What is it?
In general, it is the application of a coating to a buildings external façade, whether applied to masonry or a cement based backing board to give a textured/smooth finish and some formal protection to the face against the elements, improve the aesthetics of the building and offer some improved insulation properties.
The term “rendering” can also be used when referring to applying a slurry (Parge coat), sand/cement mix (ideally to walls that will receive a tile finish or plaster skim coat) or two coat system to internal masonry walls
Different finishes can be created using a trowel, sponge or brush. The finish can be determined by the tradesmen using the appropriate tools or methods of application and the final finish is normally determined with the top coat or thin coat
The types mainly fall into two categories:
Traditional Sand/Cement render
The mix ratios are normally 6 parts clean sharp sand, 1 part cement and sometimes 1 part lime (this addition makes it more “workable”), although there are additives that can be used to improve workability and adhesion properties. The base coat is applied to the masonry at approximately 10mm thickness and is then finished with a 6mm top coat where the sharp sand is substituted with a finer sand to give the smoother finish. Battens may be used every 1.5m to use as a straight edge to run up against when removing excess material and levelling off.
Hardwall & Skim
An undercoat plaster with high impact resistance Thistle HardWall is a quick drying undercoat plaster suitable for use on most masonry backgrounds such as bricks, medium-density and aircrete blocks. Thistle HardWall can be hand or spray applied and is ideal for use in a 2-coat plaster system where gypsum plaster is applied on top to give the desired finish.
This material normally comes premixed and of the desired colour as opposed to sand/cement render which is either left to dry a grey colour or painted over. It is still applied as a base coat and top coat as above and is applied almost like when plastering.
This material has flexible properties but does require mesh reinforcement across different substrates, joint areas or corner or window and door openings. It is used most commonly on newer properties however does not break down like sand/cement over a period of time and therefore is unlikely to be recyclable.
Whilst the sand/cement render is traditionally applied to masonry surfaces and can take up to 28 days to cure, it may require a metal lath attached to the wall as a reinforcement and method of attachment. This assists with the adherence of the render due to its “slump” characteristics and possibility of it being applied to a poor substrate.
The acrylic render can be applied direct to masonry or a cement board and may cure in 2 days. The advantage of attaching it to cement based backing board is that it can be used as part of an external wall insulation system and comes in predetermined colours, chosen by the client
When you are looking to finish your project externally, then we have the expertise to assist in delivering the perfect solution
For plastering advice call our technical team on 01553 767512
K J Plastering Ltd, a small enterprise located in Kings Lynn, has been servicing the plastering, drylining, screeding, rendering and partitioning sectors for over 18 years in Cambridgeshire, Lincolnshire, Leicestershire, Bedfordshire, Essex, London, Oxfordshire, Norfolk & Suffolk and in that time, have amassed a dedicated and qualified workforce with a wealth of knowledge and expertise.
Working with micro to macro size organisations and bringing ‘on-time, on budget’ solutions to their projects, K J Plastering Ltd has built an enviable reputation for quality service and timely completion.