Doubling joists/ damage to lath and plaster ceiling below

[ollieman]

Hi,

I'm doing a loft conversion and as part of it, i need to double some of the floor joists where the floor joists need to be strengthened. The question is that when I'm doubling the joists, I am removing 50mm or so of the plaster ribs on the of top side of the laths for the ceiling below. I would like to know if this impairs the stability of the ceiling below? can I bond something on the top of the laths to reinforce the ceiling construction?

Thanks,

Ollieman.

 

[masona]

When I did mine I was using 9"x3" joists against the 4"x2" joists bolted but I put 18mm plywood on each end under the 9"x3" joists so it didn't touch the plaster rib. What you're doing will weaken it but you may never have problem with it! Even so, there's nothing to stop you boarding over with plasterboards in the future

can I bond something on the top of the laths to reinforce the ceiling construction?

You can but the weakness is under the joists

 

[Chukka63]

i always keep the new floor joist off the old ceiling joist.