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Solid plastered surface application

Overview

The purpose of this standard is to provide the delegate with the knowledge to support the use and application of the underpinning historical, technological and theoretical knowledge and the requisite practical skills to undertake the correct evaluation and selection of materials, tools, equipment and craft practices relevant to solid plastered surface application.

Duration

Minimum 3 days of 6 learning hours per day

Purpose/scope

The purpose of this standard is to provide the delegate with the knowledge to support the use and application of the underpinning historical, technological and theoretical knowledge and the requisite practical skills to undertake the correct evaluation and selection of materials, tools, equipment and craft practices relevant to solid plastered surface application.

Scope:

  • prepare surfaces
  • apply and finish internal and external plasterwork
  • match style and textured finish of existing
  • first or pricking up coats
  • second coats
  • finish coats
  • prepare and mix lime putty
  • select sand/aggregates for mixing
  • pozzolanic additives
  • using hydraulic lime and NHL2. 3.5, 5
  • protect existing surfaces, flora and fauna
  • the main principles of minimum intervention
  • match existing work techniques and materials
  • record and survey
  • re-use of existing materials
  • running moulds in-situ
  • prepare moulds and casting
  • differences between restoration/conservation/repair and alteration

Occupational relevance

Training delivered against this standard would be relevant to the following occupational groups:

  • operative and craft
  • supervision
  • management and leadership

Delegate pre-requisites

There are no delegate pre-requisites as part of this standard.

Instruction/supervision

As a minimum, course trainers must be able to demonstrate that, in relation to this standard, they have:

  • an award in education and training (or equivalent, as per requirements for approved training organisations)
  • successfully completed training to this standard
  • at least 5 years relevant industrial experience
  • a verifiable CV

Delivery

Delivery may be in an on or off the job environment.

All materials and equipment must be of a suitable quality and quantity for delegates to achieve learning outcomes and must comply with relevant legislation.

The class size and delegate/trainer ratio must allow training to be delivered in a safe manner and enable delegates to achieve the learning outcomes.

The following delivery methods may be used in the delivery of this standard:

  • classroom
  • a blend of classroom and remote

This standard is considered to contain 51% or more practical training.

This standard is considered to be set at an intermediate/advanced level.

Assessment

For the successful completion of training, delegates must complete an end of course practical assessment or knowledge test that measures all learning outcomes and has a pass or fail criteria.

Where this training is assessed using multiple-choice questions, a minimum of 10 questions must be asked and delegates are required to achieve an overall pass mark of at least 80%.

Quality assurance

Assured

Quality assurance against this standard will require initial approval of the training organisation and their content mapped to the standard.

CITB will also conduct an approval intervention, either desk-based or centre visit, to ensure the training organisation can meet the requirements of the training standard.

Approved training organisations (ATOs) will be required to present information on records of training and assessment upon request to CITB for desk-based analysis. They will also be visited annually by the CITB quality assurance team.

Renewal

There are no mandatory renewal or recommended refresher requirements for this standard.

Classification

Lifetime

Please note standards using this classification will only be grant aided once per delegate

Approval date 

February 2022

Review cycle

On request or 3 years from approval date.

Learning outcomes

Learning outcomes
The delegate will be able to: Additional guidance to support learning outcome:

interpret information and follow advice and understand principles of working on period properties

 

adopt safe working practices

 

select materials and components

 

prepare background surfaces for internal and external plasterwork finishes, following the style of the project

to include:

  • old brickwork

    • joints raked out of approximately ¾ inch (19mm)

    • any smooth hard surfaces should be rough end by hacking or mechanical key

    • backgrounds providing no key should have a splatter dash coat applied to provide the key in an eminently hydraulic lime for a 2.5 -1 mix scratch coat.

    • background to be well brushed down to remove dust

    • scratch coat should be applied and allowed to cure a minimum of seven days

    • timber beams (lintels) should be checked for soundness and covered with wood or metal lathing (e-m-l) then counter battened or brandered and rendered approximately 7 days before new render is applied

  • stone prep for renderer’s

    • background well brushed down with coarse broom

    • well wetted to control suction

    • joints well raked out

    • face of stone works to be roughened

    • apply the scratch coat as for old brickwork

  • preparation of lathing

    • backgrounds (joists) should be checked for soundness

    • laths should be soaked 24 hours before fixing

    • lath breaks should be employed when fixing to avoid straight joints

    • laths should be fixed with the correct spacing between to allow for the mix to be pressed through to provide a secure key

    • before application of the mix laths should be mist sprayed to control the suction

    • the pricking up coat is applied diagonally across the lath background to ensure a good key is provided

    • when the prick coat is complete this coat is diagonally keyed to provide the key for succeeding coats

    • pricking up coat should be left for a minimum of two weeks and checked for hardness of the keys and between the laths prior to applying the floating coat

apply the floating coat with a devilled float to accept the final coat (left for a minimum of one week to enable the surface to firm up)

 

apply the finish coat and finished with a trowel, float, trowel operation to leave a good finish

 

work on conservation/restoration, repair and conversion projects

 

construct running moulds for in-situ work

 

cast from moulds in cement/sand/lime

 

setting jobs on site

 

identify differing types of backgrounds

to include:

  • brickwork (handmade/pressed)

  • blockwork

  • breeze/clinker

  • concrete (dense & lightweight)

  • lignacite (sawdust/cement)

  • keyed flettons (grooved to take plaster)

  • terracotta hollow blocks (partition walling)

  • sawn lathing

  • split timber lathing

  • e-m-l / rib lathing

  • reeds

  • cob

  • chalk

  • wattle

  • straw, boards

control the suction of backgrounds

 

mix materials

 

protect existing surfaces as work proceeds

 

replicate traditional plaster finishes internally/externally

 

understand the principles and methods of setting out jobs on site

to include:

  • drawings/detail/component/ assembly

  • specifications

  • preparation

  • setting out procedures

  • datum points (the purpose)

  • starting points

  • transferring datums

  • the use of:

    • laser level

    • spirit level

    • water level

    • plumb bob and line

    • straight edge rule

    • box rule

    • flexible tape

    • surveyors tape

    • scale rule

prepare plasters coarse stuff/lime putty/plaster/cement/sands and additives

 

describe how to prepare surfaces appropriate to plasterwork finish

 

explain how to apply and finish internal and external plasterwork in one, two & three coat work

 

explain how surfaces are finished to the appropriate style and textured finish of existing

 

describe how to replicate textured finishes from a range of traditional work

 

explain how plasterers coarse stuff for first or pricking up coat on lathing is as below for masonry but gauged 1 – 2.5 by volume

 

describe how plasterers finish is mixed just prior to use and consists of lime putty and a fine washed sand gauged at approx 1 – 1 by volume. This can also be gauged on the spot board with a small amount of plaster of paris which improves the finish and helps avoid shrinkage cracking

 

describe what plasterers coarse stuff for first and second coats on masonry and second coat on lathing consists of

to include:

  • lime putty to BS890 and hair

  • well graded sand (aggregate) dry if possible

  • gauge to 1-2.5 by volume

  • excess water from mature lime putty is removed and saved

  • the mature lime is placed into

  • a pan mill and given an initial mix up

  • the aggregate is then added gradually and well beaten in

  • at this stage no water should be added

  • the mixed coarse stuff should be stored in sealed bins or on banker boards covered with plastic sheeting until required, this mix of lime/aggregate matures with keeping

  • coarse stuff should be re-worked before use by:

    • chopping as this will improve the workability

    • beating

    • ramming

explain how to prepare and mix lime putty

 

describe how to select sand/aggregates for mixing

 

explain the addition of pozzolanic additives such as brick dust and pulverised fuel ash when using lime putty mixes externally

 

describe alternative mixes using hydraulic lime instead of lime putty for external areas

 

explain NHL2. 3.5, 5.

 

describe the possible damage to lime plaster on lathing caused by vibrations/movement in structure caused by people working above whilst the material is in the early stages of carbonation

 

explain how to protect existing surfaces

 

explain how to protect flora and fauna

 

explain how to validate ways in which work should be carried out

 

explain how to maintain the main principles of minimum intervention on to the building/structure

 

explain how to select like for like materials

 

explain how to use like for like work techniques to match existing

 

describe how to record and survey work surfaces to be worked on, by photos and written reports

 

describe how to salvage and re-use existing materials

 

describe how to take sections from existing mouldings in-situ

 

describe how to construct running moulds for in-situ work

 

explain how to set up running rules for in-situ work

 

explain how to prepare moulds for cement/lime/sand casting

 

explain mix ratios for cement casting

to include:

  • 3 – 1 for all o-p-c casting

  • 3 well graded aggregate

  • 1 ordinary Portland cement

describe how to select correct materials for casting

to include:

  • sand (general building grade)

  • granite chippings

  • granite dust

  • stone dust

  • white cement

explain when to use the wet/dry method of cement casting

wet method:

  • if using plaster moulds they will break down easily even when oiled and seasoned

  • there is a problem of vibrating the mix in a plaster mould

  • if the mix is not wet enough then the detail of the cast will not be produced as air will be trapped in the cast

semi-dry method:

  • hollow casts can be produced

  • the casting mix is tamped into the mould in layers of approx 40mm thick until the mould is completed

  • the moulds used in this method can be used numerous times in a working day

explain the difference between restoration/conservation/repair and alteration

 

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