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 Poor flashing leads to water ingress Mike Foster (Greater London)
o Earthy smells cannot escape from rooms Nigel Pearson (Shrewsbury)
o Professional advice to stop weathering of stone Stephen Cooper (Somerset)
o Traditional limewash provides better solution than PVA Tony Corr (Warwickshire)
o Official advice required before change of use Sandra Evans (Gwynedd County)
o Conservation requirements make roof ventilation difficult David Ramage (Dumfries and Galloway)
o Roof insulation also requires ventilation Andy Haynes (Oxfordshire)
o Asbestos tiles lead to possible concerns Julie Revans (Bristol)
o Don't hide damp deal with it at source John Albury (Gloucestershire)
o Underpinning leads to insurance problems Stuart Bell (Somerset)
o Crazy cracking requires raking & filling Sidney Jevons (Wiltshire)
o Potential purchaser faced with cannibalised stone barn Name Withdrawn (Cornwall)
o Removal of concrete screed reveals brick floor Rob & Katie Blair (Leicestershire)
o Hi-tech imaging equipment can reveal property's structure. Nick Bell (Cambridgeshire)
o Iron stains on lime walls John Galloway (Highlands and Islands)
o Can I insert a dpc in clay lump? Chris Groves (Norfolk)
o Towering Chimneys provide home for giant birds Elisa Smith (Lincolnshire)
o Lime Source Tracy Knight (Hampshire)
o Stripping in front of the fireplace Janet Shaw (London)
o Local conservation officer should have the contacts Hugh Zocher (London)
o Dusty pamments need more appeal Stephen Clabburn (Brundish)
o Sources of salvage in London Lisa Reynolds (London)
o Quarry tile floor needs sparkle Ainsley Williams (Worcestershire)
o Dirty limewash in cellar Bryan Sadler (Lancaster)
o Cob shows signs of wear & tear Louise Farrand (Dorset)
o Listed building planning permission required Chris Walsh (Clwyd)
o High ground levels cause penetrating damp Jeremy Bullock (Berkshire)
o Damp floor may lead to un-doing of previous work Claire Greene (Buckinghamshire)
o Timber floors need sprucing up Anna Erken (Gloucestershire)
o How far should I go in removing internal plaster? Alec Gunner (Cambridgeshire)
o Lime source Alison Burleigh (East Sussex)
o Crumbling Cobble Martyn James (East Sussex)
o Metal framed windows cause dilemma Lee Pearce (Essex)
o Stain barrier Mary Page (Lincolnshire)
o Have we really got rising damp Sonia Fagan (Norfolk)
o Use of mastic in timber frame house causes alarm Philip Degg (Staffordshire)

SUBJECT: Poor flashing leads to water ingress
FROM: Mike Foster (Greater London)
I am currently in the process of re-insulating my loft. I happened to be up there this rain drenched weekend, laying my foil lined moisture barrier, when I noticed a pool of water on one of the boards I was using as a platform. It seems there is a leak down the side of a chimney breast, looking out my skylight I see the flashing has been fitted under the tiling, is this normal? Surely the idea of flashing is to provide a run-off for water from the chimney breast to the tiles not under the tiles. A run off for water from the chimney breast to the tiles has been created using cement. This has worked loose over time and water is leaking through here. I have a saturated joist, will this dry over time? Will the rain damage the wood irreparably? Are there any mastic sealants I could use to provide a temporary fix? What is the best course of action to take?

Mike Foster

A flashing is intended to direct water away from an abutment. However, there are various ways to form abutments. One can simply have a flashing inserted over the tiles or one can have soakers interlinked with tile and then with a cover flashing over. One could have soakers finished with a mortar fillet. However, the mortar fillet should be of a lime mortar mix (hydraulic lime in an exposed location such as a chimney), as this retains a degree of flexibility and will not readily crack. The important thing is that the water is directed away. If this is not happening then the flashing etc. has been fitted incorrectly. It sounds to me like you have a soaker and fillet arrangement where the fillet has come away. The junction needs to be properly re-formed. The lead soakers should interlink with tiles, not simply sit under them. The fillet should be of hydraulic lime mortar (using a sharp sand not soft building sand). I would not recommend a mastic sealant unless purely as a temporary measure until you can get the work undertaken properly. However, beware in case the sealant is smeared all over and then leaves a nasty visible mark when the proper repair is undertaken. The timbers should eventually dry out provided there is good ventilation - keep an eye on them as they dry. You mention you were laying insulation. I hope that the roof is either not lined (thus providing good natural ventilation) or that there is plenty of good ventilation (by proprietary ventilators)!

Period Property UK would like to thank Stephen Boniface Associates for answering this question. Stephen Boniface can be contacted on 01279 421 509


SUBJECT: Earthy smells cannot escape from rooms
FROM: Nigel Pearson (Shrewsbury)
I own an Edwardian House built in 1902. Both the front rooms have floor boards about 1 metre above the ground (earth. All the air bricks are open and clear (they were not when we brought the house 3 years ago). We live in a damp area and have had new plaster and damp proofing as part of a renovation 2 years ago. In one room in particular, when shut up for a few hours we get an earthy smell - which clears when the room is aired. Is there anything else we can do ?

Nigel Pearson

Not really. The dense plaster used following the damp treatment will encourage condensation and moisture will be unable to simply permeate through and evaporate. Provided you have good sub-floor ventilation, it seems most likely that the problem is moisture from below the floor natural permeating through into the room and then being unable to escape so forming condensation (not always visible) on the wall surfaces. It might help to remove the plaster system applied after the damp treatment and revert to traditional lime plaster systems, as these would allow the walls and surfaces to breathe. However, for the time being I suggest that you try to ventilate the room more frequently.

Period Property UK would like to thank Stephen Boniface Associates for answering this question. Stephen Boniface can be contacted on 01279 421 509


SUBJECT: Professional advice to stop weathering of stone
FROM: Stephen Cooper (Taunton, Somerset)
I am in the process of purchasing a grade II listed building that is built of blue Lias stone. The stone is heavily weathered and flaky. Is there a recommend treatment that can be used to protect the stone from further deterioration? Could you also tell me what the recommended mix would be for relaying stone of this nature?

Stephen Cooper

Blue Lias is notorious for this. You must not try to seal it or coat it with anything that is likely to seal in moisture, as this would exacerbate the problem. Lime mortar, plasters, etc. in the traditional manner would be most appropriate for repairs, etc. It might help to give the stone a 'shelter coat' of lime wash. You should seek further specialist advice. There is a firm of surveyors in Frome you could contact: The Hartley Conservation Partnership on 01373 466618 (Email: or Web: Another firm would be Philip Hughes Associates based in Galhampton on 01963 440359. These are firms with RICS accredited conservation surveyors.

Period Property UK would like to thank Stephen Boniface Associates for answering this question. Stephen Boniface can be contacted on 01279 421 509


SUBJECT: Traditional limewash provides better solution than PVA
FROM: Tony Corr (Stratford on Avon)
We have looked everywhere, but cannot find advice on treating the interior wall of an old stone walled cottage. The treatment we are seeking is to prevent so much dust coming off the stones. We thought that some sort of PVA would be suitable, but do not wish to change the appearance of the wall (no "sheen" required). Any advice would be most appreciated.

Tony Corr

The use of PVA would effectively seal the surface and increase the risk of problems related to moisture becoming trapped in the wall. The only treatment I would suggest is the use of a traditional lime wash, which can be coloured with pigments to give a decorative finish, if desired. This would provide a protective coat but allowing the wall to breathe.

Period Property UK would like to thank Stephen Boniface Associates for answering this question. Stephen Boniface can be contacted on 01279 421 509


SUBJECT: Official advice required before change of use
FROM: Sandra Evans (Bala, Gwynedd County)
We are about to purchase an old stone/slate farmhouse. Attached to the house are a number of buildings which were used to house farmhands and pigs. We have been told that as the buildings are actually attached to the main house it would be OK to refurbish and turn them back into living accommodation without actually requiring planning permission. I would appreciate your views?

Sandra Evans

Whenever such a scheme is being considered you should speak informally with the Local Authority planners in case you need to obtain consent. It would be foolhardy to do otherwise. If the property is listed the works will almost certainly require listed building consent and to undertake the work without consent is a CRIMINAL offence. You need to speak to the Conservation Officer about this. Therefore, a meeting with the Planner and Conservation Officer would be appropriate, at which your proposals can be informally considered and they can provide advice and guidance.

Period Property UK would like to thank Stephen Boniface Associates for answering this question. Stephen Boniface can be contacted on 01279 421 509


SUBJECT: Conservation requirements make roof ventilation difficult
FROM: David Ramage (Castle Douglas, Dumfries and Galloway)
I own an 'A' listed 18th century mill in SW Scotland which has planning permission for conversion into a four bedroom house. The roof construction is of traditional slate direct on to sarking with a sandstone ridge. In order to comply with building regulation I need to find some way of ventilating the roof but to keep Historic Scotland happy I cannot alter the original construction by using vented slates or by raising the ridge and using eaves vents. Would a breather membrane be the way forward and if so can the membrane go direct onto the sarking of a cold roof design ?

David Ramage

Historic Scotland can provide full guidance on this. Here in the south of England I would be advising the omission of the sarking altogether, as this provides good natural ventilation. However, in Scotland the climate may require the sarking to be included. That said, there are some 'in-line' ventilators now on the market that slip between the courses and are hardly visible. They do not raise the roof line. An alternative may be to use a disused chimney flue as a ventilation duct, by opening up an opening in the roof space into the chimney flue and letting the flue act as the ventilator. These are matters that are best dealt with by face-to-face discussion with the Officers concerned. Most would be happy to provide assistance on such details.

Period Property UK would like to thank Stephen Boniface Associates for answering this question. Stephen Boniface can be contacted on 01279 421 509


SUBJECT: Roof insulation also requires ventilation
FROM: Andy Haynes (Oxfordshire)
We have a three storey, Victorian mid-terrace house. The third floor is an original attic room with dormer window. The roof has no real insulation and consequently the room has a greater daily temperature range than the rest of the house. The ceiling is lath & plaster, and the loft space is the small roof apex and contains the water tanks. The loft floor, tanks and rafters have been insulated by a previous occupant with fibre glass, creating a warm roof, albeit only in the vicinity of the tanks. What would you say might be the best way to put in efficient and cost effective ceiling/roof insulation? What potential pitfalls are there? What sort of contractor would be most suitable for this work? I have not had much joy using the yellow pages.

Andy Haynes

You need to try to include the loft room into the 'warm' part of the house. You will probably have to take out the insulation in the floor. There are various ways you could then insulate up the walls and over the roof space to create insulation up and over the roof area. Any vertical or sloping insulation should be carried out with a semi-rigid material to prevent the risk of it slumping. However, whenever considering insulation you must also consider ventilation. Failure to do so would usually result in condensation problems. An RICS accredited conservation surveyor in your area would be Richard Oxley of Oxley Conservation and he may be able to help further. His number is 01491 682288 and his Email is:


Period Property UK would like to thank Stephen Boniface Associates for answering this question. Stephen Boniface can be contacted on 01279 421 509


SUBJECT: Asbestos tiles lead to possible concerns
FROM: Julie Revans (Bristol)
I would be very grateful if you could give me your opinion about a property I am thinking of purchasing that has an asbestos roof. It is a 1930s end of terrace property of four houses. They have asbestos roof tiles. My valuation survey has noted that" the main asbestos slated roof covering appeared to be reaching the end of its useful life and its replacement will be necessary. In view of its asbestos content an approved contractor will be necessary for its disposal and this will prove expensive." I was in the process of buying this house and now that I have received this survey I am starting to have major concerns about this roof that they think was put on in the 1960s. It is very difficult to get an unbiased opinion and wondered if you had come across any similar properties/situations? I would be grateful if you could advise me - should I not touch this property with a barge pole or should I be relatively unconcerned?

Julie Revans

The asbestos cement slate is a common roofing material. The surveyor is correct to point out the need to use an approved contractor for its removal. However, you should be aware that the type of asbestos used in the slates is usually the least hazardous form. Many surveyors (particularly mortgage valuers) tend to use the phrase 'reaching the end of its useful life' when they are not sure and want to protect themselves from being sued later. You could find out the manufacturer of the slate and ask them for an opinion on when the covering might need to be replaced. However, the earlier man-made asbestos based slates do tend to have a relatively short life and it would not surprise me to find that the covering will need replacement perhaps within the next five to ten years, if not sooner. You should simply obtain some quotes from a roofing contractor for the removal and re-covering of the roof. The contractor should arrange for the removal of the asbestos slate and include this in the price. You will then have a figure to use in negotiating with the vendor. A competent and honest contractor can also give guidance on when replacement is likely to be necessary. If it is only the roof covering that contains asbestos and is causing concern I suggest that it is simply a matter of negotiating a price reduction to take account of the need to eventually re-cover the roof; the reduction to reflect the need to use an approved contractor for the removal of the asbestos slate.

Period Property UK would like to thank Stephen Boniface Associates for answering this question. Stephen Boniface can be contacted on 01279 421 509


SUBJECT: Don't hide damp deal with it at source
FROM: John Albury (Gloucestershire)
We live in an old Victorian school. Some months ago we had a tiled floor laid on a damproof membrane in a downstairs cloakroom with a few small areas of plaster on an outside wall to make good, before replacing the skirting board. After a few weeks I re-papered the wall after applying some damp proof coating (a product called Sealdamp). Some kind of damp has now come through & discoloured & stained the wallpaper around about the areas that had new plaster. My builder & a damp specialist say that the remedy could be to apply a thin foil product called Foildamp to hold back any damp from the paper. Apparently this Foildamp is applied like wallpaper with a special adhesive then the wallpaper applied on top in the normal way. Can you tell me a supplier of this material as nobody seems to know where to purchase it.

John Albury

Do not do it!! The approach is, in my view, fundamentally wrong. It sounds like a problem of dampness being driven in new areas because of work already undertaken. You need specialist INDEPENDENT advice. The work you mention is likely to compound the problem. It may be that you have to take out what has already been done. This type of property would normally need to be able to breathe in the traditional manner. Instead of trying to keep moisture out (which invariably fails in older buildings) it is better to manage the moisture in the traditional manner using lime. To deal with your specific problem you need someone independent to inspect and advise. RICS accredited conservation surveyors in your region are: Henry Russell (01608 643087 -Email: or Peter Rhodes (01386 446623 - Email See other articles and answers on this web site relating to damp problems.

Period Property UK would like to thank Stephen Boniface Associates for answering this question. Stephen Boniface can be contacted on 01279 421 500