Page 368 - McD_6118-AEW-XX-XX-NBS-A-001_Neat

382 STAIR SCREEDS
• Construction: Fully bonded to treads, risers and landings.
• Risers: Form using fine finish formwork.
• Wearing screed surfaces: Make good with compatible cement:sand mix. Wood
float. When hardened remove laitance.

392 GENERAL REINFORCEMENT
• Steel fabric: To BS 4483.
- Type: as table A.1 and BS 8204-1 clause 5.7.
• Installation: In accordance with BS 8204-1.

395 STRIP REINFORCEMENT
• Location: Across day joints.
• Steel fabric: To BS 4483.
- Type: as table A.1 and BS 8204-1 clause 5.7.
- Width of strips: site specific.
• Installation: Place between the two layers of screed and centre over joints. Lap
ends minimum of 100 mm.

405 JOINTS IN LEVELLING SCREEDS GENERALLY
• Laying screeds: Lay continuously using 'wet screeds' between strips or bays.
Minimize defined joints.
• Daywork joints: Form with vertical edge.

415 BAY JOINTS IN BONDED WEARING SCREEDS
• Bay sizes:
- Area (maximum): 15 m².
- Length:breadth ratio (maximum): 3:2.
• Location of bay joints: Over construction/ movement joints in substrate slab.

435 FORMED JOINTS IN WEARING SCREEDS
• Temporary forms: Square edged with a steel top surface and in good condition.
• Placing screed: Compact thoroughly at edges to give level, closely abutted joints
with no lipping.

445 CRACK INDUCING GROOVES IN WEARING SCREEDS
• Groove dimensions:
- Depth: At least half the depth of wearing screed.
- Width: As narrow as possible.
• Cutting grooves: Straight, vertical and accurately positioned. Saw cut sufficiently
early after laying to prevent random cracking.

460 STRIP MOVEMENT JOINTSas required
• Manufacturer: Contractor's choice.
- Product reference: Contractor's choice.
- Size: site specific.
• Installation: Set securely into screed to exact finished level of floor. Extend joints
through to substrate.
- Secure fixing to substrate: To manufacturer's recommendation.

RotF generic (intermediate) NBS 2014 6118-AEW-XX-XX-NBS-A-01