Guideline 9. Engineering considerations

For many commissions artists and clients will need to take specialist advice on engineering issues from a professional consultant.

This guideline has been written for Commissions North by Arup Newcastle, the regional office of Ove Arup and Partners International.

Click on a heading below for more information or scroll down the page to read the whole guideline.

• Engineering consultants
• Scope of works
• Design and construction
• Support and foundations
• Mechanical and engineering issues
• Other engineering issues
• Performance specification
• Responsibilities and duties
• Contracts
• Fees
• Terms and conditions
• Ove Arup and Partners International

Engineering consultants

Engineering consultants are professionally qualified engineers who can provide a design service to an artist or client on specific issues such as structural supports, mechanical and electrical requirements, lighting and acoustics.

The works they design – or have an input into – can be fabricated and installed by the artist themselves or – more typically – by specialist contractors.

The most commonly used consultants for artworks are structural engineers, although mechanical and electrical engineers are also required for many works.

Scope of works

Different artworks will require different input from their engineering consultants.

The list of issues that the consultant will address as part of their contract with the artist is known as the ‘scope of works’. These need to be identified as early as possible so that technical problems do not arise in the project and so the fee can be agreed.

It may be appropriate to first consider only the issues that might affect the feasibility of the scheme rather than commission a consultant to carry out design work that proves to be abortive.

There are some items that engineering consultants typically exclude from their scope of works, as these are often best carried out by others.

Exclusions will vary from project to project, but typically include:

• Fabrication drawings (if required)
  The contractor responsible for fabricating the artwork will be responsible for these.
• Ground investigations (if required)
  Although the consultant structural engineer normally specifies these, they are usually arranged and carried out by others.
• Site surveys (if required)
  The dimensions and levels of the surroundings are normally required to complete the design of the artwork and its supports/fixings. This information is sometimes available from the owner of the site, but frequently a survey is required to determine the required information. This is normally arranged and carried out by others, and may need to include a survey of the subterranean existing services in the vicinity.

Design and construction

The artist may require input and advice from a structural engineer to assist them with their design.

The level of input required will obviously vary significantly from project to project, from general ad-hoc advice to a full detailed design service, including calculations, drawings and specifications.

Items that may be considered by a structural engineer:

• Structural strength
  The artwork needs to be strong enough to support itself or span between its supports without undue risk of collapse. Some artworks will also have to withstand loads resulting from wind, snow or pedestrians. The structural engineer will be able to advise on or allow for the imposed forces and their likely effects and implications.
• Structural stiffness
  The artwork needs to be appropriately stiff so as not to deform excessively. The allowable deformation of artworks varies significantly, and may be limited by the requirements of any mechanical or electrical equipment, or the flexibility of the materials that comprise the installation.
• Material specification
  The artwork needs to be constructed from materials appropriate for the loads and environment it will be subjected to. Issues such as strength, stiffness, durability and corrosion will need to be addressed.
• Practical construction considerations
  The construction and installation of the artwork should be considered during the design process. In many cases artworks are installed in very restrictive sites that impose constraints on their construction and installation.

A brief discussion with your proposed consultant should identify the level of service that is most appropriate for your project.

Support and foundations

The artwork will need to be installed and fixed in position. This can often be achieved by fixing directly to existing construction, such as masonry walls or a building’s structural frame, but sometimes a separate supporting structure or foundation is required.

If it is proposed that the artwork be fixed to and/or supported by an existing construction, such as the wall of a building, it first needs to be determined that the owner of the existing construction will allow the artwork to be supported from their property. If this is the case, then their constraints in terms of fixings or loading capacities should be identified early on.

Should permission be granted in principle to support the artwork off the existing construction, there are a several issues that may need to be considered by a structural engineer:

• Effects on the existing construction
  The loads imposed on the existing construction from the proposed installation need to be determined by the consultant structural engineer to allow this assessment to be carried out. In many instances, the owner of the existing construction will have their own structural engineers, and the division of responsibilities between the two parties will need to be clearly defined.
• Fixings to the existing construction
  The detailed requirements of these will need to be agreed by the owner of the existing construction, as they may have specific restrictions on the size, number and type of fixings that they will allow. Consideration will also need to be made as to how the installation will be removed and the existing construction made good in the future.

Should a dedicated structure and foundations be required to support the proposed artwork, there are other issues that will need to be considered by the structural engineer:

• Ground conditions
  The ground beneath the foundation needs to be adequate to support the loads from the installation. In some instances, it may be necessary to carry out a ground investigation to determine the extents of any existing foundations or the suitability of the ground in the vicinity. Most small installations will not require this, however.
• Foundation design
  If a ground investigation is required, the foundation design can only be completed once this has been carried out. Typically, however, the engineer will make assumptions on the ground conditions and these will be verified by the contractors and/or Building Control Officers once work begins on site.

As with the design and construction of the artwork itself, a brief discussion with a consultant structural engineer should identify which means of support are most appropriate for your project.

Mechanical and engineering issues

The artist may require input and advice from a mechanical and electrical (M&E) engineer to assist them with their design.

The level of input required will obviously vary significantly from project to project, from general ad-hoc advice to a full detailed design service, including calculations, drawings and specifications.

Items that may be considered by an M&E engineer include:

• Electrical installation
  The artwork might have specific power requirements that will need to be identified and supplied.
• Mechanical installation
  The artwork might include mechanical elements that will need to be designed or specified by an engineer, often in close collaboration with a specific supplier or manufacturer.

It is often most appropriate for an M&E engineer to provide general advice and guidance to the artist, with the detailed design work carried out by the contractor responsible for the works.

Other engineering issues

Each artwork will have its own specific requirements in terms of engineering design input.

Specialist consultants might be able to assist with:

• Acoustics
  The acoustic properties of the installation’s site will need to be considered for any installation involving sound production. The impact of sound break-in or break-out may also be significant.
• Lighting
  The installation may be a light source itself or may require illumination to be viewed appropriately.
• Visualisation
  Engineers or architects can assist with the production of computer-generated graphics to assist in the design process or as a means of presenting the design prior to fabrication and installation.
• Environmental impact
  The materials, form of construction or energy requirements can have an impact on the environment that might need to be considered. Similarly, the artist may wish the artwork to include appropriate sustainability features such as photovoltaic cells or recycled materials.

Performance specification

Many projects involve specialist items that are best designed by the manufacturers or the contractors.

This process is known as ‘performance specification’, and the form of agreement with the contractors is known as a ‘design and build contract’.

In these circumstances, the consultant engineer or artist will specify the performance requirements of these items. It may also be appropriate for the consultant to review the contractor’s proposals to ensure their conformance with the design intent.

Artworks that involve significant mechanical or electrical installations, or ones using proprietary systems, such as cladding systems, may best be designed using a performance specification.

In these instances, it should be clear who is responsible for each element of the design. In some cases, it will be advisable to specify that an entire installation be contractor-designed and fabricated to the artist’s specification, with input from the consultants as required.

Responsibilities and duties

Engineering consultants are typically involved in building and civil engineering projects where there is an architect to lead the design team and co-ordinate their input.

Many artworks are highly unusual and have a significantly smaller budget than most projects that engineering consultants commonly deal with. In addition, the complexity of many artworks is such that highly advanced computational analysis might be required to justify and fully-detail a complex structure, whereas the artist might be in a better position through their practical experience to complete the design work themselves.

For many projects it will not be possible within the budget for an engineer to be responsible for the entire artwork, and their input should be focussed on specific issues.

Contracts

Should a consultant engineer be required on a project, they should be invited to write to their client – usually the artist or the commissioner – with their bid for the work.

This letter should state clearly who is to be their client, the scope of the works, the fees, the method of payment, the form of agreement and the Professional Indemnity Insurance carried by the consultant for the project. If this is acceptable, the client should write back accepting their terms and conditions.

On some very large projects, it may be beneficial to ask several competent consultants to bid competitively for the work. Otherwise, an appropriate consultant could be identified by recommendation from fellow artists or through Commissions North. Only professionally qualified Chartered Engineering Consultants should be considered.

Fees

Consultant engineers typically carry out a piece of work for a client for either a fixed fee or on a time-basis rate. It should be clear in the agreement whether the quoted figures are inclusive or exclusive of VAT.

• Fixed fee
  This offers a certainty of cost to the client, but will only cover the items that were included in the original scope of works. Should the design change significantly or if additional works are required, the consultant will be entitled to additional fees to reflect this. Additional fees can be in the form of another fixed fee agreement, or on a time-basis rate agreed as part of the original contract with the client. Fixed fee agreement is most appropriate where the scope of works is clearly defined and there are few ‘unknowns’ likely in the design process.
• Time-basis rates
  Time-basis rates offer the client good value for money but without the certainty to the overall cost. This is most appropriate where there is considerable uncertainty in the project – for instance, the overall feasibility of the design or the level of input that may be required from the consultant is unclear. No time-basis agreement should be agreed without a cap on the spending – this cannot to be exceeded without the prior written consent of the client. This will protect the client from unexpectedly large invoices at the end of a project.

The invoicing schedule – typically a single lump sum for small jobs – and the payment terms – typically 28 days from date of invoice – should be proposed by the consultant, and agreed at the outset.

Terms and conditions

The terms and conditions of the engagement with the consultant should be in accordance with the Association of Consulting Engineers Terms and Conditions of Engagement (current edition).

Professional Indemnity Insurance should be provided by the consultant for an amount appropriate to their level of advice and the value of the project, and should be provided for an appropriate time from the completion of the project.

Ove Arup and Partners International

This guideline has been written for Commissions North by Arup Newcastle, the regional office of Ove Arup and Partners International, which employs several consultant engineers who have been involved in artwork projects worldwide.

Arup also have considerable experience of project management, project co-ordination, computer visualisation, fabric structures architecture, acoustical engineering, and planning supervision.

Matthew Birchall and John Gregory, Arup Newcastle, will be able to advise on individual projects, if required. For more information, visit www.arup.com, email matthew.birchall@arup.com, or telephone 0191 261 6080.