Roof slab casting checklist: what to check before, during and after the pour

Before the pour: formwork

• Shuttering level and at the right height; props on firm ground, braced and evenly spaced
• Joints tight, so cement slurry doesn’t leak out
• Formwork clean and oiled, with no wood chips, wire or standing water
• Openings for stairs, ducts and skylights in the right place

Before the pour: steel

• Bar sizes and spacing as in the structural drawing
• Laps as long as the drawing specifies, and staggered
• Cover blocks under the bottom bars and at the edges, at the cover in the drawing (often about 20 to 25 mm for slabs)
• Top bars held up on chairs so they are not pressed down
• Steel clean: no mud, oil or loose rust
• Beam and column steel tied in as drawn

Before the pour: services

• Electrical conduits and boxes fixed, joints taped
• Sleeves for plumbing and drainage through the slab
• Fan hooks and anchor points in place
• Everything photographed, because it will soon be covered

During the pour

• The mix as specified (for example 1:2:4, or a ready-mix grade), with no extra water added to make it flow
• Concrete vibrated, especially around the steel and at beam joints
• Poured continuously, without long stops that leave cold joints
• Thickness checked across the slab
• Test cubes taken, if your engineer asks for them

After the pour: curing

• Once the surface has set, keep the slab wet for at least 7 days, longer in hot, dry weather
• Make small mortar ponds and keep them filled, or cover the slab with wet hessian
• No heavy loads or stacked material on the new slab
• Leave the props until your engineer says they can be removed

How Buildiary does this

Buildiary’s inspections turn a checklist like this into a few taps on site, with a photo for each check. Problems become snags with a person and a due date, and the owner sees the result before the pour goes ahead.