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:
How do I insulate timber framed wall?
FROM:
Paul Downham
(Essex)

I have a timber framed cottage that is heavily beamed inside. I am renewing a fair amount of the oak uprights during restoration. I need to insulate the cottage, from the outside as I wish to keep the beams inside on show. I am thinking of using lambswool insulation but what I need is some advice as to the construction in order to insulate the walls. Do I brace the beams from the outside with ply, add some batons for the insulation to sit in, apply some more ply then cross baton, lathe and lime render? What would all of this extra depth to the property sit on? I wish to keep the property breathable but I am a little stuck.

Paul Downham

Without more detailed information on the precise construction, dimensions of timbers, etc. I cannot be too specific.

Any application externally would increase the overall thickness of the wall. The increase will depend on what thickness of Thermafleece (trade name) you use, but the minimum is 50mm. This would of course impact on all windows, doors, roof eaves, etc., etc.

You could apply ply on the outer face of the frame, but is this the best solution? If it is appropriate you could indeed batten and counter-batten over this, as you mention. The web sites mentioned below give some indication of applications for Thermafleece.

Alternatively, you could install battens and reedmat or clayboard between the frame members (lime plaster internally) thus leaving the timbers exposed internally but reducing the depth of the timber exposed. The insulation would then be installed with whatever external finish you intend and the impact on the external face may be less than a system that is completely on the outside of the frame (e.g. the ply on the outer face of the frame). However, the timbers may be of insufficient depth for this.

Whatever you do, if the cottage is listed you will need consent for the work.

You talk about 'bracing' the frame with ply. If the frame lacks bracing then adding ply to the face is a method that could be used. Alternatively, could you reinstate original braces or something closer to original bracing methods? It is important for the integrity of the frame that you ensure it is braced in some way, but the best method is something that needs to be assessed from a site inspection. You should consider seeking professional advice from a Building Surveyor or Architect experienced in dealing with historic buildings.

The web site www.greenbuildingstore.co.uk has more information on Thermafleece. The Period Property Shop web site (www.periodpropertyshop.co.uk) also has some information on Thermefleec as well as information on Reedmat and Clayboard.

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:
Pocket Shutters. How do we open them?
FROM:
Christopher McLoughlin
(Greater Manchester)

My partner and I have recently acquired an apartment in a Grade II listed house dating from 1850. We are keen to be able to open the pocket shutters in the bay window in the bedroom, but these have unfortunately been very securely nailed shut.

We have been able to open the pocket shutters in the bay window in the living room by sawing through the nails with a hacksaw blade, but the nails were driven into the side of the pocket (at right angles to the shutters), whereas the shutters in the bedroom have been nailed shut both at right angles and directly through the shutters themselves.

I wonder therefore if you would be able to recommend either a course of action we could take or a specialist we could contact about this problem, as we obviously do not wish to damage the pocket shutters.

Christopher McLoughlin

There is no easy answer. To remove the nails you need to be able to grip the head to withdraw it, or get through to the side of it to cut through it. You have apparently been successful in one area. If you cannot cut through you will have to get to the nail head. This may involve very careful cutting away of the wood by the head until you can grip it. This will leave an indentation that will need filling or a small piece of wood splicing in.

An alternative is to drill out the nail using a drill bit intended for use on metal. Use a drill slightly larger than the nail and drill straight through it. This will then leave a hole that would need to be filled in some way. A variation on this is to use a core drill that would cut around the nail and take a core of the timber out. This again would leave a hole to be filled in some way.

I know recycling facilities have large magnets for drawing nails, screws, etc. from wood intended for re-use, but I do not know of a domestic application. If there are any budding inventors out there I am sure there would be a market for a hand held magnetic device that draws out nails and screws without damaging the wood.

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:
To HIP or not to HIP
FROM:
Sean Hunter
(Cheshire)

Do listed buildings require the new HIP pack ?

Sean Hunter

Yes.

There is no exemption. There has been much discussion about the HIP on the Discussion Forum of this web site.

At present the only content of the HIP that may cause a problem for a listed building is the Energy Performance Certificate (EPC). There is much research being carried out by English Heritage in particular about giving guidance on how best to deal with energy performance when dealing with historic buildings. The publication is due soon. When I know more I will post on the Discussion Forum.

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:
Should I follow advice and inject a DPC in an old Cob wall
FROM:
Richard Bence
(Greater London)

I am considering purchasing a farm in Devon which has a cob wall. However the survey found issues with damp. The cob wall is rendered on the outside with cement and coated in a weatherproof paint. The inside wall looks like it has cement plaster on it and two floors in the building have been renewed using a concrete screed presumably with a plastic membrane.

I have read pieces of literature from Devon Earth Building Association suggesting that the outside render needs removing and restoring with lime. However a preservation company has suggested just removing the plaster internally up to a height of one metre and then injecting a damp proof course. The internal plaster would the be replaced with cement based one.

I am utterly confused as to what the potential problems are, the direction to take and what insurance implications there may be in taking on the property.

Richard Bence

Please, please do not inject the wall and plaster with modern materials. This would be a certain way of shortening the life of the cob and causing serious problems.

Look at the guidance from DEBA and look also at EARTHA (www.eartha.org.uk). The Institute of Historic Building Conservation (www.ihbc.org.uk) also produce a guidance note.

Please listen to those who really understand and specialise with such buildings, not companies only interested in selling a product.

The use of modern treatments on cob walls invariably leads to an increase in dampness within them and this in turn results in more rapid deterioration - in fact some have been known to collapse. In particular the application of cement renders and modern plasters usually results in problems. With cob buildings it is vital that traditional materials be used to maintain breathability. It is also important that the roof and gutters been maintained to ensure water does not enter the head of the wall. At the foot of the wall the cob is usually built off a plinth of brick or stone with no DPC. This acts as a control system in that dampness in this plinth evaporates before it can rise far enough to cause damage to the cob. The plinth should not be rendered or painted or treated.

A DPC in a plinth might not lead to problems directly (it is the modern render and plaster that really cause the damage), but there is a risk that if moisture becomes trapped above the DPC in the zone between the DPC and cob this introduces moisture at the base of the cob and could cause problems. It is therefore not usually recommended that the plinth be treated for damp.

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 deal with our Artexed plasterboard?
FROM:
Angela Brown
(Essex)

We have recently moved into a timber framed cottage of uncertain age, approx. 300 years. There are more recent extensions on the property dating from the 1920's and 50's, many of interior walls have been overlaid or replaced with plasterboard including the main bedroom ceiling which is vaulted and has exposed beams, this plasterboard has then been artexed! According to the survey some other ceilings are fibreboard and the partitions forming the stairwell are clad with plywood sheets, to quote the surveyor ,"The original internal partitions of the cottage are of timber framed in construction originally dry lined with lath and plaster" then, "eventually, the remaining lath and plaster will suffer from more significant deterioration and will require overlaying with plasterboard sheets." All of this gives the feel of living in a large caravan and we would like to use a more substantial material/method, what would be the best thing to replace these wall and ceiling linings with, Also should we use lime render on a house of this age, a local plasterer said no need? We also have to consider costs as most, no ALL, interior walls need attention those that appear more solid have heavy duty woodchip wallpaper with many layers of paint on, These will probably need re plastering by the time we've removed the paper.

Angela Brown

Although overboarding with plasterboard is a method of keeping the original lath and plaster and providing a new sound surface it does increase the depth of the wall, which can cause problems at doors, etc. It also presents a far flatter and less interesting wall surface. Similar comments apply to overboarding ceilings, but overboarding a ceiling is perhaps more understandable in view of the difficulties of taking down an old ceiling

However, the far more important issue is what is wrong with the walls/ceilings and what method of repair is most appropriate?

Eventually lath and plaster does fail and repair or replacement has to be considered. The first question is therefore whether the surface has deteriorated to such an extent that replacement has to be considered.

There are methods of repairing ceilings and walls in situ. These include the use of long screws with mesh washers embedded into the plaster through to a fixing behind (timber studs or joists) and then the washer plastered over to disguise. Such a method can secure a loose ceiling or wall and help provide many more years service with minimal disruption. An alternative is to thread wire through to fix behind and hold up areas and wiring up plaster is more often used for decorative features (e.g. ceiling roses).

Where a section has failed, but most is sound, it should be possible to carefully cut away the loose section. You should cut around the loose area and carefully prise away the loose, leaving the rest intact. Cutting away instead of pulling away reduces the risk of loosening surrounding sound plaster. If you undercut the edges it provides a good key for the edge. The laths can be cleaned and wetted before a new application of haired lime plaster, etc.

If the surface has deteriorated to the point of having to be completely re-formed I suggest you look at using reedmat with lime plaster or clayboard with lime plaster. These provide a more 'traditional' background to a lime plaster finish. Sometimes expanded metal lath (EML) can be used and certainly could help reinforce areas of repair, but its use should be carefully considered.

As for the use of lime plaster - it depends on the situation. Strictly speaking lime plaster should be the preferred finish because it is more in keeping and matches what remains of the original. If breathability is a key issue there is no doubt that lime plaster should be used. However, with many ceilings and internal walls breathability is not an issue. I would always advise lime plaster in preference but from a technical viewpoint there are situations where modern plasters would not be harmful.

When discussing lime for internal use it is of course preferable to use traditional lime putty. However, cost and other considerations may mean this is too expensive. Rather than simply jump to modern plasters you could consider Naturally Hydraulic Lime, or even Hydrated Bagged Lime in some circumstances. There have been extensive discussions on the merits or otherwise of different forms of lime plaster. When considering internal walls and ceilings where breathability and flexibility may not be the main considerations you could consider the alternatives.

The above should not be taken as condoning the inappropriate use of modern plasters, etc., but it should be recognised that in some situations a 'purist' or even traditional approach is not always essential from a technical viewpoint. Of course other considerations can include the aesthetics; matching surrounding material; fire, sound or thermal performance (traditional lime plasters are often better than modern); etc. If the building is listed there is no question that traditional materials should be used.

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:
Poor drainage leads to wall dispute
FROM:
Tim Squire
(Kent)

Our neighbour's lack of drainage means that all surface water is running down the side of our boundary which they use to retain their concrete path and steps leading to the side of their property.

We have recently noticed that their steps and path have dropped, this is causing pressure i.e. making the boundary wall bulge out.

We accept we have to repair or rebuild the wall as it is our boundary wall. However, the neighbour says that we are liable for underpinning their path while the wall is rebuilt.

The questions are 1) can we make them install drainage to their property as rebuilding the wall without proper drainage on their property just repeats the problem. 2) Are we liable for underpinning their path. Our property was built first, previous occupants in our neighbour's property came along and simply used the wall as a retaining wall when it was never designed as such - simply as an ornamental boundary wall.

Tim Squire

From your description it is difficult to assess why the steps have dropped - are you saying that water has washed away soil below, or that there has been some other form of ground movement, etc., etc.?

Just because the wall has bulged does not mean that repair is immediately necessary. Of course, if it is moving and liable to fall over that is a different matter.

Assuming you have to rebuild the wall for safety reasons you must take reasonable steps to ensure that their path is not damaged beyond its present condition. This does not mean that you have to underpin it.

Is the wall a party wall - it could be as it is a wall separating gardens/land and might be a party wall for the purpose of the Party Wall Act etc. 1996? However, it really depends on whether the wall is astride the boundary line or whether the boundary line is to the face or beyond. If this is the case there is nothing to stop you or your neighbours from repairing, rebuilding, etc. the wall subject to the procedures of the Act being followed.

I do not believe you can make your neighbour install drainage, but it depends whether you can prove that the lack of drainage on their side is the cause. Similarly I doubt they can make you underpin their path.

These are matters that a Party Wall/Boundary surveyor should look at and consider. It may be that a lawyer will also need to give advice. It is also possible that insurers should get involved if the damage is the result of an 'escape of water' or some other insured peril.

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:
My stone mullion widows are crumbling away
FROM:
Elaine Davies
(Somerset)

My stone mullion widows are crumbling away.

My house was built in the sixteenth century. It has stone mullion windows which have started to crumble in places. Do you know what the correct mixture is that we should use to repair them?

Elaine Davies

There are various repair methods that can be used on stone - including what is commonly referred to as 'plastic repair' which involves a lime mortar being used. However, it may be that piecing in new sections of stone would be more appropriate. On the other hand it may be best to leave it alone for the time being. Sometimes the application of lime water is thought helpful, but this is not something that is commonly agreed by the experts.

The best advice I can give you is to seek advice from a local stone mason.

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:
One half is warm the other half is cold...
FROM:
Richard Tinsdeall
(Somerset)

We live in a Grade II Listed farmhouse in West Yorkshire. A few years ago we re-built the (completely) derelict barn which, although it matches the rest of the house on the outside and has matching wall depth, has a stone/cavity/insulation/block construction. End result.....one half of the house is warm the 'old' half is cold. The 'old' half of the house is of original construction, 2 skins of stone wall approx. 2.5ft thick filled with rubble in-between. I think we are losing a LOT of heat through the walls and I am thinking of getting cavity wall insulation.......only snag is...... I don't have a cavity, I have rubble instead. Is there any technique for injecting insulation into this kind of wall from the outside? I don't want to disturb the internal plaster/decoration/wall lights/electrics/microbore embedded in the plaster. And obviously in the kitchen any internal works would be realistically a non-starter.

The concrete screed floor is also something I'm looking to insulate, but perhaps this is as simple as getting a thicker, high-tog rated carpet underlay.

Richard Tinsdeall

There is no way you should be considering any form of 'cavity' insulation. The core of the wall is an integral part of the structure and anything that reduces its integrity should be avoided. If the core has voids (always a possibility) they should be filled/grouted with lime mortar, but this is a very specialist job. There have been advances with lime mortar in that the addition of hemp can significantly increase its thermal qualities. The Old House Store is the place to find out more - www.oldhousestore.co.uk. I suspect the lime/hemp mix could be used for grouting such a wall, although as far as I am aware this is not an application for which lime/hemp mix has yet been used.

The method used most commonly is to line the internal faces with an insulation board. You correctly identify some of the disadvantages, but if the lack of thermal insulation is such a problem it may be that there is no alternative.

Depending on the external finish to the building you could look at an external cladding or lime/hemp render application.

As for the floor, a good carpet is cheapest. If you change the floor you could look at a limecrete floor with underfloor heating. Bear in mind that the concrete floor could be capping ground water and a floor or base of a wall that has dampness in or near it will be colder than a dry floor or wall. I suspect that changing to limecrete floors will make a noticeable difference. However, the cost could be high.

I am afraid there is no easy or cheap solution.

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:
Following incorrect damp advice could cost me £5,000
FROM:
Jane Harp
(Powys)

I hope someone can help. I have got an old quarry tiled floor in my dining room (with carpet over them) and a cellar under the lounge which has been tanked. The house was sold subject to contract but the buyer wanted a damp proof expert to come and have a look and has since withdrawn his offer. He has detected damp salt deposits on tiles and said that there are small signs of rising damp on walls and some in kitchen. There is a path that runs by outside kitchen wall, and the damp man said because the floor was lower than the outside path, this has resulted in rising damp. He suggests replastering and putting a damp course and taking floor up and doing same with that. There are no damp patches whatsoever on walls and never has been, but can see the salt deposits on tiles. I would be grateful for any advice as he has said this could cost between 4000 and 5000.

Jane Harp

Without an inspection it is not possible to give specific advice.

It sounds as if there is lateral water penetration and that the base of the wall could be holding an amount of water. This is not necessarily rising damp and I would question the need to inject the walls.

If the external surface can be lowered (even a channel) this could help. Methods of external ground lowering, channels, French drains, etc. have been discussed here and on the Discussion Forum of this site and you should refer there for more information. However, if an external solution is not possible the alternatives would involve various forms of internal applications. These can include:

  • use of lime plaster but accepting it may need occasional replacement;
  • use of modern render and plaster (generally as you have so far been advised) but this will fail periodically and could force the water in the wall to divert somewhere else;
  • it could involve a modern cavity membrane system but you would have to drain it somewhere - although this system could also include the floor.

The works so far recommended to you are along the lines of the second method mentioned above. I generally avoid this method because I find that it is more likely to result in diverted water problems, or trapped moisture and is the most likely to cause problems in future.

If there is no major problem at present I would be inclined to leave it alone for the time being.

As you are selling the property find a building surveyor or independent damp expert who is not reliant on selling treatment systems to advise properly. Take the resulting report and show to any prospective purchaser and sell 'as seen'.

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