- The wall
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Whether a wall carries load decides almost everything after it. A partition comes out in a day; a
load-bearing wall needs a lintel sized by someone qualified to size it, propping while the opening is
cut, and a structural opinion before any of that. Nobody can tell you which yours is from a photograph.
- The state underneath
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What is found once finishes come off governs the rest: the condition of the substrate, old openings
bricked up and forgotten, services buried in walls, floors that are not level. This is the part that
cannot be priced honestly in advance, only allowed for.
- Access
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Floor, stair width, whether there is a lift and whether it may be used for materials, where a vehicle
can stand and for how long. Access changes the cost of moving a tonne of block more than the block does.
- Whether it stays occupied
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Working around people changes the order of the work, what has to be sealed against dust, and which
hours are workable. Said at the start it is a constraint to plan around; discovered later it is a delay.
- Consents and paperwork
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Some work needs a building notification or a permit, and in a block of flats it usually needs the
housing association's agreement as well. This company is not registered for design or structural
calculations, so drawings and opinions come from whoever is qualified to issue them.
None of this is a quote. It is what a first conversation is for: establishing which of these apply, what
has to be seen on site, and what has to be settled by someone else before work can be priced at all.