Ty-Mawr Lime Hemp Plaster

made from a natural, renewable plant fibre (instead of depleting a natural aggregate resource).

has greater flexural strength than traditional lime plasters making it extremely durable e.g. it is far more resilient for use on corners, reveal and other vulnerable areas of the building.

has thermal properties and can therefore be used to help improve the insulation performance of the wall.

can assist with the airtightness of old buildings, improving the comfort of the room and offering energy savings.

can be applied in much thicker coats (single coats can be applied between 10-50mm) than traditional lime plaster therefore is especially useful for ‘dubbing out’ hollows in walls prior to further plaster coats.

is a successful way of ‘patching’ old lime plasters e.g. where electricians/plumbers have been ‘chasing out’ .

is easier to use than conventional lime plaster (minimal shrinkage even on high suction backgrounds) offering labour savings.

is breathable and therefore helps to safeguard the functioning and health of the building as well as helping to regulate humidity which makes for a healthier internal environment, this make it ideal for use in older buildings.

easy to use - is supplied ready to use, can be mixed in an ordinary cement mixer, there is no requirement to use mesh or add hair.

as it requires fewer coats and less tending, it can make significant labour savings.

is beautiful - the coarse/medium plaster gives a soft textured finish otherwise the fine hemp, glaster or ordinary finish plaster can be used for a smoother finish.

What is Ty-Mawr Lime hemp plaster made from?

Ty – Mawr hemp lime plasters and renders are made from the chopped stem of the hemp plant blended with high calcium lime (also known as a fat / putty or non-hydraulic lime). Ours is made entirely from British materials.

What are the benefits of using lime/hemp over a standard lime plaster?

• Ty-Mawr hemp lime plasters requires exposure to Carbon Dioxide in the presence of moisture to harden but is faster setting and can be applied in thicker coats than conventional lime plasters.

• It is more environmentally friendly- hemp is a renewable resource which as a plant locks in CO2 as it grows. Using hemp instead of sand also avoids the removal of natural resources from the ground.

• It has better thermal properties than other lime plaster products and can therefore be used as an insulating plaster.

• The addition of hemp fibres dramatically improves the compressive and flexural strenth of the product which make its more durable and stronger that other lime plasters.

What is lime hemp plaster suitable for?

Like all lime products, it is flexible and breathable which makes it suitable for use as a lime plaster in the restoration of old 'solid wall' construction buildings as well as ecological new builds, it also provides additional insulation.

Lime hemp plaster is suitable for backing coats, textured finish coats and for external rendering.

Your finished plaster will care for your building for years to come as well as helping to control the humidity of the internal environment.  

Externally, a glaster top coat or standard lime render should be applied to give added protection.

It is often used simply for dubbing out or patching old plaster after the electricians hace been in for example becuase it is less susepctible to shrinkage and cracking and can be applied in single coats up to 50mm, it really is ideal for these situations.

Can it be used to plaster ceilings on your wood wool boards?

Yes it is very successful of these boards but please note for ceilings (heavy stress), onto Ty-Mawr wood wool boards, it is best to apply a 6mm coat of the medium grade lime hemp plaster, then the render mesh can be trowelled in, followed by a 6mm top coat of the same medium grade lime hemp plaster. If thicker coats are applied, the mesh would not be required. For ceilings (light stress) onto Ty-Mawr wood wool boards, a single 15mm coat (with no mesh) can be applied of the medium grade lime hemp plaster.

Note that 15mm boards are not usually recommended for ceiling applications.

How much will I need?

• 25kg bag covers approx 0.75m2 at 25mm coat.

• 1 tonne covers approx 30m2 at 25mm coat, 50sqm at 15mm.

Is lime hemp plaster applied in a similar way to regular plaster?

Hemp Lime plaster is easier to apply than conventional plaster because of its fibrous properties and minimal shrinkage, it can therefore be applied in thicker coats and requires less tending but otherwise it is similar in terms of control the moisture, environment, protection etc.  

Please follow the instructions in the application guide (see Documentation) of this plaster.

How is the plaster applied?

• Unlike normal lime plasters, lime hemp plasters can be applied in single coats 10-50mm thick.

• Wet the surface before working it over with trowels or floats, by splashing with water. Over-wetting should be avoided however.

How long does it take to dry?

It can take anything between 4 or 5 days up to a month or more to completely dry depending upon the substrate, thickness of application, wetness of material and weather conditions.

• Do not use dehumidifiers and heaters to speed up the set. Accelerated drying will prevent carbonation and may cause the plaster/render to fail. Gentle heat may be used cautiously in cold, damp buildings.

• Protect new work with damp hessian; plastic sheeting may also be required to prevent rapid drying in hot weather, when windy or in direct sunlight. Gentle spraying may be necessary if areas of plaster or render are drying too quickly.

What protective precautions should be taken whilst drying?

• Protect new lime plaster or render from frost - external work, wherever possible should not be carried out when temperatures are likely to fall below 5°C before carbonation has taken place. If work must continue externally, although not advisable, the scaffold should be fully enclosed and well-circulated heating supplied. Internally, it may be appropriate to supply gentle heating.

• Protect from rain - heavy rain can wash the lime out, or at least, draw it to the surface before the render has carbonated. A new render should be protected until surface carbonation has taken place.

How should the plaster be stored?

• Store airtight and frost-free

• Premixed lime hemp plaster will become hard over time and require more ‘knocking-up’.

• Use within three months of purchase.

How can it be finished?

Lime hemp plaster gives a beautiful finish that no modern plaster can replicate, the medium and coarse grades will produce a textured finish. Clients often like the finish and therefore do not go on to even paint. If a less textured finish is required, then the fine hemp plaster or a standard finish lime plaster can be used.

If you do choose to paint it, we highly recommend that you finish it with a ‘breathable’ and preferably a natural paint. Your choice will depend on the level of durability, required vapour control and desired aesthetic - there are a wide range of colours and choices in the paint section of this website that are all suitable.

Does it save time?

It seems that our hemp lime plaster is saving time on site just by reducing the time dubbing out and ending - plasterers have reported time savings ranging from 30-50%.

How insulating it is?

Although it has some thermal value it is never going to be as effective as a board or natural fibre insulation batt, but it is 3-4 times more insulating than standard lime plaster. It also helps with achieveing air tightness in old buildings which is a very important factor in improving the energy efficiency of old buildings - see our solid wall insulation sheet for more details.

Is there anywhere I shouldn't use it?

If the fibres remain wet then it can create problems so on a wall that is not likely to dry out (e.g. if there is a cement render or a bank of earth against the wall) externally, then it should be avoided.

It can be used externally but we would advise that a standard lime render or glaster top coat is used for the final top to protect it.

Why would I use a lime hemp plaster?

We would suggest that if you are replacing an old plaster then the increased ease of use and speed of application as well as the fact that it is more enviornmentally-friendly and that it can help with energy efficiency...really speaks for itself! It has many many enthusiastic followers......

Do you have a brochure?

Yes, you can simply lick here for our new 4 page colour brochure or email tymawr@lime.org.uk for a printed copy/copies. Free samples of the dried product onto our wood wool or woodfibre boards are also available, contact technical@lime.org.uk for information.

 

 This section is under development, please email tymawr@lime.org.uk for systems builds and NBS clauses-