Questions to Ask a Structural Engineer
Twenty questions for a homeowner or small builder hiring a structural engineer, whether the job is removing a wall, adding a storey, or making sense of cracks. They cover what the fee actually buys, what can only be known once the structure is opened up, and the records you should end up holding.
The questions
Open any question for the note
What will I have at the end of this, and what does the fee cover?
Why ask it
Structural work is sold as a service and delivered as documents, so ask which documents. Calculations, a drawing a builder can work from, a letter for the approving authority and site visits are often priced separately. Vagueness here is the usual cause of a second invoice you were not expecting.
Will you visit the property yourself?
Why ask it
Some fees cover a desk exercise based on photographs and a builder's sketch, which is reasonable for simple work and inadequate for anything unusual. If someone else does the visit, ask who signs the calculations, because the person taking responsibility should be the person who saw the building.
What qualifications do you hold, and do you carry professional indemnity insurance?
Why ask it
The insurance question matters more than most people realise: if calculations turn out to be wrong after the walls are closed, that policy is the only practical route to putting it right. Ask for the certificate rather than a reassurance, and check it is current.
Have you worked on a building of this age and construction before?
Why ask it
Older buildings behave differently from modern framed ones, and an engineer used to new build may over-specify or misread existing movement. What you want is a specific comparable project, ideally nearby. General experience with houses is not the same answer.
What do you need from me before you can start?
Why ask it
Usually a measured plan, access to the relevant rooms, any past survey, and a clear statement of what you want to achieve. Getting this list early prevents the common delay where the engineer is waiting on you while you assume the work is progressing.
What can you tell from today's visit, and what will only be known once things are opened up?
Why ask it
Honest engineers draw this line clearly, because foundations, beam bearings and hidden decay cannot be seen through a finished wall. An answer with no caveats at all is a warning; so is an answer that is entirely caveats and offers no working assumption.
Is this wall carrying load, and how will you confirm that rather than assume it?
Why ask it
The confirmation method is the substance of the answer: looking at floor joist direction, checking the storey above, opening a small hole, comparing to original drawings. Anyone who decides from the room alone without looking upstairs is guessing, and this is the guess that brings ceilings down.
What is carrying the load now, and what would carry it afterwards?
Why ask it
Asking for the load path in plain words tells you whether the design has been thought through to the ground. It also surfaces the part homeowners rarely anticipate: that a new beam concentrates weight onto two points which may themselves need new padstones or foundations.
Do the foundations need attention, and how would you find out?
Why ask it
The answer usually involves a trial hole, which costs money and is the single most common thing people decline and later regret. Ask what it would cost, and what the risk is of proceeding without it, so you are making the decision rather than avoiding it.
Are these cracks something to act on now or something to monitor?
Why ask it
Most cracks in most houses are not urgent, and a good engineer will say so plainly rather than generating work. If monitoring is the recommendation, ask what would be measured, over how long, and what change would trigger action, so the advice is checkable rather than open ended.
What are the options here, from the cheapest that works to the most robust?
Why ask it
There is almost always more than one solution, and the differences are in disruption, headroom lost, and how much future flexibility you keep. Ask what the cheap option gives up. If only one option is offered, ask what the others would have been and why they were ruled out.
What does your design mean for the builder's programme?
Why ask it
Steel is fabricated to order and can take weeks, temporary support has to be designed and hired, and some sequences require an inspection before covering up. Knowing this at design stage prevents the standard argument in which the builder blames the engineer for a delay nobody scheduled.
Who orders the steel, and who checks it matches the drawing when it arrives?
Why ask it
This responsibility falls between the parties more often than any other. Beams get substituted for what the supplier had in stock, and a section that is one size down looks identical to everyone except the person with the calculations. Establish now who does that check.
Will you inspect the work before it is covered up, and how many visits are included?
Why ask it
Once plasterboard is on, verification means taking it off again. Ask which stages they want to see, whether those visits are in the fee, and what a further visit costs. Fixed-fee designs with no site visits are common and you should know that is what you bought.
If the builder wants to change something on site, who decides and how quickly can you respond?
Why ask it
Site changes happen weekly and stopped work is expensive, so response time has real value. Ask for a realistic turnaround for a photo and a question, and whether verbal approval will be followed up in writing. Undocumented changes are the ones that fail an inspection later.
What paperwork will I need at the end, and what should I keep?
Why ask it
Calculations, final drawings, any inspection notes and the sign-off from the approving authority all matter when you sell the property or claim on insurance. Ask what gets issued and in what form. Missing structural paperwork routinely delays sales years afterwards.
What could you find that would change the cost or the scope significantly?
Why ask it
Experienced engineers can list them: inadequate existing foundations, a beam bearing on nothing solid, decay at joist ends, a wall that turns out to be carrying more than expected. Hearing the list now lets you hold a contingency rather than discover the need for one mid-project.
If I did nothing for a year, what would happen?
Why ask it
For a problem you are already living with, this converts a worry into a timescale. Some answers are genuinely that nothing will change, which is worth paying to hear. Others come with a condition to watch for, and knowing the specific sign is more use than a general instruction to keep an eye on it.
Where do you and my builder disagree about this?
Why ask it
Builders and engineers often hold different views on temporary support, sequencing or how much steel is needed, and the disagreement usually reaches you as delay rather than as a discussion. Asking directly puts it on the table while it is still a design question.
If this were your own house, what would you do?
Why ask it
Invites the judgment behind the recommendation, which the formal report will not contain. Many engineers answer candidly, sometimes advising a simpler scheme than the one you asked about. Note whether the answer differs from their written advice, and ask why if it does.
Working with a structural engineer
Practical guidance for the conversation itself
Getting the engagement right
Engage before the layout is fixed
Bringing an engineer in after plans are drawn means fitting structure around decisions already made, which is how you end up with a beam in an awkward place or a column in the middle of a room. An hour of advice early usually changes the design cheaply.
Keep the engineer independent of the builder
An engineer recommended by and paid through your contractor has a relationship to protect. That is often fine, but if a disagreement arises about workmanship you will want advice that is answerable to you.
Get the scope in writing before work starts
A short letter listing the deliverables, the number of site visits and the hourly rate for anything extra prevents most fee disputes. Ask for it as a matter of course; professionals expect the request.
Know which professional you need
A structural engineer designs and assesses structure. A surveyor reports on the condition of a property. If you are buying and worried about movement, you may need both, and asking one to do the other's job produces a report that answers the wrong question.
On the site visit
- Send photographs, any existing drawings and a plain description of what you want to change before the visit, so the time is spent on the difficult parts.
- Have the relevant spaces accessible: loft hatch clear, furniture moved from the wall in question, and the room above open too.
- Walk the outside as well as the inside. Ground levels, drainage, trees near foundations and neighbouring extensions all affect what the engineer will recommend.
- Write down what was said the same day and email a short summary back. Verbal advice on site is where most of the useful information is, and it is not in the report.
- Ask for a rough cost band before the detailed design if budget is the constraint. Most engineers can tell you early whether a scheme is affordable in principle.
Common mistakes
Buying calculations and nothing else
The cheapest quote is often calculations only, with no site visit, no inspection and no availability when the builder hits something unexpected. That is a legitimate product, but it is not the same as having an engineer on your project.
Skipping the trial hole to save money
Foundations are the one thing that cannot be assessed from above ground and the one thing that is ruinous to get wrong. If it is declined, record that decision and the reason in writing.
Letting the builder change the design informally
Substituted beams, altered bearings and skipped padstones are usually well intentioned and occasionally serious. Any change to the structural drawing goes back to the engineer in writing, however small it seems.
Closing up before inspection
If a stage was meant to be seen, arrange the visit before plastering rather than after. Opening finished work to prove compliance costs far more than the visit would have.