Joist span... did they used to be longer?

[Donkmeister]

I have a two-storey house, built in 1919, brick cavity wall construction. I plan to remove a wall on the ground floor, to knock two rooms together. There is no wall above this wall on the first floor, but when I lifted the upstairs floorboards it would appear that the joists are resting on this ground floor wall, mid-span. I can see the top of the bricks and the joists are resting on these.

I discussed it with some of my neighbours with identical houses. They've both had the same wall taken out, and neither had any reinforcing work done. No sistered joists, no steel beams, just wall taken out. One of them even DIY'd this wall removal 10 years ago so it can't be a case of the builder added joists when he wasn't looking.

Here's where I am puzzled... the joists are 172mm by 55mm, at 360mm centres, and once the wall is gone the span is just over 4.6 metres - this is a metre longer than the spans quoted for 170 by 50mm at 400mm centres... which makes me think that wall I want to remove must be a supporting wall.

Was wood really that much better 97 years ago, or is it pure luck that their floors haven't gone bouncy/bowed/collapsed?

 

[^woody^]

The timber was much stronger then as it was slow grown.

There is actually more capacity in timber anyway, than the slab tables state.

 

[tony1851]

Just to add to the above; when I was a lad 97 years ago, people didn't have as much crap in their houses as they do today, so floor joists were not as heavily-loaded.

 

[^woody^]

Just to add to the above; when I was a lad 97 years ago, people didn't have as much crap in their houses as they do today, so floor joists were not as heavily-loaded.

What about the 50 kids crammed into the two up two down? And wardrobes full of flat caps?

 

[theprinceofdarkness]

I am pretty sure that in my Victorian house a lot of the upstairs joists were ash, -very white and knot free, not douglas fir, nice browny yellow and knotty.
Frank