Well, the shower is in and working, but now the work continues around it. Probably not the most practical solution, but this is the reality of working in an area that needs to be kept in use. The floorboards have come up as the originals were in poor repair. Also, there was a strip in the floorboards where the original partition was. Replacing the floorboards presented an opportunity to acoustically insulate. This will be done with Knauf Earthwool Acoustic Roll. We are using the same in the partitions (between 50 and 75mm depending on partition depth), but will increase this to 100mm for the floor.
Whilst the floorboards are up, it was clear that the first floor joists, as expected for this age of property, are supported by the inner leaf of the cavity wall. Cumulatively, all these penetrations across the north and south walls, equate to a significant hole. This is estimated to be equivalent to approximately 300 x 300mm (assuming a 5mm gap around each joist). These will be progressively sealed to suit the phasing of the house refurbishment.
Sealing is fairly straight forward as long as access is possible – so it is a blue moon opportunity. It is imperative that the right sealant is used: do not use a bathroom silicone, or painters mate as both of these do not bond strongly to surrounding surfaces and all the hard work will be in vain. There are plenty of proprietary products available for sealing, but they are not readily available at builder’s merchants. In this case I opted to try and adhesive sealant (Sikaflex EBT), not marketed for air sealing, but seems to have remarkably similar properties and is available at most builder’s merchants. The robustness of this approach is being trialled on the joists in the vicinity of the bathroom and will be reviewed before rolling out across the renovation.