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 industy has grown up on the back of it, and is thoroughly nasty and aggressive when its basis for existence is challenged.
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.
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!!
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' and using the CSRT and CSSW qualifications! They are a scam - they are not academic qualifications, and you will become another victim of the damp industy.
Common Examples of 'damp', and Rising Damp Solutions...
In the room inside, the walls are damp as well - moisture has penetrated through the wall and blown the plaster on the inside. All of this render needs to be removed and the stonework requires extensive repair as a result.