Why do I need to appoint a structural engineer?

Structural Engineers are needed to advise on the design of main load-bearing elements. This includes the foundations and the main load-bearing frame (masonry, steel, concrete) to ensure stability of the structure under various loads (vertical such as gravity loads and horizontal such as wind loads).

The Structural Engineers are also needed to advise on the condition of existing buildings and structures. This covers issues such as material deterioration (steel corrosion, concrete cracking, masonry cracking, timber rotting).

The Structural Engineers are also needed to advise on the interface between various structural elements (e.g. steel to steel connection, steel to concrete connection, steel to masonry supports).

We prepare the structural design which usually includes the design report, the construction drawings and the specifications needed to ensure safety and compliance with building regulations.

We use the latest BIM Tools and Software Technology to comply with the current structural codes and building regulations.

Do I need a soil investigation for my building project?

This depends on the type of project. According to the Euro-Codes and UK Building Regulations, no soil investigation is required for basic building projects (e.g. small house extension) if the soil conditions are known. The engineer is allowed to use data from neighbouring sites and we usually refer to the British Geological Society records to establish site conditions in the project area.

A trial pit is recommended to establish exact ground conditions so that the engineer can include this in their design. The builder and the building inspector would then be aware in advance of the required excavation depth. This eliminates the uncertainty facing the contractor in pricing foundations cost if the foundation depth is not known. Knowing the required foundation depth usually results in lower bids.

A soil investigation is required and we recommend this to be done as early as possible for all cases where one of the following applies:

  • Special site conditions (e.g. sloping sites, marsh land, proximity to water)
  • Site where there is a risk of contamination
  • Basements and retaining walls
  • New developments (housing, commercial, industrial, mixed use)

 

The cost of soil investigation vary and start at £1500 upwards. We help clients by providing a precise scope for soil investigation to guide the geotechnical engineer on what is required. Our soil investigation brief would define the following:

  • The number of boreholes required
  • The location of each borehole and the required depth for each borehole
  • The tests required to establish soil properties, contamination, water level, gas presence
  • The design parameters that need to be defined by the soil investigation in the interpretive report.

 

The brief above is required to ensure the design is based on accurate data so that the contractor or subcontractor responsible for foundations installation provides accurate quotes based on well-defined site condition.

As an example, one of our clients was building two new housing on a sloping site. She had received quotes ranging between £120,000 to £150,000 for the building of an embedded retaining walls that is 30m long. We were then appointed as the Structural Engineers and defined the soil investigation brief, supervised the investigation, checked the interpretive report and carried out preliminary design of contiguous piles. This was used to request revised quotes which then dropped to £90,000. Our fees for the scope definition were £1000 and the soil investigation cost £5500 (two boreholes 9-12m deep). For more information, please read our article:

What is a structural survey report and how much does it cost?

A Structural Survey Report varies from a general Building Survey as it only considers the structural condition of a property. This means that it considers issues such as structural defects (cracks, distortions, vibrations), signs of subsidence or foundation movement, sings of material deterioration and likely causes. The Structural Survey should also extend to recommend any further investigation required (e.g. trial pits, monitoring, drains surveys). If repairs are required, the Structural Survey should provide an overall estimate for cost of repairs.

We have prepared Structural Survey Reports for the following types of buildings:

  • Residential properties (for homebuyers and homeowners) especially properties suspected of having subsidence or having various categories of cracking.
  • Commercial properties requiring alterations to establish viability of such alterations.
  • Industrial buildings requiring change of use, additional loading or life extension.
  • Energy structures requiring additional loading, change of function or life extension.

Our fees for preparing a Structural Survey Report vary depending on the type of property, its age and condition. As a guide, we charge £300 for a detailed visual inspection of a residential property and £300 to £450 for preparing the report. This does not include the cost of repair design if any repairs are required, although we advise on the cost of repairs.

Do you charge for a site visit?

Yes. We may decide to waive or defer the charge occasionally but in general, we need to charge for site visits.
In the initial stage, we need to come out to meet our potential clients, establish and confirm the scope and identify site conditions (neighbour’s boundaries, site conditions, drains, trees, slopes, services, etc). During execution, we also need to come out to meet the main contractor, discuss the specifications and drawings and communicate requirements face to face to answer queries and discuss measures required to mitigate risks.
Our scope and proposal always identify the number of visits that we include in our fees. We also state the cost of additional site visits. Our current rate for a site visit is £250 exc VAT unless a different rate is required (e.g. in cases where we act as Project Managers).

What are the fees for preparing permitted development drawings?

This really depends on the type of application. Our service includes a measured survey, initial concept design for the client’s review and drawings for existing and proposed plans and elevations with a section. This service starts at £1000 exc VAT. Some clients request additional services such as acting as their agent or preparing 3D visualization and we offer such services for an additional fee. Please contact us to discuss your exact job requirement and to obtain a binding fee.

What are the fees for preparing planning application drawings?

This really depends on the type of application. Our service includes a measured survey, initial concept design for the client’s review and drawings for existing and proposed plans and elevations with a section. They also include a design and access statement or a heritage statement if the site is in a conservation area. This service starts at £1200 exc VAT. Some clients request additional services such as acting as their agent or preparing 3D visualization and we offer such services for an additional fee. Please contact us to discuss your exact job requirement and to obtain a binding fee.

What are your fees for the structural design and calculations for an extension?

Our fees for the structural design service for an extension would vary from £700 exc VAT to £2000 exc VAT depending on the extent of our design work. The scope will cover the structural design drawings, structural calculations report required by building control to document compliance with the requirements of Building Regulations Document A (Structure). Fees vary depending on the extension shape and size and the amount of work to be undertaken. We cover all the following design activities which may not be required in all jobs – hence the fee variation.

  1. Foundation design with allowance for nearby trees to comply with NHBC requirements. Fees depend on whether this is a trench foundations, ground beams on piles or a raft. Pile design includes mini-bored piles, screw piles, secant and contiguous piles.
  2. Ground floor slab design. This may be a ground bearing slab or a suspended slab (timber or concrete or beam and block).
  3. Allowance for bridging over drains.
  4. Specifications for all standard lintels (less than 4.5m long).
  5. Design of all steel beams.
  6. Design of all bearing padstones or metal plates.
  7. Check of any masonry panels and piers (existing and new).
  8. Specification of roof timber joists size and layout.
  9. Specification of building regulations requirements on the drawing, including noggins, strapping, tie-ins.
  10. Details that affect Party Wall matters.

What are the fees for preparing structural calculations and design for a loft conversion?

Our fees for the structural design service for a loft would vary from £700 exc VAT to £2000 exc VAT depending on the extent of our design work. The scope will cover the structural design drawings, structural calculations report required by building control to document compliance with the requirements of Building Regulations Document A (Structure). Fees vary depending on the loft size and shape and the amount of work to be undertaken. We cover all the following design activities which may not be required in all jobs – hence the fee variation.

  1. Loft floor beams required (in steel or timber depending on span and loading). This also includes trimmers around the stairs, beams under walls such as the dwarf wall and other partitions.
  2. Loft roof beams required (in steel or timber depending on span and loading). This includes supports for the pitched roof and the flat roof.
  3. Chimney support beam or frame.
  4. Specifications for all standard lintels (less than 4.5m long).
  5. Design of all bearing padstones or metal plates.
  6. Check of any masonry panels and piers (existing and new).
  7. Specification of roof timber joists size and layout.
  8. Specification of building regulations requirements on the drawing, including noggins, strapping, tie-ins.
  9. Details that affect Party Wall matters.
  10. Details to prevent roof spreading following the removal of the triangulated truss action. This is crucial and would ensure lateral stability and maintain the integrity of the roof structure with the remaining structure.

Will I need a building regulations package for my loft or extension?

This package will include all the construction details for the project as they should be built. They are essential to achieve the following:

  1. COMPLIANCE: The drawings are required to secure approval from building control as they document how the Building Regulations requirements are met (e.g. thermal insulation and fuel conservation, fire protection and safety, air tightness, acoustic insulation, access and means of escape, drainage, ventilation, water supply and foul water disposal, electricity and plumbing).
  2. COST CERTAINTY: Technical specifications make it easy to get like for like construction quotations. Without these drawings, each builder will be to what they think should be done.
  3. PROGRAM CERTAINTY: Detailed drawings allow the builder to follow the latest regulatory requirements and implement on site. This would ensure a smooth flow of construction with minimum delay from potential holds by the building inspectors. This also reduces to a minimum the need to do changes and rework as mistakes are avoided and the client is encouraged to think and plan in advance.

What are the fees for preparing building regulations package for an extension?

Our fees for the building regulations package for an extension would vary from £700 exc VAT to £1200 exc VAT depending on the extent of our design work. The scope will cover the detailed construction drawings and specifications required by building control to document compliance with the requirements of Building Regulations. Fees vary depending on the extension shape and size and the amount of work to be undertaken. We cover all the following design activities which may not be required in all jobs – hence the fee variation.

  1. Insulation details for the floor, walls and roof. This is to comply with the enhanced accredited construction details and ensure meeting the requirements of document L (Fuel Conservation) of the Building Regulations.
  2. Acoustic performance details. Although this is more applicable to flats, we recommend that we incorporate some of the floor details to improve acoustic performance. This will reduce vibration, noise travel, improve the quality of the house and result and a higher property value.
  3. Water supply, sanitation, foul/waste water discharge, surface water drainage.
  4. Electricity and locations of switches, sockets, and cabling.
  5. Fire protection and details to comply with Fire Safety requirements in Building Regulations B.
  6. Ventilation and requirements for air-tightness.
  7. Stairs, access requirements and means of escape.

What are the fees for preparing building regulations package for a loft conversion?

Our fees for the building regulations package for a loft would vary from £700 exc VAT to £1200 exc VAT depending on the extent of our design work. The scope will cover the detailed construction drawings and specifications required by building control to document compliance with the requirements of Building Regulations. Fees vary depending on the loft shape and size and the amount of work to be undertaken. We cover all the following design activities which may not be required in all jobs – hence the fee variation.

  1. Insulation details for the floor, walls and roof. This is to comply with the enhanced accredited construction details and ensure meeting the requirements of document L (Fuel Conservation) of the Building Regulations.
  2. Acoustic performance details. Although this is more applicable to flats, we recommend that we incorporate some of the floor details to improve acoustic performance. This will reduce vibration, noise travel, improve the quality of the house and result and a higher property value.
  3. Water supply, sanitation, foul/waste water discharge, surface water drainage.
  4. Electricity and locations of switches, sockets, and cabling.
  5. Fire protection and details to comply with Fire Safety requirements in Building Regulations B.
  6. Ventilation and requirements for air-tightness.
  7. Stairs, access requirements and means of escape.

What are the most common mistakes that builders and clients should avoid when planning a project?

We are happy to share some open feedback regarding lessons learnt on previous projects we worked on. We aim to advise our clients to avoid some common mistakes being repeated. We have proudly been involved in the repair, regularization, and correction of projects that went pair-shaped. These are the hardest projects to work on and we certainly try to avoid them but at the same time we do not shy away from a challenge. To avoid such mistakes happening, we are very pleased to have a compiled a list of the most common ones.

MISTAKE 1: USING PLANNING DRAWINGS TO SELECT A BUILDER AND AGREE COSTS

Appointing a builder and agreeing a contract without having adequate structural design drawings is a very risky approach. This is because the planning drawings lack essential details that affect the price and the programme. Planning drawings lack details of foundations, ground slab, floor details, roof details, sizes of structural members, details of framing. All these details are main cost elements and can’t be accurately priced at the planning stage.

Clients need to establish the cost of their project so that they can plan their finances. To budget and plan, they start approaching builders after the planning drawings are prepared and submitted to the local authority or after permission is granted. This is fine as long as no binding agreement is made on that basis. Early engagement of the builders is a great idea. This allows clients to meet potential builders and find out about their resources and possibly see some of their previous work. It also allows builders to examine site and advise on logistics, project duration and initial cost and schedule. The clients should be aware that the only price that they could get at this stage would be a very initial estimate based on the area of the project and shape of its roof. Builders may be under pressure to give a price so that Clients can budget. However, no decisions should be made at this stage other than shortlisting suitable builders based on their resources and previous experience.

Clients may be put under pressure to pay a deposit to secure the services of a builder that they were impressed by – we strongly advise against this at the planning stage. Clients should be aware that any pricing at this stage is subject to variation by a percentage of -10% / +25%. Builders make assumptions when the details are not all given to them.

We also advise builders to be very careful at this stage. Two points must be taken into consideration, the foundation cost could vary considerably depending on the foundation depth and type AND steel installation cost is subject to structural design and sections sizes. Having all structural drawings prepared would help eliminate risks of hidden costs. It will also prompt the client to confirm what they want and avoid changes later on.

MISTAKE 2: STARTING A PROJECT WITHOUT NOTIFYING BUILDING CONTROL

This is a mistake mainly committed by Clients not experienced in this type of work (and let us face it, most Clients only do this once!). It is also committed by builders keen to start the demolition works, enabling works and clearance activities. It puts the design team under pressure, it puts the client under a risk of cost uncertainty and it puts the builder under risk of stop-start to their activities with costs of demobilizing and remobilizing.

Our suggestion would be to complete the design and notify building control well in advance. Two options are there: Full Plans route and Building Notice route. Full Plans are definitely highly recommended and they required six-eight weeks notice. The Building Notice route requires notification of 48 hours prior to start of works.

MISTAKE 3: STARTING A PROJECT WITHOUT A PARTY WALL AWARD

This is a fatal mistake. It could lead to disputes with neighbours with a risk of legal action and length battles. We have been involved in a case where this mistake delayed a simple development of three flats by a period of two years. Loss of potential income from three flats (say £3000 per month for an outer London suburt x 24 months = £76000) excluding loss of interest and legal/professional fees. Some may think that this is an extreme case of ignorance but the mistakes committed on the project are seen repeated in so many other projects:

  1. Failure to communicate with the neighbours.
  2. Failure to understand the implication of the Party Wall Act.
  3. Failure to obtain the award prior to works starting.
  4. Failure to understand the legal and financial impact of the act.

To avoid such mistakes, we encourage Clients and Builders to do the following:

  1. Communicate with the neighbours as early as possible – ideally at the planning stage to keep them informed, even if informally at this stage.
  2. Serve a Party Wall Notice when the structural design is completed.
  3. Obtain written agreement from neighbours to confirm that an award is in place.
  4. Make necessary appointments of Party Wall Surveyor(s).

MISTAKE 4: STARTING A PROJECT WITHOUT A WRITTEN CONTRACT

The contract document would protect both parties. It is true that a good contract is one that is never referred to as it means everything went smoothly and the intent of the contract was followed and all terms and conditions were discharged and acted upon by all parties. However, both parties should use this legal binding document to protect their interests. We suggest that a good contract should as a minimum include the following:

  1. Scope of the works broken down into activities and bills of quantities.
  2. Apportioning of costs according to clearly defined milestones (e.g. completion of foundations, completions of ground works and reaching DPC level, topping out, completion of second fix, release of completion certificate).
  3. An allowance for a snagging list and a mutually agreed retention for the sign off of the works.
  4. An allowance for a follow up within 6-12 months or some kind of warranty.
  5. Details of the course of action for potential dispute and resource to arbitration or third-party intervention (e.g. appointing an engineer or an architect) as an intermediary or adjudicator to resolve disputed quickly and outside court.
  6. Program of works and damage compensation in cases of delays.

What are my responsibilities as a client?

The client has a big responsibility and a great role in ensuring that their project is executed safely, legally within a reasonable time and to their budget. They can ensure that by:

  1. Budget: The Client is ultimately responsible for properly budgeting and controlling the finance for the project.
  2. Builder Competence: Appointing a competent contractor to carry out the works. Failure to do so could jeopardize the property safety, endanger lives and cause cost and schedule over-runs.
  3. Appointing suitably qualified professionals to deal with all the various design stages (Architect, Engineers, Party Wall Surveyor).
  4. Obtaining Planning Permission: The client should either obtain permits and permissions or delegate this to their Agent (the Architect/Planning Consultant). This includes the planning approval at the planning stage whether it is via the permitted development route or the full planning application route.
  5. Building Control Compliance: The client should notify building control prior to the start of the works (either from the Local Authority BC or by appointing an independent inspector).
  6. Obtaining Party Wall Aware: The client should ensure that an award is in place prior to the start of the works. Failure to do so would be a breach of the Party Wall Act that could lead to a legal dispute and to easily avoidable costs and delays.
  7. Insurance: The client has a responsibility to protect their asset during the carrying out of the building works so it is important that they inform their building insurance provider and seek suitable insurance to cover risks during the execution depending on the type of works being undertaken.

When do I need to inform the local authority about changes I plan to make in my property?

As a Client, it is very important that you understand how the planning system applies to your situation as you are responsible for making sure that the work complies with the planning requirements of your local authority. Usually, you (or your agent if this is delegated to them) have to obtain the permission of the local authority if you are changing the external appearance of your property.
The proposed changes may fall within permitted development, larger house extension or full planning application. Your planning consultant, architect or design firm should advise you on which route (if any) applies to your situation.

When do I need to inform Building Control about changes I plan to make in my property?

As a Client, it is very important that you understand how the building regulatory system applies to your situation as you are responsible for making sure that the work complies with the building regulations.

If you are employing a builder, the responsibility will usually be theirs – but you should confirm this at the very beginning. As the homeowner, it is ultimately you who may be served with an enforcement notice if the work does not comply with the regulations.

Some kinds of building projects are exempt from the regulations, however generally if you are planning to carry out ‘building work’ as defined in regulation 3 of the building regulations, then it must comply with the building regulations. This means that the regulations will probably apply if you want to:

  • Put up a new building
  • Extend or alter an existing one
  • Provide services and/or fittings in a building such as washing and sanitary facilities, hot water cylinders, foul water and rainwater drainage, replacement windows, and fuel burning appliances of any type.

The works themselves must meet the relevant technical requirements in the building regulations and they must not make other fabric, services and fittings less compliant than they were before – or dangerous. For example, the provision of replacement double-glazing must not make compliance worse in relation to means of escape, air supply for combustion appliances and their flues and ventilation for health.

They may also apply to certain changes of use of an existing building. This is because the change of use may result in the building as a whole no longer complying with the requirements which will apply to its new type of use, and so having to be up-graded to meet additional requirements specified in the regulations for which building work may also be required.

In summary, the following types of project amount to ‘building work’:

  • The erection or extension of a building
  • The installation or extension of a service or fitting which is controlled under the regulations
  • An alteration project involving work which will temporarily or permanently affect the ongoing compliance of the building, service or fitting with the requirements relating to structure, fire, or access to and use of buildings
  • The insertion of insulation into a cavity wall
  • The underpinning of the foundations of a building
  • Work affecting the thermal elements, energy status or energy performance of a building
  • Change of use of a building

When do I need to inform my neighbour about changes I plan to make in my property?

Our advice is to keep your neighbour informed throughout the various stages of your project, starting from the planning stage until completion. The advantage of this approach is to address their concerns upfront keeping delays and risk of rework and design changes to a minimum. We have been in many situations where a perceived risk by the neighbour could have been easily addressed if communication channels were open. There are stages where the communication has to be formal and adhere to the rules of the Party Wall Act.

What is the Party Wall Act and how does it affect me?

The Party Wall etc Act 1996 provides a framework for preventing and resolving disputes in relation to party walls, boundary walls and excavations near neighbouring buildings. As a Client proposing to start work covered by the Act, you must give adjoining owners notice of proposed works in the way set down in the Act. Adjoining owners can agree or disagree with what is proposed. Where they disagree, the Act provides a mechanism for resolving disputes. The Party Wall Act is separate from obtaining planning permission or building regulations approval.

The main types of party walls are:

  • a wall that stands on the lands of 2 (or more) owners and forms part of a building – this wall can be part of one building only or separate buildings belonging to different owners
  • a wall that stands on the lands of 2 owners but does not form part of a building, such as a garden wall but not including timber fences
  • a wall that is on one owner’s land but is used by 2 (or more) owners to separate their buildings

The Act also uses the expression ‘party structure’. This could be a wall or floor partition or other structure separating buildings or parts of buildings in different ownership, such as in flats.

The Act covers:

  • new building on or at the boundary of 2 properties
  • work to an existing party wall or party structure
  • excavation near to and below the foundation level of neighbouring buildings

This may include:

  • building a new wall on or at the boundary of 2 properties
  • cutting into a party wall
  • making a party wall taller, shorter or deeper
  • removing chimney breasts from a party wall
  • knocking down and rebuilding a party wall
  • digging below the foundation level of a neighbour’s property

What is the role of the Structural Engineer in providing an economic, safe and sustainable design?

The structural engineer is responsible for realizing the vision of the Client and their Architect in creating a building that is safe and economic to build, is designed considering how it will be lived in and maintained, using materials sourced locally and processes derived from best industry practices.

To achieve the above, we see that we can add real value through the following:

  • Understanding the client and architect requirements by thoroughly reviewing available documentation and meeting the Client on site.
  • Studying the site conditions carefully to establish soil conditions, existing services, trees and vegetation, drainage and slope, water level, adjacent structures and party walls.
  • Conducting a risk assessment to understand all hazards, probability of each risk materializing and methods that need to be used to eliminate health and safety risks. Where risks can’t be eliminated, methods to manage them shall be communicated clearly, formally and effectively to the contractor using the drawings.
  • Using the latest technology to develop a design that is efficient and complies with the structural codes.
  • Presenting the requirements clearly via construction drawings that details all the sizes of the structural materials, how they are connected and how they work with the building fabric and services.
  • Following up with the contractor on site to resolve any site issues.
  • Responding to any queries raised by Building Control.

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