A capital taken back flush with the underside of the slab, with the floor above carried on back-propping throughout.
Structure: Multi-level concrete building under major structural modification
A live, fully propped structure with a tower crane overhead. Two structural elements had to come out precisely, flush to the soffit, without touching the retained slabs. Controlled sawing did the precision work and handed the head contractor a clean, safe removal sequence.
Scope 1: column capitals chased in a 200 mm grid
The design required the flared column capitals to come back flush with the underside of the slab. Breaking them out blind was never an option on a structure that had to stay standing. Instead, a wall saw was mounted inverted against the soffit and each capital was chased in a 200 millimetre grid. That turned a solid mass of reinforced concrete into controlled sections the demolition crew could pop out cleanly, leaving an accurate flush finish with no overcut into the slab. Water-fed blades kept dust and silica down on a live site.
Scope 2: beam removed flush to the soffit
A concrete beam had to come out flush with the ceiling. The slab above was fully back-propped to carry the load before any cutting began. The beam was then sectioned with track and hand saws and removed in controlled lifts. Cutting tight to the soffit line left the retained slab clean, undamaged and ready for the follow-on works.
The cut line at the beam. Reinforcement exposed cleanly, nothing beyond the line disturbed.
Steel needle beams and propping carrying the slab while the beam below came out.
Why controlled sawing beats blunt demolition here
Everything on this job was governed by what had to stay, not what had to go. The saw cuts defined exactly where concrete stopped being structure and became waste. Propping and needle beams carried the loads while the cuts were made, and the head contractor received a sequence their engineers could sign off rather than a subcontractor swinging a breaker under a live slab. This is the difference between engineered concrete cutting and demolition by force.
Related services: wire sawing and structural cutting, cutting engineering and methodologies.
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