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Screeds

Self-compacting screed.

Screed systems that place and level without power floating or late working, keeping the method clean and the programme tight.

The work

No late working, no power floating

Self-compacting screed flows and consolidates under its own weight, so there is no need for the late power floating that traditional methods demand. That removes evening and night working on many sites.

The material is pumped into place, spread and levelled, and then left. No finishing crew has to come back at nine in the evening when the surface has stiffened enough to work. On a site with restricted hours, that single fact is often the difference between a method that is permitted and one that is not.

It is a strong fit for live environments where the method has to be clean and predictable, and for upper decks where getting a finishing gang and their plant back onto the floor late in the day is an access problem in its own right.

On site

One visit, one crew, one shift.

Fresh screed placed across a steel-frame upper deck.

The problem

The problem this actually solves

Power floating a screeded deck is a two-stage job separated by hours. The screed goes down in the morning, the surface becomes workable in the late afternoon or evening, and it has to be floated then, not the next day. That means a crew on site into the evening, plant on the deck, lighting, and a site that stays open.

Plenty of buildings will not allow that. Hospitals, schools, occupied offices, secure facilities and sites in residential areas all have restricted working hours, and a method that needs a night shift either gets refused or gets priced with the cost of arguing for it. Self-compacting systems remove the second stage entirely: one visit, one crew, one shift, finished when they leave.

Scoping

The decision you are actually making

Do the site hours permit late working?

If they do not, the choice is largely made for you. If they do, the comparison is genuinely open.

What surface do the follow-on trades need?

Self-compacting gives a clean, level surface for follow-on trades. Power floating gives a dense, hard-wearing surface that can be trafficked directly. Both achieve the specified tolerances when carried out properly.

Is it a screed or a structural topping?

Self-compacting is used both as a screed over a deck and as a topping on precast units. The depth, the bond and the specification differ.

What is the deck?

On precast plank and hollowcore, self-compacting works well and avoids the access difficulty of returning plant to an upper floor. See screeds on precast planks.

What is going on top, and when?

Drying to the moisture content the floor covering requires is a programme item, the same as with any pumped screed, and should be planned rather than assumed.

The comparison

Self-compacting versus power floated

These are not competing versions of the same thing. One removes late working on a screeded deck; the other produces a dense, hard-wearing industrial floor that takes traffic directly. We deliver both, so there is no incentive here to push you either way.

  • Choose self-compacting where the surface is a base for a floor covering, where site hours are restricted, where the deck is at height, or where a clean, predictable single-visit method matters more than surface hardness.
  • Go for power floated where the concrete is the finished floor, where forklifts and racking loads run on it directly, and where abrasion resistance is the point. See power floated floors.
  • The full comparison, with the trade-offs set out properly, is at self-compacting versus power floated.

Standards

Tolerances and standards

Screed surface regularity is normally specified to BS 8204, measured as the maximum deviation under a 2m straightedge:

ClassMaximum deviationTypically used for
SR13mmHigh specification floors and demanding floor finishes
SR25mmThe general default for most commercial projects
SR310mmUtility areas and floors taking a thick applied finish

SR2 covers most commercial work and is normally assumed where a specification is silent. Screed materials are separately classified by binder type under BS EN 13813.

Self-compacting systems achieve these tolerances consistently when the deck is prepared correctly and the pour is properly set out. Consolidation under self-weight removes the operator variability that hand finishing introduces, which is one of the quieter arguments for the method. We survey the finished screed against the class specified and issue the results.

Precast hollowcore plank upper deck before a screed pour

Capability

Plant and crews, self-delivered

Our own operatives, our own pumps, our own placing booms.

Placing is the part that decides whether this method works on a difficult site. We run our own concrete line pumps and two track-mounted placing booms, which are two of only three in the country. They deliver screed across upper decks and into restricted spaces without craning plant up.

That combination is the reason the method holds together. A self-compacting system removes the need to return to the floor late in the day, and our placing plant removes the need to get plant up there in the first place. Together they make an upper deck in an occupied building a normal job rather than an exceptional one.

Programme

Output, programme and constraints

Pumped self-compacting screed covers ground quickly, and because there is no second finishing visit the programme is simpler to hold: one shift per area, and the area is done. The constraint is usually the deck rather than the screed, so we programme from the ready date backwards and tell you at tender if the preparation will not be complete when the programme says.

  • Restricted site hours. The main reason clients choose this method. No power floating means no evening or night shift.
  • Occupied buildings. Clean, contained, single-visit work in hospitals, schools and operational facilities. See healthcare flooring.
  • Upper decks. Placing booms deliver screed at height, and self-compacting removes the need to bring finishing plant back up later.
  • Phased programmes. Screed delivered in sections around other trades, with day joints designed to suit.
  • Sites with noise or access limits. A single pumped visit is easier to fit into a constrained window than a two-stage operation with a gap in the middle.

Proof

Evidence and documentation

  • Surface regularity survey against the specified BS 8204 class
  • Delivery tickets and batch records
  • Pour records: area, depth, date and conditions
  • Manufacturer's declaration of performance for the system installed
  • Moisture readings before floor coverings where we are asked to take them
  • RAMS issued and agreed before mobilisation
  • Sign-off pack at handover

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FAQs

Common questions

What is the advantage of self-compacting screed?
It consolidates under its own weight, so there is no power floating and no late or night working on site. One visit, one crew, one shift.
When would I choose it over power floated concrete?
Self-compacting suits a clean, fast screed on a deck, particularly where site hours are restricted or the deck is at height. Power floated suits a hard-wearing industrial floor surface taking traffic directly. We advise which fits.
Does it work on precast decks?
Yes. It is a strong fit for precast plank and hollowcore upper floors, where returning finishing plant to the deck late in the day is an access problem.
Does it really remove night working?
On most projects, yes. That is the main commercial reason it gets specified. Where a project still requires late working for other reasons, we will say so.
What tolerance can it achieve?
The BS 8204 surface regularity class the specification names, surveyed and recorded. Self-compacting achieves the specified tolerances consistently when the deck is prepared and the pour is set out properly.
Is the surface hard enough to traffic?
It is a screed, not an industrial floor. It gives a clean, level surface for follow-on trades and floor coverings. If the concrete is the finished trafficked floor, you want a power floated slab instead.

Got a flooring or screed project coming up?

Send us the drawings and the specification, and we'll tell you straight whether we can deliver it, and how.

Discuss your project