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).

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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:
Stained new bricks blend in beautifully
FROM:
Michael Groom
(Hertfordshire)

Recently a car hit my neighbour's grade 2-listed house, and a section of the house had to be demolished and rebuilt. To my horror they used new bricks, but then stained them to colour match the existing brickwork and mortar. The result is amazing and it is impossible to tell where the repair was made. I want to know how this is done because I also have some brickwork I need to match.

Michael Groom

There is generally no problem with using new bricks to repair an historic building provided the bricks are a reasonable match for the originals where possible. There are a number of brick manufacturers around the country who are able to match older bricks. Of course new bricks do tend to stand out rather because they have not become dirty with age or worn by weathering etc. A certain amount of distressing can blend in new work to old. There are a number of ways of creating slightly dirty finishes to bricks including use of cold tea and dirty water etc. If lichen is required on the surface natural yoghurt could be applied to encourage the lichen growth.

However, if the new bricks are significantly different to the original and are then stained or coloured in some way to blend them in this is a different technique altogether. There may be occasions where it is necessary to use a different brick that is then coloured or stained to blend it in. This is not the preferred method when dealing with conservation and is not necessarily best practice. Nonetheless it is something that can be done.

Without knowing precisely what the builders used I cannot provide detailed advice but there are various stains and colour washes for brickwork that can help change their colour to match surrounding brickwork. There may be an element of trial and error to get the right colour if you do the work yourself. Further, care has to be taken to ensure that the stain or colour is applied only to the brick face and not across the mortar joint as well.

If you have new brickwork that has already been constructed and you wish to blend this in to older brickwork and the difference is significant it may be appropriate to use staining or colouring materials. If you search the internet looking for 'brick colouring' you will find a number of companies able to colour and stain bricks.

This is not something I would normally condone as the best action to take when dealing with an historic building but in some instances it may be appropriate where the building already has some mismatched brickwork from the recent past that needs attention.

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:
Does whitewash need to be removed before decorating?
FROM:
Isabel Wallace
(Nottinghamshire)

I need to either seal or remove whitewash from an entire cottage prior to re-decorating. What do you advise?

Isabel Wallace

It would be inappropriate to seal the whitewash because to do so would change the surface from being breathable to non-breathable and this could ultimately have a detrimental affect on the performance of the wall structure in terms of managing dampness. Further, if the whitewash is poorly adhered to the original substrate any sealant could exacerbate the problem and the new decorating will simply peel off in future.

You might find that gentle washing and a bristle brush will take some of the whitewash off but I suspect you may need to use chemical removal methods and in this regard I suggest you contact Strippers Paint Removers (based just outside Sudbury in Suffolk).

You mention redecorating and by this I hope you mean a fresh application of whitewash rather than modern masonry paint. Modern masonry paints are not usually appropriate for historic brickwork or stonework and should therefore be avoided.

In fact, if you are to use traditional limewash on top of what exists you may not have to remove it at all but simply take off flaking material by gentle brushing and washing down prior to application of fresh limewash that should then adhere satisfactorily and last for a number of years before fresh applications are then required again.

If you go to the discussion forum of this website you will find many postings about treatment of elevations in terms of decorations etc.

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:
Do I want a smooth or bumpy finish?
FROM:
Karolina Kliskey
(Oxfordshire)

Having moved into our three storey Victorian town house 8 months ago, we have decided it is time to redecorate the very dated living/dining area. We have removed the many layers of wall paper and are now down to the bare lime plaster. The ceiling in the front room is damaged in a few places but in the back room there has obviously been much water damage and we believe it needs to be replaced. The walls themselves are quite crumbly in a number of places and in some places it is right down to the brick work.

We would love to have a smooth wall to paint and have invited to plasterers to quote for the work. The first plasterer said he would replaster the areas that are down to brick and then skim the rest of the room for an all over uniform smooth finish. The second plasterer wants to use lime as much as possible. He wants to leave the intact limed walls as they are and just fill in any lumps and bumps. I want to do what is best for the house but at the same time I want a smooth finish. Can you tell me what the disadvantages of using modern plaster in a Victorian house are? What would happen if you skimmed over existing lime plaster?

Karolina Kliskey

A skim coat is a thin layer of lime that is 'floated' and sometimes polished to give a smooth appearance and flat surface for any decoration. Traditionally this final skim finish was lime plaster whereas with modern properties a modern plaster is used.

Whether you use modern plaster or traditional lime plaster a skim coat will fail if the wall is not properly prepared in advance and all previous finishes (paint, paper, etc) removed, loose material taken away and any holes etc. patched to provide a basic satisfactory coat onto which the skim can be applied.

It is likely that if a modern skim is applied to the old surfaces the plasterer will want to seal the surface first with a watered down Unibond mix or something similar. With traditional surfaces this affects the breathability of the plaster and in some older buildings this can be detrimental. In a Victorian building such as you describe it is questionable as to whether breathability is as vital to the performance of the building. Nonetheless, the use of a modern plaster with a sealant is a fundamental change in how the wall is finished and performs. That said it is quite common for Victorian and Edwardian properties originally with traditional lime plaster to be skimmed with modern plaster to provide an improved smooth finish. Such a method can be successful and in many of the Victorian and Edwardian properties I have inspected I often find modern plaster used to skim an old surface and this can then remain in place satisfactorily for many years.

However, it is far preferable to retain the breathable quality of the wall and a lime plaster skim over the surface will be a more successful finish if applied properly simply because lime plaster onto old lime plaster will tend to work better provided the substrate is properly prepared and the work is undertaken to a good standard.

I hope the above gives you a better understanding of the fact that either could be successful but a lot depends on the preparation of the wall before any work takes place. It is preferable to use traditional materials but in a Victorian townhouse I doubt whether the breathability provided by the lime plaster skim is particularly critical to the performance of the building. With older buildings (and timber framed or cob buildings) my advice would be different in that I would be more insistent on using traditional lime plaster because of the need for breathability.

Remember also that some modern plasters readily absorb damp and are then detrimentally affected by damp, whereas lime plaster tends to manage damp. Lime is a better material, in my opinion, where there is a risk of damp.

The implication of your question is however that it is not possible to achieve such a smooth finish with lime plaster as with modern plaster. This is simply untrue. Most old buildings with lime plaster have suffered movement and poor repairs over the years that have resulted in uneven finishes etc. The unevenness we now see is not necessarily the nature of the plaster or poor plaster work but simply due to age. A building with freshly applied lime plaster can have walls that are as smooth as any modern plaster. It is not the material that is the issue but more to do with the skill of the person applying it.

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:
How do I repair & preserve my concrete repaired beams?
FROM:
Alex Ford
(Berkshire)

We have a timber framed building and some of the timbers on the end of the house have been battered by the weather and have become pitted and started to rot. Previous owners of the house have painted the beams and covered parts of them in concrete (they loved their concrete render!). Obviously the concrete has come off but what can I do to repair and protect the beams from further damage. Can I use a regular wood filler to fill the pits and will paint be acceptable and if so what type would be best?

Alex Ford

We should firstly start by differentiating between weathering and rot. Some heavily weathered timbers can have very deep erosions along the grain where the softer parts of the wood have weathered away and the harder sections remain proud. This weathering is not the same as rot. Of course, over many, many years the end effect can be the same that a severely weathered piece of timber will gradually lose its strength and will deteriorate much the same as a rotten piece of timber. The main issue is the mechanism that causes it. What you describe suggests to me that you have both weathered and perhaps rotten timbers.

Where a timber is simply weathered and looks gnarled and undulates because of weathering there is rarely much that needs to be done about it. Over time the weathering will cause degradation and some replacement of timber and perhaps re-facing of the timber might be appropriate but it depends on the circumstances.

Where there is an active rot problem this is a different situation altogether because the timber is prematurely degrading due to the rot and there is a serious problem of dampness that has created conditions whereby the rot can flourish. From what you describe I would suggest the first thing to be done would be to remove the concrete and inappropriate finishes to reveal the timbers and investigate the true extent of actual failure. Once this has been done you can then establish whether timbers require replacement or strengthening in-situ. There are various methods by which timber frames can be repaired and specific timber elements replaced, strengthened or repaired by some method. Without seeing the property and establishing precisely where the damage is occurring, the extent and how that element of the frame affects the rest of the structure it is difficult to advise remotely on the best method of repair.

You mention that the exposed frame has been painted. This will exacerbate any rot problem because the paint will prevent the timber from breathing and any moisture that gets behind becomes trapped and therefore increases the risk of rot occurring. If there is already rot it will simply cause it to spread further to areas where there is trapped dampness. It is my opinion that exposed timber frames are better having the paint removed if indeed it is an impermeable modern paint.

We must here differentiate between joinery and a timber frame. Window and door joinery is planed to a very smooth finish and is usually designed to accept a paint finish that is regularly re-applied to protect the timber and prevent rot. However, with a timber frame the finish is not planed and it is therefore extremely difficult to ensure the paint completely covers the whole of the timber surface. It is also a far more extensive exercise to keep repainting the timber to provide adequate protection. I have no problem in advising the use of conventional paint finishes for joinery but have a great aversion to using those same paints on timber frames. I would rather see the paint removed (preferably by chemical means) and the timbers either left exposed or perhaps oiled (e.g. linseed oil). If the other elements to the elevation (rendered panels etc.) are lime washed you could consider lime washing over the timber as well to provide a finish to the timber. This is increasingly popular and has been used on quite prominent buildings such as the Guildhall at Thaxted. Of course the existing paint finish would have to be removed first.

In terms of filling the undulations I would advise you to avoid doing so. If there are serious gaps in the frame you might need to consider splicing in some pieces of timber to help prevent unnecessary water ingress to heavily weathered areas but generally speaking I would not normally advise filling weathered timber.

Where some of the timbers are laid horizontally and there is a risk of water laying in the recesses of the weathered grain it might be appropriate to provide a protective cap at the top edge. Sometimes a neat lead cap can usefully be installed in such situations.

This reply is deliberately vague because it is difficult to provide an answer that would apply to every situation. There are so many variables that your situation would need to be specifically inspected and advice given. As far as general guidance is concerned it is important to remove any concrete or cement based product or anything that prevents breathability, to repair timbers that are truly rotten and to assess weathered timbers as to whether they do need attention and therefore repair the frame before finishing it in a suitable method that allows breathability and this therefore does not include ordinary modern paints.

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:
How do we stop getting wet in exposed position?
FROM:
Rachel Lawrence
(Gwent)

We have a barn on top of a hill in Wales, exposed on all sides.

Our SW facing walls cannot cope with the amount of water that hits them (especially as they are not getting the chance to dry out in summer in the last two years).

This has led to water coming in through our electrical sockets which is undesirable and mould and water staining on the walls. Because of the exposure and the rocketing cost of heating oil we also want to insulate this end of the building to retain a warmer environment, reduce heating bills and hopefully do away with the mould problem.

We thought that we could create a stud wall which we then insulated (leaving a gap between the wall and the insulation), then battened the insulation, then boarded and plastered.

I have found that you can lime plaster onto Heraklith board and that it is breathable and anti fungal.

Can you offer any advice on the best type of insulation to use with the Heraklith and also what ‘ventilated dry lining’ is? Our concerns are obviously that we trap water in between the dry lining and the old wall.

Rachel Lawrence

You do not say how old the barn is or what construction it has been formed from. If you have walls that are struggling to cope with the exposure and rain thrown at them I would suggest that my first thoughts would be to provide a cladding externally that will help protect the walls and prevent such water penetration whilst at the same time allowing breathability. I am thinking here of some form of a hung cladding such as weatherboard, slate or tile. Of course if the building is listed you will need consent and this approach could radically change the appearance of the building that may be undesirable. Without knowing more about the building I cannot comment specifically but I would advise that your first thought should be to consider how to stop the excess water penetrating but at the same time retaining a degree of breathability to the wall.

The water coming in through sockets is a serious problem and indicates that the walls may be very wet in places and at certain times. To provide absolute protection from this I would suggest that you will need to create, if the water is not prevented from coming in (i.e. by external cladding), a completely false wall so that any water that comes through the wall can run down the internal face and away before it causes any damage. How much of a gap and what form the false wall takes is a matter dependant upon the nature of the structure, the amount of space you have, the appearance etc. It is certainly possible to create a false internal wall (or stud wall) which can be insulated and which leaves a gap between the wall and the insulation etc.

As far as insulation is concerned I would suggest that you need to think about something that can be held in place or is semi-rigid because it will need to be fixed vertically. Provided the original wall surface is breathable and the water can come through onto the internal face of that wall and then drain away (you will need to ensure some form of drainage at the base of the wall) the issue of breathability to the internal false wall is not such a problem. Provided the gap is ventilated and drained the stud or false wall can be formed of whatever seems most appropriate.

You could also consider the use of insulated lime plaster. Various experiments are taking place using insulating aggregates with lime to create a lime plaster that provides a good insulating quality.

Companies that may be able to help you include Anglia Lime (presently experimenting with insulated plaster) and Ty-Mawr who may be quite local to you and may be prepared to come on site and advise in specific detail.

I hope the above advice is of some use. Apologies for it being rather vague in places but it seems you may have two problems to approach, one is the issue of excess water getting into the wall and the other is to insulate the wall internally.

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:
Help - everything is turning mouldy!
FROM:
S Bush
(Worcestershire)

We live a Grade II listed thatched property. Last year the property was flooded. The floor in the first part of the lounge was replaced and the walls downstairs were done with lime plaster and specialist water based paint. We moved back into our property in March this year and everything seems fine. However in the last month or so I have noticed that upstairs all cloths in the wardrobes are going mouldy and there is mould growing on the wardrobes as well. Some of the wardrobes are touching the outside walls but some are not. I am not sure how to solve the problem. Although the walls downstairs are plastered with lime plaster, upstairs they are not.

S Bush

What you describe is fairly typical of a condensation problem. The mould growing occurs when condensation forms on the surfaces and stays there for some while.

You mentioned that the property was flooded and therefore an excessive amount of water would have got into the property and into the fabric of the structure. It may well be that the works to the ground floor are sufficiently breathable to allow moisture to escape and for the problem to be either non-existent or hardly noticeable. It is likely that the ground floor is well ventilated and therefore any excessive moisture remaining in the property will escape.

At first floor level it is not clear how the walls are finished but if with modern plasters and finishes it could be that when the property flooded and got wet that moisture remains trapped behind some of the surfaces. There is probably an excessive amount of moisture in the atmosphere in the building and within the fabric and this is then leading to condensation because the moisture cannot escape in some areas such as wardrobes.

I suggest that you open up the wardrobes and cupboards and install dehumidifiers for a while to try and extract more of the moisture because it sounds to me as if the property was not thoroughly dried out after the flood. You might need to do this for a month or more.

You need to consider what finishes exist to the first floor walls and whether you might need to change to traditional lime plaster etc.

Obviously all your clothes and belongings need to be cleaned and the areas within the wardrobes etc disinfected.

Once they are fully dried out it should be possible to re-use the wardrobes and cupboards but I suggest you consider putting some ventilation holes in them or on an almost daily basis, leaving doors open to ventilate the areas and help prevent a build-up of trapped moisture that will eventually lead to condensation and mould again in future if you are not careful.

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:
How should we hide our oak frame shakes?
FROM:
Rosemary Ryan
(Suffolk)

Our 15th century Grade II listed Suffolk cottage has recently been fortified by bolting/bars using suitably 'distressed/aged/ ironwork

Now the building is secure, we'd like to fill the large splits with a suitable plaster. Some of these splits run for several feet in length, are up to 10cm wide and penetrate the beams by 15cm.

What would you recommend?

Rosemary Ryan

It is not clear from your question how the beams are finished. If the beams are a natural timber finish fill them with plaster would not leave a particularly desirable appearance. You might want to consider carefully splicing in pieces of oak into the larger splits. However, if the beams are finished with plaster or lime wash in some way then a lime plaster might be appropriate. However, it would be sensible to consider adding linseed oil to create something like a putty as this might be more suitable for plugging the gaps. Even so, the depth you mention is quite substantial and I would be concerned that the plaster to the innermost sections would not properly cure.

I believe there have been postings regarding similar problems on the discussion forum to this site and I suggest you do a search on the discussion forum because this is quite a common problem. The solution depends very much on what finished appearance you want and provided you don't cause more damage to the original fabric. My preference would be to try to splice in pieces of timber and in some areas simply leave the shakes as part of the character and accept the shakes for what they are. However, some plaster mixes might be appropriate as indicated above.

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:
Unprofessional repair leads to bottom of villa being covered in glue and re-coated in sand.
FROM:
Liz Wilson
(Central Scotland)

We recently had a very unprofessional job done on the bottom half of our sandstone semi villa. The company spread some sort of glue on top of the sandstone and then recoated it with sand - basically threw sand at it!! The result is awful with the lower half now looking completely different from the top half - and the rest of the houses in our street. Additionally, there has been no attempt to leave the pointing between the sandstone exposed.

Can we do anything to take it all back off?

Liz Wilson

My concern with your problem is that whatever you do could result in quite extensive damage to the face of the sandstone. Once something has been fixed to sandstone so permanently its removal will often then result in part of the sandstone coming away as well because sandstone is quite soft.

What you describe sounds as if it might be some form of bitumen but I could be wrong as you do not describe the "glue". I suspect that the only way to get this off will be with some form of solvent that will dissolve the glue away. However, great care will need to be exercised in any form of removal if the sandstone behind is not permanently damaged. If a solvent is used to dissolve the glue the sandstone might absorb it into the body of the sandstone and therefore great care needs to be taken in ensuring that the solvent is used in localised areas so the glue is completely removed straight away and is not allowed to soak into the sandstone.

You do not say why the company undertook the work and what problems they thought they were trying to resolve. How you resolve any problems with the sandstone once this finish has been removed is another matter entirely. I suggest you find a local mason who can provide independent professional advice on what might be best for your sandstone.

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