Reinforcing floor for new bathroom

[qihto]

Hi all,

I'm moving the bathroom in my house (1880 stone/brick construction), building regs inspector made a passing comment about doubling the floor joists up under the bath while looking at another part of the house we are renovating. The existing floor joists are 175x50mm and span 3750mm at roughly 400mm centres. I started looking at doubling up and found a couple concerns with what they are resting on, one end is supported by a timber lintel over the front door (200mm horizontally x 100mm vertically), and the other end is supported by a single skin brick archway which I've uncovered and it looks like it's seen better days.

Can/Should I replace the timber lintel with a concrete one? It looks solid but while I've got access it seems like replacing it might be worthwhile.

I'd like to keep the archway as a feature but I don't trust it structurally, could I span the top of the arch with a double joist and hang the floor joists from the double?

Thanks!

 

[blup]

8x4 seems more than adequate for a few joists provided it is sound, noggins will help if they dont interfere with the waste. Spreading the weight of the bath evenly across the joists will help too. The arch has a good curve so should be structurally strong and looks sound. Run it by the BC, although he might ask for calcs, some Council’s still have in house SE’s.