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Building and structure design

We provide professional services for all building types, from state of the art to historic buildings, our projects range from small domestic to major projects of framed and multi-storey design.

Our design expertise encompasses all conventionally adopted materials using recognised and advanced techniques.

We regularly design projects of reinforced concrete and steel framed construction, steel concrete and other composite construction, masonry, timber, structural aluminium and glass construction.

Designs of more complex structures are undertaken, including antennae, masts, space frames, tensile, cable stayed, stressed skin, post-tensioned and or pre-stressed structures.

Dynamic analysis and design of more dynamically sensitive or critical structures can be undertaken.

Design is fully supported with computer structural analysis design aids and tools, including finite element model and space frame model structural analysis.

Design and drawing is output using CAD facilities.

We value highly and ensure development of a close working relationship with the client, Architect and other design professionals.

Foundation design

Foundation designs of the full spectrum of buildings and structures is undertaken including low rise to multi storey structures

We have expertise of foundation design of structures on difficult ground or with special design requirements.

Investigation to have a proper understanding of the ground and foundation conditions, including those of adjacent buildings and structures, is crucial to enable proper and efficient foundation design.
We regularly commission and control foundation and ground investigation.
Please refer to Ground and foundation investigation.

In addition to more straightforward conventional strip or pad foundation design more specialist foundation designs and analysis are undertaken.

These include foundation immediate and long-term settlement analysis, bored and driven piled foundations, reinforced concrete ground beam, raft, deep and water retaining basement construction.

Design of foundations upon shrinkable clays soils, e.g. London or Oxford Clay is regularly undertaken. Design solutions adopting deep pad or piled foundations with reinforced concrete ground beams or slabs are regularly used where particular adverse ground conditions and or close proximity of trees require.

Foundations upon chalk can present foundation difficulty, in particular where chalk solution features are prevalent. We have expertise in the design of alternative foundation solutions where required to overcome difficult chalk ground conditions.

We have been engaged on more complex foundation bridge or cantilever transfer structures, to avoid undue loading upon ground services or existing foundations etc.

Foundations designed for dynamically sensitive or critical structures have been designed.

Designs of underpinning or other foundation stabilisation or improvement works are part of the expert comprehensive design service we provide.

Ground and foundation investigation

Investigation to have a proper understanding of the ground and foundation conditions, including those of adjacent buildings and structures, is crucial to enable proper and efficient design of foundations, structures, ground works, retaining walls and earth supporting systems.
We regularly commission and control foundation and ground investigation.

Investigation should include detailed visual inspection of the site and adjacent buildings to ascertain the visible prevailing conditions.

Ground investigation may include straightforward trial pit exploratory work of ground and foundations. Deeper investigation may be achieved with hand-augured boreholes or with advanced techniques including machine mini - boreholes, shell and auger boreholes and dynamic probing.

Radar investigation may be used in appropriate circumstances to assess variation in ground strata.

Insitu testing of ground for soil strength parameters is regularly carried out.

Monitoring of structures, foundations and adjacent or supporting ground may form part of a proper investigation. We regularly conduct simple and or precision monitoring investigations.
PC controlled level and tilt monitoring of structures can be adopted in more sensitive or critical structures e.g. historic or structurally suspect structures.

Site investigation for retaining walls, slopes, embankments and anchorage systems should ensure the ground conditions and foundations of any adjacent buildings or structures are properly assessed in the immediate vicinity and within the zone of influence or behaviour of the ground structure. This can involve investigation some distance away from the structure and accurate monitoring of any movement.

Site investigation is normally supported with appropriate laboratory testing of soil samples.
Testing may be carried out to determine soil strength, settlement and ground movement behaviour.

Problems associated with foundation movement due to soil susceptibility to movement caused by changes in soil moisture, in particular for shrinkable clay soils, can be investigated with laboratory testing.

Investigation where appropriate may include load testing of foundation or anchorage systems. These are commonly related to pile tests and ground anchors tests for load capacity and movement data.
Foundation load tests can also include plate load testing of spread foundations, but these are adopted more rarely.

Soil and ground investigation and testing of contaminated land can be carried out to assess soil and groundwater toxicity and chemical constituents, where necessary for health and safety implications of excavations and or works affecting the ground and groundwater.

Following completion of appropriate site and laboratory investigation and any necessary ground or soil- structure analysis, detailed, clear and concise reports are prepared as appropriate and to the extent required by the brief.

Refurbishment and conservation design

We provide professional services and have considerable experience in the refurbishment and or conservation of existing and historic buildings.
Where appropriate this will include advice and design in respect of change of use.

Crucial to appropriate and economic design of such projects it is important to conduct careful inspection and appraisal of the existing building and proposed future use. This should include testing and inspection for material and timber decay, infestation, dampness and durability.

Design should encompass measures to remedy current defects, strengthen the building as necessary for its proposed use and to encourage longevity with appropriate maintenance levels and procedures.

These measures will typically include attention to the structural frame with strengthening and repair as necessary, control of dampness (from the ground, roof or enclosures), condensation, corrosion of steel, concrete and material defects, building drainage and services and fire precautions.

All such refurbishment and remedial schemes should be carried out in close liaison with the statutory authorities, obtaining all required planning, listed and historic building consents, for which we can make application on behalf of our clients.

Where appropriate archaeological investigations and ancient monument statutory approvals may be necessary.

Projects we have recently advised upon or designed include:
· Reconstruction of a timber framed museum and a flint masonry bodgers hut on an ancient monument site
· Stabilisation and repair of an early 17th century important landmark London house
· Refurbishment and conservation of a reinforced concrete framed commercial building
· Numerous refurbishment and or conversion schemes of domestic 19th and 20th century buildings.

Masts and Towers

Design of these more specialist or complex structures are undertaken, with relevant guidance including BS 8100 - Lattice Towers and Masts - Code of Practice for Loading and BS 6399: Part 2: 1997 Code of Practice for Wind loads and Eurocode 3: Design of steel structures Part 3-1 Towers, masts and chimneys Towers and masts and Eurocode 1: Actions on structures Part 1-4: General actions Wind actions.

The structures may be sole member structures, lattice structures with or without cable stays or guys.
Typically for use as telecommunications antennae and masts, power transmitting cables and water or other storage towers.

Dynamic analysis and design of the more dynamically sensitive or critical structures can be undertaken.

Design is fully supported with computer structural analysis design aids and tools, including finite element model and space frame model structural analysis.

Design and drawing is output using CAD facilities.

Where masts or towers are connected to a supporting structure the rotation and lateral deflection will depend upon the rigidity of the supporting construction.
In these cases where rotation and lateral deflection is critical, it is important to carry out a structural analysis and design of the combined structure of the proposed mast or tower fixed to the supporting structure.

Surveys, appraisals, structural investigation and reports

We are regularly engaged to undertake surveys and investigation of existing buildings or structures and to report upon various specific aspects including building and structural condition, adequacy for proposed use or implications of any proposed structural alteration.

Generally such investigations and reports may be divided into four categories those for residential properties (houses or flats), buildings for commercial office or shop use, industrial buildings and structures (free-standing or attached to buildings).

Please refer also to sections covering ground and foundation investigation and subsidence investigation, remedial design and control.

Residential properties - houses and flats

Whilst surveys, appraisals, investigation and reports can be tailored to meet precise requirements, they typically are required for three purposes:

· For sale or purchase of residential property
· For advice upon apparent foundation subsidence, building and or structural defect
· For advice upon implications of proposed structural alteration or change of use

For sale or purchase of residential property, three types of report are generally offered:

Structural Survey Report

This will involve the careful visual inspection of the property building construction and immediate environment, together with inspection of Ordnance Survey Geological Maps held within our offices, for details of general ground conditions.
Inspection will include an appraisal of the building drainage and services, but understandably the report will confirm that specialist advice should be sought for building services including power, gas, electrical and security installations.

For an average 3 - 5 bedroom house inspection will take approximately 3 - 5 hours dependent upon the construction, size and condition.

For an average 2 - 3 bedroom flat inspection will take approximately 2 - 4 hours dependent upon the construction, size and condition.

Whilst the report can be tailored to meet your specific requirements it will normally cover as appropriate aspects including: -

· General description
· Condition of roofs, party wall and chimney stacks
· Foundation movement and associated damage
· Structural general condition
· Thermal efficiency, cold bridging and condensation
· External window and door joinery
· Internal door joinery
· External rainwater goods and plumbing
· Fire precautions and means of escape in case of fire
· Damp survey
· Condition of below ground drainage
· Condition of the building services
· Sound transmission
· Building regulations and town planning
· Party wall matters
· Summary and recommendations

For practical and legal reasons, unless specifically requested and confirmed prior, surveys and inspections will not normally include any excavations to expose foundations and ground conditions, nor opening up work to expose floors or hidden elements of construction, nor moving or removal of fitted carpets, tiles, floor coverings and furniture, etc.

The survey and report will not normally involve detailed inspection or tests of the drains, electrical installations, plumbing or other building services, although these can be arranged separately as required.

Inspection of flats will usually be limited to readily accessible parts and external areas.

Inspection of flats will usually be limited to internal inspection of the flat and readily accessible common parts and external areas. Where the flat is part of a large block, inspection of the common parts and external areas will have to be limited and or agreed in detail.

Initial survey report

This form of report will be tailored to meet your requirements and usually limited to inspection and report with initial advice upon one or more of the key aspects normally covered by a full structural survey (refer above).
This might be typically limited to the main structural elements and or foundation movement and associated damage affecting the property, with only brief comment upon other associated building aspects.

For an average 3 - 5 bedroom house inspection will take approximately 1.5 - 3.0 hours dependent upon the construction, size and condition.

For an average 2 - 3 bedroom flat inspection will take approximately 1 - 2.5 hours dependent upon the construction, size and condition.

The extent of the inspection and report with initial advice, will be similar but not normally as extensive as that covered by a full structural report (refer above)
Defects, causes, with summary and recommendations will be normally outlined as appropriate.

For practical and legal reasons, unless specifically requested and confirmed prior, surveys and inspections will not normally include any excavations to expose foundations and ground conditions, nor opening up work to expose floors or hidden elements of construction, nor moving or removal of fitted carpets, tiles, floor coverings and furniture, etc.

The survey and report will not normally involve detailed inspection or tests of the drains, electrical installations, plumbing or other building services, although these can be arranged separately as required.

Inspection of flats will usually be limited to readily accessible parts and external areas.

Inspection of flats will usually be limited to internal inspection of the flat and readily accessible common parts and external areas. Where the flat is part of a large block, inspection of the common parts and external areas will have to be limited and or agreed in detail.

Homebuyers report

A Homebuyers report as defined by the Royal Institution of Chartered Surveyors guidance can be provided.
This will be essentially be on the similar basis to the structural survey report, but will be significantly more limited in detail of inspection and report.
The report will be limited to meet the requirements of the defined Homebuyers report.

Building and or structural defect or subsidence investigation reports

For advice upon apparent foundation subsidence, building and or structural defect, two types of report are generally offered (please refer also to subsidence investigation, remedial design and control):

Structural Report

Structural reports for initial advice will usually involve the careful visual inspection of the apparent building or structural defect, the property and immediate environment as appropriate.

Where the defect is associated with ground or foundations, inspection of Ordnance Survey Geological Maps held within our offices, for details of general ground conditions will be made.

When information relating to the building or structure construction or defect is made available, the investigation and report will usually include desktop examination and appraisal of the information available. This can be particularly important where building construction or structural defect is suspected and drawing or construction records are available. Also, where foundation problems are suspected and details of the ground and foundation conditions are available.

The report will advise upon the need for further investigation, including monitoring of any movement, in order to be conclusive, which we can advise upon and arrange as necessary.

Report will normally cover aspects as appropriate including: -
· Synopsis
· General description
· The extent of the defect and or movement and associated damage
· The related structure and implications generally
· Initial advice and opinion upon cause of the defect and or movement and associated damage
· Health and safety
· Remedial measures
· Further investigation including monitoring of any movement
· Summary and way forward or recommendations

For practical and economic reasons, unless specifically requested and confirmed prior, surveys and inspections will not normally include any excavations to expose foundations and ground conditions nor opening up work to expose floors or hidden elements of construction, nor moving or removal of fitted carpets, tiles, floor coverings and furniture, etc.
Investigation with opening up and exploratory works might be recommended, which we can advise upon and arrange as necessary.

Sometimes structural reports might be limited to a desktop study of information and data available and might not include site inspection. For example where we have already undertaken site inspection and investigations and given initial advice or where others provide information.
In such circumstances the report will essentially be as detailed above, but may be limited in content as appropriate.

Initial survey report

This form of report will usually be undertaken initially to advise whether a defect exists, upon the nature and seriousness of the defect and possible causes.

The extent of the inspection and report with initial advice, will be similar, but not normally as extensive, as that covered by a full structural report (refer above).
The defect, causes and recommendations and options for the way forward will be normally outlined as appropriate.

Appraisal and report for adequacy for proposed use or implications of any proposed structural alteration

When an appraisal and advice upon the implications of a proposed structural alteration or change of use is required, this will involve the careful visual inspection of the building or structure and appraisal of the proposed structural alteration or change of use.

In some instances further investigation will be necessary to advise in full detail.
For example where the building construction or structure requires exploratory works to determine the structural adequacy or where ground and foundation conditions need to be fully determined to assess the load bearing capacity.

Our advice and report can detail as required the implications of any proposed structural alteration or change of use.

A structural alteration can increase forces upon the existing structure or adversely affect the structural adequacy and behaviour of the building or structure, or any adjacent building or structure. We can advise upon the effects the proposed structural alteration might have, health and safety issues and advise upon economic, appropriate and or alternative solutions.
Advice upon anticipated building and design costs can be given as required.

Change of use of a building or structure can affect the performance of the building and may adversely affect the structure.
For example a change of use can increase the service imposed floor loading, in particular where changing from domestic or light office use to use for storage or public assembly. In such instances care must be taken to properly assess the effects of any increased loading will have on the existing floors and structure. Where appropriate this should allow for any increased dynamic load effects.
Any effects the change of use may have on adjoining buildings or structure should also be properly considered.

Other building performance issues may need to be considered dependent upon the specific change of use.
This may include affect upon the performance of the building in fire. Where an increased fire risk is presented we can advise upon appropriate fire precautions, measures for upgrading of fire resistance of the structure and means of escape in case of fire provisions.

Advice in respect of statutory approvals, building regulations and party wall matters can be provided as necessary.

Please refer sections Building Surveying -Building Regulations and Building Act, Town Planning, Buildings of Historic Interest and Conservation and Party Wall etc. Act 1996

Subsidence investigation, remedial design and control

Subsidence - ground and foundation movement with associated damage

Subsidence has in recent years become very much associated with buildings insurance claims. In particular since 1971 when cover for subsidence within household policies was generally introduced.
Buildings insurance policies cover a number of insured events, which together with subsidence should be defined within the terms of the insurance policy. Those associated with subsidence normally include heave, landslip and water damage (typically leakage from below ground drainage or water supply services).

These events may be all encompassed as events or causes of ground and foundation movement with associated damage affecting the building or structure.

In London and the south east of England subsidence has been generally associated with problems caused by clay soil movement and the affect of trees, because of the prevalence of outcropping clay.
However, it should be appreciated this is by no means the only or principal cause, nor the only possible cause in these areas.

Problems of major foundation movement and damage can be due to other causes.
For example these may include subsidence in mining areas, collapse and movement of solution features in chalk, adverse groundwater affects upon loose on granular / sandy soils, settlement or failure of made ground, landslip or retaining wall failure.

For further guidance in respect of household and or low - rise buildings you may refer to The Institution of Structural Engineers guide - Subsidence of low-rise buildings.

We regularly advise upon all aspects of subsidence, including initial appraisal, investigation, recommendations, design and control of remedial measures. Not only where insurance claims have been made, please refer below in this respect for further information.

Initial appraisal - advise and diagnose - initial visual inspection

Where requested to advise and diagnose problems of suspected subsidence, in the first instance we would usually carry out an initial visual inspection to assess the extent and seriousness of the movement and damage, general conditions prevailing, probable causes, further investigation and immediate remedial or temporary works required.

Extent of movement and damage

Not all movement and damage is abnormal or of such seriousness that it requires remedial measures to be undertaken.
The majority, if not all buildings and structures are subject to movement and some associate damage, not necessarily caused by ground or foundation movement, for example thermal or shrinkage movement.

The key issues to determine are whether the movement and associated damage is unacceptable and or is likely to continue or deteriorate without remedial measures.

Having assessed the seriousness of the movement and damage and provided any immediate remedial works or temporary works to maintain integrity and safety as far as practicable, proper investigation as necessary should be undertaken to fully assess the problem.

Initial appraisal report

Following initial inspection and appraisal we would normally provide a brief but well detailed initial appraisal report. This would include:

· Brief and reasons for the report
· General description of the building or structure
· The extent of movement and associated damage
· The related structure and implications generally
· Initial advice and opinion upon cause/s of movement and associated damage
· Further investigations including monitoring of any movement necessary
· Remedial measures and or need for temporary support
· Insurance and appropriateness of making a claim
· Summary, way forward and recommended course of action

Investigation

Subsidence investigation will often involve accurate monitoring of the building or structure movement.
This will typically take the form of precise datum monitoring of principal fractures and where appropriate precision level survey monitoring of datums fixed to the building or structure close to the foundations.
PC controlled level and tilt monitoring of structures can be carried out for more sensitive or critical structures e.g. historic or structurally suspect structures.

Whilst monitoring of fractures should normally identify the extent of continued movement and damage it will not necessarily indicate the extent and nature of the foundation movement, which is important to ascertain as far as possible.

Precision level survey monitoring can provide useful information in this respect. However, in many instances it can be hampered by lack of a stable reference datum and may only provide an indication of relative rather than total movement.

Proper investigation of the ground and foundations conditions should be undertaken.
This should include detailed investigation with trial pits to expose foundations and adjacent ground and boreholes to ascertain the ground and soil parameters and ground water conditions as far as practicable.
The location and condition of below ground drainage and services should be ascertained. There are a number of non-invasive techniques available for this other than excavation works.
The influence of environmental factors including the influence of trees, often important on clay soils, should be determined.
Please refer to section Ground and Foundation investigation for further information.

Investigation would normally include such exploratory and opening up works of the existing building construction or structure, necessary to have a proper understanding of the structure and its sensitivity to foundation movement and vulnerability to associated damage.

Report following investigations

Following completion of investigations we would normally provide an appropriately well detailed report. This would include:

· Synopsis
· Brief and instructions received
· General description of the building or structure
· The extent of movement and associated damage
· The related structure and implications generally
· Investigations undertaken
· Detailed advice and opinion upon cause/s of movement and associated damage
· Likelihood of further movement and damage
· Any further investigation necessary
· Remedial measures required with options as appropriate
· Insurance
· Approvals required including party wall agreement where remedial works might affect adjoining properties
· Summary, way forward and recommended course of action

Remedial Measures

Having conducted sufficient investigation to enable appropriate decisions to made we would then make recommendations and provide advice in respect of appropriate remedial measures, normally in the form of our Report following investigations.

This would include the need for foundation stabilisation works. This may simply be measures, not directly affecting the foundations, to avoid or limit ground movement to tolerable limits and prevent unacceptable ground movement. For example these may include tree management in clay soil areas and avoidance of undue groundwater by preventing water leakage from defective below ground drainage or water supply services.

Underpinning - foundation stabilisation

Where direct measures are considered necessary to stabilise the building and structure foundations, these may include underpinning of the foundations and ground bearing floors etc. or ground improvement perhaps by injection grouting techniques.

Underpinning may take various forms from more traditional mass concrete underpinning, concrete pad and reinforced concrete beams or slabs to piled underpinning or other more specialist techniques. Each case should be fully considered and the form of underpinning decided on its merits.

The extent of and any effect underpinning might have upon adjacent buildings or structures should be carefully assessed and understood.

Where ground movement affecting the building or structure is caused by slope instability, creep, landslip or retaining wall failure, careful consideration will need to be given to appropriate remedial and or strengthening works, where practicable.

Numerous recent modern advanced techniques are available for retaining wall or ground slopes strengthening. Which subject to the prevailing conditions may be carried out rather than major ground works reconstruction.

Remedial works - design and control

Having ascertained and agreed the scope or remedial works required we can design the appropriate remedial scheme and prepare all necessary drawings, specifications, tender and contract documents.
Dependent upon the circumstances remedial schemes may only be repair of damage to the building, superstructure and finishes. However, they might extend to foundation stabilisation, underpinning or major structural repairs perhaps including specialist groundworks, retaining wall ground anchorages etc.

We may then control the remedial scheme through selection of contractors, tendering, cost analysis and the building contract, providing necessary site inspections, contract administration and control of contractors payments until successful conclusion of the works and the building contract.

On large projects we can provide on site control with site inspections carried out by our resident engineer.
On most small scale or domestic remedial projects, for economic reasons it is unlikely a resident engineer will be used and site control will usually be limited to appropriate site inspections at key stages and or when valuation inspections are undertaken.

For insurance claim projects, unless these are of large size or special circumstances warrant it is unlikely Insurers will agree to fund the cost of resident engineer control.

For further information please refer sections including Building and structure design, Foundation design and Geotechnical Engineering

Insurance claims

We have considerable experience and regularly advise Insurers, Insurers appointed loss adjusters and the Insured regarding technical and engineering aspects of building or structure damage and or subsidence claims.
We can advise upon all aspects of insurance claims within our expertise as consulting structural engineers.

In all cases it is important and we value highly close liaison and communication with the respective parties, seeking agreement to the way forward, investigations and remedial measures at all key stages.

Provided the cause of damage comes within the scope of an insured event, professional fees for necessary investigation and remedial works are normally included within the claim by Insurers, subject to any policy excess applicable and the particular terms of each policy.

The Insured should be aware that professional fees are not covered by Insurers, for pursuing the claim beyond that required for necessary investigation and remedial works and appropriate associated liaison with the parties involved.

Dangerous and unsafe structure investigation, remedial design and control

The practice has developed expertise in investigation, design and provision of temporary and permanent works for dangerous or unsafe structures.

We can be on call and provide 24 hours emergency cover.

Andrew Dust has considerable experience dealing with dangerous structures and related legal issues.

Prior to setting up the practice Andrew Dust was engaged as a District surveyor within inner London and dealt with numerous dangerous structures, including those where formal legal proceedings had commenced.

Please refer to other related sections, these include: Building Surveying -Building and Structure design, Foundation design, Refurbishment and conservation design, Surveys, appraisals, structural investigation and reports, ground and foundation investigation and report, Subsidence investigation, remedial design and control, Temporary Works Design

Temporary Works design

Temporary works design and inspection is frequently undertaken
Temporary works are commonly necessary for a variety of circumstances for temporary support to structures, foundations and or ground structures and works.
Temporary works should be designed and carried out adopting all necessary procedures required under Health and Safety legislation and the Construction (Design and Management) Regulations 2007.

Temporary works for structures

Temporary works for structures, including needling, shoring, bracing and provision of adequate lateral support and stability are designed and provided using various available methods.
These can include the following methods with appropriate guidance codes:

· Structural steelwork: Code of Practice BS5950: - Structural Use of Steelwork in Building and Eurocode 3: Design of steel structures.
· Timber: Code of Practice BS5268: - Structural Use of Timber and Eurocode 5: Design of timber structures.
· Steel scaffolding: Code of Practice BS5975: - falsework
· Steel scaffolding: Code of Practice BS5973: - access, working and special scaffolds and BS EN 12811-1:2003 Temporary works equipment. Scaffolds. Performance requirements and general design.

Temporary works for foundations and groundworks

Temporary works for foundations and ground structures and works, including needling, shoring, bracing and provision of adequate lateral support and stability are designed and provided using various available methods.
These can include those methods for structures in addition to the following with the appropriate guidance codes:

· Structural steel sheeting, piling, steel or timber support systems
· Retaining wall, reinforced earth or embankment systems
· Ground anchors and soil nailing systems
· Ground de-watering

All carried out in accordance with relevant recommendations of:

· BS 8004: 1986 Code of Practice for Foundations
· BS 6031: 1981 Code of Practice for Earthworks
· BS 8002: 1994 Code of Practice for Earth Retaining Structures
· BS 8006: 1995 Code of Practice for strengthened/reinforced soils and other fills
· BS 8081: 1989 Code of Practice for ground anchorages
· EN 1997: Eurocode 7 Geotechnical

Please refer to other related sections, these include: Geotechnical Engineering - Building and Structure design, Foundation design, Refurbishment and conservation design, Surveys, appraisals, structural investigation and reports, ground and foundation investigation, Subsidence investigation, remedial design and control