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 (www.periodproperty.co.uk).

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...

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SUBJECT:
Damp from five flues
FROM:
Stuart Hayes
(Essex)

I have a Chimney stack in a three story Grade 2 property which has five flues. In the upper most room I have a damp patch which after replastering the wall because of dampness, a new patch about one foot down from the ceiling has progressively expanded. The patch has grown upward and sideways until it is right around both corners of the breast.

Between the ceiling and the roof walkway is about one foot depth, but the dampness did not start at ceiling level and so I do not think that it is a roof walk leak problem. The other side of the stack goes to a lower sloping roof line for the "servants Quarters" part of the house and party wall. About ten years ago a gas fitter, fitted a gas fire into the adjoining Maisonette which was home to two of the flues. However an earlier owner had taken down the brick flues that side to first floor level - philistine and fool springs to mind! The gas fitter wrongly broke into the chimney flue in my top floor room. The Fireplace had been removed and so I was unaware at the time that he had gone into the wrong flue and hence the wrong chimney. He fixed in the necessary gas tube into the chimney. My reasoning of the problem is that this flue may be causing sweating to take place at the point of entry into the wall and causing the dampness in my wall. The patch did start to appear at the centre of the chimney breast in that room.

Stuart Hayes

You really need someone to come out and inspect to investigate and establish the cause. From your description it is difficult to analyse the problem definitively.

It is possible that there is a leak from the walkway, through the chimney to roof/walkway junctions (flashings/back gutters, etc), through the brickwork (if pointing is poor), or through the pots and/or flaunchings around the pots. All of these possible points of water ingress should be examined and eliminated as the cause (or confirmed and dealt with if found defective).

The fact that the neighbour is using your flue is something you may need to speak to them about - without knowing the precise layout I cannot say for sure, but it sounds like trespass to me and you could consider legal action if a gentle chat does not resolve things.

Yes, the problem could be condensation running down the outside of the liner and dripping onto the brickwork on your side and therefore penetrating through. If the liner is to remain you could insist that it be properly insulated to help prevent the risk of this condensation problem.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at The Whitworth Co-Partnership for responding to this question.
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SUBJECT:
Insufficient ventilation in roof void
FROM:
Graeme Cooksley
(Surrey)

I am selling an Edwardian terrace house and the buyers survey states that roof void is not satisfactorily ventilated due to lack of fixed air vents which I am presuming are a modern specification. How, if at all, would have original constructors ventilated the roof void and would there be anything to look for to establish any particular methods existence? Also what would be the signs of any damage due to lack of ventilation?

Graeme Cooksley

If the roof slopes are unlined there will be plenty of natural ventilation between the tiles/slates. There would be no need for any other ventilation.

If the slopes are lined the void should be ventilated. This could be by using proprietary ventilators in the slopes and/or eaves soffits, or you could have air bricks in gable walls.

Lack of ventilation can lead to a condensation problem in the roof void. If there are white/grey (or black) mould spots on the timbers then you probably have a condensation problem due to lack of ventilation (especially if there is a water tank in the roof space to add moisture to the air).

If you have no sign of condensation and no water tanks and yet there is a lining the lack of specific ventilation may not be a major problem.

As a general rule conventional roof spaces should be ventilated above any insulation. If there is anything to the slopes that might restrict ventilation specific ventilators would normally need to be introduced.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at The Whitworth Co-Partnership for responding to this question.
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SUBJECT:
Cob walls? then limewash
FROM:
Rebecca Blake
(Cornwall)

We are about to start painting the exterior of our grade II listed farmhouse and should like advice about type of paint to be used. The walls are cob and reasonably dry and our builder says they are in good condition.

Rebecca Blake

Cob walls should be rendered with a lime render; if not you could have problems anyway and the paint is immaterial (see other posts on this subject on the Discussion Forum and past Agony Uncle answers).

If the cob is rendered with lime render the only finish suitable is limewash. Prepare the surface by gently washing/cleaning to remove dirt, etc. Repair any loose or damaged areas with lime render. Apply a minimum of 3 coats of limewash and I suspect you may need 5 coats. Apply only one coat per day provided the weather is fair and not raining or too cold (this work should not be done in winter).

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at The Whitworth Co-Partnership for responding to this question.
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SUBJECT:
Lath and plaster and fire regulations
FROM:
Helen Shaw
(Cumbria)

We want to convert our loft into a third bedroom and are coming up on a lot of barriers via building regulations. One major one is the need to ensure that our walls are 30 minute fire safe in the hall and stairway.

It is a late Victorian (1900 ish) sandstone house with lime plaster (I presume the plaster is original as it still has the horse hair in it) and lath and plaster internal walls. The building regulations person says it is up to us to prove that the lath and plaster is 30 minute fireproof, otherwise we have to take it all off and replace it with fire resistant plasterboard, which seems wasteful as well as hard work! Do you know if there have been any fire tests on lath and plaster that we could use as evidence to building regulations?

Helen Shaw

The people to ask would be English Heritage because they have worked with the Building Research Establishment on such matters.

In speaking to my colleagues we would normally assume that if in good condition lath and plaster will give 30 minute protection. However, the critical issue is whether it is in good condition. If there are cracks in it and/or the plaster is loose from the laths it is likely to provide poor resistance. Some Local Authorities have issued guidance (a search on Google produced a few results) and they have slightly differing views. Some (e.g. Cardiff) take the view that lath and plaster will generally fail quickly and to provide fire resistance the assumption is that it has to be overboarded with plasterboard. Others (e.g. Bath) take a slightly more relaxed view, but suggest that overboarding is necessary if the lath and plaster is anything other than perfect.

In your situation I suggest that to remove the lath and plaster before boarding is excessive and unnecessary. However, it may be that you will need to overboard it with plasterboard (12.5mm - screwed through the lath and plaster into the joists/frame behind) to achieve the 30 minute fire resistance required.

Unfortunately the performance of traditional materials in terms of fire resistance and thermal efficiency is a low priority for BRE and others. As a result when it comes to matters such as this the work required to 'comply' is not necessarily very conservation based. Based on the research data available at present it does seem that one cannot assume compliance of traditional materials.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at The Whitworth Co-Partnership for responding to this question.
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SUBJECT:
Laterally penetrating damp?
FROM:
Christine Boulton
(Bristol)

I have tanked & dry lined (1m up) front basement rooms. The basement well is open as per Parker Morris standards. About 5 months post completion damp appeared on the ceiling above the chimney breast which spread downwards. I had the chimney and roof checked. The boroscope showed nothing. There are no pipes anywhere so I had part of ceiling removed. The timbers are dry and there is no sign of leaks or pipework. The chimney breast dried out but damp has now spread towards the front wall and across into the bay. I am told this is lateral penetration but am dubious as first signs of damp were on the ceiling some 6' from front wall. What do you think and what should I do next?

Christine Boulton

I am sorry but this is impossible to resolve without an inspection. However, some comments follow.

Tanking usually involves applying a water resistant render to the wall face and if this is what has been done it could be that any dampness in the wall is being diverted and is finding a route out elsewhere.

You do not say whether the chimney breast is tanked. If so there could be a build-up of water at the base of the chimney (is there a blocked up fireplace that could be acting as a sump for moisture?) and this damp could be finding a way out over and above/around the tanking.

Is this a case of salt contaminated plaster absorbing atmospheric moisture? If so re-plastering may have to be considered.

You need to find someone able to properly investigate the various possible causes and eliminate them until the actual cause is found. You have started this process but it needs to continue. You should accept that the tanking may be the cause and this is something that ought to be checked.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at The Whitworth Co-Partnership for responding to this question.
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SUBJECT:
Which flu liner?
FROM:
Virginia Doran
(Cambridgeshire)

I have a Grade 2 listed thatched cottage and I want to install a multi fuel stove and need advice on which types of flu liner would be safe and appropriate please? My chimney is not lined and used at present as an open fire and we have just recently had it cleaned professionally very recently again.

Virginia Doran

I would tend to avoid a liner that involves pouring concrete into the chimney because this can cause problems and is a very permanent alteration.

A Class 1 liner is essential and a standard flexible liner is acceptable. The important thing to remember however is that there must be good insulation around the liner for its full height.

The insulation would normally help to prevent condensation problems, but in this instance it serves a very important second role - to reduce the risk of heat transference from the liner to the chimney brickwork. With thatched properties sparks are an obvious potential fire risk, but heat is perhaps as much of a problem in that below the thatch is a very dry dusty zone that has a low combustion point that only needs heat to create a fire.

How the void between liner and chimney is insulated depends on various factors. If there are no other fireplaces or holes, etc you could install a register plate at the base and pour insulation such as LECA balls down around the liner. If there are holes, etc you could find a room covered in LECA if you are not careful!

In many instances a good thick wrapping with standard insulating quilt will do the job, but care must be taken as the liner is pulled through to avoid the insulation being pulled off.

An open fire, such as you have at present, is not usually such a problem because the fire draws cold air into it and up the chimney thereby cooling the flue gases, etc much quicker than those from an enclosed burner. However, with thatch I would still think about lining the flue as a precaution.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at The Whitworth Co-Partnership for responding to this question.
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SUBJECT:
Best finish for daub panels that are not covered in lime?
FROM:
Matthew Norris
(Suffolk)

Sorry for the barrage of questions, but I'm a bit stuck...

What is the best finish for daub panels that are not covered in lime? I am experimenting with lime wash, but the results are not great as the straw in the daub is over visible.

Many of the original infill panels in the house have a ~2mm coating/covering over the daub - would this be lime plaster or distemper? These look much better and I'd like to recreate this - any thoughts?

If you think its lime, can you 'skim' lime plaster on to daub, if it does not have the 'finger' holes in the surface to key the plaster?

Finally - would the answers to the above be any different for a bathroom?

Matthew Norris

If, as it seems, you are looking at internal finishes I suggest you consider earth paints (e.g. www.earthbornpaints.co.uk). These have good covering ability and are suitable for internal use (probably better than limewash), are natural and breathable and durable (by all accounts). There have been threads on the Discussion Forum about such paints and I suggest you search the Forum for these and see what others have said.

The present coating is probably a distemper, but without seeing it I cannot say for certain. In modern times there are so many possible finishes that could have been applied including many unsuitable modern paints, etc. as well as the possibility that it has a lime skim over it.

Daub can be prepared and wetted so that a lime plaster skim can be applied, but you will need to ensure that all previous finishes are removed, especially if you are not sure what they are.

I would not regard a bathroom as different. However, if there are areas where the surfaces may suffer direct water (e.g. a shower) you should consider a suitable finish - perhaps even a glass panel - that prevents direct water penetration into the daub. To other areas provided the bathroom is well ventilated and not allowed to suffer a major build-up of condensation there should not be a problem with the finishes.

Period Property UK would like to thank Stephen Boniface, Tony Redman and other partners at The Whitworth Co-Partnership for responding to this question.
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SUBJECT:
"Nice House; Shame about the approach."
FROM:
Martin Wilebore
(Devon)

Our 1860's houses are maintained and good looking. So are the gardens. But outside our gated area is the car park, where the Victorian warehouse is a dilapidated eyesore.

We have tried to sell our house in the past two months. 20 viewings all said 'lovely house; hate the approach'.

The warehouse owner is not interested in being a good neighbour. Trees grow out of the walls and gutters, broken windows, etc.

What can we do to make him clean up his act?

The council are not very proactive: planning are about to allow bulldozers to rip up the Plympton Priory national monument just a few feet away, for housing.

Martin Wilebore

I sympathise with your problem. Too often lovely houses are spoilt by poorly maintained neighbouring houses and sites.

However, this is more of a legal question. I suggest you seek some legal advice but a web site you might find useful is www.boundary-problems.co.uk.

If the trees, etc are over-hanging the boundary you have the right to cut back the over-hanging parts to the boundary line (provided that in so doing you do not kill off the tree/vegetation). You have to give (offer back) the neighbour the branches, etc that you have cut off.

If you have the space you could consider erecting a more attractive boundary feature within your site to screen the offending area. Such a screen could be natural (trees, bamboo, etc) or some form of fence or a combination of both. Provided it is within your site and does not exceed the heights now stipulated by law there is nothing he can do to stop you screening his building.

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