Because of their method of application, installed synthetic resin floorings will inevitably follow the profile of the underlying substrate. The agreed standards for flatness, regularity and conformity to datum plane should therefore be provided in the base concrete or levelling screed. When upgrading existing floors, the means of obtaining the required levels and flatness need to be agreed in advance.
Surface regularity or flatness is a measure of the deviation of a floor surface from a parallel plane over a large area, as well as over small local areas.
The datum plane for most floors will be horizontal but, on occasions, sloping. In the latter case, departure from datum should be measured from the sloping plane.
The class or category of surface regularity required for a floor surface will depend upon the use of the floor. Insistence on a higher tolerance than necessary will result in unnecessary higher costs and this should be borne in mind in selecting a surface regularity standard.
The straightedge method given in BS 8204-1 is generally satisfactory for the majority of floor uses and the designer should specify one of the classes of local surface regularity given in Table 1 below.
Table 1:
| Class | Maximum permissible departure from a 2m straightedge laid in contact with the floor (mm) | Application |
| SR1 | 3 | High standard: special floors |
| SR2 | 5 | Normal standard: normal use in commercial and industrial buildings |
| SR3 | 10 | Utility standard: other floors, where surface regularity is less critical |
Where the straightedge method of specification is used it will be necessary for the various interested parties in a contract to agree the sampling rate for testing the floor to check conformity before the flooring is installed. This will include the number and locations of positions where the surface regularity is to be checked.
In service, the suitability of a floor surface in terms of surface regularity is governed by its radius of curvature and changes in height over short distances. It is recognised that the simple straightedge method of specifying floor surface regularity does not consider the ‘waviness’ or rate of change in elevation of a floor over any specified length. The method is therefore only suitable for floors finished by conventional finishing techniques that will produce a smoothly undulating surface rather than an irregular ‘washboard’ finish.
The difference in height across any joints in the concrete base should be less than 1 mm with no abrupt changes in level. Because of the relatively low thicknesses of the synthetic resin flooring, it is essential that any significant differences in height across the joints in the concrete base or fine concrete screed are ground flat before the flooring is to be applied.
Where a very high degree of accuracy is required, e.g. for high level racking, the recommendations of the Concrete Society Technical Report 34 should be adopted for specifying the base concrete. See Table 2 below.
Relevant information has been highlighted.
Table 2: Permissible 95 percentile values on Properties E (Elevation) and F (Flatness).
| Class | Typical floor use | Property | |
| E | F | ||
| FM1 | Where very high standards of flatness and levelness are required. Reach trucks operating at above 13m without side-shift | 4.5 | 1.8 |
| FM2 | Reach trucks operating at above 8-13m without side-shift | 6.5 | 2.0 |
| FM3 | Retail floors to take directly applied flooring. Reach trucks operating at about 8m without side-shift. Reach trucks operating at about 13m with side-shift | 8.0 | 2.2 |
| FM4 | Retail floors to take applied screeds. Workshops and manufacturing facilities where MHE lift heights are restricted to 4m | 10.0 | 2.4 |
The Concrete Society’s TR34 (table 2 above) recommends that 2 basic properties of the floor’s surface regularity is surveyed:
1. Flatness – Property F, the change in elevational difference between two consecutive measurements of elevational difference each measured over 300mm.
2. Levelness – Property E, as the difference in elevation between two opposing points 3.0 metres apart, set out on a 3.0 x 3.0 metre grid.
In addition, the deviation in height of the surface of all new floor construction should be within +/-15mm of a fixed datum plane. The level data from the Property
E survey is used for this purpose.
As a synthetic resinous flooring applicator, you are encouraged, or you should ask for the concrete floor slabs surface regularity compliance certificates and also cross these figures yourselves before you commit to the flatness, levelness and thickness of the flooring system that you will apply on these concrete floor slabs so that you do not face bitter experiences with your client and his expectations.
Courtesy – FeRFA and TR34, 4th Edition.
Author
Mr. Muralidhar. V
Industrial Flooring Consultant
Phones – +91 990 089 1994 / 966 383 6275
E-mail – muralidhar0707@outlook.com