What Happens During a Structural Engineer's Site Visit? A Step-by-Step Guide.
If you've booked a structural engineer to visit your property - or you're about to - you might be wondering what they'll actually do when they arrive. Will they need access to every room? Will they be there for an hour or half a day? What happens after they leave?
This guide walks through what a typical structural site visit involves, how to prepare, and what you can expect to receive at the end of the process.
Why a site visit matters
Structural engineering isn't purely a desk exercise. Drawings and plans give us a starting point, but a property always has details that aren't captured on paper - the condition of existing materials, how previous alterations have been carried out, quirks in the original construction, signs of movement or deterioration that only become visible in person.
For most domestic projects - extensions, loft conversions, structural alterations, appraisals - a site visit is an essential part of the process. It's the difference between engineering that's based on the building as it actually exists, and engineering that's based on how it was assumed to be.
What we're looking at and why
The focus of a site visit depends on the nature of the project, but broadly speaking we're assessing three things:
The existing structure
We'll look at the walls, floors, roof structure and foundations as they currently are. For a proposed extension or alteration, we need to understand how the existing building is put together before we can design what's being added to it. For an appraisal, we're looking for evidence of movement, deterioration, or structural deficiency.
This often involves checking which walls are load-bearing, assessing the depth and condition of existing foundations where possible, and understanding how the building transfers loads down to the ground.
The condition of materials
Older properties in particular can have materials that don't behave in the way you'd expect from a modern building. Lime mortar, soft brick, cast iron columns, timber that has been affected by moisture - all of these affect how we design any new works, and all of them need to be seen rather than assumed.
The proposed works in context
If you're planning an extension or alteration, we'll look at the areas directly affected alongside the parts of the building that connect to them. A new opening in a wall, for example, affects not just that wall but the structure above it and the floor or foundations below. Seeing the full picture helps us design works that are both structurally sound and practical to build.
What access will be needed?
For most domestic projects, we'll need access to the areas directly involved in the works - the room where a wall is coming down, the loft space if roof structure is involved, the proposed extension footprint in the garden.
We'll also typically want to look at adjoining spaces - the rooms above and below a proposed opening, for example - to understand how loads are distributed through the building. It's worth making these areas accessible in advance where you can.
For a structural appraisal, the scope of access depends on the concern being investigated. If we're looking at cracking in a specific area, we'll focus there first - but we may want to check adjoining areas to understand whether the issue is localised or part of a wider pattern.
How long does a site visit take?
For a typical domestic project - a loft conversion, a single-story extension, a knocked-through ground floor - expect a site visit of one to two hours. More complex projects, or appraisals covering a whole building, will naturally take longer.
We'll usually let you know in advance roughly how long to allow. If access is straightforward and you've been able to clear the relevant areas, visits tend to run efficiently.
What happens after the visit?
Following the site visit, we move into the design and calculation phase. For a straightforward domestic project, this typically produces:
Structural calculations - the engineering analysis that demonstrates the proposed works are safe and compliant with building regulations
Structural drawings - plans and sections showing what is to be built, the sizes and specifications of structural elements, and any temporary works requirements
A specification:
For an appraisal, we produce a written report setting out our findings, conclusions and recommendations - including, where remediation is needed, what we'd recommend and why.
These documents go to building control as part of the approvals process, and to your builder as the basis for pricing and carrying out the work.
A few things worth doing before we arrive
Clear access to the areas we'll need to inspect - moving furniture, opening lofthatches, unlocking outbuildings
Have any existing drawings or survey reports to hand - even if they're old,they can be useful context
Make a note of anything specific you want us to look at or any questions youwant to raise - the site visit is a good opportunity to talk things through
Most site visits are straightforward. Our job is to understand the building well enough to give you reliable engineering input - and the more context you can give us, the better placed we are to do that.
Ready to book a visit?
CWT Partnership carries out structural site visits for homeowners, developers and architects across Essex, London and the surrounding areas. If you'd like to talk through what your project needs, get in touch at cwt@cwtpartnership.co.uk or call 01702 540146.
