How do you stop lime mortar from drying out?
Summer protection is vital to stop lime mortars/plaster/paints from drying out too quickly from winds and direct sun – (hessian is ideal as it can be wetted down). Lime should be kept damp for at least 7 days from application otherwise it will just dry and crumble.
Why choose lime mortar for your heritage home?
Many heritage homeowners choose to repair using original material and preserve period details. Lime mortar is breathable, it can prevent and alleviate damp problems, particular in old buildings with solid walls. Lime mortar is relatively flexible, accommodating a greater degree of movement.
What is lime mortar pointing and how does it work?
Lime mortar pointing is permeable and allows water to leave the building. On the other hand, rigid cement joints force water to seep through the stone or brick on the way out and can cause them to crack or otherwise degrade. What Is Lime Mortar Repointing?
What is the difference between lime mortar and cement mortar?
Lime mortar is more porous than cement mortars, and it wicks any dampness in the wall to the surface where it evaporates. Thus any salt content in the water crystallises on the lime, damaging the lime and thus saving the masonry.
What is Lime Mortar?
What is BS EN 998-2?
What is a pozzolan?
What is mortar mix ratio?
What is BS 8104:1992?
Why add water to mortar?
How to prevent moisture from mortar?
See 2 more
Does lime mortar help with damp?
Lime mortar tends to let walls 'breathe': lime-pointed brickwork can take in, but also release moisture from the atmosphere. If a house was made with bricks that aren't particularly porous or breathable, then lime mortar offers an important way for moisture to make its way out of the house.
Does lime mortar absorb water?
Because lime mortars and plasters are porous and open-textured, moisture will be absorbed and released thus stabilising the humidity within the building whilst reducing surface condensation and mould growth.
What stops rising damp in brickwork?
The most effective and economical way to treat rising damp is with a damp proofing injection cream. You can choose between complete kits or individual cartridges of cream from leading brands such as Kiesol C and Aida. The cream is injected or hand-pumped into specially-positioned holes in the mortar course.
Why did we stop using lime mortar?
With the introduction of Portland cement during the 19th century, the use of lime mortar in new constructions gradually declined. This was largely due to the ease of use of Portland cement, its quick setting, and high compressive strength.
Does lime hold moisture?
It can absorb moisture, which is why it's used for treating waste and spilled chemicals. And it could be used for pest control, because it's fatal if ingested. However, there are significant downsides to using it for either of these purposes.
Will lime dry up standing water?
LIME IS THE ANSWER! of either quicklime or hydrated lime, dries up wet soil quickly, so that it can be compacted readily, forming a working table that will resist further wetting as well--you can get back to work!
How can I stop damp permanently?
Here are a few quick and simple remedies for how to stop condensation on walls and ceilings.Wipe down windows and sills every morning. ... Deal with steam from cooking. ... Get rid of bathroom moisture. ... Ensure ventilation. ... Keep your house warm. ... Install insulation. ... Buy a dehumidifier. ... Don't hang clothes to dry inside.
How do I permanently fix damp walls?
Tips you can take to get rid of mould. ... Cleaning the damp off the wall. ... Tip one: Ventilate the house. ... Tip two: Invest in a good mould cleaner. ... Tip three: Rent or buy a dehumidifier. ... Tip four: Invest in new fabrics and clothes. ... Tip five: Seal tiles and grouting.
How do you fix damp permanently?
Keep on top of outdoor home maintenance. Prevention is better than cure when it comes to damp problems. ... Make sure your home is well-ventilated. ... Avoid producing lots of moisture. ... Take care when cooking. ... Remove excess moisture. ... Choose moisture resistant paint and wallpaper. ... Leave room to breathe.
How long does lime mortar last?
Lime should be stored as long as possible before use: two months is the absolute minimum; after six months the lime will be much easier to use; and after one year it will be better still. Well stored, it will last indefinitely. There are many outlets for lime putty, some of whom hold stocks of older putty.
Is lime mortar breathable?
Breathability – lime materials are highly breathable. Their vapour permeability means they allow water to pass through them, as either a gas or a liquid. This avoids the build-up of moisture, reducing the risk of damp or condensation.
When should you use lime mortar?
Using lime mortar instead of cement for pointing stone masonry or brickwork is a wise choice. Lime is a softer material which allows moisture to move through the joints.
Does water seep through mortar?
There are many ways in which water can swiftly enter your bricks. It can make its way directly through brick surfaces, mortar surfaces, or through the contact zone between the brick and mortar. Besides, it is very common for leaks to enter though the vertical joints.
Does mortar absorb water?
Mortar is also able to absorb water and a water repellent will stop it from doing so. A silane/siloxane water repellent works by being absorbed into the brick, below the surface. Once there it reacts with the free-lime content that is present in both the brick and mortar.
Does water pass through mortar?
Yes, mortar is waterproof. It is "relatively unaffected" by water "under specified conditions".
Does water drain through mortar?
Drainage mortar consists of gravel, cement and water. Once dried out, it is completely water permeable. As a result, the water always flows away and there is no chance of your terrace floor freezing or expanding, so that the floor finish lasts much longer.
What is Lime Mortar?
It is a traditional building material that was used predominantly until the turn of the 20th century . In light of common misconceptions, it is just as important to state what a lime mortar isn't .
What is BS EN 998-2?
The Specification for masonry mortar, BS EN 998-2:2016 is a Eurpoean Standard that specifies requirements for masonry mortars for bedding, jointing and pointing. It applies to manufactured mortars but is naturally the go-to guide for anyone producing or specifying a mortar for general building.
What is a pozzolan?
A pozzolan can be added to an "air lime" mortar to induce hydraulic setting characteristics. An initial hydraulic set drives early strength and can introduce some frost resistance in non-hydraulic and hot-mixed lime mortars. Pozzolans are natural materials that come in various forms, most commonly:
What is mortar mix ratio?
A mortar mix ratio is directly related to the percentage of voids in the sand, this is established by void testing . The void percentage determines the amount of lime binder that can be safely introduced, excessive binder (over-binding) can produce a heave effect and cause cracking, insufficient binder (under-binding) will impair the bond strength. Finally, with the optimum proportion of lime binder calculated, these percentages are converted to a mix ratio.
What is BS 8104:1992?
BS 8104:1992 is a code of practice to estimate exposure to wind-driven rain throughout the United Kingdom. This simple map of masonry exposure shows an overview and suitable lime mortars.
Why add water to mortar?
Adding too much water will cause separation of the lime from the aggregate, it can also affect the colour of the mortar. The idea is to add just enough water to make the mortar workable, the masonry itself can be dampened to reduce the absorption of the moisture if you’re working with porous masonry.
How to prevent moisture from mortar?
Dampen the masonry surface before placing the mortar. This will prevent the masonry from absorbing the moisture from the mortar too quickly. The degree to which the masonry is dampened will depend on the porosity of the masonry and the temperature. The mortar will “go off” (stiffen) much more quickly on absorbent surfaces such as sandstone and limestone, especially on a hot day. This will take much longer on denser materials such as granite and slate and on cooler days.
What is lime mortar?
Lime mortar is composed of lime (hydraulic, or non hydraulic), water and an aggregate such as sand. Lime mortar today is primarily used in the conservation of existing old buildings or the recreation of new ones using traditional methods. Its use dates back at least 6,000 years, to the Ancient Egyptians who used lime to plaster the pyramids.
How does hydraulic lime set?
Hydraulic lime sets by hydration so it can set under water. There are three strength grades for natural hydraulic lime (NHL);
What is non-hydraulic lime?
Non-hydraulic lime is produced from a high purity source of calcium carbonate such as chalk, limestone or even oyster shells. Hydrated lime is any lime other than quicklime, and can refer to either hydraulic (hardens under water) or non-hydraulic (does not harden under water). Hopefully this has shed some light onto this ancient building material.
How much pressure is 3.5?
For example, the NHL 3.5 strength ranges from 3.5 N/mm 2 (510 psi) to 10 N/mm 2 (1,450 psi). These are similar to the old classification of feebly hydraulic, moderately hydraulic and eminently hydraulic, some people continue to refer to them interchangeably.
Is lime mortar good for building?
Whether it’s working with green oak or wattle and daub, at some point you will need to know about lime mortar . Despite its enduring utility over many centuries, lime mortar’s effectiveness as a building material has maintained an air of mystery. Only during the last few decades has testing provided a scientific understanding of its remarkable durability. Previously time-honoured practices were based on local tradition, folklore and trade knowledge, vindicated by the vast number of old buildings that remain standing.
Is lime mortar stronger than masonry?
When lime mortar is used, the lime is the weaker element, and the mortar cracks in preference to the masonry. This results in much less damage, and is relatively simple to repair.
Is NHL3.5 a good builder?
NHL3.5 ideal for general building, for moderately permeable masonry materials. Basically, if it’s not essential to use NHL 2 or NHL 5 then use this. NHL5 sets faster and is stronger, more suitable for dense, durable or impermeable materials with severe exposure to weather or water.
What causes dampness in a building?
The excess is always caused by one of two things: a sudden increase in the amount of moisture entering the building, or. a gradual local build-up of moisture caused by an imbalance between its rate of entry and its rate of escape.
Why did hybrid houses fail?
These barriers were intended to reduce the need for high quality building materials and good building practice. Unfortunately, the moisture barriers in these hybrid houses have turned out to be a long term failure. It turns out they interfere with the correct operation of the natural moisture controls, and often increase dampness and decay.
Why do old bathrooms have a damp patch?
Old bathrooms may have leaking waste pipes or seals around baths, and showers are notorious for leaks. Any tiny leaks from plumbing can be the cause of a large intense damp patch – the leaks may be small, but they are often very regular and are concentrated on the same spot.
How does moisture pass through a house?
This allows moisture to pass freely through the walls, floors and ceilings. Instead of being sealed into rooms as condensation, airborne moisture inside the house is not only able to pass from room to room, but is also drawn from the rooms into the outside walls (the outside walls being drier than the room air). During periods of rain, some water is absorbed by surface of the outside walls, but like with a tent or umbrella, it generally doesn’t penetrate beyond the surface. If any water does enter into the walls, because they are very permeable, it rapidly spreads out as it moves from wet to dry. This water is then drawn back to the surface when the rain stops, as the water at the surface evaporates back into the air again (outside air being drier than the walls even immediately after rain).
Why do period houses get damp?
Nowadays, the majority of dampness in period houses is caused by inappropriate building work that stops moisture escaping . Dampness caused by local build-ups of moisture is often erroneously given a variety of common names depending on where it shows up, such as 'penetrating damp' and 'rising damp'.
Why does my house get damp?
Any dampness in your house is due to the failure of moisture to escape efficiently. This failure could be due to: the normal escape route being overwhelmed by a sudden increase in the amount of moisture; changes to the building that stop moisture escaping properly;
How long does it take for a damp house to disappear?
In houses built before the second world war, it can also disappear just as quickly in the early days.
What kind of plaster should I use to make my walls breath?
On the inside I'm probably going to apply hemcrete and lime plaster to the walls, which should let the walls breath. The hemcrete acts as an insulation layer - something I could do with.
How far from the floor was the wall damp?
the wall was very damp up to about a metre from the floor.
What is the best way to find moisture in cement?
You'll need to first locate where the moisture comes from, whether it's cracks on the cement render, ground dampness or leaking seals. An electric resistance meter is normally used to identify the surface moisture content while drilling is sometimes required to get a more accurate result.
What is non-breathable wall?
The modern (non-breathing) approach is to make everything waterproof and hope nothing get wet in the first place. If the external wall fabric is non-permeable you'll need to have a vapour control layer (plastic sheet/foil) behind the plaster. Mechanical fans and window trickle vents are designed to get rid of the internal moisture that can't breath out. Vented wall cavities are required to let any moisture trapped inside the wall to escape.
Why do we breathe in walls?
A proper breathing wall construction have to breath all the way through otherwise moisture would be condensed on the cold and non-permeable layer within the wall and. Moisture buildup comes from the inside as well as water from the outside. The traditional approach is to let everything breath so that moisture can be driven out. In old buildings this is helped by the regular use of fireplaces.
Why do we dry out over a long time?
dry out over a long time to ensure completely dry and no more water is coming in - the reason for waiting so long? the water table and groundwater flow varies throughout the year and from year to year.
Is lime plaster better than cement?
3 moisture resistant / insulated plasterboard actually works better than sand and cement with waterproofer.
What to do if a qualified surveyor tells you that an independent timber and damp survey is required?
If a qualified surveyor - a Chartered member of RICS - tells you that an independent 'timber and damp' survey is required - I suggest you tell them you are not paying the bill. These people are incompetent. If they cannot diagnose the REAL reasons for damp in an old house - tell them to go survey a dolls house. Peter is Joint Author of the new RICS dampness diagnosis methodology, and anyone not knowing about this needs re-training!
How to avoid condensation in a house?
Temperature is a vital component. To avoid condensation, you MUST keep your home constantly heated at a gentle, low temperature. Aim to keep it at 15 degrees C. Run heating all the time, but at a low temp - radiators just warm, not blazing hot. Heating must not come on for 2 hours and go off again - it must be constantly on, but set VERY low. If you want more heat in a room, just use additional heat in that room - a wood burner, or fan heater for an hour or two. Constant heating ensures building fabric stays warm, and thus does not get cold enough for interstitial condensation to form within your walls (this is what the damp wallies call rising damp). Believe me, it doesnt cost any more to run heating like this - and many modern heating boilers are now designed to run this way.
Why do I have damp in my house?
Incredibly, one of the biggest causes of damp problems in homes nowadays is the push by the Government to insulate homes. I do dozens of surveys in which the complaint is mildew, mould, water running down walls and windows. When asked when the problem started, the answer is always the same - 'We had a grant to get insulation installed - it was after the insulation went in'. Insulation traps heat. Heat = warm air = more water held in the air as humidity. When all this humid air finds a cold wall (you insulated the roof, right? You didn't make the walls warmer... ) it condenses as mould, water, mildew on clothes and so on. Read the humidity pages to understand more about the problem... the solution - better ventilation and humidity extraction.
What were the causes of damp in pre-1920s buildings?
Most problems of damp in pre-1920's buildings have been caused since the war, when cement and gypsum plaster became widely available - these two materials are responsible for over 90% of the damage that we see. They are impervious, they trap moisture and cause rot - they are death to an old house.
How does moisture diffuse through a wall?
Moisture diffuses through all building fabric (Walls, stone, mortar, plaster, paint, timber), regardless of temperature. This process of diffusion is known as 'Breathing' when applied to walls and other parts of the building fabric like the roof for example. It is shallow when there is little temperature variation and deepest when the daily range is greatest. Water always moves from where it is more concentrated to where it is less (humid to dry). If air within the wall is humid, and the wall cools below dew point then water vapour condenses as water droplets in the pores of the masonry ( this is what Rising Damp actually is ), though the wall may still appear ‘dry’. During warmer and drier times, some of this water will evaporate and leaves the wall. Even walls which seem dry will contain water, the amount varying with changes in the season and climate. If there are salts or other hygroscopic (moisture-attracting) materials in the masonry, the amount of water drawn into (and retained in) the wall can be sufficient to make the wall visibly damp, even in dry weather. This is the same as happens when you leave a pot of salt on the kitchen table - it gets wet.. Most of the time, the inside of a house will be 'wetter' than the air outside, because we humans produce a lot of water from living.
Why do old houses get damp?
The worst enemy of old houses is we humans - it's what we do to them, or fail to understand about them, that causes problems and makes you think you have to 'Damp Proof'. Almost 100% of damp issues in buildings are caused by condensation, and lack of adequate ventilation.
Why is my brick wall wet?
The worst cases of seriously wet walls that we have to deal with are caused by the wall being encased in cement - external cement render, and internal 'damp proofing' plasters and renders underneath gypsum plaster. This combination is certain death to a stone or solid brick wall, and we have often removed internal plaster in cases like this to reveal crumbling brick and stone which you can poke a finger through. Left to dry out, with the offending render and plaster removed, the stone hardens and the wall dries out on its own.
What is Lime Mortar?
It is a traditional building material that was used predominantly until the turn of the 20th century . In light of common misconceptions, it is just as important to state what a lime mortar isn't .
What is BS EN 998-2?
The Specification for masonry mortar, BS EN 998-2:2016 is a Eurpoean Standard that specifies requirements for masonry mortars for bedding, jointing and pointing. It applies to manufactured mortars but is naturally the go-to guide for anyone producing or specifying a mortar for general building.
What is a pozzolan?
A pozzolan can be added to an "air lime" mortar to induce hydraulic setting characteristics. An initial hydraulic set drives early strength and can introduce some frost resistance in non-hydraulic and hot-mixed lime mortars. Pozzolans are natural materials that come in various forms, most commonly:
What is mortar mix ratio?
A mortar mix ratio is directly related to the percentage of voids in the sand, this is established by void testing . The void percentage determines the amount of lime binder that can be safely introduced, excessive binder (over-binding) can produce a heave effect and cause cracking, insufficient binder (under-binding) will impair the bond strength. Finally, with the optimum proportion of lime binder calculated, these percentages are converted to a mix ratio.
What is BS 8104:1992?
BS 8104:1992 is a code of practice to estimate exposure to wind-driven rain throughout the United Kingdom. This simple map of masonry exposure shows an overview and suitable lime mortars.
Why add water to mortar?
Adding too much water will cause separation of the lime from the aggregate, it can also affect the colour of the mortar. The idea is to add just enough water to make the mortar workable, the masonry itself can be dampened to reduce the absorption of the moisture if you’re working with porous masonry.
How to prevent moisture from mortar?
Dampen the masonry surface before placing the mortar. This will prevent the masonry from absorbing the moisture from the mortar too quickly. The degree to which the masonry is dampened will depend on the porosity of the masonry and the temperature. The mortar will “go off” (stiffen) much more quickly on absorbent surfaces such as sandstone and limestone, especially on a hot day. This will take much longer on denser materials such as granite and slate and on cooler days.
What Is Lime Mortar?
Why Use Lime Mortar?
- There are various reasons you might want to use a lime mortar. 1. Building Conservation Legislation stipulates the use of lime mortar for listed buildings and buildings in conservation areas. 2. Old Property Many heritage homeowners choose to repair using original material and preserve period details. 3. Prevent Damp Lime mortar is breathable, it can prevent and alleviate …
Lime Mortar Composition
- A lime mortar is made using traditional lime, sand and water. Traditional limecan be grouped into two broad categories; air lime (non-hydraulic limes, those that set when exposed to air) and water lime (hydraulic limes, those that set when immersed in water). 1. Natural Hydraulic Lime (NHL) (Water Lime, Hydraulic) 2. Non-Hydraulic Lime / Lime Putty (Air Lime, Non-Hydraulic) 3. Quickli…
Pozzolans
- A pozzolan can be added to an "air lime" mortar to induce hydraulic setting characteristics. An initial hydraulic set drives early strength and can introduce some frost resistance in non-hydraulic and hot-mixed lime mortars. Pozzolansare natural materials that come in various forms, most commonly: 1. Pulverised Fly Ash / Pulverised Fuel Ash (PFA) 2. Ground Granulated Blast-Furna…
Choosing A Lime Mortar
- Mortar, by design, is a sacrificial element of the structure. As well as binding masonry units together, a lime mortar introduces a flexible, breathable layer that absorbs movement and expels moisture. This supports and protects the masonry, being much easier and cheaper to replace. There are a few principles that are balanced to specify a type of lime mortar, there isn't always …
Lime Mortar Design
- A lime mortar's functional and aesthetic properties are drawn from its ingredients. High-quality materials are therefore essential but the proportions also equally important, it is the correct mix ratio that ensures the whole is greater than the sum of its parts.
Consistency
- A mortar’s consistency is varied by adding more or less water. The ideal consistency is something a tradesman learns instinctively from experience over time. It may vary on personal preference but typically depends on the work at hand.
Suitable Conditions
- Lime mortars are subject to the same temperature limitations as cement mortars and should not be applied in temperatures approach freezing. Do not apply mortar externally in temperatures falling below 5°C. The curing process depends upon the temperature; this takes much longer in winter and the performance of the mortar may be reduced. Starting late on a morning (10am) an…
Protection
- The work is at risk until the mortar has adequate time to cure. Although often overlooked, protection is critical in the meantime: 1. Rainmay wash out the mortar before it has adequate time to set. 2. Coldtemperatures may cause the mortar to freeze. 3. Sunlight and strong winds both accelerate the drying process. This leads to colour alterations (bleaching) and cracking (shrinka…
Wet Curing
- Wet curing or "cherishing", as it is known in the trade, is a technique that provides the ideal curing conditions for lime mortar. The hessian sheeting (or other breathable membrane) is sprayed regularly with water, this simple procedure increases humidity and controls moisture loss. Maintaining a stable, high level of humidity aids carbonation (for air lime) and hydration for (wate…