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Superflat Floors: FAQ
What is a superflat floor?
Compacting and finishing the surface of wet concrete is an inherently imprecise process. For an
ordinary concrete slab to be laid within tolerance, engineers can only realistically expect the
surface to be finished to plus or minus 5mm. By contrast, superflat concrete floors are finished to
meet extremely close tolerances, being accurate to within 1mm across their upper surface.

Where are superflat floors used?
Floor surfaces with extremely tight tolerances are frequently specified in warehouses where
Automated Guided Vehicles operate. Uneven floors are especially problematic in high bay
warehouses, which use automated forklifts with a vertical reach of 30 metres or more. At such a
height, slight variations in floor level are amplified in the form of vertical tilt, causing inaccurate
manoeuvring at high level. If these variations are outside tolerance they can lead to collisions
with racking elements, or cause items to be dropped from pallets.

c In pairs, discuss what is meant by tolerance in the context of dimensions and precision.

d Complete the following expressions from the web page which are used to describe
tolerances.

1 tolerance (inside the limits of a given tolerance)
2 or 5mm ( + /-5mm)
3 tolerance (close tolerance)
4 tolerance (not inside the limits of tolerance)

e Complete the following sentences using the expressions in Exercise 6d.

1 The frame’s too big for the opening. The opening’s the right size, so the frame must be
.
2 The total tolerance is 1 mm. The permissible variation either side of the ideal is
.
3 The engineer specified +/ - 5mm for the slab finish, and we got it to
+ /- 2mm. So it’s well .
4 You can’t finish concrete to + / - 0.1 mm. There’s no way you can work to such a
.

f In some situations, engineers describe tolerances using plus or minus, for example +/-
1mm, and in other situations as within, for example within 1mm. In pairs, discuss the
difference in meaning between these two descriptions, giving examples of situations where
each description might be used.

7a ►4.3 Mei, a structural engineer, is talking to Lewis, a project manager, about the floor
specification for a manufacturing plant that is currently at design stage. Read the
conversation and answer the following questions.
1 What has the client requested with regard to the floor slab?
2 What are free movement floors and defined movement floors?
3 What issue does the engineer discuss regarding quality?
4 What option is discussed involving grinding?
5 What can be done to the reinforcement to permit grinding?

Mei: Basically, the client has said they want a superflat finish over the entire floor area. That

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