Will a decent underlay get me through the Sound Test?

Don’t I just fit a thick underlay and carpet? it’s a question we get asked a lot. But the short answer is no; the structural floor (without final floor finishes) is the part that needs to pass an Approved Document E Sound Test and in many situations the carpet is removed prior to testing. This was highlighted this week when asked to test a 1980’s conversion in Dartmouth, Devon. The floors were finished in ply and in good condition but the sound testing performance was awful (a DnTW+Ctr of 37dB and an LnTw of 70dB) – in layman’s terms … sh*t. We lifted the floors to determine what the construction might be to find that the 9mm ply was nailed over 2 layers of carpet underlay and into the floorboards below. So, an amateur attempt at flooring isolation was completely undone by the few hundred nails connecting the walking surface with the flooring base. It probably wouldn’t have worked anyway, but we have now come up with a acoustic design solution that should achieve the clients requirements for the renovation – top marks for the developer who spotted that he might have a problem in the first place.