Hi selfbuild,
+1 what Superman has said and I note the following -
The co-ordination falls to the architect who in theory pulls it all together, but there may have been mitigating circumstances centring on the complexity of the co-ordination and late calls on site.
The co-ordination in a private house is a five way split between client, architect, structural engineer and mechanical engineer/heating contractor/electrical contractor and interior designer.
The stairs section is the essential part of the tender and working drawing set because the stairs is where all these details meet plus the stairs has its own detailing.
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The setting of the structural slab levels (or joist levels at 1st floor if its in timber) works "backwards" (downwards) from the finished floor level [FFL] datums shown on the planning drawings.
The overall Floor Build Up to FFL from the structural slab on ground or first floor will include
(i) Finishes - any timber floor boards, stone or thick tiles and also
(ii) Services - UFH pipework and insulation and/or electrical service ducts.
The setting of the stairs structural level similarly works "backwards" (downwards) from any applied finish such as stone or timber treads. This is expecially important if a concrete stairs are used. The surfaces of the stairs finishes define the rise and going and must be from the finished floor surface to the finished floor datum.
So its kind of counter-intuitive - the finished floor level is an "imaginary level".
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Typical mistakes include -
- setting the 1st structural slab or joist tops at the finished floor level
- applying thick (50-100mm) floor finishes/build ups after setting the stairs tread levels
The interior designer and the client have huge input into floor and ceiling finishes.
The Mechanical and Electrical services routing tend to affect the total floor build up.
These things all need to be considered, agreed and signed off before proceeding to site.
Any late calls may require repositioning of floor structure and/or the redesign of the stairs.
That's as clear as I can make it but feel free to ask a question.
ONQ.
[broken link removed]
All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matter at hand.