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...


SUBJECT: Limewashing problems in Cellar.
FROM: Chris Duncan (Bristol)
I have tried to use limewash on the walls of our Victorian cellar, but with poor results. Having followed the manufacturers' instructions, I put three very thin coats on leaving the walls for two days in between coats. However, the limewash has started to flake off. Where the substrate was Victorian bricks, the limewash is almost completely off the wall now. Where I filled holes with lime render prior to limewashing, I am getting efflorescence. The Victorians clearly had a solution as there are parts of the walls where the original coating is still in good condition and dry to the touch, despite being below ground level.

Chris Duncan

It is hard to say what has caused this. If the walls were too damp, then it can cause the lime wash to go translucent, rather than flake off. Could there be something else on the walls which the lime wash is fetching off? That often happens in old basements. You say that it is worse on the clean bricks, which could suggest a high salt content to these, where they have been damp for a long time. As ever, sound preparation and good ventilation are probably the best one can suggest at this stage. This is a problem that should be assessed by a local architect/surveyor experienced in older properties and particularly in the application of limewash.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at the The Whitworth Co-Partnership with Boniface Associates for responding to this question.




SUBJECT: Paint source required to match colours used in market town.
FROM: Simon Walstrom (Buckinghamshire)
I am looking at purchasing a Grade II listed property in the old market town of Olney, Buckinghamshire. The property is painted white with cream and green windows. I am aware that possibly Olney has a range of limited heritage colours that can be used for external painting, but I have tried looking everywhere with no luck. Do you know what the position is on changing external colours and if Olney does have a range of colours that can be used?

Simon Walstrom

I am sorry, but I do not know specifically of Olney colours. One often finds the remnants of estate colours in rural areas. Were these the colours of a local estate which owned a lot of the properties in the town? If the colours are very specific and special (regarded as part of the 'character' of the property, street scene, etc) you will need to get listed building consent to change the colour. If you simply wish to re-paint using the same colours (or those within a given range) I suggest you ask the local Conservation Officer, other local residents, etc. I cannot believe that they are that difficult to find, otherwise how do other occupiers deal with this problem? Nonetheless, there are some specialists on paints and colours. For example Patrick Baty (Papers and Paints Ltd - 4 Park Walk, Chelsea, London SW10 0AD - Tel: 020 7352 8626) may be able to give further guidance and could probably even match colours, if necessary.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at the The Whitworth Co-Partnership with Boniface Associates for responding to this question.



SUBJECT: Does central heating draw damp into a property & advice concerning insulating roof space?
FROM: Graham Earl (Eastbourne)
We are about to start renovating a Georgian 3 storey Limestone slate roof property.

The house has what I believe is called a French ditch around it. A previous owner has concreted parts of this and the lower ground floor is quite damp. Is the best way to solve this to dig the ditch out again?

I addition related to the damp issue I was advised not to install central heating as it attracts damp into the property which would negate any benefits derived from repairing the ditch, is this true?

I was interested to see a previous question about slate roofs and I am a little unclear, did the point about allowing air to circulate around the slate mean that using roofing felt immediate under the tiles would be counter productive, or did this refer specifically to insulation products? I would to say that I think the site is great value.

Graham Earl

What is often refereed to as a 'French Drain' is often a ditch that has been back-filled with shingle. Sometimes it may contain a land drain and sometimes it is simply an open trench. If parts have been concreted over it will not be of any assistance. It sounds as if you may have to excavate it and re-form it to some extent. A shingle filled trench will ensure that water around the building will drain away quickly. However, the presence of the shingle still inhibits (to some degree) the breathability of the wall at low level. I therefore often prefer to simply have an open trench, provided it can drain away quickly and provided there is some form of grille to prevent it becoming blocked with leaves, etc.

Heating does not 'attract' damp as such, but the presence of heating can draw damp in. Where there is heating internally the internal face of the wall will dry, because warm air can hold more moisture than cold air and the warm air internally will absorb the moisture at the face of the wall as a vapour, thereby increasing the 'humidity' of the internal air (although this may not actually be noticeable). The movement of the air should take this away. The fact that the moisture in the wall has been absorbed into the neighbouring warm air internally will leave a 'void' within the wall. The moisture in the outer section of the wall can then migrate over to occupy the dry section of wall where it will then be absorbed into the warm air, thus continuing the cycle. The usual result is that the face of the wall remains relatively dry, but that moisture is gradually being drawn through the wall. Where the internal air changes are regular (good ventilation and air circulation) this will allow the moisture to be drawn out of the wall into the air and away. If ventilation, etc is poor the result could be an increased internal moisture problem, primarily in the form of condensation. If the section of wall is below ground, the presence of heating can be positive, but there is a risk that it will make no real difference. Further, as the moisture is drawn through and evaporates it could leave salt deposits on the wall surface (efflorescence). If the wall is above ground the presence of heating is more likely to have a positive effect, but the risk of efflorescence remains.

Slate is an overlapping roof covering with usually three layers of slate over any part of the roof. Although driven rain or snow could be forced under the edges it is unlikely that this would be a serious problem in most roofs. I therefore take the view that slate, plain tile or other overlapping roof coverings would not normally require a lining (the exception might be where the pitch of the roof is low). I would therefore normally prefer to see linings removed. However, this primarily applies to impermeable linings (plastic or bitumen based materials). Some modern linings are 'breathable' and are more acceptable. In my view the above comments apply regardless of the presence of insulation. However, where there is insulation in the roof with a void above and then an impermeable lining to the roof slope there is a risk of condensation forming to the underside of the lining, etc. In such situations the lining should be cut away or specific ventilators installed. Where there is insulation a void and then a roof covering this is referred to as a 'cold' roof. Where the insulation is immediately under the covering and the void is on the warm side of the insulation it is referred to as a 'warm' roof - this would not require ventilation, but there is a need for a vapour barrier. The problem with the various spray-on insulation materials is that they create a warm roof without the vapour barrier. My concern is that this will result in failure of the battens and rafter faces that are hidden by the spray. These products have not been around long enough to be certain of how they perform over time. In my view the spray-on insulation would not comply with Building Regulations for warm roofs if being applied in a new property. As Building Regulations do not apply to repairs may render such comment irrelevant. Nonetheless, I believe that this is an important consideration, because it shows that the material cannot be used in accordance with what is regarded as good practice for warm roof constructions.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at the The Whitworth Co-Partnership with Boniface Associates for responding to this question.


SUBJECT: Does tar seepage from chimney present health hazards?
FROM: Duncan Haigh (Hampshire)
I am about to purchase a property, estimated to be over 200 years old. It is a cob built construction. I have been advised that there is evidence of "tar" seepage through the chimneybreast both inside and outside to the Gable end. The lining has been replaced and correctly packed to avoid contact with the inside of the chimney - this cuts off the route cause of the problem. The flue lining now runs down to a gas-boiler in the cellar. I would like to know.

1 - for how much longer will the seepage persist - months, years?

2- will the chemicals in the seepage damage the brickwork, mortar, lime render or external "breathable" paintwork. (I am reluctant to seal a cob wall)

3 - is there any course of action to prevent seepage?

4 - finally as an asthmatic - is this seepage or any of its bi-products in any way an irritant or toxic?

Duncan Haigh

The answer is not encouraging, unfortunately. To take your questions in turn:

1: Decades, probably, depending on how well the tar has emulsified with the moisture in the flue. If the seepage is through the surface, the only thing you can do is seal it, or hide it. It will always react with paints, whether old or new.

2: Paints, yes, other substrates, unlikely. You are right to be concerned about sealing a cob wall, but chimneys in cob built properties are often brickwork (at least they are in my experience here in East Anglia). If sealing is inappropriate you could dry-line the wall to hide it.

3: see 1 & 2 above.

4: Coal tar steam inhalations used to be a standard way of relaxing the airways, although not any more because of toxicity problems. The side effects are unlikely to be any worse than the lime wash you will be using on the outside. But ventilation is always important, not only for the lungs, but for the building and to discourage what grows on the surfaces of buildings, which my GP tells me is more likely to affect me as an asthmatic than the building itself.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at the The Whitworth Co-Partnership with Boniface Associates for responding to this question.



SUBJECT: Removal of chimney to maximise space.
FROM: Carol McCaffery (Berkshire)
Our property is a grade II listed building. We need to maximise the space by taking out a small chimneybreast in one room downstairs, thus enabling us to turn it into a dining room. We are an end of terrace and the other properties in the row, also grade II, have had a lot of internal work carried out. However, the Conservation Dept are stating that we cannot remove the chimneybreast, which is very plain not an inglenook and unused, even though precedence has been set by the other properties. If we cannot maximise living space we will have to move from the house we have lived in and owned for 12 years, the Conservation Dept have stated that this is our problem and will not take this into account. Can you advise us please.

Carol McCaffery

The fact that other properties may have had their chimneybreasts removed is not necessarily setting a precedent, as the requirement with a listed building is that each application must be considered on its own merits. Your primary argument/justification will probably be that the chimney is of no historic merit and its removal will not harm the character of the property. Whether such an argument is reasonable will be for a local conservation surveyor/architect to advise upon. I must say that your comments do not seem logical from what you say. If this is only a small chimney breast its removal will not make a significant difference to floor or wall space. Further, you have lived in the property for 12 years with no problem, why is it that you now need to maximise the space? How can the removal of a 'small' chimneybreast make so much difference that you say without this change you must move? I am sorry, but on the information you provide my sympathies are with the Conservation Officer.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at the The Whitworth Co-Partnership with Boniface Associates for responding to this question.


SUBJECT: Should we remove harling to reveal external stone walls?
FROM: Sarah Benfield (Fife)
My boyfriend and myself are considering purchasing a small cottage built in the early 1900's near Biggar. Whilst the front of the cottage is stone, the sides and the rear walls have been harled and painted grey. We wondered firstly why this had been done and if there was anyway to know whether there was stone underneath the harling and if so how difficult it would be to remove? Ideally if there was a stone wall beneath at the rear we would like to expose it and have it as a feature wall within a conservatory. If it can be removed could you recommend who we should approach to carry out such work?

Sarah Benfield

I cannot claim to be a specialist on Scottish buildings, but I am aware that harling is common. Its purpose is primarily to give added weathering protection. I suspect that the harling is on the more exposed walls. In view of the age of the property I also suspect the harling to be original. I would urge caution about its removal. Although I often speak out against the use of cement renders, because of breathability, proper harling is a lime-based render which provides good protection for the wall whilst allowing breathability. Although your building may not be listed I suggest you speak to Historic Scotland, who are best placed to assist you and give guidance. They have publications on harling and other wall finishes. Where you intend to build a conservatory and expose the wall, this might be acceptable from a practical viewpoint, but if the stone was never intended to be exposed to this section of the building its appearance might not be quite what you expect. You really should seek advice from an architect or surveyor local to you with experience of this type of property and materials. Again, Historic Scotland should be able to point you in the right direction. [Note: Historic Scotland are the Scottish equivalent of English Heritage]

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at the The Whitworth Co-Partnership with Boniface Associates for responding to this question.



SUBJECT: Should we use a RICS or TAS surveyor for the full structural survey of our thatched property?
FROM: Bob Gee (Berkshire)
My wife and I want to buy a Thatched Cottage near Salisbury. We understand the property to be 16th Century. Surveyors? Which would be the best for a Full Structural Survey, "The Thatching Advisory Service" or a local RICS Surveyor?

Bob Gee

Thatching Advisory Service (TAS) is a subsidiary company of NFU Mutual - the insurance company. It was once an independent thatching company and there are a number of thatchers across the country who belong to the TAS franchise. They also used to run an intensive short course to learn how to thatch (many of their franchise thatchers took this route), but I am not sure whether this continues. Members of TAS would probably be able to offer a service to look at and advise on the thatched roof only.

Some years ago Surveyors and Engineers agreed terminology. A structural survey is something only engineers do and this is a survey of the structural components of a building (primarily the walls, but including the roof and floors). It would not strictly include other elements or even issues such as timber and damp. That said, many engineers provide 'condition surveys', which are more extensive. Surveyors on the other hand provide 'Building Surveys' (the word Full is sometimes used in front of this). Whilst this survey would also consider the structure of a building it would include all other elements. I suspect the term you use is really referring to the latter.

If you are looking for a survey that discusses all elements of the building then an engineer's 'structural survey' will not provide what you want. However, you could ask an engineer to prepare a condition survey, but I do not know of engineers experienced in the survey of thatch and very few would properly understand the nature of an old roof structure for thatch (thatch being lightweight often has a rather rustic/crude roof structure). It should be mentioned that Architects will often also provide condition surveys, but again not all will properly understand thatch and thatched roof structures.

Chartered Building Surveyors are best placed to prepare a Building Survey dealing with all elements. Some Chartered Surveyors carrying out mortgages or offering other services will offer to undertake a building survey, but there is greater risk of finding someone competent of dealing specifically with an historic thatched building. Note my specific use of the designation Chartered Building Surveyor - not just Chartered Surveyor. All full members of RICS can call themselves Chartered Surveyors and for example whilst some may be very competent at discussing geomatics they would not have a clue about thatch. Some Chartered Surveyors are what used to be referred to as 'General Practice' and could undertake building surveys, but do not have the designation Chartered Building Surveyor. This all sounds very complicated, but the intention is to safeguard the public from surveyors undertaking work they are not properly trained to deal with. For the public it is safest to use a Chartered Building Surveyor and if you are unsure of the proper designation of a specific surveyor the RICS can advise you on details of any given member.

Within the RICS there is the Building Conservation Forum and as a further safeguard you should use a surveyor who is a member of the Forum. Further, within the Forum are members who specifically have a post-graduate qualification in Conservation. Beyond this there are a few members who have achieved Accreditation in Building Conservation. The Forum is administered by Kieron Higgs who can be contacted by phoning the RICS switchboard on 020 7222 7000. Kieron can provide names of 'conservation surveyors' close to your location.

Turning now to the survey of the thatch, there are some surveyors who are capable of providing an initial competent report on thatch, but perhaps no more so than engineers or architects. With regard to the thatch itself, I suggest therefore that you have a local thatcher undertake an inspection. This could probably be organised in conjunction with the main survey and the two reports combined by the surveyor to give a complete picture.

For a survey of the thatch you could use TAS, but you could consider using a local thatcher member of a regional Master Thatchers Association (an MTA affiliated to the National Council of MTAs). The surveyor you choose may know of a thacther he/she trusts to give an independent report. Remember, as with other trades, a local practicing thatcher may have a vested interest in 'finding work' to do. A retired thatcher or someone with no such vested interest might give a more independent report.

I would not recommend having a thatcher undertake a survey of the whole property, as they are not trained to deal with the other elements of building structures - would you normally ask a roofer to discuss the rest of the structure - it is like asking a plumber to discuss subsidence!

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at the The Whitworth Co-Partnership with Boniface Associates for responding to this question.



SUBJECT: Can I have sash windows dipped to remove paint?
FROM: Keith Wade (Hertfordshire)
I am refurbishing an early Victorian property and we are repairing the sashes and there is a considerable build up of paint on the sliding sash which will involve a lot of preparation prior to painting it has been suggested that I take the sashes out and have them dipped /stripped would this be a good idea?

Keith Wade

For the purpose of removing paint this would seem the quick solution, but there are a number of drawbacks. I have never seen a sash window that has gone through this process, but I have seen many doors and they are usually warped with joints loosened, etc. If the same were to happen to a sash the repairs would probably be so costly that you might as well have had new windows made. Other problems include what would you do about the glass? If the glass is OK, but breaks during its removal it will have to be replaced. Modern glass is heavier than old glass, therefore the sash weights will have to be adjusted (otherwise the sashes will not work properly). Sashes are relatively easy to get out of the box frame and onto a workbench, where they can be prepared and repaired with glass left in place. Whilst the sashes are out the box frames can also be dealt with. The sashes can even be re-painted before being re-hung. The only precaution is to avoid painting the surfaces that slide, it is often the paint build-up on these surfaces that make sashes difficult to operate. These are hidden in terms of weathering and the lack of a paint finish is rarely a problem. The Society for the Protection of Ancient Buildings publishes a very useful leaflet on window repairs.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at the The Whitworth Co-Partnership with Boniface Associates for responding to this question.


SUBJECT: Efflorescence leads to concerns over appearance of chimney.
FROM: Nicholas Coope (Cambridgeshire)
I have a back to back fireplaces in a 17th Cent baffle entry timber framed cottage. I have exposed most of the bricks to let them breath. I am getting a lot of white crystals on the surface. How can I get rid of this permanently or temporally?

Nicholas Coope

It sounds like you have efflorescence. This is the crystallised salt deposits that have been left as the moisture evaporates and the salts deposited on the surfaces. This is an indication of moisture evaporation (either having finished or ongoing). You should use a dry brush to carefully brush them away and then sweep or vacuum them up. Such removal will be necessary on a regular basis to start with. Over time the amount of efflorescence should reduce, as I suspect that the initial outbreak is due to excessive residual moisture that had been trapped previously within the brickwork. In extreme situations it is possible to use a poultice to try to draw salts out of brickwork, but I would not suggest that for you at this stage. I would be hopeful that most of it will gradually disappear with perhaps only periodic reappearance.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at the The Whitworth Co-Partnership with Boniface Associates for responding to this question.