Successful lime and conservation work depends on more than choosing the correct mortar, plaster or insulation material.
Preparation, curing, reinforcement and the compatibility of adjoining materials can all influence the finished result.
Our additional products collection brings together specialist materials used alongside lime mortars, renders, plasters, breathable insulation systems, masonry repairs and limecrete floors.
Hessian for Lime Mortar & Render
Correct curing is particularly important with freshly applied lime mortar and render.
Hessian sheeting can be used to protect new work from direct sunlight, wind and rapid moisture loss. In suitable conditions it can be dampened to help maintain a humid environment around the fresh lime work.
During colder weather, protective coverings may also form part of the measures used to protect fresh work from adverse temperatures.
Hessian should be positioned so that it protects the work without damaging the fresh surface.
Fibreglass Reinforcement Mesh
Alkali-resistant fibreglass mesh is used within selected plaster and render systems to provide reinforcement across larger areas.
It can be particularly useful within insulation-board systems, over areas of differing background material and where reinforcement is specified as part of a complete plaster or render build-up.
Mesh should be fully embedded within the appropriate base coat rather than simply fixed to the surface.
Always follow the requirements of the particular plaster, render or insulation system being installed.
Pozzolanic Additives
Pozzolans are reactive materials that can be added to suitable lime mixes to modify their setting and performance characteristics.
Products such as Trass and Pulverised Fuel Ash (PFA) can react with lime in the presence of moisture and introduce varying degrees of hydraulic behaviour.
The effect depends on the particular pozzolan, lime, proportion and application, so additions should be selected deliberately rather than simply added to make a mortar “stronger”.
For conservation work, the required strength, permeability and compatibility with the existing masonry should remain central to the mortar design.
Fibres for Lime & Flooring Mixes
Fibres can be incorporated into selected mortar, plaster or floor mixes where additional reinforcement or crack-control characteristics are required.
Different fibre types serve different purposes, so the quantity and type should follow the requirements of the particular system or specification.
Roundtower stocks specialist fibres for use across selected traditional and modern breathable construction applications.
Geotextiles & Geogrids
Geotextile membranes are used within selected floor and ground build-ups as permeable separation and filtration layers.
Within breathable floor systems they can help keep adjoining aggregate layers separate while allowing water to pass through the material.
Geogrids perform a different function and may be used where additional reinforcement or load distribution is required within the floor build-up.
The correct layer arrangement should follow the floor specification rather than treating geotextiles and geogrids as interchangeable products.
Pigments, Marble Dust & Chalk Dust
Traditional decorative finishes and specialist lime mixes can require additional fine materials.
Pigments can be used to colour compatible lime-based finishes, while products such as marble dust and chalk dust can form part of selected decorative plaster, limewash, filler or repair formulations.
Careful batching is important where consistency of colour or texture is required across a larger area.
Small trial areas are advisable before applying a modified or pigmented finish extensively.
Specialist Masonry Treatments
The collection also includes selected products for cleaning, filling and treating masonry surfaces.
The correct treatment depends heavily on the substrate and the problem being addressed.
Before applying a cleaner, water-repellent treatment or filler to historic masonry, consider the stone or brick type, existing mortar, moisture condition and the effect the treatment may have on future drying.
A product should not be selected simply because a wall is described as “damp”.
Fixings & Washers
Breathable insulation-board and render systems often require specialist masonry fixings, washers and associated accessories.
The correct fixing depends on the substrate, board type, required embedment and system specification.
Fixing length should account for the thickness of the insulation or board together with the required penetration into the supporting masonry.
Choosing Compatible Supporting Products
Traditional buildings generally benefit from materials being selected as a compatible system rather than as isolated products.
A mortar additive, reinforcement mesh, fixing or surface treatment can influence the behaviour of the surrounding construction.
Where there is uncertainty, consider the existing substrate, moisture conditions, proposed build-up and required finished performance before specifying an additional material.
Frequently Asked Questions
Why is hessian used with lime?
Hessian helps protect freshly applied lime mortar and render from rapid drying caused by wind, direct sun and warm weather.
When appropriate, damp hessian can help maintain more favourable curing conditions.
What mesh should be used with lime plaster?
Where reinforcement is required, an alkali-resistant mesh compatible with the plaster or render system should be selected.
The mesh should normally be embedded within the appropriate base coat.
What is a pozzolan?
A pozzolan is a reactive siliceous or aluminosilicate material that can react with lime in the presence of moisture.
Adding a pozzolan can modify the setting and performance characteristics of a lime mortar.
Can I add Trass or PFA to any lime mortar?
Not automatically.
The type and quantity of pozzolan should be selected according to the lime, application and required mortar properties.
What does a geotextile do in a limecrete floor?
A geotextile can act as a permeable separation and filtration layer between materials within the floor build-up.
Its exact position depends on the specified floor system.
Can pigments be added to lime products?
Selected mineral pigments can be used with compatible lime-based materials.
Trial mixes are advisable because pigment type, dosage, lime and drying conditions can all influence the final appearance.
Do insulation boards need specialist fixings?
Many systems do.
The required fixing type, quantity and length depend on the board, substrate and complete system specification.
Can Roundtower help identify the correct supporting product?
Yes. Where you provide details of the substrate, existing construction and proposed system, Roundtower can help identify suitable supporting materials and accessories for the application.
Need Technical Assistance?
If you are unsure whether you need reinforcement mesh, a pozzolanic additive, specialist fixing, geotextile or another supporting product, contact Roundtower Lime with details of the existing construction and proposed build-up.
Our team can help identify the most appropriate products for lime, conservation and breathable-building applications.
