for People with a Passion for Period Property
Ask an Agony Uncle!
Stephen Boniface - Stephen Boniface specialises in building conservation providing multi-disciplinary consulting services. He is Chairman of the Building Surveying Faculty and member of the Residential faculty. He serves on the RICS Building Conservation Forum Board and is the 'Agony Uncle' on the Period Property UK website (www.periodproperty.co.uk).

Ask our Agony Uncles ...

You can write to our panel of experts free of charge on any subject, providing it's got something to do with Period Properties.

Our experts are all specialists in matters directly involved with older properties. So, if you have a problem with an older building - or if you think you might have a problem - ask an Agony Uncle...

 

SUBJECT: Repair of floor leads to modern building regulations vs. traditional conservation problems.
FROM: Martin Spice (Greater London)
In the renovation of my Grade II listed house (converted from a C16th or earlier timber frame house), we have found part of the groundfloor sub floor to be severely rotten from water penetration. There is a stunning timber binder (original to the 1700 house or earlier) across the centre of the room bearing joists which run to brick courses at the sides of the room. Sadly the binder and joists are rotten, as are some of the floorboards and the brick course has broken away - the floor actually slurred and bounced it was so loose! The builder suggests concrete binders centre and sides with surmounted engineering bricks all on damp membrane and then joists and oak boards on top. Replacing the timber beam does not meet with modern building regulations, yet concrete, engineering bricks and membranes go against the purist restorer in me. The floor needs to be safe, stylish, yet move with the house, be dry, free from drafts, and suit modern living. What is the right thing to do?

Martin Spice

The works you mention would seem to be repairs and as such would not normally fall under the influence of building control - or at least that is the argument I would put forward. Without seeing the building I cannot provide you with a specification, but my first impression is that your engineer is not sympathetic to old buildings. Before anything else you must look at why there is dampness causing this deterioration. The problem of dampness must be addressed first. There are many postings about damp problems on the Discussion Forum section of this site.

Removal of original fabric is not good conservation. I therefore suggest some lateral thinking. For the 'binder' it should be possible to ensure that it is isolated from the damp wall and re-supported at its ends. This may be on suitable metal brackets (perhaps specially made - in the past I have had such brackets made up by a local blacksmith) or on a new brick pier (independent from the wall).

For the joists a much simpler solution is to lay new timbers alongside and bolted to the original. The new timbers could be the length of the original or slightly shorter. The overlap length should be at least four times the joist depth and there should be at least four bolts (with toothed washers between the timbers). The new timber can be taken through to bear upon a new wall plate. This can also be of timber, but set on a damp proof layer so that the timber is not in direct contact with the brickwork. I prefer continuous wall plates rather than engineering bricks, because it helps tie the floor in to the wall and there is less likelihood of individual joists suffering localised settlement.

Whilst you could cut away ends and join on new end sections this does tend to be a weaker form of repair. Although perhaps not as aesthetically pleasing the idea of re-supporting ends and bolting new timbers alongside originals is actually easier (usually) and better conservation.

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: How should we deal with property we wish to buy which has suffered from subsidence?
FROM: Ms Visavadia (London)
We are looking into buying a period property (approx. 100 yrs old). After having agreed a price with the vendor, we have been informed that the property has been underpinned and that there is an insurance guarantee on the work.

My question is, is the property worth buying?. Are we going to have problems getting a mortgage on it now, and will we be able to sell the property later? (I have heard that you should stay clear of any properties with a history of subsidence) I really do like the property, but I do not want to buy a white elephant.

Ms Visavadia

There is not enough information to give a specific answer, but I hope the following helps. In some parts of London and the South East subsidence is common. It can occur for several reasons, including the influence of trees on sub-soils, leaking drainage systems, or very dry summers. If you were to claim now the problem would be investigated at length and underpinning would only be undertaken as a last resort. The same cannot be said for what happened in the 1970s and into the 1980s. During that period insurers tended to underpin first and investigate after. Some of that underpinning is now considered unnecessary and in a few instances is actually now causing problems. Partial underpinning is now also frowned upon as it can set up a situation whereby differential settlement occurs. As you can gather from above, there is no easy answer.

If the work was undertaken many years ago and there is no evidence of a recurrence of any movement, etc it would seem reasonable to assume that there is nothing to worry about. If the work was undertaken more recently, ask to see all of the documentation, such as the investigation reports, the engineer's recommendations and the specification of works, as well as any guarantees.

Most mortgage lenders will lend on a property provided insurance can be obtained. The key here is whether you can get the building insured. It is certain that you will need to have the building inspected by a building surveyor or engineer who can provide a report on its present condition, but taking account of its history. The professional employed should be able to indicate whether there is a high or low risk of a future problem. This will then enable insurers to assess whether they are prepared to provide cover. In any event there is a specialist insurer who only takes on previously underpinned properties. The scheme is run by Bureau Insurance Service (in Bexhill) and their details are: Tel 01424 220110 or www.bureauinsure.co.uk.

As for the attitude of purchasers, this may depend on the area. There are some districts known to suffer problems and purchasers of properties in those areas would probably prefer an underpinned property than take the risk of a future problem on a house that has not been underpinned. In any event, if the cause of the problem has been identified and properly dealt with there should be little risk of an ongoing problem. It is my opinion that if a property needed underpinning and it has been properly dealt with there should be no adverse affect on the marketability of the house. I think you will find a range of attitude from purchasers, but I suspect that many will take a pragmatic view. If you are able to provide a documented history and up to date professional report these will go a long way to allay a purchaser's concerns.

As for your purchase now, the same applies. If there is good documentation and a surveyor or engineer can confirm that there is no ongoing problem I do not believe that underpinning should necessarily deter you. The mortgage lender will usually only become concerned if insurance cannot be obtained and this will usually only happen if there is an adverse report - in which case I would not advise purchase anyway.

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: Loft conversion may result in the loss of period features
FROM: Tam Hobbs (Central Scotland)
I am doing a loft conversion in my two-storey 1873 house. Building control have advised me to replace all doors in the house leading on to the stairs in both the ground floor and 1st floor to FD30 fire doors, 7 1873 original doors to be replaced. I stated that this could not be right but they assured me that is the only way I would be able to get a building warrant and completion certificate. Who is correct, them or me.

Tam Hobbs

When loft conversions take place it is necessary to ensure that there is adequate fire protection and a protected route or easy escape for the top floor. What the officers have asked you to provide is a protected route down through the building. This is a method of resolving the fire regulation issues. In fact I am surprised they have not also asked you to upgrade the floors (usually by laying hardboard over all floor surfaces) as well! However, it may not be the only way.

Without sight of your building I cannot provide detailed advice. I can suggest that there may be other ways. You need to think about how someone in the top of the building could escape in the event of a fire below. Is there another route out (e.g. over the roofs)? Is it possible to provide fire protection to the loft area alone (e.g. a fire lobby to the loft room) on the assumption that someone would remain up there (rather than attempt to come down and out) until rescued through a window at top floor level?

I suggest you find an independent fire consultant (many ex-firemen provide such a service) and ask him/her to act on your behalf and negotiate a suitable solution. That said, be prepared for the possibility that a fire protected route is the only solution possible in your specific situation. If this is the case you could look into whether existing doors, frames can be upgraded. In some properties (e.g. SPAB HQ in Spital Square) they use intumescent coatings and an elaborate fire alarm system to get around the need to upgrade doors, etc. I have even seen (admittedly on a Grade I building) the doors cut in half and a fire proof layer sandwiched in it. In some I have seen the door retained, but with fire board panels over or in place of the original panels in the door.

Therefore, a number of ways exist whereby the need to comply with fire regulations can be overcome satisfactorily. If the building is listed any solution would need to be agreed with the conservation officer.

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: Low ceilings in period properties cause headache for London giant
FROM: Richard Maynard (London)

Many period properties have rather low ceilings. As a 6'6" keen cook, this causes potential problems in the kitchen!

What is the feasibility of lowering floor levels to create more headroom?

Richard Maynard

If the building is listed you would need to get consent, but in many instances this is forthcoming for such work. It often depends on whether the floor is original and therefore important historic fabric, or a later surface. It is usually quite simple to excavate to lay a new floor at a lower level. The things you need to consider are:

Whether the excavation will take the levels (either temporarily or permanently) below the level of the foundations/footings? If so, how this will be overcome? What type of floor will you install? If solid, will it be a modern floor (i.e. with a damp proof membrane, etc)? - in which case watch out for the problems of damp in walls, etc (see the discussion forum for more on this and possible traditional floor solutions that nonetheless meet modern requirements). If the floor is to be suspended timber, how will you ventilate the void below?

Before embarking on this project you need to look at the floor level in relation to the external ground level and likely footing (sometimes the top is visible externally). It would be sensible to excavate a trial hole externally to establish the depth of the footing. In extreme situations you might have to consider underpinning the footings simply to enable you to excavate to a suitable depth to form a new lower floor.

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: What? not enough slates?
FROM: Duncan Macrae (Central Scotland)
We live in the top two flats of a sandstone tenement building built about 100 years ago. 20 years ago the roof was re-slated with the original states used together with some repairs to the woodwork. The slates were laid directly on the battens on to top of the boarding, no underlay felt was used. When a slate is blown of the roof water comes directly into our ceiling after it has soaked the boarding. Is there any way that the roof could be improved to form a watertight roof without taking the slates off and putting the felt layer on? i.e. is there something that can be done from inside the roof space.

Duncan Macrae

Slates form a roof covering by overlapping. Over any one part of the roof there should be two or three layers of slate. One being blown off in wind should not lead to direct water penetration. In any event, the boarding is a form of lining and should provide a layer of protection (much the same as a modern lining). There are many slate covered roofs with no lining and no boarding and yet do not leak with the loss of just one slate.

That said, I am therefore concerned that the work undertaken may not have been to the highest of standards. If this is the case you may find that you regularly have to repair the roof. At some point it will be better to consider stripping and re-covering.It may be tempting to install some form of material internally, but this does not solve the basic fault in that slates should not be coming off so easily or leading so directly to water penetration. There are many concerns about some of the products being brought onto the market for application from within roof spaces. However, I do not support such an approach. Some of these materials simply hide a more fundamental problem. Some materials are totally irreversible and render the materials useless for salvage, etc. There is concern about the problems of interstitial condensation, rot and damage to timbers caused by some products and methods of repair from inside a roof. You will find some discussion on this on the Discussion Forum pages. One method I often find undertaken by DIYers is to install roof lining felt to the underside of rafters. This may stop leaks dripping onto the ceilings, but because the lining is under the rafter it runs into (not over) the eaves. What then happens is that if a leak occurs it runs down the lining to the eaves, where it causes rot. I therefore do not recommend internal installation of a lining.

Sorry to be negative about internal solutions to your problem, but the best way to solve any roof leak is to tackle it externally. I therefore suggest you get an independent competent roofer (experienced in slate) to inspect and advise you.

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: Advice required on common defects to external walls in Victorian properties.
FROM: Katherina Madden (Bristol)
What are the common defects affecting the structural stability and appearance of external walls to terraced Victorian properties and what are the remedial solutions for the defects involved?

What are the signs of rising and penetrating damp in such properties and what are the modern methods available for curing these methods?

Katherina Madden

Your question could give rise to a book! However, some pointers:

Failure of footings due to trees, leaking drains, etc. This leads to cracking and distortion particularly around openings. The cracking is usually diagonal, but not always. Solution - get a professional in to check and investigate. Settlement - often from when originally built - can lead to distortion of door heads, windows, etc. Solution - do nothing, but keep an eye on it.

Bomb damage - usually in cities. There are many possible defects, all of which are historic. Some typical ones include gaps between window frames and walls and bulging walls. Solution - do nothing - it is old. Lateral movement due to insufficient restraint (provided by floors) - bulging walls, gaps between first floors and walls (sometimes disguised by beading). Solution - sometimes lateral restraint is necessary, or re-building in extreme cases. Alterations in the subject or even in neighbouring properties. In a terrace the integrity of the individual buildings will in part rely upon the integrity of the whole. Removal of internal walls (even if properly undertaken) can result in 'knock-on' movement to properties. Removal of chimney breasts can lead to subtle rotation of party walls, etc. Solution - depends, but generally get professional advice.

Insertion of new windows. Many window companies aim to knock out the old quickly and insert the new before movement occurs! Guess what? It doesn't work. In many older buildings the windows can be part of the load-bearing structure, especially if the hidden lintel has failed. I see many bays that have moved during window installation because the installers forgot that the bay also carries the load of the roof. Typical defects are unequal gaps around the window and cracks vertically where the bays adjoin the main part of the building. Solution - its too late, the damage is done. Fill the gaps. In extreme situations new lintels may be required.

Thermal movement - most old buildings were constructed without allowance for the expansion and contraction of materials. This can lead to cracking - usually vertical and often in the middle of an expanse of wall (although sometimes at corners). Solution - often, do nothing, but sometimes you need to create a thermal movement joint.

Modern repairs - use of dense mortar for re-pointing, rendering, etc. This can lead to moisture becoming trapped in the wall structure, spalling of brickwork, etc. Some modern mortars are vulnerable to chemical reactions/attack. Solution - repoint in a softer mortar (usually lime mortar).

The above is a very brief overview of some typical problems. The suggested solutions are also very generalised. If there are any obvious defects (cracks distortions visible failure of surfaces, bulges, etc) get a professional to look at it and advise fully.

The matter of dampness is one raised often and at length on the Discussion Forum. Rather than go through a lot of what you can read elsewhere on this site I would highlight the following: Rising damp is very rare indeed. Most 'modern solutions' are designed to tackle rising damp only. More often than not I see modern rising damp treatment where the problem was not rising damp and therefore the treatment was unnecessary and ineffective.

If there is low-level dampness in a wall (a tide mark up the wall, a line of salt's efflorescence, rotting skirtings/floor edges, etc) look to see why. The building would not normally have been constructed with a fundamental flaw. There is usually a reason for damp and it nearly always relates to something that has been done (or not done). I am thinking of ground levels being increased, renders taken down to ground, air bricks being blocked, downpipes leaking, dense renders/pointing on wall faces, etc, etc. Many damp problems are resolved by reversing what has previously been undertaken or by doing work/maintenance that has been ignored. Most damp problems are resolved by common sense good building work rather than specialist treatments.wary of any reading that is the result of a hand held moisture meter only. These are sensitive instruments but merely give an indication of whether there might be moisture. They were originally developed for use in timber and are only calibrated for use in plaster, etc. They can be unreliable. That said, to answer your questions: 1) Penetrating damp due to leaking/overflowing gutters, defective pointing, defective joinery, severe weather exposure. Leaks from buried pipes in the wall (e.g. rising main). Condensation, particularly if the wall in question gets most of the prevailing wind and rain. To the basement areas the problem is most likely to be dampness penetrating laterally through the wall where the wall is below ground level and then travelling up through the structure, plaster, etc. The problem in the basement could be exacerbated if a concrete floor has been laid (that is not original), as this could be forcing ground moisture to find another route out, i.e. into and up the walls.

In my experience the most common forms of damp are due to leaks (gutters and downpipes externally, plumbing and heating internally) and condensation. Condensation is not always straightforward to tackle but a solution would usually involve consideration of the heating, insulation and ventilation of the property (one, two or all three to varying degrees). The most common and easiest solution to condensation is ventilation, but in some circumstances additional and other works are required.

I am sorry that this is not a comprehensive list but I hope it gives some pointers and answers what you wanted to know. That said, if anyone is hoping that reading this they can avoid getting professionals involved, remember that the above is a very brief and general view. We spend years learning (both academic and experience) before understanding what we are looking at. Knowledge of a wide range of building materials and techniques is needed before being able to properly analyse building defects and provide sound solutions to problems. Remember that there are always exceptions to the rule and not all buildings are precisely what they seem at first.

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: Solution required to stop damp & flooding without causing bankruptcy?
FROM: Phil Tebble (Gloucestershire)
Our house, originally built approx. 1840, had the ground around it raised by some half metre some time in the before WWII. The main part of the house (lounge, hall, dining room and kitchen) has foundations, but the bathroom and utility room at the rear of the house, which are extensions, have none. The house has no damp-course, except an ineffective electrical system. The land behind the house slopes down towards the house (approx. 3-4 metre drop over 20 metre) with two terraces 'held back' with Cotswold stonewalling. A spring at the top of the garden is piped around the house to join a stream at the front. This pipe is joined to a buried concrete tank behind the house by a (now jammed closed) ball valve. If the tank is pumped out it gradually fills to about half a metre deep, so it is presumably cracked. The lounge (at the front of the house) has damp along its side and rear wall, although forming a 'ditch' along its side wall as gone some way to alleviating damp in this wall. The pantry, in one of the rear extensions, floods in periods of heavy rain. Due to the lack of foundations on the two rear extensions we cannot lower the ground level below the floor level. Also one of the terrace retaining walls is only one metre away from the extension and sitting on top of the raised ground level. Any suggestions to solve damp and flooding that won't bankrupt us?

Phil Tebble

My first reaction is that you really do need professional advice from someone who can come and look at the problem first hand. In general terms it sounds as if the system previously installed (taking water around the building) was sound and this is certainly the approach I would consider in the first instance. I suggest you look at whether the improvement or replacement of the basic system would solve your problems. The intention being to divert water around the building and away from it so that as little as possible reaches it. At low level you could consider some external protection, but without seeing the building I am wary because this could also cause moisture to become trapped in the building.

I do not think modern damp proofing (chemical or electrical systems) will help in this instance. It is possible that a physical DPC inserted in walls would help, but the cost would be horrendous and if the problem is penetrating lateral damp a horizontal DPC will not help much.

Although you cannot lower the ground where the extensions have no foundation you could probably install a form of land drain slightly set away from the walls (say 500-1000mm away). This could then divert ground water away and help reduce the amount of moisture getting into the base of the wall. A more extreme alternative is to carefully underpin the extensions down to a suitable depth that would enable the ground to be lowered. This could be undertaken using brickwork footings (instead of concrete) so that the basic structure remains much the same. It would have to be done in sections and the underpinning and lowering of the ground would take place at the same time. However, I suspect that without a land drain as well you would still get a lot of water and could still experience some problems.

The problem with land drains is that unless they are protected from fine material they get silted up. It is now recognised that a land drainage system should be wrapped in a geotextile membrane to prevent finer material getting in AND have rodding points along its length so that it can be cleared.

The pump you mention sounds as if it needs replacing. Generally, before embarking on major new work I would focus on getting the old system working properly and then see what extra work is needed to help prevent the dampness problems.

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: House prices appear to increase but ours falls by £43,000 in 12 months
FROM: Elizabeth Grieve (Cambridge)
Who do we pursue for wrong valuation? We have lived in our home for a year and now have to move due to work. It was priced at £350,000 and we paid £343,000. We had it valued by 3 local agents this week and they all valued it at around £300,000. We have done nothing to the property except paint some interior walls and doors, and are shocked at the difference in prices. We have a mortgage, and had a Homebuyer's report from the surveyor appointed by the bank. He valued it at £350,000. Please help!

Elizabeth Grieve

No one. A warning should be placed on houses much the same as for investments - PRICES CAN GO DOWN AS WELL AS UP.

Do not believe everything you read in the papers, not all areas have benefited from rising house prices. One year ago a fair market value for your house could well have been £350,000 and unless the surveyor had good reason to doubt that this was reasonable he/she is nowadays likely to go along with the agreed price unless it is clearly out of line with market values for the area, or unless there is a defect that has not already been reflected in the price being paid.

There may have been changes in your district that have affected house prices. For example, the government's announcement regarding Stansted has resulted in some areas nearby suffering a downturn in prices. Speak to the agents and ask them if prices have gone down or something happened to affect the price of your house. You mention that you have decorated, have you painted it bright pink with green spots? If so, this could have a detrimental affect on price. If you find that you really did pay above the market value one year ago you could try suing the mortgage company and/or surveyor. However, you admit to paying less than the valuation anyway. Why did you do so? Was there something the surveyor did/could not know that you did? If you pursue a case you would have to show that the valuer did not properly take into account the market evidence, etc. If you find that the valuer did no market research and simply went with the price for no reason than laziness then you might have a case. I think this is unlikely however. Further, you would have to prove a financial loss, which at present is unlikely because you do not say you are selling for a loss. There are many of us who purchased a property only to find that within months the prices achieved had dropped. This is a risk with buying any property. You may have to simply wait until the market recovers.

I was involved in a case a year or so ago where the judge considered the purchaser's own knowledge of an area critical as well. If the purchaser had come from outer space with no knowledge then one can reasonably expect that they would offer a silly figure in total ignorance. However, if you spent months looking for property in the area and eventually negotiated a price (and in this instance the price was below the valuation) you cannot claim total ignorance. The fact that you spent time looking meant that you were as aware as any valuer might be of the local market and market values. It is therefore reasonable for a valuer to use the agreed price itself as evidence of the market value. This was the view of a judge. Whilst you could seek legal advice I have serious doubts as to the validity of any claim in the circumstances you describe.

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: Guidance required for colour of sash windows.
FROM: Andrew Knightly-Brown
Although 99% of sash windows in Georgian/Regency/Early Victorian houses are now painted white, I believe that this was not the case when they were originally built. Is there any authoritative guidance on original colours, and did the colours change through these periods?

Andrew Knightly-Brown

Brilliant white is a modern colour. Historically white was difficult and the nature of paint meant that it often faded and went slightly off colour quite quickly. There are a number of manufacturers making off-whites and creams that are probably closer to the historical whites. That said, other colours were used. In fact, research indicates that some properties were far more highly coloured than they are now. Modern tastes are more subdued than historically. There are a number of books that might help. The publishers Phaidon produce a series of books on architectural style, including décor, etc; including ones for Regency style, Adam style, Elizabethan style, etc. There are a number of properties where original paint schemes have been used. A good example is the Queens House at Greenwich.

However, with window frames it has long been known that white finishes last longest because of the effect of heat (sunlight) on light and dark surfaces (think back to your physics lessons). Historically many windows were not painted and simply waxed, or painted a form of white. In the Victorian period when paint became more accessible to the ordinary home owner various colours could have been used. However, over time they discovered that white lasts longest, particularly in bright sun.

Although I have not provided a definitive answer I hope this points you in the right direction.

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: Underground lake beneath ground floor flat gives cause for concern.
FROM: Bruce Haines (London)
We have an 1890 built Victorian ground floor flat in Streatham, South London. Under the floorboards at the back of the house is a 1.8mvoid, with 20 cm of water on the ground creating 3000 gallons in all. We have pumped it away three times this year, and each time it comes back. It is level with the ground level outside. It is smelly when disturbed and is causing 20% humidity under the boards, threatening dry rot. No one seems able to tell us where it might be coming from, and so we can't address the problem nor move ahead with refurbishing the flat. Our surveyor missed the water during a full survey when we bought the house, but is liable, we hope, for some repair costs, when we can find out how to remove the water from the basement. Can you suggest some causes and remedies? We have checked the fowl disposal pipes with a camera survey and the down pipes from the roof and waste and they are all ok. The water board has said no sewage or chlorine is in the water, but another expert suggested that chlorine would be contaminated by the time it had reached us from an underground leak anyway.

Bruce Haines

From what you say and from my own (admittedly limited) knowledge of the area, I suspect that this is a ground water problem. You could have a borehole drilled to investigate the nature of the sub-soils down through various depths. In one property I know of (not London) they found a permeable layer of soil through an impermeable layer. They then drilled through to form 'drain holes' so that ground water could drain away into the lower permeable layer. Boreholes could help educate regarding the nature of the soil and likely causes. As for solutions, apart from drain holes, there are several possible, but you really need professional advice. You could form a sump and install a semi-submersible pump so that the water is regularly pumped out and into the surface water system. You would need to liaise with the water authority and they may not like this solution. You could consider filling the void in part to a level above the water, so that it is displaced elsewhere. If the 1.8m void is filled with 0.5 hardcore and oversite the water may not show and may be dispersed. There would still be a void of 1.3m. This can be ventilated.

Alternatively, you could simply increase the ventilation significantly and cross board the floor surface (to prevent the smells). The risk of rot is perhaps not so great if there is very good ventilation and for dry rot the timbers themselves have to be at or above 23% moisture content. I hope this gives you something to consider, but I think you will need to get a surveyor or engineer to assist you.

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: How do I support my Corbels?
FROM: Simon Hughes (London)
Our terraced 4 storey 1843 house has a corbel-supported white-painted decorative 'shelf' about 2 feet below the top of the rendered facade. The top of the north-facing facade has no obvious coping. Below the corbels, most of the facade is exposed brick. Cracks in the rendering above the 'shelf' correlate with rapid loss of render and paintwork from the lower surface of the 'shelf' between the corbels (that is, on a surface facing vertically downward). However, rapid degradation of this paintwork seems a common feature of the entire row. I suspect water somehow penetrates the 'shelf' and leads to weakening of render and paintwork on its lower surface. What can/should be done to achieve a fix that will last more than five years?

Simon Hughes

Many older properties have projecting decorative features that create a horizontal shelf on which water can rest and even penetrate into the wall. The most common and usually successful method of dealing with this is to install a lead cover. This is hardly visible from ground but gives the horizontal surface a protective layer, preventing water getting in. This cover needs to be carefully detailed to provide adequate protection without being highly visible. The topmost parapet should of course have a coping of some description, which can be stone, brick on edge, lead, etc. It may be necessary to form a coping if one does not exist. If the parapet deteriorates to the point of needing rebuilding it should be rebuilt with a horizontal DPC in it.

As for the render, although dense modern renders are thought to keep damp out, they will often cause problems. Being brittle it cracks and once moisture gets in it cannot escape and therefore causes a problem, including further cracks, failed render and failed paint finishes. Far better is to have a traditional lime render. A naturally hydraulic lime might be best for exposed locations. This can be coated with limewash.

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.