---
title: Screed on Beam and Block and Hollowcore Decks
description: "What changes when the screed goes on beam and block or hollowcore: camber, joints, depth from survey and reaching upper floors without a crane."
---

[Concrete Floor and Screed Guides | Trent Construction](https://www.trentcs.com/knowledge)

# [Screed on Beam and Block and Hollowcore Decks](https://www.trentcs.com/knowledge/screed-on-beam-and-block-and-hollowcore-decks)

 Written by [Trent Construction](https://www.trentcs.com/knowledge/author/trent-construction) | Oct 3, 2026, 8:43:21 AM

## Same family, different jobs

Beam and block and hollowcore are both precast floors, and both end up under a screed. From the screeder's side of the pour they are different jobs, and pricing them as if they were the same is how a tender ends up carrying somebody else's risk.

**Beam and block** is prestressed concrete beams with infill blocks between them, typical on ground floors of housing, schools and smaller commercial buildings. **Hollowcore planks** are wide prestressed units with continuous voids, craned in to span whole rooms, typical on upper floors of teaching blocks, student accommodation, apartments and hospitals.

## What changes on a beam and block floor

- **The surface is stepped.** Beams and blocks sit at slightly different levels, so the screed depth varies across every bay. Minimum depth applies at the high point, not the average, and the volume calculation has to respect that.
- **Insulation usually sits on top.** Most beam and block ground floors take rigid insulation under the screed, which means a floating screed with its own minimum depths, a continuous layer with taped joints, and a perimeter upstand done properly.
- **Grouting comes first.** The beam and block surface needs brushing with grout before insulation or screed goes anywhere near it. A pumped liquid screed will find every gap that has been left.

## What changes on a hollowcore deck

- **Camber is designed in.** Prestressed planks arrive with an upward camber and deflect under load. A screed laid to a nominal depth across a cambered deck will be thin at midspan and thick at the ends, or it will not be level. The depth range has to come from a level survey of the actual deck.
- **Weight is not a free variable.** Every extra millimetre of screed is load on a frame designed to a number. Thin pumped screeds set from the survey are preferred over thick traditional screeds for exactly this reason.
- **Joints need grouting and sealing.** Plank joints, movement joints and the perimeter detail are agreed and closed before the pour.
- **It is an upper floor.** Getting material to the deck is a placing problem before it is a screed problem. Our track-mounted placing booms reach upper decks without craning plant up, which is what makes [screeds on precast planks](https://www.trentcs.com/screeds/precast-plank) a routine job for us rather than a special case.

## The questions that price the job

Bonded, unbonded or floating? Flowing or [self-compacting](https://www.trentcs.com/screeds/self-compacting)? Calcium sulphate or cementitious binder? Is acoustic performance specified on the separating floors? And above all: has the deck been surveyed? The survey sets the real depth range, the real volume and the real load. On both floor types it is the difference between a price built on the building and a price built on a drawing.

Surface regularity is normally specified to BS 8204, with SR2 the usual default. On a precast floor the achievable class depends on the deck as much as the screed, which is one more reason the survey comes first. We survey the finished screed against the specified class and issue the results.

## Common questions

 Can you lay liquid screed on a beam and block floor?

Yes, and it is common on ground floors with insulation and underfloor heating. The beam and block surface is grouted first, the insulation laid and taped, and the screed pumped as a floating layer to the specified minimum depth.

 What depth of screed goes on a hollowcore deck?

The depth range comes from a level survey of the actual deck, because planks are cambered and deflect under load. Nominal depths from the drawing understate volume on real decks, and depth is also load on the frame, so it is agreed with the engineer.

 Do plank joints need treating before screeding?

Yes. Joints are grouted and sealed and the perimeter detail agreed before the pour. A pumped screed will find any gap that has been left open.

 Beam and block or hollowcore: which needs more screed?

It depends on the levels, not the floor type. Beam and block carries a stepped surface; hollowcore carries camber. In both cases the survey, not the drawing, sets the real volume, which is why we survey before we price.

 Can you reach upper floors without a crane?

Yes. Our track-mounted placing booms deliver screed across upper decks without craning plant up, so the screed does not queue for the tower crane.

Got a precast floor to screed? Send the drawings to [info@trentcs.com](mailto:info@trentcs.com) or call 01283 480110. Directly employed teams, own pumps and booms, nationwide.

[View full post](https://www.trentcs.com/knowledge/screed-on-beam-and-block-and-hollowcore-decks)

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