The work
Flowing screed arrives as a liquid, is pumped into place and levels itself. There is no laying to rails, no tamping and no hand finishing across the bulk of the area. That produces a flat, dense floor far quicker than traditional sand and cement, with excellent coverage around underfloor heating pipes.
You will see the same product called liquid screed, flow screed, self-levelling screed or self-compacting screed depending on who is writing the specification. They describe the same method: a pumped, free-flowing screed that consolidates under its own weight. We use the terms interchangeably here because the market does.
Speed and cleanliness are the reasons it wins. A crew, a pump and a hose replace a barrow run and a floor full of labourers, which is what makes it viable in live and occupied buildings where a traditional screed simply cannot be programmed.
This is the comparison most estimators are actually running, so here it is straight. For the wider choice between flowing, self-compacting and traditional systems, see screeds.
Four questions set the price and the programme.
Which binder? Liquid screeds are broadly either calcium sulphate based (also called anhydrite) or cementitious. Calcium sulphate screeds flow well and are widely used, but they are moisture-sensitive, they form a surface laitance that usually has to be removed before adhered floor coverings, and they are not suitable in permanently wet areas. Cementitious flowing screeds avoid the laitance and the moisture sensitivity, and cost more. The floor covering and the room use should decide this, not the price.
Bonded, unbonded or floating? A bonded screed goes directly onto a prepared base. An unbonded screed sits on a membrane. A floating screed sits on insulation, which is the normal arrangement over underfloor heating. Each has a different minimum depth and a different consequence if the base is out of tolerance.
What is the base doing? Screed follows the base. If the deck is out of level you either add depth, which adds weight and cost, or you regulate first. Confirm the deck survey before the screed is priced, not after.
What is going on top, and when? Moisture-sensitive floor coverings drive the drying programme, and the drying programme often drives the whole fit-out. If a vinyl or resin finish is following, the screed date and the covering date are linked and both need to be real.
Hospitals cannot stop. Wards, theatres, corridors and plant rooms all need floors, and none can be handed to a screeding gang for a fortnight. Pumped liquid screed goes down fast, in a clean, contained method, phased around clinical activity. We have delivered flowing screed in an operational hospital. See healthcare flooring.
Schools, colleges and universities have hard programme constraints set by term dates and exams. A pumped screed fits a holiday window in a way a traditional screed does not. See education flooring.
Where coverage and flatness both matter over a big area, liquid screed delivers both quickly, and its cost advantage is clearest.
Precast plank and hollowcore decks are common in modern multi-storey construction, and they need a screed that levels fast and reaches every part of the deck. Our track-mounted placing booms deliver screed across upper floors without craning plant up. See screeds on precast planks.
Any UFH project is a natural fit. Full pipe encasement, thinner cover over the pipes, faster response and better efficiency. The commissioning and heat-up regime has to be planned in, because the screed cannot be force-dried until the heating is available and the manufacturer's heat-up profile is followed.
Screed surface regularity in the UK is normally specified to BS 8204, which sets three classes measured as the maximum deviation under a 2m straightedge:
| Class | Maximum deviation | Typically used for |
|---|---|---|
| SR1 | 3mm | High specification floors and demanding floor finishes |
| SR2 | 5mm | The general default for most commercial projects |
| SR3 | 10mm | Utility areas and floors taking a thick applied finish |
SR2 covers the large majority of commercial projects and, where a specification is silent, is normally what is assumed. Screed materials themselves are classified by binder type under BS EN 13813, which is what the manufacturer's declaration of performance refers to.
We survey the finished screed against the class specified and issue the results.
Our own operatives, our own pumps, our own placing booms, start to finish. Nothing about the screed package is subcontracted out.
Placing is the part that catches people out. A liquid screed is only as good as the pour that delivers it, and on constrained sites getting the material to the deck is the whole job. We run our own concrete line pumps, and two track-mounted placing booms, which are two of only three in the country. That reach is why we can screed upper decks, restricted spaces and buildings that are still in use, on projects other subcontractors decline.
Because the placing plant is ours, the method is planned as part of the works rather than bolted on. Pump positions, hose runs, boom set-up and wash-out are agreed before we mobilise.
Pumped screed covers ground quickly. The constraint is rarely the screed itself. It is usually access, delivery, the number of pump set-ups the building allows, and how much of the deck is genuinely ready.
We programme from the ready date backwards, and we will tell you at tender if the deck preparation, the insulation, the UFH installation and the edge detailing are not going to be complete when the programme says they will be. That conversation is cheaper before the pump is booked.
Live and occupied buildings are the reason most clients call us rather than a general screeder.
Phasing is agreed around the building's use, not around our convenience. Access windows, out-of-hours working, delivery routes, lift and door restrictions, noise limits and dust control all get designed into the method statement before we arrive. On healthcare and education sites that usually means working to somebody else's calendar, and we plan for it.
Restricted access is handled with plant rather than optimism. Where a pump cannot reach, the boom can. Where neither can, we will tell you at tender rather than find out on the day.
We are Constructionline Gold registered, Avetta and SSIP accredited, and a member of the Nuclear Industry Association.
FAQs
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