Two jobs go by the same name and they are not close in price. Taking out a stud partition is a day's work for a builder and a skip. Taking out a load bearing wall means a steel beam, a structural calculation, temporary support while the wall comes down, padstones at each end and a building control sign off. The first question is therefore never what it costs but which of the two you have, and that is answered by a structural engineer rather than by a builder's opinion on the day.
Telling a load bearing wall from a partition
The reliable signals are structural rather than visual: a wall that runs at right angles to the floor joists above, one that sits directly over another wall on the floor below, and one that continues through to the roof, are all likely to be carrying load. Thickness and whether it sounds hollow are weaker signals and mislead people regularly, because a solid block partition can carry nothing and a slim wall can carry a great deal. Nothing here is a substitute for an engineer looking at it, which is the point of the next section.
Why the engineer is the cheapest line in the job
A structural engineer specifies the beam, the bearing at each end and the padstones, and issues calculations that building control accepts. That fee is a small fraction of the total and it is what makes the rest of the work quotable: without it a builder is guessing at a beam size, and a beam that is guessed at is either dangerously light or needlessly expensive. It is also the document that a buyer's surveyor will ask for later, and its absence is a familiar reason for a sale to stall.
What the work actually involves
Temporary support, called propping or needling, holds the structure above while the wall is removed, and it is a real cost that some quotes omit. The beam goes in, bears onto padstones, and is then fire protected. Services buried in the wall have to be diverted before anything comes down, which on a wall carrying a consumer unit or a soil pipe is the part that dictates the programme. Then the making good: the ceiling, the floor across the old line, the skirtings and the decoration, which together are frequently more than the structural work.
Building control, and what to keep
Removing a load bearing wall is notifiable work. The route is either a building notice or full plans, and it ends in a completion certificate that is worth as much as the beam itself when you come to sell. Keep the engineer's calculations with it. A partition removal is usually not notifiable, but if the wall was doing anything at all, including bracing, the safe assumption is that it was and the check costs very little.
Other questions people ask
How do I know if a wall is load bearing?
The useful indicators are that it runs at right angles to the joists above, sits over another wall below, or continues to the roof. None of these is conclusive, and thickness and a hollow sound mislead people constantly. A structural engineer settles it in one visit and that visit is cheap relative to the consequences of being wrong.
Do I need building regulations to remove an internal wall?
For a load bearing wall, yes: it is notifiable work and ends in a completion certificate. For a non structural partition, usually not, though anything that affects fire separation, means of escape or ventilation can bring it back into scope.
Why do quotes for the same wall differ so much?
Usually because one has priced temporary support, service diversions and making good and the other has priced the beam and the labour. The structural part is rarely where the difference sits; the propping, the diverted services and the ceiling and floor repairs are.
Can a builder tell me the beam size?
They should not. The beam is specified from a calculation by a structural engineer against the loads actually above it, and building control expects that calculation. A size offered from experience without one is a guess, and it is guessing in the direction of something holding your house up.