What is at the end of these joists?

[Transylvania]

These photos show the joists that run front-to-back in my house. They're heading towards what looks like a perpendicular steel beam or a wooden joist but I can't tell which. Whatever it is, the bedroom wall is sat on top of it. 1930s construction, if that helps.

So given all of that, the two wooden joists in the left and right hand side of the photos, how likely is it that these joists run all the way from the front to the back of the house without a break? If they don't, and they butt up against the perpendicular beam, how would they be attached/supported?

Is it a case of lifting a few boards and having a look? (hate doing that as they never go down as well as they were before I disturbed them)


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[noseall]

Looks to me as though you have an overlapping join on your joists, similar to the image below....

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• noseall
• 22 Jan 2015
• 1

Is there a wall below supporting the join? The last three images all show the end of an overlapping joist and you can see the subsequent set-back on the next joist along.

 

[Transylvania]

That's a possibility, but in the diagram you posted there is a clear space/view from the end of one joist to the end of the other joist, whereas in the photos there is something at right angles to it halfway along.

I can't get a good enough view, but could this be a steel beam/wooden joist supporting the bedroom wall? The end of such a beam could rest on the end of the ground floor wall. The corresponding ground floor wall is actually another 3 feet towards the front of the house - in fact, both of our upstairs dividing walls are offset from the dividing walls downstairs, so I'm wondering what's holding them up?

Would a first floor dividing wall ever sit on floorboards/joists with no other support underneath it? I'm assuming they're made of brick, they might not be.

[this diagram might help, the overlay shows where the first floor walls are not directly above the corresponding ground floor walls]

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[noseall]

in the photos there is something at right angles to it halfway along.

Probably solid bridging.

This is usually fitted at either 1/3rd spans or more commonly 1/2 span in order to take the twist out of joists as the weight is applied. It serves to stiffen floors with larger spans.

Modern day floors incorporate a double joist whereby a stud wall is built above it and in line with it. Where a stud wall crosses joists at 90 degrees there is no need for reinforcement.

Older internal masonry partition walls were built off a timber sole plate fixed on top of the floor boards. I have this design my own house and the wall is off set compared to the position joist below, i.e. there is floor boards then fresh air directly beneath the masonry wall.

 

[Transylvania]

If I wanted someone to check out the condition/situation with our joists and floorboards, would that be a joiner or a structural engineer? We're getting floorboards loosening themselves up, and I want to make sure there's not some joist movement/sagging going on that's causing this. Or could this just be due to the cold weather and the heating going on and off?

If it's a case of just screwing the loose floorboards back down again, does any allowance need to be made for movement due to temperature fluctuations? ie if I did it in the middle of winter, would they split when they expanded again in the summer?