Ask our Agony Uncles ...

SUBJECT: How do I create a suspended timber floor.
FROM: Elizabeth Woodman (West Sussex)
We have just bought a 16 C timber frame farmhouse. We have taken up the concrete floor in the scullery and to our delight have found a floor of Horsham flags. Unfortunately when we took the concrete floor up in the kitchen we found poor quality quarry tiles laid directly on to earth. We are not interested in damp proof courses and are happy to have floors, which breathe. However, I like the idea of a suspended timber floor laid over the earth floor in the kitchen. How much ventilation do I need to provide underneath and round the edges and how can we protect the joists underneath from the damp ground?

Elizabeth Woodman

It really depends upon how deep the excavation for a void can be taken. This will depend on the footings to walls, which must not be undermined! You will need a local surveyor or architect to inspect and advise in detail. In theory you will need to provide ventilation at the perimeters (more than one) to get air flowing through the void created. If you can ventilate to one side only you may be able to insert vents in the floor surface (opposite side to the external vents) under a radiator, as the warm air will pull through air from the sub-floor void and dry/warm it (so you don't notice draughts). I suggest that the minimum depth for the void should be the depth of the joists + depth of wall plates + one brick (dwarf support wall). If you cannot achieve this I suggest you abandon the idea of a suspended floor, but if the void is sufficient for air to flow over under and around the timber joists (and any/all timbers forming the floor) you might be able to get away with a shallower void. The timbers themselves should be pre-treated and where any timber rests on dwarf brick walls or is in contact with a potentially damp surface there should be an isolating membrane. Please note that where an isolating membrane is installed it should not wrap the timber completely because this could cause problems, rather, it should be inserted between the timber and damp surface only.

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: Limewater can help solve dust problem
FROM: Fiona Baldwin (Norwich)
Can you use PVA to seal lime and cobble brick internal walls, in order to prevent dust debris and bring out the colour of the cobble?

Fiona Baldwin

No I would not seal them in this way as the PVA will create an impermeable barrier. This might not be such a problem with the cobbles, but could cause problems with the pointing and brickwork in the long term. If the pointing is crumbling it might be time to consider some careful re-pointing with lime mortar. You could consider using lime water (very thin lime wash) over the surfaces as a general sealant, but this might form a slightly misty surface, which would not matter on the pointing but might show on the cobbles and brickwork. A gentle wash down occasionally might be sufficient to hold back the dust?

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: Shelter coat of limewash will help to protect stonework
FROM: Jonathan Pickard (Northampton)

We have just bought a 300year old stone-built cottage in a conservation area. The front of the property has been rendered but the back of the property (south facing) is exposed stone. Some of the stone has eroded and crumbles when touched. We wondered if there was anything we could do to stop this worsening (without rendering it)? The stone appears to come from sedimentary rocks (and is pale cream in colour).

Jonathan Pickard

This sounds as if it is normal wear and tear over time. I suspect it is a limestone. If the deterioration is serious you may have to consider cutting out and replacing, or at least re-facing, individual stones over time. A local stone mason should advise further on repairs. However, if the deterioration is not yet so serious and you simply wish to slow down the deterioration, you could consider limewash over the face of the wall, as a 'shelter coat'. This would give it a white appearance (although a pigment could be added to get it close to the original stone colour). It would retain the appearance of the stones (unlike render) and would provide some weather protection, whilst still allowing the wall to breathe.

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: Uninhabited Scottish mansion poses problems for DJ
FROM: Dennis Johnstone (Skipton)

I'm buying a large, stone farmhouse in Dumfries and Galloway that requires substantial renovation. The house was built in the mid 1800s. It has not been occupied for two years, resulting in burst central heating pipes, blocked gutters and roof valleys, and failed flashing around the dormer windows. Water ingress has then led to the partial collapse of several ceilings and walls.

The problem is that the house is so big (four receptions, five bedrooms, huge farm kitchen, back kitchen, pantries, two bathrooms etc) that replastering the most decayed rooms would be prohibitively expensive. There's also a time factor as we need to get some of the house habitable reasonably quickly.

One suggestion has been that we gut and dryline the four worst rooms with clayboard, a breathable substitute for plasterboard. It's made from clay, reed and hessian with hessian facing. It's compatible with lime plaster and can be used for both walls and ceilings. (The plaster in the remaining rooms is repairable.)

Do you have any experience or knowledge of clayboard?

Also, the underlying floor appears to be flagstones, probably on to levelled bedrock (which is only six to 12 inches beneath the topsoil around the house). While we're happy to revert to flagstones in the working part of the house (kitchen, family room, pantry, and downstairs bathroom), they would be out of keeping with the formal reception rooms and main hall. What we have found in these rooms is flagstones, overlaid by some form of parquet floor (six-inch squares of oiled hardwood), then quarter-inch felt, then an early form of linoleum (hessian backed and very brittle), then half-inch thick felt, then very thick '50s or '60s wool carpet (half-inch pile and obviously expensive when new).

There are a few damp spots (due mainly to faulty guttering and dormer windows), but otherwise the floor appears very dry and sound. My instinct is to go back the parquet floor (which looks quite old) and carefully restore that, then use rugs in the rooms. However, what are the implications of that for the flagstones underneath?

Finally, we've had two surveyors look at the house, and suggest that it has rising damp and subsidence. When we've pointed out that the house is built on a rock outcrop, that the roof is leaking, and that the cracked stonework (about eight blocks) is heavily weathered along the edges of the cracks, they mutter about people who think they know better than a professional! There has certainly been some cracking at some point, but it's been well repaired with a softer mortar than the original and this has clearly lasted well for many years. I suspect the original mortar was probably too strong for the stonework, and that this is what caused the movement and cracks. (My grandfather was a master stone mason and I remember him talking about the need for the right mortar for different types of stone.) I'm not sure what type of stone it is, but it's red-brown to grey, fine-grained and resistant to scratching with a steel screwdriver.

Dennis Johnstone

Clayboard: I do not have personal experience of this, but have heard encouraging reports from others. In the circumstances you describe, it seems to be a sensible compromise. There are posts on the discussion forum about use of clayboard and I suggest you look there for more information direct from those that have direct experience of using this material. Parquet flooring: Without taking up the parquet flooring it is impossible to know what condition the flagstones underneath are in. To take up the parquet floor will cause it damage. My suggestion is that you go back to the parquet flooring, as proposed, and use rugs, etc, as you seem to intend. As you gradual expose the whole of the parquet floor surface you will be able to get a better indication of whether there are more serious underlying problems. If the parquet flooring is as old as you suspect I doubt if retaining it will have major implications for the flagstones below, beyond whatever damage (if any) they have suffered over the years already.

Damp and subsidence: These are two very different problems. Regarding dampness, there have been many questions on damp and postings on the discussion forum and I suspect that if you have read through the various comments on this site you will have a good 'feel' for what approach you should be taking. It sounds like you have identified the main problems. Deal with these and monitor the situation. If dampness persists, investigate further. I would only advise modern intervention methods if there is a serious damp problem that cannot be resolved any other way.

Regarding subsidence, this is a term often used for forms of movement that are not really subsidence at all. Without seeing the property I cannot comment on what movement has taken place, what was/is the cause and whether there is anything that needs to be done about it now. However, you can assess for yourself and monitor over time the various cracks to establish whether there is a historic, seasonal or ongoing problem. If there is a seasonal movement problem it is unlikely that you will need to undertake major work, unless the movement is causing other serious damage, etc. However, if there is evidence of an ongoing problem you ought to have the matter checked by an engineer (or building surveyor) who properly understands historic buildings and how they function. From your brief description it seems unlikely that there is a serious ongoing problem, but if there are cracks it would be sensible to investigate repair in any event, if for no other reason than to remove a potentially weak spot in the building and an area where water ingress could occur and cause damage over time. If the mortar was/is too strong it could explain the cracking and it might be necessary to eventually re-point or partially re-build an area using a weaker lime mortar.

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: DPC company provides incorrect advice for Clunch property.
FROM: Angela Barkes (Cambridgeshire)
We have just bought a house in Cambridgeshire estimated to be over 200 years old. A dpc was applied approx 10 years ago - predominantly externally. A variety of factors such as the external rendering extending lower than the internal floor, and inferior internal plaster seem to have been the causes of further damp.

We contracted a dpc company (not original company) however hacking off the plaster revealed not brick walls but clunch. It is very damp and has seriously eroded in places up to about 2 feet. Above that it is drier but crumbly. In some places there is old lime plaster underneath a very thin layer of pink stuff - however on some walls the old render has been covered (wallpaper and all!) with an inch or more of what looks like (grey) cement. I have no idea how much of the rest of the walls/house have been cement rendered. The company has suggested putting in expanded metal lathe and building up the plaster over the eroded bits. They have been dismissive when asked about lime and said that lime is only used in listed properties where original materials must be used. I am now extremely worried about further damaging the clunch and the whole house falling about our feet! So what should we do? The dpc company surveyor is coming out tomorrow.

Other info: not grade-listed; not conservation area; concrete floor (possibly dpc or membrane underneath); old front doors in both rooms have been blocked up with breezeblocks. A lot of work seems to have been done on the building around the '60s or '70s.

Angela Barkes

The company you refer to do not understand the materials and are incorrect in their suggestion that lime is only for listed buildings - I know of modern buildings constructed with lime mortars. I suggest you do not take the matter further with them, pay them for what they have done to date and say goodbye to them.

The most important thing is to revert to a breathable structure. No amount of modern damp-proofing will reverse the damage and in fact further modern treatments and repairs could exacerbate the problem. It will be necessary for someone experienced in dealing with such material to come out and assess the damage and what needs to be done in terms of repair, before considering the re-plastering with lime plaster, etc. Mindful of the fact that most home owners do not have an endless supply of money, you should aim to tackle first the areas already exposed and/or those deemed to be in most urgent need of attention. It is likely that other parts of the building (still covered) will need attention, but deal with the works in a managed way progressing over time rather than trying to tackle all at once. Although damage will continue to occur the property ahs stood thus far and will probably survive a while longer until you have the funds, etc to gradually do all work necessary. I often advise owners in such situations to concentrate on the worst elevations and then on the ground floor areas first, work around the building in a logical manner and if necessary deal with sections on a year-by-year basis, until it is eventually finished.

Although the building is not listed, etc the important thing is to take the correct technical approach for the building that exists. It is far too simplistic and incorrect to suggest that simply because it is not listed you can ignore what is technically best for its actual construction.

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 professionals fail to give correct advise on damp gable end wall.
FROM: Andrew Parkin (Pembrokeshire)
I am having trouble getting a definitive answer regarding treatment of damp in a gable end wall. This wall faces the prevailing weather and has badly cracked render that has had many coats of modern paint. A specialist damp proofer reckons that we have penetrating damp coming in through a wrongly constructed chimney and also through the roof where the roof slates are flush with the end of the wall and sealed with cement (which is cracked), as well as through the cracked render on the wall. There is also a possibility of rising damp and the ground levels outside are above the height of the slate damp proof course by a few inches.

So far the consensus is to rebuild the chimney, make the slates overlap the end wall and seal with silicone, hack off and re-render the outside, hack off and tank the inside downstairs wall from floor to ceiling and inject a damproof course.

I have two main concerns which do not seem to bother the various builders and damp proofers:

1. By re-rendering the outside with modern materials and tanking the inside and injecting a damp proof course will we not be trapping a lot of moisture in the wall? Does this matter?
2. No consideration has been given to using traditional materials.

PS The inside downstairs wall was dry lined which when removed revealed that the lower half of the plaster had been hacked off in the past and the timber supports for the dry lining were completely rotten. There are high levels of damp 2m up the wall over the fireplace (tested using a radar? damp meter) The remaining plaster over the fireplace is cracked and damp too touch (does not appear to be condensation though).

Andrew Parkin

In answer to your specific questions:

1. it is likely that modern renders will trap existing moisture in the wall as well as any that might eventually penetrate the wall in future. It is not an approach I would favour.
2. say thank you and goodbye to the builders.

From other answers and postings (on the discussion forum) on this site you probably already know the answers to your questions.

Deal with the obvious problems first - lower ground levels, remove materials likely to be trapping moisture, etc, etc.

Repair the building, as necessary, improve any weathering details (e.g. roof verges) to ensure that the building has as much protection as can be provided.

You do not define what is meant by 'wrongly constructed chimney', but if there is a problem you should have this sorted out.

Use traditional materials to allow the wall to breathe. It is wrong to believe that traditional materials do not provide protection to weathering. However, you might need to use a stronger semi-hydraulic lime mortar. In extreme circumstances other forms of external cladding might be needed to provide sufficient protection. For example, in parts of the UK hung tiling is used, as is weatherboarding, harling, etc.

The internal damp problem that has caused the rotting battens behind dry-lining is probably due to dampness trapped within the wall. Use of traditional materials, etc should resolve the trapped moisture problem.

I would mention that once moisture has saturated a wall and found a route through it generally gets through easier thereafter. Providing a breathable render to the exterior will not make this problem worse, but you should ensure that the wall face is well maintained in future with a good coat of limewash regularly applied.

Turning back to the internal problem, you may have to accept that the wall structure itself will never be totally 'dry' and that there is always a risk of some moisture penetrating through. In such circumstances the presence of dampness is not necessarily a problem if there is no timber in contact with the damp and therefore no material to rot. In such a situation the only problem will be spoiled décor. In some extreme situations it might be appropriate to consider works to protect vulnerable timber and other vulnerable material and then provide a form of dry-lining to ensure a dry internal surface. Traditional timber battens with lath and plaster fixed over an isolating membrane can provide suitable dry-lining, or you could use a modern drained/ventilated cavity proprietary system.

I suggest that you consider these various matters and seek further specific advice from a local surveyor/architect with experience in dealing with historic buildings.

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: Solving condensation may require a lifestyle makeover
FROM: Ian Johnstone (Somerton, Somerset)
I have steel-framed windows set in reconstituted hamstone mullions with sliding secondary glazing. I have been informed that PVC windows will cure the massive condensation on the windows. This may be true, but the surrounding mullions also run with water in cold weather as, I suspect, they are acting as a thermal bridge. Previous owners have covered the internal mullioned sections with a range of materials from cork to polystyrene, but with limited effect. How can I prevent this condensation on internal mullioned sections?

Ian Johnstone

I certainly do not believe that plastic windows will solve the problem. I also think you have identified the problem in that the stone mullions will act as a cold bridge in much the same way as the metal frames.

Warm air holds more moisture than cold air. When warm saturated air meets a cold surface it reduces the temperature and it has to release the moisture. The actual dew point (the temperature at which the moisture is released) depends on the actual air temperature and the moisture content of the air (humidity). The moisture can be very visible (running down windows) or it may be just enough to manifest dampness by way of stains and/or mould. This moisture is what we refer to as condensation.

There are many factors that can cause condensation and it is not always an easy problem to sort out. As a general rule there are three factors to consider: heating, insulation and ventilation. It is often a matter of balancing these three that resolves the problem. However, the lifestyle of an occupant can also be a factor. A house where the windows are never opened, the heating is kept high and much moisture is introduced (washing, cloths dried indoors, etc) will be very vulnerable to condensation problems.

Returning to your specific problem, you need to consider if there is a way of helping warm moist air to escape the room/house quicker. Is there something about your lifestyle that needs to change? [E.g. do you hang wet clothes on a radiator under the window?] In the kitchen and bathroom do you ventilate sufficiently after cooking, washing, bathing, etc? If you have extractor fans, do you use them, or should you have some installed (specifically kitchen and/or bathroom)?

Is your heating providing good general background heat? I often find that if the radiators are in the middle of the building the perimeter walls are relatively cold and vulnerable to condensation, unlike houses where the radiators are situated on external walls under windows. Also consider whether your heating fluctuates considerably during the day?

Insulation is more of a problem, because it is often more difficult to improve insulation. I always suggest looking at obvious upgrading of insulation such as roof spaces. Heavy curtains can be a very effective for of insulation in front of windows.

Draughts can be a problem area. Draughts provide ventilation, but are not good for insulation. My preference is that you should have a sensible level of draught proofing around doors and windows because I do not believe that ventilation by draughts is necessarily a significant help in combating condensation.

I am not in favour of trying to coat/cover the surfaces of the mullions, as I am doubtful of the benefit. I would normally expect secondary glazing to help, but it seems not in this situation. I wonder if a double glazed system of secondary glazing would help (i.e. the secondary glazed panels are sealed double glazed units)? It would be an expensive experiment. I therefore suggest that you look at the other matters I have mentioned to see if there is a way of reducing the amount of moist warm air that reaches the window. If you can do this you should see a reduction in the amount of condensation occurring in the window area.

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: Noisy neighbours are driving us bonkers.
FROM: Lucy Brown (Cambridgeshire)
My partner and I rent a beautiful one bedroom flat - one of a number of flats condensed into what is a old Victorian building. The ceilings are very high and the floors and walls extremely thin. The floors in particular are an absolute nightmare. Despite remonstrations with our neighbours it is becoming impossible to have a quiet night in at home - the floorboards creak constantly and every noise is amplified, the TV being unbearable. Can we demand that our landlord soundproof the floors and / repair the floorboards to restore our peace of mind? How long is this kind of process likely to last? We have rented there for over two years and otherwise have no cause for complaint

Lucy Brown

The first thing to consider is the formal aspects of the 'conversion' to flats. If the property was formally converted the work should have complied with building regulations (although with regard to sound insulation the regulations have been toughened in recent years and were poor some years ago). Unfortunately Councils are time-barred from taking enforcement action on building regulation matters if one year has passed since the work was completed.

Let us therefore consider planning, which has a four year period for enforcement. Find out if planning permission was obtained. If not and the work was undertaken over four years ago the Council may still have the power to take some action. Get the planning officers to consider the matter.

If planning permission has to be sought it might be possible to tie this in with upgrading to comply with building regulation approval.

However, I suspect you will have more success in looking at the legal aspects. Although you do not state the precise nature of your tenancy agreement, it is usual for the landlord to have a responsibility to provide quiet enjoyment of the accommodation. You may therefore be able to take action to force the landlord to upgrade the sound insulation. You should seek legal advice on this - the matter of sound nuisance is not an easy one to prove. An issue that will arise is whether there would be a sound problem regardless of who lives above, or whether the problem is the neighbour. It could be a combination of both.

The environment officer of the Council now has some power to deal with sound nuisance and it might be appropriate to start here. Contact the Environmental Health Dept of the Council and get one of their officers to advise and perhaps attend to assess. The officer could possibly serve notice on the neighbour and/or the landlord depending upon who it is felt is the 'cause' of the sound nuisance.

Should improved sound insulation be required there are various means of dealing with this, both from below and above the dividing floor. In any event, the work can be very disruptive.

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: Efflorescence on stonework raises damp concerns
FROM: Brian Phillips (Cambridgeshire)
I own a house to which I intend eventually to retire, but at present I only visit it every other weekend. The house is made of stone (I believe it is grey sandstone, but I am no expert) and rendered on the outside. After four years of occasional patches of efflorescence on some of the walls and a few small areas where the interior plaster appears to have become hollow, this Spring I noticed that the skirting boards were beginning to rot. This is happening both on external walls and on an internal thick wall separating the lounge from kitchen. A surveyor has said that it is likely to be a problem of rising damp made worse by the condensation which inevitably forms while we are not there. I have a guarantee stating that the building received an injected damp proof course in 1989, but the company concerned no longer exists. Is it reasonable to expect the damp proof course still to be effective after 14 years, or could its deterioration really be responsible for the problems with the skirting boards (wet rot, according to the surveyor)? Is it possible that this might simply be a problem caused by condensation, and might not require the rather drastic solution of reinstalling the DPC? I don't want to go to that expense if it is not going to sort the problem. If condensation rather than rising damp is the problem, what possible solution is there, given that I cannot visit the house more frequently while I am still working? Also, is it possible for a problem like this to come on relatively suddenly, as our original survey on buying the house in 1999 stated that the walls exhibited only the degree of moisture you would expect in a stone cottage with injected DPC? The house was being permanently lived in then, which makes me wonder if the real problem may be more to do with lack of ventilation than rising damp.

Brian Phillips

As you may have read elsewhere on this site, injected dpcs are rarely effective in stone walls. I would not pursue the matter of the injected dpc and would not recommend further such treatment.

The efflorescence is an indication of moisture gradually evaporating - the salts crystallising as the moisture evaporates, hence the efflorescence. I therefore suspect that a hidden dampness problem has existed for some time. The level of damp might have been low and not high enough to cause any concern at the time of survey, but the continuous moisture over time could have resulted in the rot. It could have worsened, particularly as the property was constantly occupied then and only occasionally now. [I doubt if you would easily prove negligence against the surveyor.]

There are numerous possible reasons for the dampness and condensation is but one. As mentioned elsewhere on this site, you should look at all of the obvious problems (gutter leaks, high ground levels, lack of ventilation, impermeable finishes, render bridging down to ground, etc, etc, etc). Deal with the obvious problems first and remove or at least reduce the moisture trapped in walls.

You mention your occasional occupation compared to the previous owners. This could be a factor and some of the moisture could be condensation, or condensation could exacerbate the general problem.

You can overcome the lack of regular occupation by putting heating and ventilation systems in place that run on timers. This will result in regular air changes and perhaps a more constant temperature (the fluctuations of heat often being a significant factor in condensation problems). You should seek further specific advice from someone experienced in dealing with such problems in older buildings.

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.