New floorboards upstairs now sounding drum-like when I walk on it. How do I add sound proofing after gluing the panels in?
What is the spacing of the joists? Whatever it is the &quot;best&quot; way is to reduce that spacing perhaps by adding intermediate joists.
The drummimg is due to the frequency or vibration produced by the joist/board combination. One way to stop this is to put an isolation band between the joist and board when fitting. This allows the boards to expand/contract as they change with temperature without loading the joists. As you have screwed and glued them together you may end up with problems.
If you completely fill the void with an insulation which is in contact with the underside of the floor then this might help reduce the noise produced. I am not sure if spraying foam will be effective unless you get good coverage and volume fill.