600mm joists

[Andrewr4]

Hi
I’m renovating part of our upstairs. The house is of different ages and in one part has 200x50mm joists at 400mm centres, but the other part has 150x50mm joists at 600mm centres. They’re different parts of the house (old and new) with a step between the different heights.
The floorboards in the part with 600mm centres, which have clearly been taken up and gone back down a lot in places, are 18mm. While it’s not what I would call ‘bouncy’ there is a difference in how it feels compared to the newer part of the house. But is it a problem? Shall I just leave it alone, or is it worth replacing the floorboards for 22mm, or doing something else to make it feel more solid?
All advice welcome.
Thanks

 

[Deleted member 174758]

That floor is likely to be a bit bouncy because the boards are relatively thin, relative to the joist spacing. Depending on the span the joists may be undersized by modern standards, too (200 x 50 on 400 centres tends to indicate a span of circa 15ft, 150 x 50 on 600 would be more like 8 or 9 feet these days). That's the difference you can feel

As to being a problem, that depends on whether or not you think it is one. If the house has stood a couple of hundred years that way, then it'll likely continue standing - just so long ss you don't want a piano on that floor!