Monday, 18 May 2015

Some of the pitfalls of listed building ownership and the need for professionals

If you're new to the concept of listed buildings, or are currently thinking about having work done to yours and are not sure about which materials to use or the possible legal implications concerning alterations (however minor), then this is for you. 

The definition of what it means to be a listed building owner is one which states that you are charged with the guardianship of the building. You might own the title deeds but your ownership is in name only. The Conservation Department of your local council can exercise its rights over you as far as upkeep, maintenance and alterations are concerned. There's just so much you can't do so if you're desperate to knock down walls and put your modern stamp on an old building then it might be wise to look for something which isn't listed. 

The aim of this article is to give owners and potential owners a greater understanding of their rights and responsibilities. Hopefully it will enhance the ownership experience and help you to add value to your house whilst making it more saleable. 

Firstly, contractors. With ready and willing hands only too eager to pocket a pile of hard earned cash in exchange for some inappropriate work it’s rare that one comes across a listed property which has not had the addition of cement for rendering and repointing over the last 50 or 60 years. In fact, it’s likely that 98% of listed buildings have had the wrong materials used on them at some point in recent history. Not only might the house come with the addition of icky cement, you may also find walls covered in gypsum and none breathable paint. If you're in the market to buy and you spot that gypsum might have been used then make a note and ask your surveyor to check it out. Look at the walls and if they appear really flat - a smooth almost mirror finish - then this might be evidence of a gypsum based multi-finish. Check to see if an effort has been made to make the interior look as smooth as a new build and bear in mind that an uneven surface is actually a good sign. Don’t be afraid to ask the vendor if they can prove they instructed a contractor who used lime – an old receipt could go a long way to dispelling fears. If gypsum has been used then it might be worth asking the current owners to consider a reduction in price as it means there will  be  trouble ahead as gypsum will only last a few decades and will blow once moisture gets behind it. It will also crack where there's even just a fraction of settlement.

A more common and quick to appear issue of modern plaster is the fact that condensation rapidly gives rise to mold. The problem being that it will hold moisture but is not porous enough to aid its evaporation.

If the pink stuff or cement has been used in any area of the house then consider how much its removal might cost as it could be an expensive job or a time consuming pastime for you. 

When mulling over a purchase it's worth the effort to check out whether listed building consent has been sought for previous work. No record will indicate lack of consent. And this cannot be given retrospectively. Conservation departments may go so far as to allow that repairs have been made but it is always noted that that these were made without permission.

Thankfully, when buying a property, it is likely that your surveyor will be of great help where highlighting the incumbent issues inherent in the use of inappropriate products. One concern relating to cement mortar repointing will be the depth to which it has been applied. Deep might result in recommendations to leave it alone as damage to the masonry is likely should its removal be attempted.

Although you might be very confident at DIY, it's a very different state of affairs with a listed building. With modern builds a splash of paint or a quick repair might improve the property but once you start making changes to a period property then the results might substantially reduce its value. In many cases, using professionals from the smallest to the largest repair is often the best way.
I decided to have a ring round a few chartered surveyors to test a few hypotheses and was recently talking to Charles Brown from Cotswold surveyors ( who not only stated that contractors who understand traditional products are an absolute necessity but also employing the services of a specialist architect for large jobs was a prerequisite when making major changes to a listed building.

All surveyors are very observant and have trained for years to achieve their level of understanding of the way buildings work. Most are experts in the mechanics of older buildings and can spot an inappropriate repair a mile off. If you have not sought permission for one of these then it could result in potential buyers removing their offer. Hall and Ensom (, for example, are another like minded company of surveyors who are happy to espouse the virtues of traditional products and the use of professionals on period homes. Speaking to them recently revealed that it can be helpful to have the input of the vendor during the survey as there'll often be questions about the products used for repair and refurbishment i.e. whether the paint which has been used is a porous clay, lime or chalk based product.

And even if everything appears in order, the path to period living can still be fraught with difficulty. For example, there are often issues with lenders such as banks and building societies. Although attitudes are slowly changing, for some reason a few believe that it would be unwise to supply funds unless there's evidence of a servicable damp course. Of course, as a listed building owner, the last thing you would want is one of these as they create more problems than they could ever solve. 

What could also trip up the selling process is a good solicitor. If experienced enough, he will be able to spot whether a potential seller is trying to pull the wool. For example, new laws of disclosure as from 2014 now state that a seller must provide information concerning work which has been done on a property especially if it will interfere with the future enjoyment the new owner expects from the house. I can see it now. "So Mr Jones, you've stated in your disclosure report that you've had no work done on your grade two listed property over the last ten years yet the estate agent's details state that this is a property which benefits from extensive recent updating. Did you apply for listed building consent? You didn't."

It could spell the end for the cost cutter, bodger and cowboy owner where listed properties are concerned because being one or employing a rogue could make a property unsaleable. The reason? Lenders will only lend if a potential buyer is able to get insurance against work undertaken that may have been done without listed building consent. If the survey highlights the possibility of such work then the buyer might not be able to move forward and you could end up having to reduce your price for cash only.

My main priority at this point is to try and advise you, coerce you, cajole and persuade you to only ever use natural materials during refurbishment and repair-work. Natural is always best when it comes to older properties as modern products tend to work against the house rather than with it. Using lime lime based products on listed buildings is always preferable. Not only from a personal health perspective but also from a legal one as the Conservation Department have powers to bring owners to the courts. And with very expensive outcomes. It’s certainly not unheard of for large fines to be imposed on those who’ve effected repairs without consent or have demolished parts of the building without permission. In the worst case the ultimate course of action (although extremely rare) is imprisonment or the confiscation of property. 

Should you choose to go down the route of employing contractors who are unused to working with traditional products then I can give you a hint as to what you may encounter. As a craftsman I've had the displeasure of working for owners and with tradesmen who are only too willing to apply cement and gypsum to properties. I've even asked them why. The answers usually reflect very little knowledge of the requirements of the local authority. They are simply unaware of the requirements of these bodies and are also unaware that products other than the ones used on modern buildings must be used on old houses. Most have less than a modicum of knowledge of the mechanics of older properties and their knowledge of their own products is limited.

If you do not instruct a plasterer to use lime then the result will be two coats of cement render and a couple of applications of multi-finish. You may be informed that the first two coats are breathable as they contain lime but what won't be mentioned is that it's hydrated lime which will be shovelled in alongside the cement. All you'll end up with is double waterproofing. It'll be finished with Multi or Board Finish and this is also non-breathable. The result will be that moisture will not pass through the wall and you'll get rising damp, problems with condensation and also the issue of salts rising to the surface of the plaster causing bubbling. 

Incidentally, there's a current trend for manufacturers of some cements based renders to refer to them as 'damp control'. All this means is that moisture will be stopped from evaporating away from the surface of the wall because the product will have waterproofed it.

So staying away from gypsum plaster and cement is always advisable as the upshot is that their use will almost certainly result in cracking due to seasonal changes and thermal movement. All newer products including Tarmac's Limelite have waterproofing qualities as well. Basically this stuff is exactly the same as a 6:1:1 cement render mix using Perlite to substitute some sand. Tarmac say it's a favourite of the conservationists. But try specifying it with the Conservation Department and see how far you get. 

But I digress. Back to gypsum: one of the eventual outcomes of using it might be that it will simply peel away from the surface of the wall should there be any moisture behind it. The reason for this is that gypsum comes in two forms: either mildly soluble or totally waterproof. In direct contrast, lime will allow moisture  to pass through it and simply wick it away. Although some contractors will say gypsum is porous, just because something holds water does not necessarily make it so.

As mentioned earlier, many contractors are simply unaware of the implications of working on period properties and most are certainly ignorant of the fact that they too can be prosecuted for undertaking inappropriate work on them when they’re listed. What you'll get from most plasterers is Unibond and render, or PVA and render, or PVA and British Gypsum's One Coat because that can look like lime when it's trowelled down. What you might even get is a light Multi Finish skim over your existing lime and that will be considered normal and good practice. 

If you'd like to do a bit more research then I've found a youtube clip on the use of gypsum versus lime mortar and also one on the virtues of using natural paints which you may find useful watching.

There’s also the author Marianne Suhr who is an expert on older buildings and she’s written a number of books which are available online. However, should you require something more brief then there's always Period Living magazine which is out every month and costs only £3.70. It’s always good to familiarise yourself with as much as you can as forewarned is forearmed.

Tuesday, 5 May 2015

Correct aggregates for repointing where lime mortar is concerned

Firstly, let us take the ordinary and mundane subject of sand. As we all know, that which is used to lay bricks and stone is mostly sold from quarries and local builders’ merchants. It's called screened sand, soft, or building sand and is made to a particular recipe where different types of fines are combined with larger grains. But what if you want a soft sand for building or pointing with lime mortar? Can you throw a few bags in your boot and get going with a project? In short, the answer is yes, of course you can, but after reading this you might not consider it an option. The main reason for this is that building sand is too soft and this means the lifespan of your mortar will be reduced if you use it. Care must also be taken where colour choice is concerned as soft sand comes in a multitude of colours and if you or your contractor pick the wrong one then you’re in trouble.  You may even devalue your property.

At this point I need to be careful otherwise I’ll run the risk of revealing trade secrets so it’s probably best to keep this brief: for repointing with lime mortar you need a combination of two types of sand and both have to be washed. However, most trade and DIY outlets do not supply what's necessary. So if you use unwashed sand then impurities which have not been removed will rise to the surface of newly applied lime mortar.

Sharp sand, on the other hand, has very little influence on colour. But it will have a direct affect on texture and therefore finish. Ordinary sharp sand from a quarry or builders yard is a fairly uniform texture with aggregates large enough to make it qualify as sharp. In sum, it’ll do the job but it’s nothing special. It’s the type of aggregate which is perfect for laying patios or putting down a base for a shed. However, if you want sharp sand which is going to make the mortar in the joints of a period property look sublime then you need to extend your search beyond the average home improvement retailer. This is because when lime mortar is brushed, the larger particles of sand are brought to the surface and only a top quality purposely blended mix of sharp and soft sand will recreate the depth of shade and texture needed to replicate the highly desirable effect which is so enticing where beautifully maintained period properties are concerned.

I use what I consider to be the perfect blend of sand. It consists of a mixture of soft and sharp sand to the specifications which my experience dictates is correct. It looks superb, there’s no colour leaching and the aggregate sizes and colours go together to create the ideal tint which complements natural stone. Not only this, but it also conforms to
BS EN 13139:2002 Aggregates for Mortar which is the current standard.

Secondly I wish to highligh the issue of exacting standards in the use of natural hydraulic lime (NHL) and lime putty as both are obviously a priority of mine. They're flexible and porous and need nothing added to them except the appropriate sand. But unlike many other contractors I do not adhere to the widespread practise of adding cement to make my mortar cure more quickly as this pollutes the mix and simply turns good quality lime mortar into plasticised cement mortar. This is the last thing any owner of a stone built property needs – specially one which is listed. 

And finally there’s the finish. Lime must be brush finished and should never be trowel finished. However, it takes time to dry sufficiently before any  brushing should take place. Brushing prematurely not only results in cracks but also in the appearance of what look like damp patches. They're not really damp patches, it's just that the brush forms the calcination coat and brushing too early creates a mottled effect in places. Although over time this does fade, it usually takes a couple of years. 

Furthermore, omitting any of the brushing stages - or brushing improperly - not only results in a poor finish, but any lapse also means that imperfections remain as these are never revealed and therefore never attended to. None of this may matter to a potential customer if price is the only issue but employing a contractor who fails to attend to mortar correctly during its drying stages results in a job which will not stand the test of time.

In sum, lime takes time and the process of lime mortar repointing is very labour intensive. Mess up on something as simple as wetting up joints before applying mortar and things start going downhill rapidly. Leave it too long before brushing and things look even worse.

Recently I was discussing the merits of lime after I’d removed a wall full of horrible grey cement mortar and mentioned the fact that you’ve got to fight with it to know it and only when you’ve fought with it for long enough will you be its master. But mastery is  not about thumping it into place and being boss. It's about the relationship you have with it and how you must allow it to be what it is and work with it  and not against it. The reason for this  is that it's a natural material and these need comprehending. If I were ever to use an analogy to describe it then I'd equate working with lime to training a dog. At some stage you realise that many of your ways aren't productive but you have to get to that point before a lifelong relationship forms.

Anyway, I hope what’s written above has been informative in some way and that you can now see at least some of the reasons why the Conservation Department requires an example square metre before allowing contractors loose on listed buildings. 

Thanks for reading.

If you would like further information concerning the use of lime mortar please see the ‘blogs links and articles’ page at

Sunday, 18 January 2015

Oxford brick repointing

The advantages of lime mortar where the repointing of brick built period properties is concerned in comparison to cement mortar.

Cement has been around for decades but in relation to lime it is a relatively new building material.
Invented in 1794, and patented in 1824, cement was originally intended for engineering works and never domestic dwelling construction. Nevertheless, it has now become one of the most prolific building materials due to its use in house building being popularised after the Second World War.
But why substitute lime, a perfectly good building material, which had been around since Roman times and has enjoyed worldwide success?
1) In the 1940s it was well known that non-porous mortars were not ideal for building. However, as traditional building materials were in short supply after the war it was considered a viable and necessary alternative as  there was a massive housing shortage and new buildings needed to be built quickly and cheaply. 
2)      Cement was cheaper than lime and the war effort had cost everyone in so many ways so it was the obvious choice. Even now a 25 kg bag of cement can be bought for a third of the price of a bag of lime and it will also go much further.
3)      Cement is quick. Once a course of bricks has been laid, or a strip of pointing mortar applied, there should be no need to attend to it afterward except for a quick brush. This is in direct contrast to lime which has to be attended to until dry.
4)      Contractors who use cement do not need to be as skilled as those who work with lime and often charge less.
The art of good mortar was not lost the minute cement became popularised because many builders applied their knowledge of lime mortar to the emerging and widespread use of cement. They understood that the ratio of sand to cement and the grading of sand particles were key issues where the use of building with bricks was concerned and therefore they always mixed a weak mortar to accommodate movement and thermal expansion. In many cases this was 13:1:1. That's 13 parts sand, I part hydrated lime and only 1 part cement. It still meant there was no porosity in the brick joints but a softer mix meant less chance of cracks as buildings moved due to thermal changes and shifting ground. Subsequently, new developments in construction soon meant that eventually solid walls began to be phased out in favour of those built with cavities and air bricks. These, and the introduction of deeper foundations,  further negated the need for a soft and flexible mortar. It was also understood that a strong mix was more weather resistant and mortar mixes eventually became harder than the brick and stonework it was holding together.

The result of the above was the eventual extinction of knowledge concerning lime mortar from the building trade and the introduction of an ideology based around the belief that hard mortar was in some way a good thing. This happened as older craftsmen retired and others made their exit from the profession - those left were men who had never used lime and knew nothing about it. England quickly became the European capital for the use of Ordinary Portland Cement (OPC) whereas other countries simply banned its use where brick and stonework were concerned from the get-go.

Nearly 70 years on we find ourselves beginning to understand our OPC inheritance. The widespread use of cement where repointing old buildings is concerned has had far reaching consequences. Delightful brick built period properties which used to please the eye have simply been covered in unappealing grey cement. This is unfortunate for a number of reasons; one of which includes that the once porous joints which the buildings and their occupants used to enjoy are now sealed and moisture cannot be wicked away.

People often say that when a building has been repointed in cement mortar that it is no longer able to ‘breath’ in relation to moisture expulsion. Unfortunately this term has almost become a cliché. A more appropriate anology would be transpiration because porous joints have always enabled the built environment to expel moisture away in the same way as a plant or tree transpires it. Lime enables moisture to travel through a wall in the same way a plant employs capillary action. Water molecules are able to cross a network of microscopic bridges which eventually lead to the atmosphere. Add cement to a lime mortar mix and it becomes polluted. The upshot is that the potential for the development of this bridging network is either curtailed or destroyed all together. The result is often damp.
Using cement mortar to build with effectively glues the bricks together. This gluing effect creates further problems as the moisture trying to escape from joints rots the bricks when it is held back.  It’s always worth remembering that bricks – especially those used on period properties - are very soft. Sticking them together with rock hard cement damages them.  
Another problem inherent in the use of cement mortar trowelled over lime joints is that it results in cracks because the cement is brittle. When the cement cracks, it eventually falls  out.  It could be argued that at least the cracks open up the building a little and allow some free movement of moisture. However, all that happens is that moisture is held behind an impervious cement shield and is unable to escape. The end result is that using cement over already lime mortared joints simply results in the property being unable to self-heal. 
I read a surveyor's report recently and it highlighted that there are a limited number of contractors who are experienced in working with lime mortars  and with stone walling.  In fact, "Finding people who understand lime can be difficult and a lack of understanding" – as Kevin McCloud from the TV program Grand Designs has pointed out – "can be detrimental to a build or property refurbishment." However, skilled and knowledgeable craftsmen do not come without a  price tag. The problem many people have with this is that they don’t understand why lime mortar repointing costs what it does. The fact is, joints have to be well recessed - I usually go down at least 25mm - and this takes time. Add to this the fact that the joints often differ in size and therefore require investment in different  tools with which to rake out and you're half way to realising why it costs what it costs. Couple to this the fact that the mortar has to be applied when it is stiff  and you can see that it's a slow process. Of course, different size joints (it's usually the verticle ones which are much narrower) doesn't just mean a selection of machines and hand tools to remove the mortar, it also means a selection of hawks and trowels to apply it. I'd like to say it stops there, but it doesn't. When cement became popularised everyone was using it and now just about every wall or house that I work on has some. It needs to be removed and again this takes time - specially if the cement to sand ratio is high or it's been mixed with sharp sand.

The above photo is taken from one of my jobs and shows the necessary depth which one needs to go to in order to achieve good adhesion of mortar where NHL 3.5 mortar is specified.

The issue of higher cost is further compounded by the fact that lime simply won’t go as far as cement because the modern mix is approximately 5 to 7 parts sand, 1 part cement and 1 part hydrated lime. In direct contrast, a lime mortar mix is 2 to 3 parts sand and 1 part lime. What this translates to is twice as much bonding material is needed at three times the price. Once applied – as mentioned earlier – lime must be attended to and, depending on the situation, might not be ready to be brushed for days. Once dry enough however, the mortar then needs to go through various different trowelling and brushing stages. During these, cracks are ironed out and the aggregates are brought to the surface. In direct contrast, an adequate rake out depth for cement is only a few millimetres and the rapid chemical set simply means a quick whizz with a pointing trowel completes the job. There’s no need to keep returning to site after the last trowel full has been applied, the tools can be packed away and an invoice submitted. In direct contrast, a lime mortar repointing job might mean a few return trips to site to check that the mortar has reached a certain point in the curing process to be brushed. In the case of lime putty it could take longer.

The above photo show what mortar looks like after its been applied and before it's been brushed.

 Touching up the finished article

From the above information it should now be clear that embarking on a relationship with an older property is something to be viewed with caution. However, even more prudence should be used when considering an older property which comes with the addition of modern building materials used as a substitute for traditional ones. I’ve recently been working on such a property and I can tell you that the damage which cement does to older houses is more than can be imagined when initially viewed by the uninitiated.  

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