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NBS SPECIFICATION CLAUSE
SECTION M13 - Calcium Sulphate Flowing Screeds
SECTION M1O - Cementitious Flowing Screeds
This specification is designed to encompass Clauses 110, 115, 120, 130, 140, 160 within Section M10 of the NBS specification for cement based screeds.
Ecoscreed Rapid Drying Flowing Screed Laid Unbonded Floating
PROPRIETARY FLOWING CEMENTITIOUS SCREED
GENERALLY / PREPARATION |
| Base: |
Precast Slabs – (min 150mm, 300kg/m2) |
| Construction: |
Floating as Clause 290 |
| |
220 - SUITABILITY OF BASES
Before starting work ensure that:
Bases are sufficiently regular to permit specified levels and surface regularity of finished surfaces, bearing in mind the permissible
minimum and maximum thicknesses of the screed.
There is a suitable Damp Proof Membrane provided above or
below the base where deemed necessary.
Remove any projections that may puncture the separating layer
260 – FLOATING CONSTRUCTION
OVER INSULATION & POLYTHENE
Minimum screed thickness to be 35mm
Lay insulation with tight butt joints and tape all joints.
Fix 5mm border edging strip to all walls.
Lay screed over single sheet polythene not less than 500 guage. Edges to be overlapped a minimum of 100mm.
Use unfolded polythene on rolls (folds can act as crack inducers).
Tape all overlapped polythene edges except at border edge.
OVER UNDERFLOOR HEATING
Minimum screed thickness of 30mm screed cover over the top surface of the underfloor heating pipes.
Lay insulation with tight butt joints and tape all Joints.
Tape all overlapped polythene edges except at border edge.
Fix 5mm border edging strip to all walls.
Isolate the screed at all abutments with walls, columns, bases etc to the full depth of the screed using a resilient polyethylene minimum 5mm.
Note: Where a damp proof membrane is required, the polythene layer should be DPM grade, minimum 1200 guage
BATCHING // MIXING
315– MIXING
To be by dedicated volumetric truck with fixed calibrated settings thereby ensuring that the correct batching proportions of
binder and glass sand are blended and mixed with the correct
amount of water on site.
No mixing is to take place off site.
Use within the working time of the material.
Do not mix or apply at temperatures below 5oC.
340 – ADVERSE WEATHER
Prevent wind tunnelling or drafting over the product.
Maintain surface temperature above 5oC for four days after laying.
Prevent rain or water to contact the final finish.
LAYING
350/351 – SCREEDING TO FALLS OR RAMPS
This flowing screed cannot be laid to falls
355 – FLATNESS / SURFACE REGULARITY
Sudden irregularities NOT permitted
Dapple screed twice in perpendicular directions
Deviation of the surface to be measured from underside of a 3m
straightedge (between points of contact), placed anywhere on the surface using a slip gauge to BS 8204 – 1 or 2 (or equivalent).
SR1 : 3mm under a 3metre straightedge
SR2 : 5mm under a 3 metre straightedge
(Note: Insistence on very close tolerances may result in high costs. Therefore it is recommended that the standard surface regularity be chosen as SR2 as defined in Table 2 of both BS 8203 and BS 8204)
405 / 406 JOINTS & BAY JOINTS
Lay continuously using wet screed between strips or bays.
Minimise defined joints Length : Breadth ratio max 3:2
Daywork joints form with vertical edge.
Maintain structural movement joints through the screed.
Where screed is receive rigid tiles laid in bays, a saw cut should be made through approximately half of the screed depth, coincident with the bay joints of the tiles. The saw cut is to be made at the time the tiles are laid to ensure accurate positioning.
Isolate the screed at all abutments with walls, columns, bases etc to the full depth of the screed using a resilient polyethylene minimum 5mm.
NBS SPECIFICATION CLAUSE
SECTION M1O - CEMENT SCREEDS
This specification is designed to encompass Clauses 110, 115, 120, 130, 140, 160 within Section M10 of the NBS specification for cement based screeds.
Ecoscreed Rapid Drying Flowing Screed Laid Unbonded
PROPRIETARY FLOWING CEMENTITIOUS SCREED
GENERALLY / PREPARATION
|
| Base: |
Precast Slabs – (min 150mm, 300kg/m2) |
| Construction: |
Unbonded as Clause 280 Generally in accordance to BS 8204-1 |
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210 - SUITABILITY OF BASES
Before starting work ensure that:
Bases are sufficiently regular to permit specified levels and surface regularity of finished surfaces, bearing in mind the permissible
minimum and maximum thicknesses of the screed.
There is a suitable Damp Proof Membrane provided above or
below the base where deemed necessary.
Remove any projections that may puncture the separating layer.
280 – UNBONDED CONSTRUCTION
>Minimum thickness of 30mm.
Fix 5mm border edging strip to all walls.
Lay screed over single sheet polythene not less.
Than 500 guage. Edges to be overlapped a minimum of 100mm.
Use unfolded polythene on rolls (folds can act as crack inducers).
Tape all overlapped polythene edges except at border edge.
Isolate the screed at all abutments with walls, columns, bases etc to the full depth of the screed using a resilient polyethylene minimum 5mm. |
BATCHING // MIXING
|
|
330 – MIXING
To be by dedicated volumetric truck with fixed calibrated settings thereby ensuring that the correct batching proportions of
binder and glass sand are blended and mixed with the
correct amount of water on site.
No mixing is to take place off site.
Use within the working time of the material.
Do not mix or apply at temperatures below 5oC
340 – ADVERSE WEATHER
Prevent wind tunnelling or drafting over the product.
Maintain surface temperature above 5oC for four days after laying.
Prevent rain or water to contact the final finish. |
LAYING
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350/351 – SCREEDING TO FALLS OR RAMPS
This flowing screed cannot be laid to falls
355 – FLATNESS / SURFACE REGULARITY
Sudden irregularities NOT permitted.
Dapple screed twice in perpendicular directions.
Deviation of the surface to be measured from underside of a 3m
straightedge (between points of contact), placed anywhere on the surface using a slip gauge to BS 8204 – 1 or 2 (or equivalent).
SR1 : 3mm under a 3metre straightedge
SR2 : 5mm under a 3 metre straightedge
(Note: Insistence on very close tolerances may result in high costs. Therefore it is recommended that the standard surface regularity be chosen as SR2 as defined in Table 2 of both BS 8203 and BS 8204)
|
405 / 406 JOINTS & BAY JOINTS
Lay continuously using wet screed between strips or bays.
Minimise defined joints Length : Breadth ratio max 3:2
Daywork joints form with vertical edge.
Maintain structural movement joints through the screed.
Where screed is receive rigid tiles laid in bays, a saw cut should be made through approximately half of the screed depth, coincident with the bay joints of the tiles. The saw cut is to be made at the time the tiles are laid to ensure accurate positioning.
Isolate the screed at all abutments with walls, columns, bases etc to the full depth of the screed using a resilient polyethylene minimum 5mm. |
NBS SPECIFICATION CLAUSE
SECTION M1O - CEMENT SCREEDS
This specification is designed to encompass Clauses 110, 115, 120, 130, 140, 160 within Section M10 of the NBS specification for cement based screeds.
Ecoscreed Rapid Drying Flowing Screed Laid Bonded In Direct Contact
PROPRIETARY FLOWING CEMENTITIOUS SCREED
GENERALLY / PREPARATION
|
| Base: |
Precast Slabs – (min 150mm, 300kg/m2) |
| Construction: |
Bonded as Clause 260 Generally in accordance to BS 8204-1 |
210 - SUITABILITY OF BASES
Before starting work ensure that:
Bases are sufficiently regular to permit specified levels and surface regularity of finished surfaces, bearing in mind the permissible
minimum and maximum thicknesses of the screed.
There is a suitable Damp Proof Membrane provided above or
below the base where deemed necessary.
The base is of a moisture content of 5% or below.
NB. Care must be taken to grout all joints or penetrations in the
substrate as failure to do so will result in a loss of screed below.
260 – FULLY BONDED CONSTRUCTION
Substrate Preparation: Generally in accordance with BS 8204-1
Ecoscreed Rapid can be applied to dry primed surfaces that are hard, sound and free from dirt, dust, oil, grease, paint, plaster, laitance, asphalt or other contaminants which could act as a barrier to adhesion The preparation of substrates by mechanical methods such as shotblasting , scabbling or diamond grinding are considered the most effective means of providing a suitable mechanical key. On direct to earth concrete floors ensure that a suitable damp proof membrane is installed via either a suitable intact polythene DPM under the main slab or by using Ecoscreed Epoxy DPM fully blinded with 14/25 sand over the substrate.
Bonding / Priming:
Priming of the prepared surface should be carried out using a minimum of two coats of Ecoscreed Primer AP1000 applied using a soft broom and ensuring that any ponding of primer or puddles are fully brushed out and dry prior to screeding. DO NOT USE ROLLERS.
First coat: 1 part primer to 3 parts water (allow to fully dry ie 2 - 3 hours)
Second coat: 1 part primer to 1 part water (allow to dry overnight)
Particularly absorbent substrates may require a further coat to prevent air bubbling in the final finish. A priming trial is recommended
Thickness:
Minimum 20mm - Maximum 50
BATCHING // MIXING
330 – MIXING
To be by dedicated volumetric truck with fixed calibrated settings thereby ensuring that the correct batching proportions of binder and glass sand are blended and mixed with the correct
amount of water on site.
No mixing is to take place off site.
Use within the working time of the material.
Do not mix or apply at temperatures below 5oC
340 – ADVERSE WEATHER
Prevent wind tunnelling or drafting over the product.
Maintain surface temperature above 5oC for four days after laying.
Prevent rain or water to contact the final finish.
LAYING
350/351 – SCREEDING TO FALLS OR RAMPS
This flowing screed cannot be laid to falls
355 – FLATNESS / SURFACE REGULARITY
Sudden irregularities NOT permitted
Dapple screed twice in perpendicular directions
Deviation of the surface to be measured from underside of a 3m
straightedge (between points of contact), placed anywhere on the surface using a slip gauge to BS 8204 – 1 or 2 (or equivalent).
ZR1 : 3mm under a 3metre straightedge
SR2 : 5mm under a 3 metre straightedge
(Note: Insistence on very close tolerances may result in high costs. Therefore it is recommended that the standard surface regularity be chosen as SR2 as defined in Table 2 of both BS 8203 and BS 8204)
405 / 406 JOINTS & BAY JOINTS
Lay continuously using wet screed between strips or bays.
Minimise defined joints Length : Breadth ratio max 3:2
Day-work joints form with vertical edge
Maintain structural movement joints through the screed.
Where screed is receive rigid tiles laid in bays, a saw cut should be made through approximately half of the screed depth, coincident with the bay joints of the tiles. The saw cut is to be made at the time the tiles are laid to ensure accurate positioning.
Isolate the screed at all abutments with walls, columns, bases etc to the full depth of the screed using a resilient polyethylene minimum 5mm. |
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