Closing the ceiling/floor hole after removing an old staircase

I'll soon be taking-out an old "back staircase" and closing the ceiling. AFAIK the staircase was fitted as an afterthought (it's not shown on the 1930s architect's drawings) so I assume they cut the joists and fitted a trimmer some time in the 40s or 50s. The plan is to simply attach joist hangers to the trimmer (fixings at about 300mm), fix a wall plate opposite the trimmer, attach joist hangers to the wall plate and drop-in the joists. The span is 1500mm and the joists are 8", on 400mm centres. The ceiling around the opening is lath'n'plaster so I'll probably pull this down and replace with plasterboard, or I might just over-board it.
The walls are lime plaster over solid concrete blocks so getting good fixings for the wall plate should be straightforward, probably using large frame fixers (or ???)
Is there anything else I should be thinking about?
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On 23/04/2018 16:22, snipped-for-privacy@aolbin.com wrote:

Depending on how it was done originally, you may find there is already provision for support of some kind on the wall. Having said that, hangers are preferred for new work in most cases.

Patching and over (or under if you prefer!) boarding is *so* much less mess than pulling down a L&P ceiling. So I would leave it well alone unless there is a pressing reason to remove it.
--
Cheers,

John.
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On 23/04/2018 19:19, John Rumm wrote:

Yes, I had to pull the L&P ceiling down in another room (boot room and historic coal store) and the mess was almost unbelievable ... but it was an excellent source of kindling ;-)
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