floor joists in new extension

[vonspritz]

I'm self building a two storey extension, the block work is nearly to first floor level. What are the pros & cons for either building the floor joists into the internal skin of the wall, or taking the wall up flat & using hangers?
All advice & comments appreciated.
Vonspritz

[xavi99]

Building into the wall is not as common because of timber movement leading to gaps and air leakage and sound transference.

Joist hangers ok but now superceded by plastic shoe which is built into the internal skin and then the joist slides in. This is best for air leakage and limiting sound transference.

For extensions it can come down to preference of BCO, might be best to check first?

Good luck.

99

[jhonackerman]

This can help you.
The joists in place will be ceiling joists, designed only to support ceiling boards light and attic loads.

Typically ceiling joists consist of two, narrow, low grade timbers, bolted together above a supporting wall.

Ceiling joists haven't the integral strength to take the loads of a further storey, nor of everyday household loads, e.g. people, floors and furniture.