for People with a Passion for Period Property
Ask an Agony Uncle!
Stephen Boniface - Stephen Boniface specialises in building conservation providing multi-disciplinary consulting services. He is Chairman of the Building Surveying Faculty and member of the Residential faculty. He serves on the RICS Building Conservation Forum Board and is the 'Agony Uncle' on the Period Property UK website (

Ask our Agony Uncles ...

You can write to our panel of experts free of charge on any subject, providing it's got something to do with Period Properties.

Our experts are all specialists in matters directly involved with older properties. So, if you have a problem with an older building - or if you think you might have a problem - ask an Agony Uncle...

o How do I know whether its a good buy? Robert Woolf (Gt Shelford, Cambridge)
o Removing crusty white deposits Buz Millar (Nuneaton, Warwickshire)
o Repairing Brick and Flint Andrew Pritchard (Petersfield, Hampshire)
o Removing paint from eighteenth century fireplaces JohnLockwood
o Clunch drying out Jonathan Nicoll (Burwell, Cambridgeshire)
o Original fireplace? Vanessa Jackson (Clitheroe, Lancashire)
o Making daub mortar Mick Thawley (Pulham Market, Norfolk)
o The formerly internal now external wall Stephanie Hughes (Dumfries and Galloway)
o Damp converted cellar Adam Hunter (Norwich, Norfolk)
o A legacy of unauthorised work P Smithson (Coggeshall, Essex)
o Damp patches in the bedroom Karen Murphy (Twickenham, London)

SUBJECT: How do I know whether its a good buy?
FROM: Robert Woolf (Gt Shelford, Cambridge)
I am about to buy a 15th-16th century house which was renovated in the late 19th century. It is timber framed with a plaster + lathe infill, a peg tiled roof and Victorian rendering. Everything looks good but how do I know? Can you help me with respect to the principal areas I should be concerned with prior to my purchase please?

Robert Woolf

Robert, any attempt to provide you with a 'DIY' surveying guide is a very difficult task to achieve within the limitations of the Agony Uncle Q&A section. But the following notes are a general guide and should be used in conjunction with a full survey from an experienced conservation surveyor. Secondly, please take a look at the information section of the site where Ian McCall has written an article providing an insight to 'what to expect' from a surveyor's report.

Below I have listed some general points, but remember without removing some the property's plaster or using a specialist non-destructive testing surveyor it is difficult to assess the true condition of the timber frame. The use of a cement render and sandtex should sound a warning shot across your bow.

  • Are any dips or depressions in the roof which may have been caused by timber decay.
  • Look into the roof space to ensure no timbers such as ties and collars have been removed which would have prevented the pitched roof spreading.
  • Has cement incorrectly been used around the chimney instead of lead flashing.
  • If roofing felt does not exist and the roof is structural sound then leave it alone. A roof without felt is a well ventilated roof where any damp evaporates with ease.
  • Have any of the tiles slipped or moved due to the decay of the pegs holding them in position.
  • Ensure that the ground levels outside the house are level with or below the floors inside the house.
  • Ensure all doors close neatly into their door frames rather than catch ceiling joists due to movement of the walls. If door lintels are slanting or doors fail to close check for bulging or leaning walls.
  • If sandtex or cement have been used on the plinth or walls the likelihood of timber decay within the frame is relatively high.
  • If the house is carpeted or has a lino floor covering check underneath of damp.
  • Lift manhole covers and ensure all water from the bath, loo and sinks drains freely away. If a septic tank is in operation has it been recently installed. If it's an old cesspit do the occupants illegally use a Heath Robinson pumping system to drain water from the pit into soakaways to save on emptying fees
  • Always test the boiler. Ask the owners to turn it on as soon as you enter the property so before you leave you can test to see if the radiators have heated up and hot water is available.
  • If your exposed timbers are dotted with small woodworm holes, but the house is centrally heated, the infestation is likely to have died out due to the drying out of the timbers.

In essence most of the above areas revolve around two areas. Damp/timber decay and movement. Once modern materials and structural alterations take place the likelihood of damp, timber decay and structural movement increase. The property to watch out for is where the owners have used modern materials to hide and camouflage faults.


SUBJECT: Removing crusty white deposits
FROM: Buz Miller (Nuneaton, Warwickshire)
We have removed old lino and fitted carpet off the original ash laid quarry tile floor of our 100 year old terraced house. The floor has dried out over the last three years but is unsightly. The surface of the tile has been lost. After reading your comments on the recommendations regarding damp-proof membranes and concrete, we are happy to abandon that idea, which didn't appeal to us anyway. Would using a commercial drum sander, to remove the crusty white deposit on the floor, give us a suitable surface for some sort of restoration of the tile surface?

Buz Miller

Buz, quarry tiles were common from the 18th Century and made from clay and water mixed together to a plastic condition. The clay was then moulded in presses and fired in a kiln. The firing process in the kiln provides the tile with a hard wearing surface called a fireskin. The use of a drum sander will further damage the fireskin therefore accelerating their decay and providing an even more uneven surface for dirt and grime to collect.

The crusty white deposits on the tiles derive from the moisture in the floor evaporating and leaving the white soil salt deposits on the tile surface. Normally, the salts can be simply swept off of the surface. Although in this instance you seem to have a particularly bad case. The Society for the Protection of Ancient Buildings recommends that damaged floors like yours can be given a protective coat of beeswax and turpentine polish once the surface has been thoroughly brushed down to remove the salt deposits. The polish will reduce the need for washing the floor, provide marginal protection against grease and stains and improve the floors appearance.

If the above fails carefully attempt to lift one of the tiles to inspect its underside. If the surface is in satisfactory condition turning the tiles over may be the next option. If you do decide to reverse the tiles bed them into sand or lime and avoid cleaning them with the various floor cleaning acids which only etch and damage the tile surfaces.



SUBJECT: Repairing Brick and Flint
FROM: Andrew Pritchard (Petersfield, Hampshire)
I am currently attempting to repair a damp brick and flint "cold" north facing elevation on our 18th Century cottage. The wall has been penetrated by water over the winter and I have started to strip the old paint work in order to allow the wall to dry. I intend to re-point using lime, as you have suggested on your web site but would like to re-paint the wall, once it has completely dried. A local builder suggested High Build (Sandtex) but I am concerned that this will trap moisture. I was also advised to line the inside of the wall with a thermal board such as Rockwall and cover this in foil backed plasterboard. I would greatly appreciate your advice on this.

Andrew Pritchard

Andrew, you are absolutely correct. The use of Sandtex will ensure any moisture within your wall is trapped leading to further dampness. Traditionally flint and brick walls are not normally painted. Internally, it is still important to allow your wall to breathe thus ensuring any moisture from within the wall evaporates away into a well ventilated room. Therefore lime plaster can be used again followed by limewash or a distemper. Finally, please check all guttering and downpipes to ensure both are draining freely. Finally, how are you removing the paint from your flint and brick wall or are you simply raking out the pointing between the paint covered flint and bricks?


SUBJECT: Removing paint from eighteenth century fireplace
FROM: John Lockwood
I have an eighteenth century brick fireplace which has painted several times over the centuries. What is the best method of removing the paint from the bricks?

John Lockwood

John, contact Strippers on Tel. 01787 371 524 . They will be able to supply you with a poultice which is used in conjunction with cling film to naturally breakdown the paint before removal with water and a soft schrubbing brush. Using this technique you can do small areas at a time and maintain the natural colouring achieved through wear and tear over the years.


SUBJECT: Clunch drying out
FROM: Jonathan Nicoll (Burwell, Cambridgeshire)
I am thinking of purchasing a Grade II building (1740) which has been renovated with a silicone damp proof course. A surveyor has indicated that as the walls are of clunch construction and there is concern that there may be drying out with likelihood of flaking in the future. We are given to understand that renovation was carried out with approval from the relevant authority so am a bit bemused as to how this renovation could have been carried out in the first place. Would you have any comments on whether there would be a major problem and if so, is there any way to remedy what has been done? Also the tiled floors in all but 1 of the rooms have been lifted and a membrane inserted.

Jonathan Nicoll

Johnathan, your surveyor is correct to point out to you the possible future damage which might occur due to the installation of a chemical dpc in a clunch (earth) house. Because advocates conservation methods to maintain period homes we would advise all homeowners to investigate alternatives to chemical dpcs. Two such areas are the improvement of land drainage around the property and the removal of earth from around the property's foundations which may have led to damp penetrating the earth walls. In addition, it is advisable to use of lime plaster on the clunch walls instead of cement to ensure any moisture within the earth walls evaporates naturally

As a general rule if a chemical dpc is to be installed is should be installed in the brick plinth which the earth blocks are laid upon. Under no circumstances should the dpc be injected into the earth blocks. For a fuller explanation of the problems associated with damp and earth buildings read the article entitled 'Earth Buildings and their Repair' by Dirk Bouwens in the articles section of Dirk Bouwens is the Secretary of the East Anglian Earth Buildings Group which encourages the proper repair and conservation of earth buildings.


SUBJECT: Original fireplace ?
FROM: Vanessa Jackson (Clitheroe, Lancashire)
We have just purchased a 1800 Georgian townhouse in Clitheroe, Lancashire. The fireplace is very unusual and have had builders round who are unable to help us discover whether it is an original feature or whether it has been added on at a later date please can you put us in touch with somebody who will be able to help us.

Vanessa Jackson

Vanessa, contact the Georgian Society on Tel. 020 7387 1720 or visit their website They should be able to put you in contact with a local expert to advise you on your fireplace.


SUBJECT: Making daub mortar
FROM: Mick Thawley (Pulham Market, Norfolk)
I need to repair some clay lump outbuildings which require both a render layer and deeper areas of repair. The walls are generally in good structural condition but several areas have suffered through weather, bee, bird and animal attack. How do I make a daub mortar suitable for this job? The buildings are grade II listed and about 300 years old.

Mick Thawley

Mick, firstly may I congratulate you on focusing the repair of a clay lump building with a traditional 'earth' repair. Normally, in these circumstances a cement mix is used to fill the areas of decay resulting in accelerated further decay due to damp penetration.

Essentially, the materials you require should be in the general locality. Earth mixes for repairs vary due to the variation in subsoil mixes resulting in their being no definitive ingredients. However, all earth mixes contain two key ingredients in water: an aggregate such as sand or chalk, and clay which coats the aggregate particles and acts as a binder. Other ingredients include straw and ox hair and in some instances animal waste. The addition of straw or animal waste helps to reduce cracking as the materials dries. Therefore, get digging and make up some trial mixes using local materials and start with a trial patch on a sheltered elevation.

On your test patch ensure the area to be filled is damped down. This ensures the earth mix dries slowly rather than the drier surround sucking the moisture from the earth mix - this helps to avoid cracking. Next, ensure you force the clay into the area to be filled, building up layer after layer, after each layer has dried, rather than simply attempting to fill the void with your mix. However if the areas of damage are large it may be necessary to cut out any damaged blocks and replace them with new blocks. Once the earth repair is complete render with lime and limewash for further protection.


SUBJECT: The formerly internal now external wall
FROM: Stephanie Hughes (Dumfries and Galloway)
My house was built in 1803, it used to be joined to another single storey building which was demolished. This wall is now damp and I am having it re-pointed on the outside with lime, internally the previous owner masked the problem by putting up a plasterboard wall. This is now so damp it is caving in and I intend to remove it, but what do I do to the wall behind it.

Stephanie Hughes

Stephanie, it appears that your wall is particular damp and still drying out. By re-pointing the exterior brick or stone work you are helping any moisture within the walls evaporate. On the internal wall can I make three suggestions. Firstly you could hack-off the internal plaster and re-render the wall with lime - I'm assuming its not a lime plaster. Alternatively you could remove the plaster as above, but then attach sheets of corrugated plastic to the wall ensuring the bottom and tops of the sheet do not touch the floor or ceiling. This acts as a vertical dpc (damp proof course), with the corrugations enabling air to circulate behind the wall and a key for the plaster on the front of the wall. Finally, if your gable end is a victim of severe driving rain leading to penetrative damp it may be necessary to hang tiles or slates to provide some additional protection.

Period Property UK would like to thank Stephen Boniface from Boniface Associates for answering this question.


SUBJECT: Damp converted cellar
FROM: Adam Hunter (Norwich, Norfolk)
I am renovating a mid 19C town house. The cellar was converted into living accommodation in the 1970s. The walls were tanked and a plastic membrane was placed on the floor. The floor is dry but the walls are damp, although not excessively damp, 1 meter from the floor above the tanking. If I tank above approx. 2 meters in total will the dampness rise above the new tanking level? The ground level outside is 2 foot higher than the inside floor level and to complicate matters further the walls are approximately 18" thick and are made of broken brick and stone, which turns to brick after 9'. What is the best way to contain the dampness? I am reluctant to get contractors due to the many horror stories about expensive ineffectual work. I have been told to inject but how would this work with neighbours adjoining walls combined with the fact the ground level is higher outside and there is no solid brick to inject into? Please help!

Adam Hunter

The system used in the 1970s on your property was common at that time. Unfortunately, we now know that such systems do not last long and in my experience they fail after about 10-20 years. Chemical injection is unlikely to do any good in terms of remedying the problem, as the dampness is likely to be penetrating laterally - particularly as a section of the basement is clearly below ground level. If there is any 'rising damp' it is most likely to be rising by capillary action between materials, etc. I suggest that any attempt to prevent dampness penetrating through will ultimately fail. It is far better to manage the dampness. My advice is that you consider a ventilated/drained system whereby a proprietary membrane (e.g. those made by Platon or Newton) is installed (perhaps to walls and floor) leaving a gap between the original wall surface and the membrane. This is ventilated and/or drained at the top and/or bottom. Without precise details of the basement I cannot be more specific. The surface can then be plastered (preferably with traditional lime plasters) and finished to your requirements. The system results in a slight loss of floor area, but is the least likely to fail of all the possible solutions. You should ask a surveyor or architect experienced in dealing with such matters to inspect and specify a system. Nevertheless, I always prefer to manage moisture than to attempt to exclude it, as the latter usually fails in due course!


SUBJECT: A legacy of unauthorised work
FROM: P Smithson (Coggeshall, Essex)
I would like to purchase a Grade II Listed farmhouse but the current owners have undertaken a great deal of unauthorised work. Many period features have been removed and internal partitions knocked through. All sash windows have been replaced with upvc etc. The agent has stated that this work was done prior to listing therefore the local authority cannot order us to make good. Therefore is the onus upon the authority to prove this work was done illegally or is the householder required to provide evidence that it was all done prior to listing (by provision of photos etc.) As far as I am aware nobody from the planning dept has visited or viewed internally for at least thirty years. I am very keen to buy this house and restore it to its former glory but I am unwilling to land myself with open-ended liability through the action of others.

P Smithson

BEWARE! The agent would say that wouldn't he/she! There are no time limits on the Authority taking action and the onus will be on the owner (whether the existing or you!) to prove that the work was undertaken before listing. I do not believe for one minute that the work was undertaken before listing (get the list description and find out when it was listed - compare to the likely age of the windows). The property as you describe it is unlikely to have been listed after the works you describe and if it was the list description is likely to have made mention of such things as plastic windows. Your desire to restore the building properly is admirable and should be encouraged, but before you buy you MUST get the conservation officer on to the site to discuss what you want to do and how to go about getting the approvals. The officer may take the view that they want to encourage you and hold off from taking action, but they may want to pursue the present owner for unauthorised work. If the latter is the case, keep clear until the dust has settled and any legal/planning matters have been resolved. Whatever you do, you must consult with the conservation officer, or you could find yourself in trouble and having to fight an action. If the owner refuses to let you bring an officer on site alarm bells should ring very loudly!!


SUBJECT: Damp patches in the bedroom
FROM: Karen Murphy (Twickenham, London)
We have recently purchased a Victorian end-of-terrace house built in the 1880's. In the main bedroom, we found a number of very damp patches in a line along the wall. It had been covered in synthetic wallpaper which had bubbled badly. The main damp patch was very wet and had black mould. The damp patches appear to have spread horizontally from that main patch. On the outside wall in the corresponding position we found that the pebble dashing (this is the only wall pebbledashed) had been patched. Our neighbour said that this was the outlet pipe for an old gas heater/boiler. My partner wants to refill the old hole and then seal the external wall with water repellent. Can you advise us on the best way to repair the external and/or internal walls to prevent a recurrence of this damp?

Karen Murphy

Until the cause of the damp (if it is still actually damp?) is properly established it is not advisable to start discussing remedial work. There are many possible causes. From what you describe the most likely cause is damp penetration, whether this is through a disguised hole, etc. is impossible to say without looking at the property. It could be residual damp and it may be the wall surface simply requires exposure to allow it to dry. It could be condensation, which is a complex issue that would require careful assessment. At this stage I would not recommend sealing the walls as you could simply be trapping moisture in the structure. The fact that the manifestation of damp is in a line suggests that there might be a hidden building element (e.g. a buried timber). The wall might need to be opened up to investigate whether there is a hidden problem. You would not want to undertake superficial repair only to find that there is a buried rotting timber! You should seek advice from a surveyor or architect who understands old buildings and can oversee the investigation and advise further. As far as the investigation is concerned this is likely to involve careful removal of the existing wall finishes, some of which you may be able to undertake yourself. Failure to assess properly in the first instance could result in the repairs failing.