General guidance only — all construction work must be overseen by a supervising engineer This handbook is compiled from standards and laws with every source cited, andis being reviewed for certification by engineers Use it to know what to look at, what to ask and what evidence to request on site It is not an engineering determination and can't replace an engineer · Terms of use · Limitations of the handbook

Structure

Ground-floor beams and slab — precast planks, cast-in-place slabs and pipes under the floor

Page code P08 · 209 inspection criteria · 24 illustrations

The ground floor of a house can be built with two systems: precast planks laid on beams, or a cast-in-place slab on grade. Both are called a “floor”, but the steps, the moments you can inspect and the mistakes that can't be fixed are completely different. Precast planks cover…

This page contains
Precast plank floor sequence — eight steps in a few days
Before laying the planks — beam tops must be level and pipes must be finished
Bearing length on beams, notching planks and ledger beams
Precast planks — inspect once laid, before the topping is poured
Propping under the slab — planks carry themselves but not wet concrete
Lock bars, wire mesh, spacer blocks and mortar pads
Plank ends and joints between planks — steel you must see before the topping is poured
Topping pour day and curing the slab
Before the first bar is laid — beam string lines, and the hold point people often skip
Steel not yet tied — the steel stack, hooks and cranking bars through the column core
Tied beams — six things you can see with the naked eye, and the cover people often get wrong
Photos that count as evidence — a whiteboard with the grid line
Top steel and bottom steel — different jobs, different positions
Beam stirrups and cover
Pipes that must pass through beams — holes to plan in advance, not drill afterwards
Cast-in-place slab on grade — another system, nothing like precast planks
Sanitary pipes under the floor — work that can never be repaired for the life of the house
Pipes coming up through the slab — holes that cut the steel, and the steel that must replace it
Soil, sand and lean concrete — formwork that can't be removed
Tying the steel for a cast-in-place slab — spacers, bar chairs and hooks
Pouring day for a cast-in-place slab — what must be ready before the first truck arrives
Slab on grade — work for which Thai standards give no figures
Permitted tolerances for beams and slabs
Photos and videos of the floor work

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