Structural Engineering

A structural engineer works out how a building carries its own weight and everything acting on it: the loads from floors and roofs, the wind on its faces, and the way those forces travel down to the ground. On a project that means choosing the frame, sizing every member and connection, and issuing the drawings and calculations a builder works to and a building control officer signs off.

In practice, yes. An extension changes how the existing house carries load, and any new opening, beam, foundation or roof needs designing. A planning application is usually made with structural drawings behind it, and an extension over 45 m² needs a Certificate of Compliance on Completion unless the owner opts out, so the engineer is involved from the first sketch rather than called in at the end.

It should not be. Removing a load bearing wall transfers everything above it onto a new beam, and that beam has to be sized for the load, sat on padstones that can take the bearing, and checked against what is underneath it. Doing it without calculations risks cracking, deflection and, at worst, collapse, and it leaves the work uncertifiable when the house is sold.

It depends on the work, and it is quoted rather than priced off a list. A report or a survey is normally a fixed fee, because the scope is a single visit and a document. Design work on a new build or an extension is quoted against the size and complexity of the frame, sometimes as a share of the build cost. Ask for a fixed quote against a written scope so the two can be compared.

The visit itself is usually a matter of hours. The written report follows within a few working days for a house, longer where the structure has to be opened up, monitored over time, or analysed before an opinion can be given. Where a report is needed for a sale or a mortgage, the date it is needed by is worth saying at the outset.

They are two halves of the same job. The survey is the inspection: what is looked at, opened up and measured on site. The report is what comes out of it, the written record of the condition, the cause of anything found, and what should be done about it. Clients use the words interchangeably, and what is actually being bought is the report.

It is a written opinion from a qualified engineer that completed works substantially comply with planning permission and the Building Regulations. It is asked for when a house is being sold or remortgaged and no Certificate of Compliance exists for work already done, such as an old extension or attic conversion. Without one, a solicitor or a lender can hold up the sale.

Where hand methods stop being reliable: flat slabs on an irregular grid, transfer slabs, large openings, punching around columns, and walls that act as deep beams. We model in SCIA Engineer and check the results by hand, because a model is only as good as its supports and its mesh, and a peak at a support is not a number to reinforce for.

A chartered engineer or another qualified certifier. New work is certified on completion against the permission and the Building Regulations; work already standing is dealt with by an opinion on its compliance. Either way the certifier has to be professionally indemnified, which is what makes the document worth anything to the lender relying on it.

It is worth having one before you sign the contract, particularly on an older house, an extended one or one with visible cracking. A mortgage valuation is not a survey: it tells the lender what the house is worth, not what is wrong with it. A structural survey looks at the frame, the walls, the roof and the signs of movement, and the report says what was found, what it means and what should be done about it, while the price can still be talked about.

Most are not. Fine cracks in plaster from shrinkage or temperature are common in any house and are a decorating job. The ones worth an engineer's visit are cracks that are wider at one end than the other, that step through the brickwork, that come back after being filled, or that arrive with doors and windows starting to stick. An inspection finds the cause, and the cause is what decides whether the answer is filler, monitoring or a repair.

Subsidence is the ground under a building moving down, and taking part of the building with it. A subsidence report sets out whether that is what is happening or whether the cracking has another cause, such as settlement of a new extension, roots, a leaking drain or the house itself. Insurers usually want an engineer's report on the cause before they decide a claim, and the same report tells you what the repair has to be.