Which is better? Plank on Ply or Direct Fix?

These are two different approaches to putting down a timber floor. You will find just as many people claiming that either one is better than the other. The reality is that they are simply different ways of putting a floor over concrete.

In the early 1990's we didn't have the adhesive systems available that we have today. So when we wanted to put timber boards over concrete we had to use very short lengths [no longer than 300 mm] or else the floor would twist.So to allow us to install over concrete we first put down plywood. We could then install longer boards over the plywood. It solved a problem. It also introduced another problem which was height. 12 mm plywood plus 12 mm timber plus glue etc means that these floors are over 25 mm high. This is OK until you transition to other surfaces. Height differences are important.

In the late 90's we got polyurethane adhesives and moisture barrier technology. This changed everything. Initially we had adhesives that were too flexible but in time Sika developed just the right degree of flexibility for timber. Now we could install floors with confidence and these could be installed directly to concrete. This solved the problem of height transitions between areas. With floors installed at similar heights the whole area flows perfectly.

So why do some people still use plank over plywood? There are two areas that make it worth considering. Firstly concrete floors are not level. Sometimes they require so much remedial leveling that it isn't worth spending the time. It is cheaper to line the concrete with ply sheeting which will tend to improve levels greatly due to sheet sizes. Secondly, less visible fixings; you can use adhesive and very small c-brads with tiny heads. Less obvious fixings looks very good.

The cons in the use of plywood do also exist. There is considerably greater cost. Essentially you install two floors: one made of plywood and one made of boards. So expect a 30% premium. The other is an urban legend or myth. Some people claim that plank on ply feels better underfoot. We did a trial years ago that asked people to walk on three floors and see if they could tell which was which underfoot. The results clearly showed that no-one could pick the plank on ply over direct fix consistently.

So by all means use plank on ply if it is needed but it is hard to argue that one is better than the other. It simply is a different way of installing a floor.

Direct fix requires a considerable bed of flexible adhesive over a primer epoxy surface. The floors are well engineered and the adhesives are about twice the strength actually needed to hold a floor in place. As a result almost all floors we see are installed using a direct-fix method over flexible adhesive. Sika T55 over Sika MB Primer is generally the choice.

So which is better? They are two different approaches to putting down a floor and they both perform really well. Some people will ague that one is better than the other in the same way that some will ague that one brand of car is better than the other. It becomes an emotive discussion. At VCS we don't mind which system you select. We will make recommendations according to your site and make sure that we install our system to the warranty code used in our triple warranty program. The adhesives will be flexible and the floor will perform as a natural timber floor should.