In the third part of his series on inspections, Richard Renouf says understanding flooring failure starts with assessing the subfloor and ensuring it meets key structural requirements before installation begins
THERE are many reasons flooring may fail. In many cases it’s because the installation has not been done in compliance with the fitting instructions and/or British Standards (see last month’s article in the archives via the CFJ website), but the issues may also be the result of a manufacturing fault, poor storage or transportation, or even something the end user has done or is doing that’s causing damage.
The start of any flooring project is to check the subfloor and to identify any materials and processes that are needed to bring the floor to a suitable standard. There are four basic requirements:
1 The subfloor must be sound
2 The subfloor must be smooth
3 The subfloor must be flat
4 The subfloor must be dry
In this article we’ll look at the first of these, then consider the others over coming months.
What does it mean for a subfloor to be sound?
For a solid (screed) subfloor this means that the floor should be free from cracks (other than expansion joints) and should not move underfoot or, where the subfloor is to be used for heavy traffic such as forklift trucks, under load. It includes the perimeter of any room or area where gripper or edge trims might be fixed.
For a timber subfloor the requirements are similar. The floor surface should be solid and secure, without creaking and with minimal movement underfoot… There shouldn’t be any gaps between floor boards or floor panels, and there should not be any signs of woodworm or other insect attack.
Raised access floors should be stable and secure, with none of the panels rocking or dipping underfoot.
Where the subfloor is not sound, the appearance of the finished flooring can be affected as some types of flooring ‘telegraph’ any unevenness so it can be seen through the flooring. It may cause poor bonding of stuck-down flooring, or it may cause flooring and ancillaries to come loose over time. In extreme cases there could be more serious problems: I once went to inspect a church hall which had been sanded and refinished a couple of times over the course of several decades.
Everything looked fine, but several years after the last sanding and the use by, amongst others, a regular ballroom dancing group, the stiletto heel of one of the dancers hit a weak spot. Fortunately there was no injury, but there was panic in case there were other weak spots waiting to be discovered.
At the estimating stage and again at the installation stage any such problems can be addressed. Subfloor preparation manufacturers have resins to bond cracks in screeds and make them secure, and repair mortars that can fill gaps and holes as long as the remaining subfloor is sound. Wooden subfloors can be strengthened using plywood or hardboard and there are other products, such as Jumpax, which solve subfloor issues. Raised access flooring can also be overlaid with plywood and there are some suitable smoothing compounds available, too. Identifying what needs to be done can increase the value of the contract. Conversely, not attending to such issues can result in failure.
A flooring inspector should know how to assess the original subfloor and any subfloor preparation work and to be able to tell if this was inadequate or has contributed to any flooring failure.
The contractor should be asked for details of any subfloor preparation products used, and for sight of any photographs taken during the floor laying process as these can avoid any need to lift flooring and dig into the subfloor which could make any problems worse than when the inspector came onsite.
In our next article we’ll look at the next basic requirement – smoothness. What is it? And why is it important?
www.richard-renouf.com
Richard Renouf is an independent flooring consultant
