inject and which you spray.. Funny, when you don't need any chemicals in the first place. All Peter Cox damp reports have pages of 'qualifications' and 'guarantees' to try and justify their respectability. It's all a con.
More importantly, research the 'Organisation' that homebuyer surveys almost always recommend you use. The Property Care Association. Have a look at the members, the Directors - who they are, what they are - people making a very good living out of selling damp proofing chemicals, with no desire to come up with a solution that doesnt involve them selling you some form of snake oil. Do some serious research into the Property Care Association. Look carefully - the deeper you dig, the more shocked you will be.