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: Are my bricks under attack by mould causing them to crumble?
FROM: Ryan Eaton (West Midlands)
In our loft we have a problem with crumbling bricks - seeming to be caused by a fluffly white 'mould' type substance that is on them. The wall it is occurring on is adjoining the next door neighbours house which makes me think that the efflorescence stuff you mentioned before might not be the culprit - as I cannot see where the damp would be coming from?

It is obviously a concern as it is crumbling off small 'sheets' off of the face of the bricks (which fall on me whenever I open the loft hatch which is located by this wall!)

Ryan Eaton

Without a photograph of the substance, the wall it is on and shots showing the general location (external of the roof, etc.).

I maintain it is likely to be efflorescence, but cannot say further without the information mentioned above.

Are you sure there is no leak from a roof or chimney near this area, or is there a serious condensation problem?

If it is a mould it will not be 'growing' on the brick as brick does not usually provide the required nutrients to sustain a growth. Therefore, if it is mould there will be a damp problem affecting timber nearby.

Either way, I suspect some form of damp either ongoing or historic being the fundamental cause.

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: Where does my extractor fan flue go?
FROM: Andy Shelley (Essex)
I have recently moved into a Grade 2 Thatched cottage which was restored approximately six years ago. The thatch is in good order [long straw]. An en suite shower room has an extractor fan fitted into the ceiling [no window] and appears to have no external visible termination for the extract air. To discharge into the roof void is in a conventional house unacceptable, what about a thatched house?

Andy Shelley

Also unacceptable, as it introduces moist air into an enclosed area and this could result in mould and degradation of the thatch from the underside.

Trace the route of the extractor duct and re-direct it to an external wall somewhere, or perhaps penetrate the thatch. If you opt for the latter a thatcher will need to finish the junction of the pipe to the thatch. An alternative might be to use the chimney (if not used for a fire).

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: Do I need listed building consent to re-roof my slate roof?
FROM: Brenda Potter (Merseyside)
I have a listed building Grade 11 with a slate roof which, according to three roofers, is getting beyond repair. I have been told I don't need planning permission or listed building consent to replace it as it is new for old. Can you confirm or refute this for me please.

Brenda Potter

What are you replacing it with?

With most slate roofs it is possible to salvage quite a lot of the slate for re-use (often between 50 and 70%). If this is the case you will need to get slate that will match the original. Matching slate could be slate salvaged from another building, but you may find new slate from Wales or Cumbria that matches satisfactorily.

There is much debate over the merits/demerits of foreign imported slate (Spanish and Chinese) and I suspect that if you want to use foreign slate the Conservation Officer may have something to say about it.

The recovering of a roof would not require planning permission. Re-covering with salvaged and matching slate would not normally require listed building consent. Re-covering with foreign slate or another material altogether may require consent.

In any event, due to the fact that this will be major work anyway it would be best to liaise with the Conservation Officer and seek his/her opinion on your proposals. Even if you need to submit an application for listed building consent this should not be onerous for re-covering a roof. It is better to speak to the Conservation Officer than risk it.


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: Lack of consents could hold up house sale.
FROM: Cal Johnson (East Sussex)

We bought a pretty Grade II listed cottage in East Sussex about 5 years ago. We are now selling because the place is too big for us, but we are now faced with potential difficulties. The buyer's solicitors have asked to see buildings consents for a wooden fence that we repaired (unattached to the cottage), repairs to the roof of a separate garage (which is not listed and was erected about 30 years ago) and repairs to the drive, which again was modern. Although none of these items I felt needed special permissions, the materials used for the repairs were the same as the originals. They also want a consent for a shower cubicle in a bedroom and an outbuilding both of which were already installed when we bought the property (the outbuilding looks like it was erected about 40 years ago but after the property was listed). We did not receive any information about the shower or outbuilding when we bought the property 5 years ago. We have written to the District Council, explaining our position, enclosing as much information as we could find about the repairs that were carried out, a request for information about any consents on the outbuilding or shower cubicle if necessary, and requesting their advice on whether we would need to seek retrospective buildings consents.

We have not yet received a reply from the council. Meanwhile I'm a little worried. Is there anything else I should know or do that would help our position?

Cal Johnson

Another case of a solicitor being over cautious and/or ignorant on the specifics of conservation and appropriate consents.

The works you describe to the fence, garage roof and drive are all matters that I would not normally regard as requiring consent. The only thing you can do on these matters is to get a letter from the Conservation Officer confirming that the works did not require consent and/or that no retrospective consent is required.

The shower room and outbuilding are matters for which I would normally expect consent to be required. However, if they are works that were undertaken some years ago I doubt the Council would be inclined to take action now. Again, you should ask the CO whether he/she can confirm that the Council are not interested in taking action or that retrospective consent should be sought. If the latter is the indication given you should also ask whether there is likely to be any problem or whether this is to be a formality.

As for what action the Council could take if they viewed the works as not only unauthorised but unacceptable, I do not think any Council would take out prosecution when they have no information as to who actually undertook the work - who would they prosecute? However, they could take out enforcement action. This could affect any owner regardless of whether that person actually undertook the work. With enforcement proceedings they would have to state what action they want taken. In such circumstances the owner can Appeal and/or make a retrospective application. However, in many instances a CO would normally discuss such matters with an owner first and might even agree to wait for removal of the offending work until such time as is convenient for the owner, especially if the owner is planning or work in the near future.

Based on what you have said I doubt there is any need for concern on your part. I would continue to pursue a discussion with the CO and get some form of letter from the Council. Otherwise, or as well as, get your solicitor to speak sense to the purchaser's solicitor.

Failing all else there is the possibility of getting insurance against Council action. I have found solicitors favouring this approach, but when they also have links with insurers, etc. I have to wonder if their motives are always as pure as protecting their client's interests!

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: Do a require a lead soaker?
FROM: Peter Downhill (Cambridgeshire)
A builder is restoring a large bay window, including the roof. He has removed the old lead flashing connecting the roof to the wall of the house, but has put a mortar haunching in its place. Aside from the fact that he actually quoted to fit new lead flashing (!), should I be concerned by this? Is it more likely to crack/leak than lead flashing?

Peter Downhill

Yes. However, what mortar has been used? If the mortar is lime based there is much less risk of cracking.

Is there a lead soaker under the mortar? If so this helps reduce the risk of leaks even if the mortar cracks.

Ask the builder why he has changed the specification.

Is there a local tradition for mortar or lead in the district? Generally mortar was used on older buildings and lead used after the 18/19 century.

Lead flashings generally provide a better finish from a leak prevention point of view, but mortar can look better and if properly formed can provide good performance for a number of years.

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: Someone's sealed my 'Grumplings'!
FROM: Ruth Talbot (Buckinghamshire)
We have a period property made out of wychertt, the walls of which have been sealed in cement render (including the grumplings). In addition, we are told that the ground outside the house is slightly higher than the floor level within. This is causing some damp problems within the house. We've spoken to a specialist building company about lowering the external ground level (eg by installing a French drain), but they suspect the soil pipe will prevent this being done. Would it be worthwhile removing the cement render from the grumplings? Are there any further actions we should consider? I'm concerned with both addressing the damp problems and preventing (further!) damage to the wychertt.

Ruth Talbot

Wychert = earth walls.

Grumplings = stone bases of walls.

I would suggest that removing the cement render from the whole wall area is the most important item of work. The cement will be causing moisture to be trapped in the wall structures. When this happens the walls will degrade more rapidly.

However, you must take care because if the earth wall has deteriorated the removal of the cement could result in collapse. The render should be removed carefully and in sections to ensure that the earth wall can be made stable and repaired (as necessary) as it is exposed. You may find nothing wrong with the earth wall, or you could find that the render is now the structural element of the wall! Until exposed it is difficult to know what you might find.

In any event, the presence of cement render is the cause of damp because it is trapping moisture in the wall.

Lowering the ground level is of course also important. I prefer an open channel rather than a gravel filled channel because an open channel will allow the wall to breathe whereas if the channel is backfilled with gravel it reduces the breathability of the wall.

When all is finished you should use a lime render on the wall with a limewash finish. Because an earth wall needs breathability and flexibility I would suggest using a 'fat lime' render (not NHL).

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 mastic sealer?
FROM: Wendy Lund (Shropshire)
We live in a grade II listed half timbered cottage. How would you suggest that we create some sort of seal between the timbers and the brick work in between to prevent gales blowing through and water entering? There are also a few holes to fill in the timbers. The previous plaster over the joins has cracked and, in many places, allowed water to become trapped causing some outer rot in the timbers. One recommendation is to use mastic sealer. What do you think?

Wendy Lund

Without knowing what else has been done I cannot make any specific suggestion. If the building retains traditional finishes a lime mortar filler would be best and a limewash over the timbers and brick would also help provide a seal.

If the building has modern finishes there is an issue of whether these are causing damage anyway. I would generally advise removal of cement renders, pointing, modern paints, etc because these all prevent breathability. If this is your situation you could temporarily use a mastic to seal gaps, but ONLY for a short term fix until such time as you completely remove modern finishes and revert to traditional.

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: So-called damp proofing causes more problems than it potentially cures
FROM: Roland Brewer (Shropshire)
Four weeks ago we had damp proofing on our cottage(turn of the century). since then on the interior walls the new plaster has been getting large amounts of efflorescence. the dampproof company have told us this is normal and in time will go. the problem we have, is that we need to seal and paint the plaster asap in order to fit the radiators as autumn is setting in & we have very young children. can you recommend any tips or products in speeding this "drying out".

Roland Brewer

I am sorry, but I suggest you have wasted your money and caused problems for your house. Without knowing more I cannot be specific, but even a turn of the century house would generally be built with traditional materials and would be breathable. The sort of work you describe is about the last thing I would normally recommend.

Who said you had 'rising damp' that needed such treatment? I would be very surprised if you had such a problem in the first place.

The damp 'problem' should have been properly assessed and in the vast majority of cases if there is a genuine damp problem it can be resolved by appropriate building works rather than rely on chemical treatment. However, when chemical treatment is undertaken it is nearly always accompanied by internal rendering (the Agreement certificates often referred to only apply if the internal wall is also tanked - it is the whole system that has the certificate - not just the chemical treatment). As moisture continues to escape efflorescence will occur.

Yes, you will continue to get salts through and no there is no easy fix. Sometimes the plaster needs to be hacked off and replastering undertaken - only time will tell.

There is no 'seal' that would be appropriate. The usual method of dealing with modern plaster is to apply a thinned matt emulsion (mist coat) first and then further matt coats. These allow a degree of drying out while also sealing the surface. When the wall is eventually dry you can then paper or decorate as you wish.

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.