Roman Stucco Exterior Wall Render

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A fast setting Roman Cement based decorative render. Can be used in the repair and replacement of decorative mouldings and cast elements as well as plain rendering.

Stucco has been historically used as an exterior wall render to create highly detailed and decorative finishes on building facades, such as those on the many fine Regency houses of Cheltenham, Hastings and Leamington Spa.

Lime green Roman Stucco is based upon Roman cement, a traditional binder invented around 200 years ago. Using this, we have created a contemporary product that sets rapidly, with a fine texture and an innate strength which ensures it can be cut, carved and shaped with remarkable detail.

These characteristics mean Lime Green's Roman Stucco is specified for high profile projects such as the refurbishment of Osborne House (Queen Victoria and Prince Albert's family home on the Isle of Wight) and the recent re-development of King's Cross in London.

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Availability

Made to order in 25 kg paper sacks.

"Coarse" 0-3mm Render undercoats and building out; 

"Fine" 0.7mm Finishing coats.

  • Completely natural Binder, nothing added or removed in manufacturing 
  • Fast setting typically 40min at 15°C 
  • Low shrinkage 
  • Excellent bond strength 
  • Resistant to acids and alkalis  
  • Render mouldings - In-situ or run work
  • Good vapour exchange (breathability)
Application guidance

Application: onto clean and dry background, not water proofed. Repoint masonry as required with the correct mortar. Adequately dampen dry or high suction surfaces beforehand, for best adhesion apply a slurry of neat natural cement and water prior to application.

Each coat must be applied to the previous once while the previous is still damp working "fresh on fresh". Typically leave no more than 2 hours between coats.

Mixing 

Mix in drum mixers or by mixing whisk. Carefully add clean water, between 4.5-5 litres per 25kg bag and mix for approximately 5min. Prompt mortar will rapidly set, typically within 30 - 50 mins, depending on temperature. Do not use in temperatures less than 5 ºC or over 30ºC.

Roman stucco for decorative cornice at King Cross

London's King's Cross is undergoing extensive development and regeneration. But as a landmark location, special care must be taken to preserve the area's historic character and nature.

The organisation responsible for doing this is English Heritage. In particular, they are keen to retain the ‘natural' look of King's Cross, meaning that the renovation of existing buildings has to be undertaken sympathetically and in keeping.

 

The Requirement

So when it came to the repair of brickwork and high-level decorative cornices damaged during the Second World War and left untouched since, they set out a very detailed specification for their reinstatement.

 

This meant ensuring that, particularly when it came to mortar, the colour should remain consistent throughout, so as not to give a patchwork appearance to hundreds of square metres of wall.

The Problem

However, there were a number of fundamental problems in achieving this:

•    Artificial pigments couldn't be used in the mortar because they were not used originally, so any colour had to come from the materials alone.

•   There was the added difficulty of maintaining consistency of colour, so that the mortar applied on the first day had the same colour and texture as the mortar applied on the last.

•   For health and safety reasons no dust could be created that might affect the public or machinery, so any batching had to be done off-site.

 

The Solution

Lime Green was asked if it could meet those requirements. After numerous site visits, and much research and experimentation that saw us carefully mixing and remixing the constituent materials, we had a nine-ingredient mortar that was the perfect colour match for the one already in place.

With English Heritage and their architects satisfied, and our Prompt-based Roman stucco plaster also chosen for the cornices, work began.

To ensure consistency of product was maintained throughout the process, the mortar was carefully mixed. Checks were then made on each batch, before being sent to site 10 tonnes at a time.

 

The Benefits

Besides being of high-quality, our specialist products also had other advantages.

•   The mortar was as easy to use as a cement-based product, so contractors could work more quickly than traditional site batched lime-based mixes - important when they were on a tight time schedule to complete or face stiff penalty clauses.

•   Our Roman stucco sets repidly, therfore the contractors could work more quickly - which meant that the plasterers could build up the cornice to size as they went, using zinc blades to shape and maintain the cornice's still soft profile.

•   And because of both products inherent flexibility, there was no need for unsightly expansion joints in the facade, as there would have been if cement-based plaster had been used.

 

Our products were the only ones that ticked all the boxes, not just for English Heritage, but also for their teams of advisers and their contractors, who found working with our mortar and plaster quicker, easier and more enjoyable than using standard site mixed mortars and plasters.

 

And so pleased were English Heritage with our mortar, that having discovered it, they have specified it again for other projects elsewhere.