Working with lime mortar
Here's some good advice from long-established specialists in lime -
Mortar. Plastering in hydraulic lime mortar normally consists of two or three-coat work. Lime plaster made
with feebly or moderately hydraulic lime and sand is the basis for this guide. This type of lime sets and hardens
predominantly by an hydraulic set and re-absorption of Carbon Dioxide from the air. By its nature the drying and
absorption process is slower than gypsum plasters, therefore lime plaster curing should not be hurried allowing
approximately 3-5 days per coat depending on the hydraulic lime used.
Background. When applying Lime Plaster on the hard, the background will normally be brick or stone. The
surface should be clean, free from dust and any organic materials such as lichens etc. Test the surface of masonry
backgrounds for dust by applying a piece of masking tape to the background and immediately remove, examine the
sticky side for traces materials that may affect the bond between the plaster and the wall.
Internal walls can be uneven and rough, often with areas that have been altered. Different background
conditions are therefore common and this needs to be addressed before plastering. Deep holes, wide joints or
pockets should be dubbed out in thin layers of mortar with pinnings tightly bedded in mortar, keyed and left to cure.
The aim of preparing the background should be to achieve a surface that can take a first coat of consistent thickness,
and to provide an adequate key for this first coat. The quality of preparation work is vital to the quality of the
finished job. Suction between the first coat and the wall (and between all subsequent coats) is the primary means
of bonding although a physical bond is also important. Different materials have different levels of suction, so for
instance where a door way has been knocked through a stone wall and the edges built in brick, the brick may well
have a different level of suction to the stone. Understanding and controlling suction is important for successful work.
For wood lath and plaster work, laths should be fixed by butt and break joints to joists or battens securely
fixed back to wall or ceiling, with gaps between the laths of approx, 8 - 10mm . The support battens or ceiling joists
should be spaced so that the lath does not give unduly in the centre. Wide spacing of battens or joists may require
intermediate support or thicker laths. Sawn or riven laths (traditionally hand made) should be thoroughly damp
before fixing. Dry laths swell when wet mortar is applied to them, sometimes causing the laths to bow in or out.
Nails for fixing laths should be thin shank to avoid splitting the ends. Building paper and insulation is occasionally
placed between laths and outside walls to comply with current building control requirements, this will have an effect
on the drying rate and prevent proper rivet formation when fixed hard against the back of the lath. If building paper
and insulation are essential,
use moderately (NHL 3.5) or eminently hydraulic lime (NHL 5) for the first coat as they have faster natural sets,
maintaining at least a 20mm gap between the paper and the lath.
How to clean grime from Victorian bricks
A dilute solution of hydroflauric acid is generally considered to be suitable for removing ingrained dirt from the facings of old brickwork. Of course the condition of the bricks needs to be checked before you start as any eroded bricks will be damaged further by the acid. The mortar pointing should also be in good condition. Unfortunately hydroclauric acid isn't nice stuff to use, so protective goggles, masks and gloves etc need to be worn at all times.
Dilute the acid, work in small areas at a time, and then wash it down thoroughly with a high pressure hose (bear in mind that very wet ricks can absorb damp through to the inside of a solid wall, so try not to soak the walls for longer than necessary).
Work from top down, so that the areas you've already cleaned aren't then stained with dirt from above. Don't leave the chemical on the brickwork for too long, as making the bricks 'overly clean' may not look appropriate on a Victorian house. It is essential to carefully mask windows and openings, as the acid can etch the glass making it obscure.
Alternatively, alkali based cleaners can be used, but these are not so and easy quick to use.
How the judge a roof
An abridged version of this article first appeared in ‘ Build It’ magazine Feb 2006
There are many challenges that house buyers may be prepared to accept when planning the
refurbishment of an older property. But the prospect of dealing with a dodgy roof can be one
risk too far, enough to deter even the most determined of renovators.
Roofs have a certain intimidating mystique since everyone knows they are a Big Ticket
Item - get it wrong and your carefully planned budget will be comprehensively trashed. And when
rogue trader reality-TV programmes seem to invariably feature cowboy roofers, it’s little wonder
that many of us dread the sight of a leaking roof.
Such apprehension is compounded by the fact that roofers’ estimates are notoriously baffling,
carefully laced with (often inappropriate) technical terms designed to bamboozle the customer
into whimpering cheque-signing submission. So who can you turn to for advice?
Chartered surveyors offer professional impartial advice, but sometimes suffer from a tendency
to err on the side of caution – conscious that no one gets sued for being overly pessimistic -
so anything that looks a bit dated may get unfairly condemned as ‘nearing the end of its useful life’.
Unfortunately, roofs are more likely to suffer from defects than many other parts of an older
building. Which is no real surprise given that they’ve often had to withstand driving rain, baking
heat, storms and blizzards for a century or more. Clearly, this is one part of the property
that it is essential to check thoroughly prior to purchase. So what defects should you look for on
an older property?
First, consider what kind of coverings you are dealing with. The traditional roofing material on
many period properties was hand-made clay tiles, or perhaps ‘stone slates’ in some rural areas.
Georgian townhouses popularised the fashion for lightweight natural slate which became almost
universal on Victorian dwellings until superseded later in the 19th century by manufactured plain
clay tiles. Large wavy pantiles and Roman tiles were a popular regional variation in areas such as
East Anglia. From the late 1930s, clay tiles started to be gradually superseded by concrete tiles.
So question number one has to be ‘does the property still have its original roof coverings ?’
If the answer is ‘no’ it may not altogether be good news. Generous Council grants in the 1980s
provided the incentive for many Victorian properties to be unnecessarily re-clad with large heavy
Redland concrete interlocking tiles – the main attraction of which was their cheapness and ease
of laying. Plenty of cowboy firms failed to beef up the roof structures to take account of the
substantial extra loadings – resulting in extreme sagging, and in some cases, collapse.
Today, modern artificial slates (composite fibre) are generally considered to be a suitable,
cost-effective alternative to real slate, although earlier asbestos fibre artificial slates haven’t
lasted well and may now be due for replacement (when contractors get wind of the ‘A’ word
this can prove costly ).
As you can see from the table below, the lifespan of traditional handmade natural roof coverings
was far superior to modern manufactured stuff. In fact it tends to be the fixings that fail first.
Slate roofs commonly suffer from corroded nails, and ancient ‘peg tiles’ or stone slates may start
to slip due to rotten timber pegs. Salvage yards can bear witness to the longevity of such traditional
materials, normally being well stocked with handmade clay tiles and recycled Victorian slates
awaiting their second incarnation.
A rough guide to the lifespans of different materials
Things to check outside
It will pay dividends to spend a few minutes casting a critical eye over your roof. There are a
number of clues to possible problems that can be spotted fairly easily:-
1. Firstly, take a good look down the street at nearby houses of the same age – if any have new
roofs, there’s a greater chance that yours may also need to be re-clad.
2. Are the main roof slopes reasonably level and even ? Slight settlement is not usually a problem
and is particularly common next to gable ends where the rafters have settled more than the adjoining
masonry. If the ‘dishing’ is more pronounced, then it may be the result of past recladding with
heavy concrete tiles, so you’ll need to check the support in the loft (see below). If the structure is
satisfactory and there’s no leakage, a fair amount of historic settlement can be acceptable.
3. Are there many slipped or missing slates / tiles, or any that are sticking up ‘proud’ (usually due
to poor repair work)? The need for some localised refixing is not unusual. The odd slipped slate
can be re- fixed using small folded metal clips known as ‘tingles’, but if there are more than about
6 or so tingles on one roof slope, the need for complete stripping and recovering may not be too far off.
4. Pay careful attention to all roof junctions (e.g. where the roof meets a stack or joins another roof).
These joints are covered with flashings – a major weak point. The worst offenders are cement mortar
‘fillets’ which are very prone to cracking and should be replaced with lead flashings. But even
good quality original lead or zinc flashings may now be living on borrowed time. Another weak
point is at the valleys where two adjoining roofs meet (e.g. where a bay roof joins the main slope).
These are typically lined with lead sheet and pointed up with mortar at the sides. The pointing tends
to crack and fall out in lumps and the metal can suffer corrosion from acid rain pollution.
5. The ridge tiles running along the top of the roof commonly suffer from eroded mortar joints
and may need pointing up, or even re-bedding. They are notably vulnerable to storm damage with
potentially lethal consequences for anyone walking below, and unless well maintained can allow
damp to enter the roof. The ‘verges’ at the edge of a roof slope also commonly require routine
maintenance in the form of pointing up with mortar.
6. You may be (un) lucky enough to own a Georgian-style property with an elegant front facade
concealing an ‘M’ shaped ‘butterfly’ roof, invisible from street level. The bottom of the ‘M’
comprises a valley gutter running from front to rear above the bedroom ceilings. Being out of sight,
they are particularly prone to neglect, blockage and leakage with dire consequences for those below.
Anticipate the significant expense of re-lining and replacement of rotten support timbers.
7. Victorian flat roofs were commonly clad with lead, or cheaper zinc, both of which will now be
well past their prime. Modern flat felted roofs can have a lifespan as short as 12 years. Flat
roofs are of course not flat, but need a minimum 1:40 slope to disperse rainwater and prevent
ponding; many fall short of this requirement and the decks may need upgrading.
Things to check inside
To fully assess the condition of a roof, you cannot overlook the structure. Popping your head into
the loft space (assuming there’s a loft hatch) can tell you a lot about the wellbeing of the property.
* If your loft is draughty and there’s no underfelt below the slates or tiles, don’t be alarmed –
that’s the way it was built. Felt provides a secondary line of defence against driving rain, but
was only widely installed on new houses from the 1950s. Old roofs rely on decent ventilation so
that any rain that blows in can safely evaporate away. There may be small chinks of light visible
between the rows of tiles or slates, which is normally OK. But any larger gaps, particularly at roof
joints can spell trouble.
* The main rafters on each roof slope are normally supported by a large horizontal beam called a
purlin, which in turn usually employs a wooden strut for support. If the roof sags, improved support
may be necessary here. This is fairly simple carpentry and shouldn’t be too expensive, if access is
* White powdery salts under the tiles can be indicative of erosion. Especially check the condition of
the projecting ‘nibs’ at the top of each tile (where they are hung from the battens).
It is also here on the underside that slates tend to first soften and ‘de-laminate’ indicating the
need for renewal.
* Check whether the firebreak party walls are in situ. If not they will need to be built up in
thermolite blocks or fire-resistant plasterboard.
Finally, it’s worth bearing in mind that many original roofs will exhibit very few of the above defects
and will be perfectly satisfactory with a little routine maintenance from time to time. Premature
replacement is an unnecessary expense and roofers may well utilise inferior cheaper modern materials.
How to spot a cowboy builder
Don't take our word for it - this is what the confederation of
master builders say:-
Cowboy builders are very much in the minority, but they are out there, so
how can you protect yourself. Treat them with suspicion if they:
The following article appeared in The Observer
A deadly plague
in all our houses?
Right now, there is every probability that you are sitting just a few feet away from a substance that can make the risks from cigarette smoking seem trivial by comparison. In fact, if your lungs had to choose, nicotine-laden tobacco smoke would be infinitely preferable to deathly cancer-causing asbestos fibres.
The chances are, your workplace incorporates the substance in some form and, if your home was built between the 1920s and the 1980s, you may well have been coming home oblivious to the presence of the 'lurking menace' for years. It seems many of us were raised unwittingly surrounded by the stuff.
Asbestos is the largest occupational health killer in the last 50 years. Since 1968, 50,000 people have died after painful and prolonged illness from asbestos-related diseases such as mesothelioma. A quarter of these worked in the building trade. If you thought BSE sounded gruesome, get this: inhalation of any form of asbestos can lead to virtually untreatable disease, but you wouldn't notice it for years - it can take up to 40 years to develop and it is reckoned that by 2020, 10,000 people a year could be dying from fibres already in their bodies.
Asbestos-ridden council estates and potentially toxic public premises have long been the subject of screaming headlines in local papers. Now the latest Control of Asbestos At Work regulations provide that from 21 May 2004 all non-domestic premises, including your place of work, must have an asbestos audit to verify just how safe (or unsafe) the work environment is. It is estimated that 1.5 million commercial buildings contain the substance, so until an audit has been done, property owners must presume asbestos is present.
But what of Britain's 21 million residential dwellings? What isn't often appreciated is the extent to which asbestos-based materials exist in our homes. Amazingly, the use of asbestos in buildings was not totally prohibited until November 1999, so pretty much any building can be at risk.
The bad news is that homes are excluded from the legislation, with the exception of communal areas in blocks of flats. However, you can be pretty sure that when you bought your house the chartered surveyor who inspected it would have been alert to the risk of potentially hazardous asbestos- containing materials (ACMs). But if you were one of the eight out of 10 buyers who choose not to have a private survey and instead rely on a second-hand copy of the mortgage valuation, you may be none the wiser.
Asbestos was a 'wonder material' of the pre and post-war construction booms, part of a holy architectural alliance with reinforced concrete and flat roofs that was deemed to be the face of the future. A material that was light, strong, massively fire-resistant and relatively cheap seemed a good bet.
Probably the most common form you will come across in a typical house is the less harmful 'asbestos cement' compound, which you will often find as corrugated roofs to garages and sheds, or as flues and insulation in boiler cupboards. It is quite common in post-war semis on gutters, downpipes and soffits. You even come across it in some artificial slates and roof tiles. You can normally spot asbestos soffits (under the eaves) by their predictably flaking paintwork or their naked grim grey colour; paint peels off reliably no matter how much sugar soap or 'No More Nails' you apply prior to decorating.
Asbestos flues are typically hidden away, but are often found serving old floor-mounted kitchen boilers or back boilers in living rooms. Perhaps the most insidious form of domestic ACMs lie within many 'Artexed' ceilings in houses of all ages.
The difficulty faced by your surveyor is, on the one hand to create awareness that your lovely new home may incorporate the stuff, but on the other hand not to have you run screaming from the estate agents in a state of demented panic.
There is much arcane debate in the profession about the relative horrors of white, brown, blue varieties - which is a bit academic as they can be extremely difficult to tell apart outside a lab. Blue and brown were banned in 1985 and the arguably less toxic white (chrysotile) wasn't banned until the 1990s.
So what should you do about it? Briefly, don't panic. Asbestos-cement material in the home need not be an issue. The consensus is that asbestos materials in good condition and not releasing fibres which are unlikely to be disturbed should be left in peace. Materials which are damaged or deteriorating can often be safely sealed.
So in most houses the advice is to leave well alone and for heaven's sake don't drill it, grind it, sand it or breathe it in. But be warned, there are some real nasties still out there - the serious ones that I have personally come across include fluffy white asbestos pipe insulation (in the loft), and huge ceiling panels with taped joints (often in pre and post- war flats). These can drastically reduce the value of a property due to the potentially huge expense of a licensed contractor having to remove them. Employing men in space suits does not come cheap. The irony of the legislation introduced this week is that very few employees get their power tools out at work; you are far more likely to accidentally cut into hidden ACMs in the house and breathe in the dust than you are sitting in your office. Yet the legislation, while good news for maintenance workers, does little to safeguard those of us engaging in the great British passion for DIY.
My advice? Be vigilant, and if in doubt ask a qualified chartered surveyor for advice. Oh, and take a break with the Black & Decker, guys.
The Victorian Society Guides to:-
The Victorian Society is the most authoritative source of historical information on properties of this age
- see end of feature for website details.
PAINT COLOURS & FINISHES
stripped pine an authentic Victorian finish?
Expensive timber such as solid oak or mahogany was polished or varnished, to enhance its natural beauty and to make it easier to clean.
like the natural wood look. How can I get that look if I don't strip the paint
brilliant white an authentic Victorian colour?
it true that Victorian iron railings were always painted black?
dangerous to keep old paintwork, which may contain lead?
I use lead-based paint to redecorate my house?
What is distemper?
How can I find
out what colours were used in the original decoration of my house?
What kind of
paint did the Victorians use on the exterior of the house?
On stucco: some stuccoes are self-coloured and need no paint coat. Lime-based washes in a range of stone colours were used in some cases. Towards the end of the nineteenth century it became fashionable to paint stucco with oil-based gloss paint, especially in towns and cities, where the gloss surface would repel dirt
On render, pargetting, wet dash and pebbledash: lime-based washes.
On exterior joinery: oil-based gloss paint.
What is the
difference between encaustic and geometric tiles?
Encaustic tiles were relatively expensive, and were often combined with quarries (plain square tiles) and geometric tiles in order to cover large areas at less cost. Sometimes erroneously referred to as 'mosaic' tiles, geometrics are small, usually unglazed, tiles in straight-edged shapes such as triangles and lozenges, all based on subdivisions of a 6-inch (150 mm) square tile, that can be combined in a variety of patterns. Most geometrics are of natural clay colours, ranging from off-white through red and brown to blue-black.
sort of tiles would the Victorians have used for the kitchen floor?
What sorts of
tiles were used on kitchen walls?
want to put a tiled dado in my porch. What design should I choose?
Before you make a final decision, however, are you sure that a dado is appropriate for your porch? Look at neighbouring houses of similar age and date to confirm whether any decorative treatment was originally intended. Some porches had bare brick or plain plastered walls, and genuine Victorian architecture, however plain or modest, is preferable to fancy fake 'Victoriana'.
What sort of
tiling was used in Victorian bathrooms?
How should I
clean ceramic floor tiles?
I have removed a fitted carpet to reveal the geometric
tiled floor in my hall. What can I do to disguise the holes left by the carpet
There are a
few loose tiles in my geometric tiled floor. What is the best method of repair?
If you need to replace missing geometrics, it is sometimes best to look for plain unglazed tiles of the right colours that can be cut to the shapes and sizes required. This is because many modern geometrics are made to slightly different sizes and have cushioned edges that do not align well with the Victorian originals. Many modern tiles are thinner than Victorian ones, so it may be necessary to build up the substrate below the patched-in tiles with cement, to bring them up to the right level.
What sort of
finish should I give a tiled floor?
On no account should tiled floors be sealed or varnished with any kind of resin-based or polyurethane finish. Besides their unpleasant plasticky appearance, these may cause long-term problems by sealing in damp under the floor.
Are there any special
techniques for installing tiles that would help me to achieve a more authentic
New grouting can be coloured to match old by mixing it with universal stainer (an oil pigment sold in tubes and available from good paint suppliers). These stains become lighter in colour as they dry so do a test patch first to check the colour match before grouting a large area.
MOULDINGS & DADO RAILS
mouldings made of?
should my dado rail be?
Victorian reception room have a ceiling rose?
You can usually tell if a rose has been removed, from unevenness where the ceiling plaster has been patched. When reinstating ceiling roses, align them with the centre of the chimneybreast (which may not be the geometric centre of the ceiling).
How can I
remove old paint from plaster mouldings?
interior mouldings were stripped out of my house in the 1970s. How can I find
out what was there originally?
Should I pick
out the detail of my cornice in different paint colours?
I want to open
up a blocked fireplace. How can I tell whether it is safe to do so?
Inside the house, remove whatever has been use to seal the fireplace, but do not demolish any brickwork outside the 'builder's opening'. Light a spill or twist of paper in the opening. If it burns well and the flame is drawn inwards and upwards, the flue is clear. Get a chimney sweep to clean and inspect the flue before proceeding further. The National Association of Chimney Sweeps, Unit 15 Emerald Way, Stone Business Park, Stone, Staffordshire ST15 0SR. Tel: +44 (0)1785 811732. Fax: 01785 811712. Website: www.chimneyworks.co.uk Email: firstname.lastname@example.org.
live in a conservation area. Do I need permission to put back a Victorian
live in a listed house. Do I need permission to put back a Victorian fireplace?
fuels am I allowed to burn on my open fire?
How can I find
out what sort of fireplace my house originally had?
When choosing a replacement fireplace, take into account the status of the house and the room where the new fireplace is to be installed. An elaborate, oversized grate will not suit the living room of an artisan's cottage and be equally out of place in a maid's bedroom in a mansion.
can I get paint off a cast iron grate?
What is the best finish for a cast iron grate?
is the best finish for a timber fire surround?
Suggestions for suitable paint finishes for pine fire surrounds are given in our fireplaces booklet or The Victorian Society Book of the Victorian House.
can I clean smoke stains off a marble fire surround?
Household detergent dissolved in warm, distilled water
What was the
purpose of the scullery?
How did the Victorians decorate the walls of their kitchens?
Why were the
windows in Victorian kitchens so high?
When did gas cookers become available?
floorcoverings were used in Victorian kitchens?
materials did the Victorians use?
Where can I see a real Victorian kitchen?
WINDOWS & DOUBLE GLAZING
My house has replacement windows and I want to reinstate the original design. How can I find out what sort of windows it originally had?
can I improve heat and sound insulation without replacing my original timber
Timber shutters provide very good sound and heat insulation, and improve security.
Thick, lined and interlined curtains cut down heat loss and draughts very effectively. They can be fitted behind front doors using specially designed portière rods.
Secondary glazing (see below) improves insulation without the need to alter the existing windows.
can I improve the security of my windows?
Locksmiths carry a wide range of window locks. The type that uses a steel screw through the meeting rails is less visually intrusive than surface-mounted designs.
is the difference between double-glazing and secondary glazing?
Secondary glazing is an independent system of windows fitted to the inner window frame. The gap between the outer and inner windows is consequently much wider than in sealed double-glazed units. The secondary frames are aligned with the external window frames, to cause the least possible visual disruption. The advantages of secondary glazing are:
it possible to fit double-glazing in a traditionally-made timber sash window?
style of window is best for a loft conversion in a Victorian house?
The same care should be taken over the choice and placing of rooflights. The aim should be to use the smallest size and number of rooflights as possible, and to replicate the proportions, glazing bars and profiles of Victorian iron rooflights. Replicas of traditional rooflights are available.
Every aspect of Victorian house design and interior decoration is described in detail in The Victorian Society Book of the Victorian House. www.victorian-society.org.uk
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