How can we stop or limit the vibration in our loft conversion

This is a awkward one ! As i scratch my head ! I can imagine the vibration you mean from double deckers , its some kind of breaking vibration i think . I did a job on the main Manchester road (very heavy traffic )and through my choice i double boarded the whole loft with 12.5mm boards , as i get feed back on everything i do , the client have never heard a vehicle pass their home so this could be a option if only at the road side . I'm guessing you here the buses too . One more thing that has just come to mind is , if you have a dormer then it could be the bus vibrations against the glass acting like a drum and giving you a sense of movement . Paul

It would seem that there is insufficient cross bracing in the wall / roof structure. You do not say but assume the vibration is felt in the floor and again bracing or strutting should have been installed at the time of conversion. This is usually installed to avoid 'bounce' in the floor by walking on it, but what you describe could also be contrbutable from the external movement causing this to move.

The vibration is most probably caused from movement of the joists or rafters. Lifting the floor boards and adding dwangs should ease it. If there are insufficient dwangs between the rafters you may need to strip off the plasterboard to add more. It is unfortunate both jobs will create upheaval but you must weigh up how important it is to get rid of the vibrations.