While we were having a general discussion about who were the worst subcontractors in terms of building installations – subcontractors as in electricians, plumbers, plasterers, et cetera – we came up with a shortlist, which I will now share with you. I am not sure if the shortlist will be of any use but it serves as a record, I think, of our experiences as acoustics engineers specifying various types of finish.

Window suppliers, in our experience, are bad. The quality of the installation they supply is, in most cases, poor. There is, in our experience, one window supplier who is very good, but this is like having one good cow in the herd. All the large window suppliers are useless. I am sure this statement will upset a lot of window suppliers.

Let me give you two examples which will speak for themselves. Example 1: as acoustics engineers, we draw up detailed specification for glass to be fitted to the windows of a hotel. Our specification states that windows are to be soundproof to a standard. We list the standard. When the window installation is completed, it is clear to us that, owing to the poor window frames, incorrect glass and poor installation, the windows provide no soundproofing at all. We meet the window supplier on site. We do measurements to show how bad the windows are. The window supplier calls our measurements “mumbo jumbo” and storms off. Subsequently, he claims never to have seen our specification and that our specification is unattainable rubbish.

Example 2: in our specification, we stated clearly and accurately that, for a new building, the windows facing the highway are to be a certain thickness laminated glass. The window supplier installs windows with a thinner glass, hoping we would not check. We check. The window supplier then retreats into a world where he claims that our measurement technique is wrong and that his glass is fine, based on the fact that some glass of similar thickness, when tested in China, gave better results than the glass he installed.

Next on our shortlist are ceiling subcontractors. They know that, once the ceiling is up, you cannot see what is above it. So they are very quick to close the ceilings and then ask us to inspect them. We know this trick, so we ask them to take the ceiling down so we can inspect what is above. All too frequently, the insulation that should be above is not there. So we say well, whoops, better put the insulation in. They then call a meeting with the client and the quantity surveyor and the architect and the builder to explain that to take the ceiling down and put the insulation in is going to cost money and will delay the project. Thus, we have all the people at the meeting looking at us and asking the silent question: “Is this insulation really necessary?” It is unpleasant but we insist.

Next: roofing contractors. They are similar to ceiling contractors in that they know that once the roof is on you cannot see what is below it, which, again, is insulation. But, importantly, it is not only insulation but often plywood or particleboard between layers of insulation for noise control purposes. It is cheap and convenient for them to leave the plywood or particleboard out. They are also experts at getting the site agent to agree that they can put the plywood or particleboard at the very bottom of the insulation layer. This means it can catch fire very easily. We go through the same charade as with the ceiling contractor.

Next: door suppliers. Most door suppliers belong to a cartel which imports doors by the container load. These are all hollow-core doors, having an air gap between the front and back panel. If you stuff the air gap with newspaper, they call the door a semi-solid door. Both door types easily transmit noise. Thus, we specify for privacy solid-core doors. The usual circus of them trying to get round the specification occurs. Who, you may ask, in our experience, are the best subcontractors? We have a clear winner: the carpeting people – efficient, pleasant and accurate. Oh, well.