Conserve, restore or retrofit earthen structures

Business Sectors (Suites): Heritage Skills (Construction)
Developed by: Construction Skills
Approved on: 15 Dec 2022


This standard is about conserving, restoring or retrofitting earthen structures, interpreting information, adopting safe, healthy and environmentally responsible work practices, selecting and using materials, components, tools and equipment, in accordance with organisational requirements which are equal to or exceed current statutory and legislative requirements

This standard is for people working in the occupational area of heritage skills and can be used by operatives, supervisors and managers

Performance criteria

You must be able to:

Interpretation of information
P1 interpret the information relating to the work and resources as relevant to geographical location and climatic conditions to confirm its relevance for the following:
method statements
risk assessments 
manufacturers’ and suppliers’ information 
oral, written or electronic instructions 
current regulations, legislation, official guidance and permits 

Safe work practices
P2 comply with the relevant, current legislation and official guidance to carry out the work and maintain safe and healthy work practices relating to the following:
methods of work
safe use of appropriate personal protective equipment (PPE)  
safe use of access or lifting equipment
safe use, storage and handling of materials, tools and                equipment
safe use of health and safety control equipment
specific risks to occupational health and safety including mental health awareness
specific risks associated with hazardous or asbestos containing  materials

Selection of resources
P3 select the required quantity and quality of resources for the methods of work for:
materials and components  
tools and equipment

Minimise the risk of damage
P4 comply with organisational procedures to minimise the risk of damage to the work and surrounding area by:
taking relevant steps to protect the work and its surrounding area from accidental or unintended damage
working with an awareness of the environment in liaison with other occupations 
maintaining a safe, clear and tidy work area
disposing of waste in accordance with current legislation

Meet the contract specification
P5 comply with the contract information to conserve, restore or retrofit earthen structures efficiently to the required specification by:
demonstrating earth and turf building work skills to:
    -     select
    -     measure
    -     mark
    -     mix
    -     fit
    -     finish
    -     cut
    -     lay
    -     position
    -     bed
using and maintaining hand and power tools and ancillary equipment 
conserving, restoring, repairing, maintaining or retrofitting earthen structures by:
    -     observing, recording and reporting the structure’s condition and any defects
    -     installing temporary coverings
    -     observing the drying of wet walls 
    -     executing horizontal bracing
    -     forming new openings:
        o       inserting and fitting lintels 
        o       plates
    -     filling holes and cracks with earth material, masonry 
    -     connecting new and old earth structures and materials 
    -     connecting woodwork and earth 
    -     applying surface finishes 
and at least two of the following:
    -     securing or propping structure  
    -     repairing below or reinforcing existing structure 
    -     rebuilding masonry or monolithic systems 
    -     applying sacrificial plasters to remove efflorescence 
    -     chasing or building in services (pipes, boxes, fixing)
    -     apply insulation materials (light earth)
        o       by hand or
        o       by machine 

Allocated time
P6 complete the work within the estimated, allocated time, taking account of climatic conditions, in accordance with organisational procedures, the programme of work and to meet the needs of other occupations and/or client

Knowledge and Understanding

You need to know and understand:

P1 Interpretation of information
K1 why organisational procedures have been developed and how they are implemented

K2 types of information, their source and how they are interpreted in relation to:
method statements
risk assessments
manufacturers’ and suppliers’ information
contractual information
current legislation, regulations, official guidance and permits including but not limited to listed buildings and scheduled monuments 
conservation reports and plans 
oral, written or electronic instructions
K3 the importance of organisational procedures to solve problems with the information, and why it is important to follow them

K4 information for relevant, current legislation, official guidance and site-specific requirements and how it is applied

P2 Safe work practices
K5 how emergencies should be responded to in accordance with organisational authorisation and personal skills in relation to:
fires and the types of fire extinguishers and how and when        they are used in relation to water, CO2, foam and powder
spillages and injuries
emergencies relating to occupational activities
identification of and reporting of hazardous                                substances including but not limited to asbestos containing          materials and lead carbonate

K6 the organisational and site-specific security procedures for tools, plant and equipment in relation to:
the general public

K7 how to report risks and hazards identified by the following:
methods of work
risk assessments
personal assessment
manufacturers’ technical information
statutory regulations
official guidance
Control of Substances Hazardous to Health (COSHH)

K8 the accident reporting procedures and who is responsible for making the report

K9 why, when and how health and safety control equipment identified by the principles of prevention should be used in relation to:
collective protective measures
personal protective equipment (PPE)
respiratory protective equipment (RPE)
local exhaust ventilation (LEV)

K10 how to comply with environmentally responsible work practices to meet current legislation and official guidance when dealing with potential accidents, health hazards and the environment whilst working in the workplace in relation to:
below ground level
confined spaces 
working at height
tools, plant and equipment
materials and substances
moving and storing materials by manual handling and                mechanical lifting

P3 Selection of resources
K11 why the characteristics, quality, uses, sustainability, suitability, limitations and defects associated with the resources are important and how defects should be reported

K12 why sustainable and ethical work practices and materials should be adopted

K13 the organisational procedures to select resources, why they have been developed and how they are used

K14 how to confirm the resources and materials conform with the specification

K15 how the resources should be used and how any problems associated with the resources are reported in relation to: 
aggregates, bio aggregate, fibres, earth, binding materials, finishing materials, turf, masonry elements, building mixes
geo grid and wire mesh
lintels, plates, other interface systems and materials 
hand and power tools and ancillary equipment for:
    -     mixing
    -     cutting
    -     lifting
    -     laying
    -     placing
    -     compacting
digital equipment
responsible sourcing and use of earth products
timber, manufactured sheet material, limes
choice of vapour permeable materials to include paints and other forms of cladding (surface finishes)
sacrificial plasters

K16 how to identify and report the hazards associated with the resources and methods of work and how they are managed with reference to method statements and risk assessments

K17 methods of calculating the quantity, length, area and wastage associated with the method and procedure to conserve, restore or retrofit earthen structures

P4 Minimise the risk of damage
K18 how to protect work and its surrounding area from damage and the purpose of protection from general workplace activities, other operations and adverse weather conditions and how to minimise damage

K19 how to, and the importance of, carrying out the safe disposal of waste in accordance with the following:
environmental responsibilities
organisational procedures
manufacturers’ information
suppliers’ information
statutory regulations 
official guidance

K20 why it is important to maintain a safe, clear and tidy work area

P5 Meet the contract specification
K21 how the methods of work to meet the specification are carried out, and how problems are identified and reported, by the application of knowledge for safe, healthy and environmental work practices, procedures and skills, relating to:
the versatility and different qualities of different building types:
    -     mass 
    -     framed 
    -     rammed 
    -     light 
    -     masonry
    -     earth
    -     turf 
varying density and its impact on thermal conductivity
the issues affecting traditional and modern earth building techniques:
    -     geological
    -     geographical
    -     cultural 
how covering choices for protection before, during and after building aids or impedes drying 
building physics and structural behaviour:
    -     how moisture and heat move through different materials (vapour permeability) 
    -     how solid wall buildings function
    -     the compatibility of additions with existing structure
    -     factors affecting indoor air quality, such as:
        o       humidity
        o       CO2
        o       volatile organic compounds (VOCs)
the inappropriateness and consequences of using cement renders on vapour permeable materials
when to remove deteriorated and inappropriate materials
the inappropriateness and consequences of using non-vapour permeable insulation on vapour permeable materials
why it is important to observe, record and report on the:
    -     structure’s condition 
    -     drying of wet walls
    -     defects, issues and underlying conditions and pathologies
why it is necessary to repair below or reinforce existing structures
how to produce surface finishes and make and apply surface treatments and repairs 
the difference between energy efficiency and sustainability in earthen structures
when to use sacrificial plasters to remove efflorescence
when to execute horizontal bracing
height and width ratio (slenderness) in humid and dry state, to include how high to build according to regional technique, weather and site conditions
the impact of ground water on earth structures foundations, and wall bases 
issues with scaffolding to include: 
    -     fixing
    -     splash-back
the different methods to connect new and old earth structures, materials and woodwork
the different types of openings to include: 
    -     frames
    -     lintels
    -     sills
how to create and form openings to include:
    -     inserting and fitting lintels
    -     plates
how to identify defects, signs of deformation and collapse or slumping, 
how to prevent defects, signs of deformation and collapse or slumping
the impact of drying on speed of build
methods to test and control moisture content (site or lab)
the drying process and shrinkage
damage to earthen structures to include:
    -     cracks
    -     loss of material
    -     degradation
    -     deformation
    -     tilting
when to get advice from a structural engineer
how to prevent water damage and abrasion
repair or rebuilding techniques to include:
    -     masonry
    -     monolithic systems
    -     others
repair materials to include:
    - burnt and un-fired bricks
    -     stones
    -     mortars
    -     fibres
    -     ties
    -     threaded bar
    -     mesh
building formwork and frames
finishes, thermal insulation, air tightness and moisture protection
the treatment of:
    -     openings
    -     floors
    -     edges
    -     tops of walls
how to secure and prop damaged structures and temporary coverings
why it is important to maintain heritage and archaeological integrity
why it is necessary to maintain the principles of minimum intervention and reversible alterations
why it is necessary to record work carried out (written and digital formats)
why it is important to recognise and report protected flora and fauna (mortar bees)
why it is important to store salvageable fabric, materials and structural components
why it is important to recognise and determine when specialist skills and knowledge are required and report accordingly
the relevance of an assessment of significance
why it is important to determine specific requirements for:
    -     structures of special interest
    -     traditional build (pre-1919) 
    -     historical significance
how to use all hand and power tools and ancillary equipment
how and why operative care and maintenance of all hand and power tools and ancillary equipment is carried out
how to work at height using access equipment
how to work with, around and in close proximity to plant and machinery

K22 the organisational procedures with respect to site behaviours, and recognise and action fairness, inclusion and respect within the working environment, and how to address and report inappropriate site behaviours

K23 the importance of methods of work, interpersonal relations and communication and the needs of other occupations associated with conserving, restoring or retrofitting earthen structures

P6 Allocated time
K24 the programme of work to be carried out including the estimated and allocated time, and why deadlines should be kept or reported if likely to be missed

K25 the types of progress charts, timetables and estimated times and the organisational procedures for reporting circumstances which will affect the work programme


Scope Performance

Scope Knowledge





Links To Other NOS

External Links

Version Number


Indicative Review Date

15 Dec 2027





Originating Organisation


Original URN


Relevant Occupations

Earth Builder

SOC Code



Limes; Earth; Turf; Cob; Rammed earth; Mud; Earth mortared masonry; Mass earth; Light earth; Moulded earth brick and block