Lime Hemp Plaster (Non-Hydraulic)
Ty-Mawr Lime Hemp Plaster is made from a high calcium lime (also known as a fat/air/putty or non-hydraulic lime) blended with the hemp fibres.
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Ty-Mawr Lime Hemp Plaster is made from a high calcium lime (also known as a fat/air/putty Lime or non-hydraulic lime) blended with the hemp fibres.
It requires exposure to Carbon Dioxide in the presence of moisture to harden however, it can be applied in thicker coats than conventional lime plasters and is easier and quicker to use.
Like all non-hydraulic lime products, it is extremely flexible and breathable which makes it suitable for use in the restoration of old 'solid wall' construction buildings and ideal as a 'wattle and daub' replacement in timber-framed buildings. It is also suitable in ecological new builds as it can be applied to a variety of substrates e.g. woodfibre boards, wood wool boards, strawbale.
The addition of hemp fibres not only improves the strength and flexibility of the product, it also increases the thermal properties of the plaster and so is an excellent way of adding some insulation to your wall. Please contact us with details of your building so that we can assess the suitability and the likely improvements to performance.
It is available in two grades - medium and fine and is ready to use in 1 tonne bulk bags, and 20 kg bags.
To learn about colour variation please click here
30mm thick hemp plaster is 1.26w/m2k
Email tymawr@lime.org.uk for a printed copy/copies of the catalogue. Free samples of the dried product on our wood wool or woodfibre boards are also available, contact technical@lime.org.uk for information.
To see an example of this product in use, see our case studies of Plas Newydd, Llangollen and Maesgwyn Cottage, Carmarthenshire.
Preparing the mix
- The plaster needs to be ‘knocked-up’ - a process of chopping, beating and turning which will release some water. Water should be added cautiously to make a workable mix.
- A bell mixer is the ideal way to ‘knock-up’ the lime hemp plaster. It should be left turning for long enough to achieve a suitable consistency (20-30 minutes). Smaller quantities can be ‘knocked-up’ with a whisk and bucket if no mixer is available. If preparing the fine hemp & superfine 50/50 mix (by volume), empty 1 bag of each in to the mixer and “knock-up” until desired workability and finish is required.
Preparing the surface
- Hemp plaster should not be applied to walls that have a problem with damp. This can dramatically extend the setting times, especially during winter months. If in doubt refer to manufacturer for guidance
- Sometimes there is no need for extensive prewetting of backgrounds (but please assess first) before applying lime hemp plasters as they hold more water than standard lime plasters – just a mist down should suffice. The suction created by differences in background moisture will help. Onto high absorption backgrounds these will definitely need pre-wetting.
- If Celenit wood wool boards or wood-fibre boards are being used as the background, they do not require damping down. N.B. Do not put scrim or mesh directly onto the boards.
Application of lime hemp plaster
- Lime hemp plaster is suitable for base coats, dubbingout and textured top coats.
- Unlike standard lime plasters, lime hemp plasters can be applied in single coats 15-25mm thick (thickness will depend on the substrate and application, see above, remember, the thicker the coat, the slower the drying).
- A dry premix is now available for more extreme conditions e.g. if the substrate is damp, during the winter months, please seek advice and see notes below.
- Lay on and trowel up with a steel trowel.
- Wet the surface of the plaster before working it over with trowels or floats, by splashing with water. Overwetting should be avoided.
- Feather edge and soft brush the base coat to give a key then apply a top coat of fine lime hemp plaster at 6mm
- For a smoother finish Top Coat (internal) Plaster can be gauged into Lime Hemp Plaster (fine) in any proportion from 1 to 100 % by volume. Blending these together also helps when plastering ceilings as it creates a “stickier” mix.”
- It is advisable that test panels are made to ensure the desired finish is achieved prior to the works commencing.
- Following good practise, this should be applied before the base coat is completely hard
- 10cm wide jute scrim should be trowelled into the basecoat Lime Hemp Plaster at corners or at wall/ ceilings junctions. This will help counteract shrinkage in these areas.
- After 3-4 weeks, it is possible to finish the plaster with a limewash or breathable paint if required.
Application on ceilings
- For ceilings (heavy stress), onto 25mm Celenit wood wool boards, it is best to apply a 6mm coat of fine grade lime hemp plaster, then the render mesh can be trowelled in, followed by a 6mm top coat of fine grade lime hemp plaster or 3mm Finish Plaster.
- For ceilings (light stress) onto 25mm Celenit wood wool boards, apply 6mm coat (with no mesh) of the fine grade lime hemp plaster, followed by a 6mm coat of fine grade lime hemp plaster or 3mm Finish Plaster.
Suitable For
- Internal Plastering
- Boards (Wood Wool/ Woodfibre / Cork)
- Lath
- Cob
- Masonry
Coverage Rate
- 2.5m2 at 6mm per 20kg Bag
- 1.6m2 at 9mm per 20kg Bag
- 1m2 at 15mm per 20kg Bag
- 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 10-25mm) 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, finish plaster can be used for a smoother finish.
- Lime hemp plaster replies on the correct environment to 'carbonate', if your substrate is wet or there is little heating or ventilation in the property in which you wish to use it, please call us for advice.
20kg Bag
Tonne Bulk Bag
Customer Questions
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