In defence of Cement

[Anonymous]

Having received a good old wrist slapping for ignoring the well intentioned advise of various members of the forum and going along with our builders advise, I wanted to throw something into the mix which I don’t think anyone here can ignore.

The number of people who are actually aware or care about what type of mortar there house is rendered, plastered or pointed with is miniscule, most people want a classy looking job done as quickly as possible for the least amount of money. I can drive through any number of towns anywhere in the country and see lots of very attractive well maintained period houses, the vast majority of them have been altered and maintained using all sorts of modern materials including cement. As an example, my uncle who has just retired after fifty years of running a medium size building firm specialising in barn conversions can count on one hand how many jobs they have used lime mortar. He is old school apprentice trained and received numerous awards over the years for quality work on thousands of public and private buildings. The point is that it is now realised that lime is far more suited to these type of buildings, but it does not alter the fact that 99% of all the work done in the last fifty years has been done with cement, and probably 98% of them are perfectly OK, if they were all falling apart because of the use of cement I’m sure there would have been a national crisis a long time ago. To say you would not trust any builder who mentioned cement around a period property is crazy, look at the regeneration of the hundreds of thousands of Victorian terraced houses which were all given grant aid to have new solid concrete floors put in and re pointing work and injected damp proof systems. I have lived in this type of property I have visited many of them, they are not damp, full of cracks and spalling stones and bricks, they are pleasant comfortable period homes. Of course some will go wrong and these are the ones you hear about on this site, but this is a tiny fraction of the millions of people living happily and in total ignorance of whether their house has been repaired with lime or cement.
In an ideal world every period home owner would have the knowledge and the means to use lime rather than cement, but the truth is most people don’t give a rats backside as long as the job gets done.

 

[Ian Bond]

You've been given some sound advice, and whether you choose to heed it or not is up to you.

True, most people use cement, as they are relying on what the builder tells them. To be fair to modern builders, they are used to modern materials such as cement, and are working to modern regulations and specifications.

I've done it myself, in my ignorance. Having read and researched over the years about these things I would not use cement in conjunction with masonry, whether modern or ancient. And I'd certainly avoid using cement in a period property in most cases. Including your chimney stack.

The more I work on old buildings, and the more I read up on the subject, the less I realise I know. A little humility is no bad thing.

Some of the modern methods you mention are at best a complete waste of money, and at worst risk causing damage and deterioration to your building. Note the word risk.

In an ideal world every period home owner would have the knowledge and the means to use lime rather than cement, but the truth is most people don’t give a rats backside as long as the job gets done.

You're not telling us anything we don't already know here. The evidence is all around us. Often in our own homes.

We won't win people over by slapping wrists or being overly critical here. It's more important to share experiences and information, so that we can hopefully prevent ourselves and others from having to learn the hard way all the time.

Ian

 

[Anonymous]

Fair Comment Ian, but I still don't think you can argue with the fact that the vast majority of buildings that have, and are still being repaired with cement are any worse off, and we are not talking about five or ten years ago we are talking fifty years and more. I remember as a child living in a brick terrace with horrible crumblimg damp plaster on the walls and I can remember the builders knocking it all off then painting the walls with some evil smelling black solution and then sticking a couple of coats of cement render over it, that was forty odd years ago, ten years ago the wall was still dry. You are right there is a risk, but it is obviousley slight otherwise the UK traditional housing stock would be in a right state.

 

[Nemesis]

Much of the work done to these houses is causing problems and will cause problems in future. Look at the pics of Gervase's house - he has first hand knowledge. I could show you the gable wall on my own house, pointed in cement about thirty years ago - and that's caused damage. The stone is flaking badly. Thankfully it is now loose enough to remove and point properly. If this was ashlar or brick, the damage would be pretty nigh irrepairable.

And a great deal of work carried out is not at all necessary - it's simply making money for some. Chemical injection 'damp proofing' is one such. Read Matt Green and realise it's not necessary in the huge majority of cases, there are alternatives. Cheaper ones in the long term, ones which actually work.

That's Matt from Ridout Associates, one of the most respected firms in the field of damp and timber diagnosis for historic buildings. PC is another professional who posts here who will say the same.

Apart from which, to anyone with any interest in historic buildings, much of the work done to so many in the past few decades has taken away a great deal of their historic interest. It's not conservation. And generally the ethos of this forum is about conservation and gentle repair, retention of historic fabric wherever possible.

Some of those who gave you advice are award winners in their own right - Andrew Gayton for example, whose qualifications include those in conservation from the Architectural Association and who is a member of the IHBC. The stuff he quoted was from one of his technical publications for Breckland Council, where he is Historic Buildings Officer. He's just won two awards (and was involved with another) for conservation work in the CPRE Norfolk Awards. One of those was for his exemplary work on his own home. There are awards and there are awards of course... these ones are respected.

Many people who post here have technical expertise and vast practical and theoretical experience and involvement with period buildings.

Sure you can ignore it, but the evidence is out there - lots of spoilt buildings, and more cash spent in the long term through use of wrong materials and attemps to 'modernise' in the most inappropriate manner.

Many people haven't a clue - this forum, and the work on conservation organisations sich as SPAB, is there to try to stop the rot - literally.

 

[Flyfisher]

I doubt many people would seriously dispute that cement render and 'plastic' paint can't create a very good looking job (allowing for the fact that some would always prefer a limewash 'look' anyway). Such a job would probably not cause any problems for the building for a few decades and might even outlast the present owner. From that perspective, it's easy to see the attraction of modern materials.

But, from the perspective of a 400 year old timber-frame building, inappropriate materials that can cause serious structural problems within, say, 50 years (maybe less) are a big problem when it might be expected to survive another few hundred years with the right materials.

Would a smoking analogy be appropriate here? Something that's known to be detrimental to general health, causes many complications and can seriously shorten your life, yet millions of people happily ignore all this because there are no short-term side effects. The fact that we all know someone who smoked 40+ a day all their life and died peacefully in their sleep at 95 doesn't mean smoking is perfectly safe.

 

[Nemesis]

I recall a telly prog last year where Ptolo Dean was given the job of working on a very nice timber framed historic house. It looked OK from the outside, but when the cement started to be removed the dreadful damage done to the timber contained within the panels was there in all its awfuless.

I have several horror pics which I could post - I think I'm not alone.

I also think that in recent times there has been a great deal more technical research such as the Smeaton Project. Organisations such as EH can point to buildings in their own care which have been repaired in 'wonder materials' in the past where remedial work is now having to be carried out.

Cement pointing and render is mostly bad for traditional buildings. When the damage will show will depend on a number of variables, but eventually damage will occur. Same with timber framed buildings.

A breathing building in traditional materials is still the best in the long term.


http://www.bcmsteeplejacks.co.uk/services/limeservices.html

http://www.mikewye.co.uk/CementPointingLongwell.htm

http://www.visitnorthwilts.co.uk/print/repointing_-_web-friendly.pdf

http://www.ingarsbyconservation.co.uk/ingarsby/info/faq.htm

Why natural materials?
Traditional Buildings
The term ‘traditional building’ describes buildings which were constructed before about 1900 with solid walls, shallow foundations and before 1875 with no damp proof course. The soft lime mortar and plaster gave the buildings flexibility to move on their shallow foundations without causing permanent cracking. The use of stone, soft bricks, clay and timber with permeable lime mortar and limewash allows the buildings to ‘breathe’ and thus avoid damp problems.

Repairing an old building using modern materials creates problems, in particular re-pointing or rendering with cement and trying to keep out damp with waterproof coatings. Traditional lime mortars and plasters preserve breathability and flexibility. They prevent frost, water and salt damage to masonry, damp in plasterwork and floors and rot in timbers.

Repairs and decoration using traditional, natural materials also look better and are more in keeping with the traditional appearance. The finishes have soft variations and the colours a natural subtlety that cannot be achieved artificially.
New Build
Lime is also making a comeback for new build ranging from prestigious projects, such as the new headquarters for the RSPB to starter homes for Housing Associations . It should not be overlooked that it was used for virtually all new-build until a hundred years ago. Lime has many advantages for new build including environmental, avoiding unsightly expansion joints and producing a healthier living environment.

A number of interesting pics and reading here too:

http://www.nsiuk.org/Culzean04.html

 

[Ian Bond]

Risk is the key word. No one is saying otherwise.

The risk of damage to an Edwardian terrace built in hard brick is not on the same scale as when dealing with a timber framed Tudor building, 17th century limestone farmhouse, Georgian rubbed-brick facade, and so on and so forth.

In the scheme of things a bit of cement is neither here or there in conjuction with a strip out, re-roof and uPVC windowing job. It is just another piece of incremental damage.

Cement pointing can and does cause terrible damage to some building materials in considerably less than 50 years. I have seen it time and time again. Even on hardy Yorkshire gritstone.

Some fat limes should not be used with certain types of masonry either, as that can cause problems.

Having the basic knowledge, and being prepared to research the proper solutions can help overcome the pitfalls that others fall into through ignorance.

In this case, ignorance is no longer an excuse.

 

[Ian Bond]

Flyfisher - I like the smoking analogy. A similar thought had occured to me, as an ex-smoker!

 

[Nemesis]

The number of local authorities with technical information available of the appropriate repairs of traditional buildings now is growing - here's just one example from many:

http://www.macclesfield.gov.uk/pdfs/Repointing%20your%20building%20for%20web.pdf

A large number of building firms are now realising the truth of the 'lime is best' approach too:

For too long the building industry has accepted modern materials applied with modern practice on traditional structures and this needs to be addressed.

http://www.traditionalmasonry.co.uk/lime-harling-and-pointing.shtml

If your building is suffering from internal dampness and stone erosion more often than not it is the cause of modern cement mortars that coat or form the pointing between the stonework joints. No matter what type of stone, the cement is sure to be incompatible and cause detrimental and irreversible damage to the stonework.

This case study is well worth reading:

http://www.traditionalmasonry.co.uk/case-studies/case-study-four.shtml

The original lime finishes that had been removed many years ago had been replaced with a hard, dense and impermeable cement harl coat. As a consequence of this inappropriate finish a catalogue of defects had become apparent. These included moisture entrapment within the mass masonry walls, internal dampness and decay of in-built timbers such as joist ends and internal wooden safe lintols.

How lovely the building now looks.

 

[middi]

Let us get two points clarified here.

There is NO place where CEMENT should be used in an AUTHENTIC restoration of a period building.

1) Cement was never used in the original construction, and if now used it would make a mockery of the words AUTHENTIC or RESTORATION.

2) Due to the type of materials and method of construction of these period buildings, the "patchy" use of cement is deterimental to their welfare for a variety of reasons.

People that ARE involved in period buildings can easily associate with two points above.

I must also add that if someone wishes ( and can ) to deviate from authenticity and as long as they understand the needs of the building to be " repaired", cement CAN be used without deterimental effect in some circumstances. It must first be understood as to how, where and when.
( I don't think it would win any awards for restoration though)

Apart from an ecologigal deterimental effect, cement is an exellent( and fast) building material, it is keeping " skyscrapers" over many people's heads.

 

[biffvernon]

but I still don't think you can argue with the fact that the vast majority of buildings that have, and are still being repaired with cement are any worse off,

I can argue with that.

And if you want an anaolgy, the Mona Lisa is really looking a bit dowdy these days. How about brightening her rosy cheeks with a blob from a felt tip pen?

 

[Nemesis]

http://www.buildingconservation.com/articles/ten/tenways.htm

 

[MD]

I am no expert, but can speak from experience. While renovating my timber-framed house, I have found that the areas of timber-frame that needed repairing or replacing were either covered with, or in direct contact with cement. When I needed to replace or repair lime render/plaster, the oak next to or underneath it was in good sound condition - maybe a little beetle damage, but tht was it.

I'm not sure about other period properties, but it certainly seems to me that timber-framed houses and cement don't mix. I think the point Whitby is missing is that a house renovated with cement may look fine, but the damaged being caused does not come to light until it is too late. It doesn't take all that long either. In my house, a section of the timber-frame was replaced only 6 or 7 years, but when the cement was removed recently, the oak had already suffered a significant amount of damage from damp/rot.

 

[PC]

Must of missed this one first time around.

As someone who spends each and every day of his working life looking at and surveying old buildings (and some newer ones) I can state that in my experience at least 80% of the properties that I survey for damp are damp for one reason only......... 'CEMENT' .....take the cement away (render or pointing) and they dry out.

I accept that most properties over the past 50 years have been cement rendered etc...........WHY? Cheaper and easier to use. However 50 years on the problems are now becoming apparent.

It is however also accepted that there are probably thousands of properties that have been given the 'cement treatment' that may or will not ever have a problem. That I'm afraid is more down to luck that judgement!!

PC

 

[Nemesis]

It's interesting to see how many specialists there are now using the internet to educate and advertise. Another informative site:

http://www.jjsharpe.co.uk/faq.html

Several examples of work carried out, and this is another area where using cement can cause total failure and collapse of walls - cob.

Cob requires lime render as protection and cement can prove catastrophic. And yes we have had posts here in the past where exactly that has happened.

Here's a picture:



[Open Image] [Hosted by PhotoGalaxy.com]


that's from here, where there is an after pic too.



http://www.jjsharpe.co.uk/workdevoncobcottage.html


Cement pointing, as Biff has pointed out, isn't anything like as aesthetically pleasing, either, as lime.

More interesting examples here:

http://www.architecturedevon.co.uk/smokey.htm

http://www.hullcc.gov.uk/pls/portal/docs/PAGE/HOME/PLANNING/CONSERVATION/LISTED%20BUILDINGS/LIME_POINTING.PDF

It's a pity that this otherwise excellent design guide to barn conversions still has lime/cement/sand as an alternative to lime, and it is now known that certain lime/cement mixes, while uneccessary, can also not be particularly durable.

http://www.ncdc.gov.uk/media/adobe/Conversions.pdf

 

[Cloudscape]

Not meaning to hijack this thread, but, well... read on.

My house is in a village where all repointing and repair work has been done with cement. I sometimes wander forlornly round my house, inside and out, looking at the hamfisted "repairs". I've removed some large bushes and climbing plants and found areas of wall that still have lime pointing and limewash. These areas are tatty, but holding up, despite having had numerous nails driven in to support plants.

Where I have large areas of cement pointing, the walls look a little ill in places. A small amount of the pointing has hairline cracks around it. Here and there, small bits of pointing (not as much as I'd like!) looks like it might be being rejected.

Where major amounts of cement have been used in fixing in a new lintel or (seemingly) changing a window's shape, and where purlins have been fixed (in a stable block extension), the mortar isn't moving with rest of the building. Cracks clearly outline some of the newer work. Cement render is failing badly in one (indoor/outdoor) room, while areas of old lime plaster in the same room are still hanging on.

My house is built with (seemingly) any stone that came to hand - bits of granite, slate, quartz and who knows what. The walls are very random and ragged textured, so the external repointing sometimes blurs into areas that just have a few bits of stone poking out. I have noticed that, here and there, some of the stones have spat off their surface covering of limewash/Sandtex/whatever-it-is. Just small eruptions, but quite clear to see.

Each room in my house has been treated totally differently, plaster-wise. I have original lime lath/plaster, lime plaster with a gypsum skim, and even walls where the gypsum is very thick and has been daubed on in a "cottage stylee".

I could easily lie awake at night wondering what's happening to all the timber embedded in these walls. :shock:

The sad thing is, this house would have been largely cement-free, right up to the 1970s. And a lot of this work (and work done on buildings all over the UK, and probably all over the world)) was done, sometimes, in good faith. People really believed that cement and gypsum were 'better' and 'stronger' - giving some of them the benefit of any doubt that the newer materials were 'easier'.

The oldest houses I've lived in before were Victorian. When I saw lime plaster and lime mortar, I had no idea what I was looking at. I still have a Victorian house (not for much longer) and I can now see that a lot of the bits that are giving problems are the cement-y and gypsum bits. I wish I'd known about lime sooner. I'd quite like to have taken an (unspecial) Victorian house back in time a bit.

I don't currently have any obvious damp problems in the stone house, but I do take on board what the experts say about what can happen to timber, where it's embedded in walls that cannot breathe.

I'm wondering what to do next. I can remedy the internal plastering. This will mean the walls breathe better inwards than they do outwards. Is this a good or bad situation?

If I replace areas of external repointing (small areas that look easily removeable) with lime, will these areas be happier, or should I avoid creating areas with different flexibility and beatheability?

I can't rebuild areas that have been reconstructed around windows, doors and lintels. I would also like to avoid hitting the house, doing damage, or making matters worse.

 

[Nemesis]

Interesting reading here too:

http://www.cornishlime.co.uk/html/projects/projects_rogue_gallery.php

and horror pics.

A ROGUES GALLERY OF DAMP AND ITS CAUSES
The following are a selection of images taken during various site visits, for many it is simply too late for them to justify the use of lime, given that they have usually laid out a lot of money for “remedial” works to have been carried out, or the thought of doing exactly the same again simply using a different binder is untenable.

This particular building has been subject to monitoring (to the rooms where works has been undertaken) both prior to, and following the works, as part of the surveyors ongoing studies into the use of cement V lime on older buildings and the evidence gathered thus far is overwhelming in favour of the lime approach. A fact we have been personally aware of for many years, but it is very reassuring to have an empirical understanding backed up by scientific methods. The testing methodology has been undertaken as part of a PHD study using a combination of Protimeter Hygrosticks and Data loggers.

Many other buildings under the care of the same Surveyor where lime has been used, have also been closely monitored and the results when published should make very interesting reading. We are certainly encouraged with the limited information we have been offered thus far and it will be his intention to submit a résumé in the Journal of the Building Limes Forum in due course.

As far as removing the loose mortar is concerned. it may look patchy but it can do no harm to patch with lime. Eventually you can only hope the rest will come loose too.

I have some horrific pointing in the hardest of mixes on a few elevations, yet the places where the lime has been left shows it to be in pretty sound condition, requiring only maybe a little repair here and there. Why did they do it?!!!

In some places the cement will have been simply smeared over the existing lime - you may find it not hard to remove. I agree there is nothing much to be done where rebuilding has happened around windows etc, without major disruption, but as long as what you do in future is more appropriate then maybe those areas will be OK, although you may get cracking which will need filling with lime. We have a similar problem in a couple of places.

 

[Anonymous]

Very compelling stuff, but let me respond to a couple of things.
With due respect to the small number of building professionals who may have commented on this subject, I also have a proffesional qualification in an un related field, this does not mean that my proffesional opinion is always correct, merely that people are prepared to listen to what I say. What worries me slightly is the fact that my partner recently attended a short course giving advise on the use of lime in old buildings, hence our decision to use lime in our own property, the course was run by not a craftsmen or architect but by a manufacturer of lime products. There were maybe 10 to 15 other people on the course, a number of them were employed by the local authorities as Conservation Officers, if this is typical of the sort of experience that these people have before going out and preaching about the de merits of cement and benefits of using lime on listed buildings then I would listen to the stonemason every time. Of course there are lots of people offering advise on the internet because they want to sell you their services or products, in just the same way as a company offering injected damp proof courses do. The comment about 80% of all houses surveyed for damp having problems caused by cement, I'm sure you are correct, but your 80% is only a tiny fraction of the total housing stock that has and will not suffer any problems at all through the use of cement and other less traditional materials. If this is such a time bomb then why are prudent lenders who rely on surveyors and structural engineers who should know better still happy to secure billions of pounds on property which apparently will fall over before the loan matures?

 

[Nemesis]

Well, we've said our piece if you aren't interested it's your problem.

Here's a link to the other thread:

http://periodproperty.co.uk/forum/viewtopic.php?t=8869&start=0



If you think SPAB, CADW EH and HS are vested interests without any idea of what they are talking about, that's your problem too.

Do you think organisations such as EWH run lime courses and advocate the use of lime for repair of buildings within the World Heritge Site because they are daft?

http://www.ewht.org.uk/Forthcoming-Events.aspx


Lenders are only interested in getting back cash on the property, but we've been over this a number of times too. That's a separate subject.

People like Stephen Boniface (PPUK Agony Uncle) whose piece I posted on your other thread - he does mortgage surveys too. He also is a former Chair of RICS Conservation Group, and is now in an even higher position at RICS.

I think you'll find he will tell you that lime is best and cement is damaging. As he said in his article. And frankly there are many surveyors who haven't a clue about period buildings. They have no specialist training.


As an aside, Ive just been to a National Trust property today, where in the not so enlightened past a wall was rendered in cement. I note today that this has failed at the bottom of the wall, taking chunks of stone off with it.

I also saw a wall which had in the main the original lime which looks beautiful, with the aggregate of a similar colour in the mix to the stone. Some unenlightened person in the past has 'mended' it with bits of grey flat cement. It looks dreadful.

And many of us here are involved in conservation, have been for many years, have friends who work in conservation, who have higher degrees in conservation, and are not talking out of their rear ends but have studied the subject in considerable detail.

 

[Flyfisher]

Fair point about many advocates of lime having a vested commercial interest but that's the challenge that customers always face - deciding what's the best advice and, therefore, the most appropriate solution.

Of course, the 'best' decision usually arises out of a complex mix of tradeoffs. We've all heard of the 'no expense spared' approach to things but for the vast majority of people this is simply not a practical basis for any buying decisions. If it was, we'd all be driving Roll Royces and drinking £200 bottles of champagne (well, you know what I mean).

So, faced with expensive house repairs, a limited budget, the speed advantages of working with cement-based materials compared with lime and (possibly the clincher in today's short-outlook society) very little practical short-term difference in the finished job, it's easy to understand why cement is so widely used. The fact that structural problems might arise after a few decades is likely to be quite low on the priority list.

But all of that is just to understand why cement is so persistently used; it says nothing about its suitability for traditional buildings.

The comment about 80% of all houses surveyed for damp having problems caused by cement, I'm sure you are correct, but your 80% is only a tiny fraction of the total housing stock that has and will not suffer any problems at all through the use of cement and other less traditional materials.

Yes, but I think we're concerned with an already tiny fraction of the total housing stock, i.e. period properties built with 'traditional' materials. I'm not aware of cement being completely demonised, it's more the mixture of modern and traditional materials that seems to be the recipe for disaster - for the building, if not the builder's bank balance.

If this is such a time bomb then why are prudent lenders who rely on surveyors and structural engineers who should know better still happy to secure billions of pounds on property which apparently will fall over before the loan matures?

There are, I think, a few possible answers to this.
1. It may be a timebomb that the lenders are unaware of, but the problem is likely to be confined to a tiny proportion of their property portfolio so the actual financial impact is possibly minimal.
2. Period properties are less likely to be granted 100% loans, so there is some inherent safeguard for the lender in case of structural problems.
3. House price inflation protects the lenders from a crumbling house in the longer term. Over 25 years a house could probably completely fall down but the land alone would likely be worth more than the original loan amount. Banks might not know much about building techniques but I suspect they know how to secure their loans.