When embarking on any construction project, whether building your dream home or a commercial development, one of the most crucial decisions you’ll make is selecting the right structural Engineer. A structural engineer’s expertise and guidance can significantly influence your project’s success. This guide will provide valuable insights into the considerations and factors you should consider when choosing a structural engineer.

HOW EARLY SHOULD I APPOINT A STRUCTURAL ENGINEER?

The earlier in the process that you appoint an engineer, the earlier they can influence your design proposals and provide an essential perspective on maximising efficiency and buildability.

At Allan Corfield Structures (ACS), we encourage clients to have us onboard with their build as early as possible, as this engagement allows structural considerations to be identified and incorporated at a point in the design process where changes can be accommodated more easily.

This will also reduce the likelihood of design changes post-planning/warrant submission. Value engineering opportunities will be highlighted for client consideration to give clients confidence in making informed decisions about building layouts and design features.

HOW DO I APPOINT MY STRUCTURAL ENGINEER?

Do your homework and identify structural engineers experienced in self-build design and your preferred construction method. Awareness of detailing requirements and the importance of early coordination with architecture/MVHR design can be critical to a successful project.

Send all information that you have on your project to the Engineer, including current design proposals and any survey information you may already have.

ACS are happy to arrange a pre or post-fee proposal submission telephone/video call with a prospective client to discuss client and site-specific requirements.

For ACA Clients, ACS can join early Client consultations without any obligation of appointment to provide initial insight into design considerations.

On receipt of tender returns, it is important to review the scope of works to ensure that the service proposed is like for like. For example, some engineers may provide a restricted scope, excluding items such as steel connection design or not allowing for an initial site visit.

HOW DOES ACS SPLIT THE PROJECT STAGES, AND WHAT IS THE TIMEFRAME FOR EACH STAGE?

ACS split its project stages to align with the architectural stages:

Stage 1: Site evaluation to identify site-specific considerations and prepare specifications for the site investigation. ACS will assist in appraising tender returns (1-2 weeks) and summarise findings and foundation recommendations (2-3 weeks).

Stage 2: Early design review of architectural planning drawings. Structural guidance was given to layout options and construction methods being considered. ACS provide a PDF overmark identifying anticipated structural requirements and value engineering opportunities that can be used to aid preliminary costing and inform final decision-making. (2-3 weeks)

Stage 3: This stage represents the traditional offering by Structural Engineers who normally only join the project team once architectural warrant drawings are well advanced. Scope of works includes preparing structural warrant drawings, specifications and supporting calculation packages for either submission to building control or SER Certification. (4-6 weeks)

Stage 4: SER Certification for projects in Scotland (2 weeks)

Stage 5: ACS can offer supporting specialist contractor design calculations for elements such as feature glazing, steel stairs and balustrades if not provided by the client’s preferred specialist manufacturer. (Time varies depending on design elements.)

Stage 6: ACS can provide ongoing assistance throughout your project on a time-charge basis to suit client preferences and requirements.

WHAT ELEMENTS WILL ADD TO THE COST OF MY PROJECT?

The main architectural features that will add structural complexity and cost to your project are:

– Thermal breaks are required for external structures supported by internal structures, particularly where high thermal performance requirements apply.

– If wall layouts do not align between floor levels, this can introduce additional transfer structure and complicate achieving sufficient structure stability.

– Tall, narrow structures, particularly those with limited internal walls, can only be able to stabilise by introducing steel stability frames.

– If accessibility is restricted, large/heavy structural elements to the rear of the property may necessitate crane access, significantly increasing the construction cost.

– Building location relative to site boundaries should be carefully considered to minimise the influence risk on neighbouring structures and ensure sufficient space for scaffold access and welfare facilities.

– Large spanning transfer structures can add additional cost to your project, and layouts should be adjusted where possible to avoid additional costs.

– Cantilevers are a popular design feature. Consideration needs to be given to thermal break requirements and ensuring that sufficient depth for beam backs is provided within the building (this may impact structural opening locations through internal walls.

– Careful location of plant rooms where MVHR is required. Coordination of ducting requirements with structure is critical and is complicated if the MVHR unit location needs to be carefully considered.

WHAT ARE THE MAIN SITE CONSIDERATIONS TO CONSIDER WHEN ASSESSING SITE SUITABILITY?

When looking at a site for your build, it is worth considering some of the considerations listed below. This can guide you in deciding the suitability of your site for your build type.

– Made ground can require additional testing to establish the soil classification for off-site disposal and gas protection measures.

– Depending on depth, foundations must be taken down to suitable natural bearing strata, and trench-fill foundations may be required. Piling may need to be considered at greater depths.

– High water tables may influence buildability, require dewatering during construction, and require testing to identify contamination.

– When concentrations exceed acceptable levels, remediation strategy and protection measures can be a significant additional cost before the project gets out of the ground.

– Plots should be checked to identify if they are located on a coalfield and whether a mining report is required. This will help identify the risk of subsidence and any remediation measures that may be required.

– Existing services running through the site should be identified before the commencement of the intrusive site investigations.

– Plots where clay is anticipated, and the proposed building location is within the influence of mature trees will require boreholes as part of the site investigation to determine the minimum foundation level.

– Sloping sites will likely require some level of cut and fill to site intruding retention and potential spoil that may need to be disposed of.

– Sites with variable ground conditions require additional care during construction to ensure suitability.

– Existing structures are to be removed to facilitate the development, and foundations should be fully cleared up to avoid clashes or hard spots for the proposed foundation.

DO I LEGALLY REQUIRE A STRUCTURAL ENGINEER FOR MY PROJECT?

Appointing a Structural Engineer for your project is not a legal requirement. However, we highly recommend having one on board for any project involving structural modifications, alterations, or any new construction that will impact the safety of a building.

Under CDM 2015 obligations you will need to be able to demonstrate that you have appointed the right people at the right time to support your project team and ensure building regulation requirements are achieved.

It is important to note that supporting structural calculations will be required to be submitted to Building Control in support of your application. In Scotland, Certification of Design can be provided by an SER Certified Structural Engineer.

The IStructE (The Institution of Structural Engineers) guide “Your Home Project Guide To Appointing A Structural Engineer” provides an insight into the process of identifying, assessing and appointing your Structural Engineer. As noted in the guidance, it is recommended that your Structural Engineer is a member of IStructE or are Chartered Engineers of another institution (e.g. ICE). Your chosen Engineer should be able to demonstrate their competence through qualifications and experience and provide proof of professional endemity experience.

Extract from IStructE Home Project Guide for considerations specific to alterations to existing structures:

“It should be remembered there have many instances of partial or complete collapse of buildings as a result of alterations as a result of alterations being carried out without proper or adequate structural advice. It is also worth being mindful that inappropriate alterations may invalidate a buildings insurance.”

HOW DOES THE ACS FEE PROPOSAL COMPARE TO OTHER ENGINEERS?

When considered in isolation, the ACS total fee may appear higher than other engineers. However, it is important to consider that this allows for earlier engagement and a higher level of collaboration to help you achieve a more economical design.

IF I APPOINT A SPECIALIST MANUFACTURER, HOW DOES THIS AFFECT THE ACS FEE PROPOSAL?

We collaborate closely with various specialist manufacturers. The cost for their specific work is managed directly by the manufacturer from their allocated budget for engineering design, and it’s excluded from your overall project fee. This means that we handle the core structural design aspects, ensuring a smoother process, fewer last-minute alterations, and simplified coordination, planning, and responsibility. If you have a preferred manufacturer in mind, we’ll exclude their portion of the work from our scope, but we’ll still work closely with them to ensure everything goes smoothly for your project.

Do you have any question regarding your project?

Contact us, and we will help you move on with your Self Build dream!

DOES ACS WORK ON ALL SIZES OF PROJECTS?

ACS works on projects from internal alterations to multi-plot developments and steading conversions. ACS works on new build projects of all sizes throughout the UK and will support ACA’s Swindon office with any smaller extensions in England. ACS have an office in Fife, and with engineers benefiting from the flexible working arrangement, we also have a presence in Glasgow, Edinburgh and Midlothian, allowing us to provide engineering services on smaller projects throughout the central belt.

ACS would always recommend a site visit for any projects requiring structural alterations and would therefore be unable to efficiently service smaller projects outside these areas.

SER CERTIFICATION

As a SER Certifying body, our in-house SER Certification ensures your project complies with Building (Scotland) regulations. SER Certifiers act as self-certification officers for your project’s structural design.

To certify your project, SER Certifiers require:

– Checked supporting structural calculations.

– Architectural warrant drawings.

– Structural warrant drawings.

– Depending on project size and risk category, specialist contractor design elements can be submitted after SER Certification. For instance, glazing, balustrades, balconies, piling, and steel connections.

Specialist contractor design packages needing supporting calculations are identified on the SER certificate’s Schedule 1. These are crucial for the final project sign-off as a Form Q.

DOES ACS WORK WITH EXTERNAL ARCHITECTS?

ACS work with several external architects and are happy to provide their unique architecturally enlightened brand of engineering on your project should you already have an architect on board.

Embarking on your construction journey with ACS means you have a dedicated team fully invested in realising your dreams.