Most homeowners never see the raw survey data, only the drawing that comes out the other end. That's fine when the survey was done properly, but it means a thin or rushed survey can travel invisibly all the way through design and into a building control submission before anyone notices something was missed.
A short list of questions, asked before design work is commissioned off the back of the survey, catches the gaps early rather than expensively.
Was the whole building actually measured?
Ask whether every room affected by the proposed works was measured directly, including height and level, or whether some dimensions were taken from an existing plan and assumed to still be accurate. It's reasonable for unaffected rooms to be measured more lightly, but anything within the footprint of the proposed work should have been walked and measured in person.
Where a loft conversion or roof alteration is planned, check that the roof void itself was entered and measured — rafter sizes, purlin positions and existing insulation depth all affect what's achievable, and none of that is visible from the garden.
Were levels recorded, not just assumed flat?
On any plot with a visible slope, a step between buildings, or a garden that clearly falls away from the house, ask to see the level readings. A design based on an assumed flat site will need reworking once real levels turn up during groundworks, usually at extra cost and always at extra delay.
Where levels were taken, check they cover the full extent of the proposed works and not just a single spot check near the house.
Were constraints written down, or just mentioned in passing?
A verbal comment on site about a tree, a shared drain, or a neighbour's overhanging structure is easy to forget by the time drawings are being produced weeks later. Ask for constraints to be listed in writing as part of the survey output, even briefly, so the designer working from it has the full picture rather than a partial memory of the visit.
This is particularly important where more than one person is involved between survey and design — the surveyor, the designer and the builder are not always the same person, and written notes are what keeps everyone working from the same facts.
Does the survey identify construction type with any confidence?
If the surveyor states the wall construction, foundation type or roof structure without having opened anything up, ask how confident that assessment is and what it's based on. On period buildings and non-traditional post-war construction in particular, a wrong assumption here can undermine a structural design produced weeks later.
Where genuine uncertainty exists, a small inspection opening before design proceeds is cheaper than discovering the real construction type once a structural engineer's calculations are already finished.
Local designations worth confirming
If the property sits in a conservation area, an Area of Outstanding Natural Beauty, or near a listed building, check that the survey notes this and records any relevant original features. Councils across Kent and East Sussex, including Ashford, Maidstone, Tunbridge Wells, Rother and Tonbridge & Malling, take these designations into account at planning stage, so the survey needs to have flagged them rather than leaving the designer to discover them independently.
Ask whether previous extensions or alterations to the property were noted, since these can affect remaining permitted development allowances regardless of what the current owner believes was done.
Common questions
Should I be present during the site survey?+
It helps. Being there means you can point out anything you already know about the building — past leaks, boundary disputes, or previous structural work — that might not be obvious from measurements alone, and you can ask questions on the spot rather than after the fact.
Can I ask to see the raw survey notes?+
Yes, and it's reasonable to ask for them, particularly on a project of any complexity. A professional surveyor or builder should be able to provide a written record of dimensions, levels and constraints, not just the finished drawing.
What if the survey turns up something the seller didn't disclose?+
Findings like undocumented previous extensions, an unrecorded shared drain, or signs of past movement should be raised with your solicitor if you're still in the buying process, and factored into the design regardless of whether they change the purchase itself.
Ask us to review a survey before you commission design work
We can look over a survey, flag any gaps, and give you a straight answer before you spend money on drawings.