Coloured Lime Mortars and Lime Renders: Checklist & Guide

If you have any queries or doubts about any of the information contained in this checklist, remember we are here to help. Please feel free to contact us.

Coloured lime renders require precise and exact working methods. This checklist covers the basic requirements for the correct design and use of our coloured lime renders. Following this advice will help eliminate common bad practice and mistakes but it is not exhaustive. See our Guidance sheets for more detailed information.

This Lime Green checklist is generic and not all clauses will apply to all jobs. If in doubt, please consult your supplier for written advice. If for any reason you feel unable to comply with any of the advice contained in this checklist, please do not proceed with the job without first consulting your supplier.

Design

Do:      

  Agree a style and quality of finish between all parties before rendering commences.

Construct a large test panel on site, to be kept for reference until the job is signed off.

Refer to British Standards BS EN 1996 Eurocode 6M Design of Masonry StructuresandBS 13914 Design, preparation and application of external rendering and internal plastering from where much of this guidance is derived.

  Specify a lime mortar weaker than the masonry unit.

  Specify robust detailing including gutters, good overhangs on the roof, drips on cills.

  Specify 16mm minimum thickness of lime render in moderately exposed locations, or 25mm in very exposed locations.

  Consult your supplier for backgrounds with very high or low suction.

 

Don't:

        Specify lightweight blocks with coloured lime renders.

        Leave out movement joints where they are needed! (Changes in background, over movement joints in blockwork etc.)

        Specify lime render on sloping or horizontal surfaces.

 

Planning and Sequencing

Do:

  Allow adequate time to apply and cure all coats.

  Order enough coloured lime render or lime mortar to complete the job.

  Order a sheeted scaffold suitable for rendering (must not be tied against the wall - allow enough space for the plasterer to trowel the lime render freely.)

  Ensure a safe working environment. Please follow all Health & Safety guidance.

Don't:

        Lay floors, fit windows or doors after rendering has started.

        Mix different batches of lime render on the same elevation.

 

Preparing the wall

Do:

  Remove contaminants before rendering. (salts, lichen, dust and road dirt)

  Dampen the wall with water.

  Fix temporary gutters to drain rainwater away from the wall.

 

Don't:

        Allow the wall to become saturated.

 

Application

Do:

  Consult BS13914 Design, preparation and application of external rendering and internal plastering and the product Technical Datasheets.

  Have enough material on site to complete the job before starting.

  Render complete elevations / panels in a day.

  Work with a wet edge.

  Add the same amount of water to each bag and mix for the same time.

  Work around a building in the shade, behind the sun.

  Cure the material properly, following manufacturer's instructions.

  Protect from the weather. (sun, drying wind, rain, frost)

 

Don't:

        Mix batches on one elevation.

        Float or sponge topcoats thicker than 6mm.

        Bridge DPCs or movement joints.

        Apply render to saturated blocks.

        Apply in temperatures above 30°C or below 5°C.

        Apply less than 16mm of render in moderately exposed locations or 25mm in very exposed locations.

        Polish and overwork the topcoat to a smooth finish.

 

Inspection

Do:

  Inspect under diffused lighting, square on to the wall.

  Compare the render against your reference panel.

 

Don't:

      Inspect in bright or glancing sunlight, or rain.

      Inspect the render before it has dried and cured.

      Inspect the render from side on.

 

Version 2: 12-02-12

© Lime Green Products Ltd 2010