We are currently in dispute with our builder and the NHBC about the inconsistency in the level of the floor post the Amtico flooring being installed. We instructed our builder to complete a survey as we were not happy with the unevenness, and they were only happy to repair one part of the floor. Due to this we instructed the NHBC who I believe are not conforming to the correct guidelines when measuring the high\low points of the flooring, although they identified two areas, one of which the builder identified.
The entire of our ground floor is a concrete slab...
To my understanding the standards are as follows
9.1.5 - This is the tolerance of the unfinished floor to +\-5mm
and
9.3.7 - Flexible finish, in our case Amtico is a flexible vinyl and as such has to be installed to the manufacturers guidelines +\-3mm
Amtico have advised, along with the Contract Flooring Association, the flooring is to be installed on a concrete screed to BS8203 SR1 (this is +\-3mm) however the NHBC are saying it is their guidelines which are to be followed, and they are using +\-5mm which I can only assume is related to 9.1.5 - an unfinished floor. This information has been emailed to the NHBC as an attachment from the manufacturer.
Over multiple emails, I have asked the NHBC to clarify why they are choosing to ignore the wording in standard 9.3.7, where the flooring should be installed to the manufacturers specification - sadly they keep ignoring this item and continue to state they measured to the correct standard, a standard they wont confirm the specification of, apart from +\-5mm and it has to be reasonably level.
When the NHBC measured the floor it was at the maximun +5mm tolerance, which is over the 3mm it should be. The other issue is when measuring they used the high points, but didnt offset these against the low points over the 2M length defined in the standard, making the deviation in level looking to be more than 5mm.
If anyone would like to look at some poor quality pictures of mine, here is my dropbox
https://www.dropbox.com/sh/0fdbjr6u24h4kjq/AAC09j_lHo7AKPYNP4z5U_RHa?dl=0From Amtico
'The quality and preparation of subfloors, testing for moisture content and relative humidity, and installation procedures must be in accordance with Amtico International technical guidelines and country specific standards (BS 8203 and BS 8204 for UK).'
From CFA
'The British Standard (BS 8203, SR1) and the Amtico instructions stipulate that the floor must not deviate by more than 3mm over a 2 metre span. It is also reasonable to expect the smoothing compound will befree from trowel marks and other irregularities caused by poor installation.'