I was just wondering about this.
What holds the floor to the brickwork?
Does it rest on some bricks which 'stick out'?
Or are there 'holes' in the wall where wooden joists are slotted in?
Actually I think I may have seen pictures of such hole on old historic ruins etc.
Such as here for example
Not usually - although this technique (called corbelling) is sometimes used for supporting some of the larger roof timbers.
In older properties yes, this was the common way. Its not favoured these days since it tends to leave more air passages through the building (so lower thermal performance), and there is more danger of the timber rotting at the contact point should the wall get damp.
Modern builds will use steel joist hangers built into the wall during construction instead. Like:
Mystery solved, however, I wonder what the life span of such joists is? I mean after a while those things will have rusted away. I guess the builder will be dead by then though!! (As will the people in the house when the floor collapses!!)
maybe "roof"'s brother "floor" will be along to advise soon.....
There's no reason they should rust away since they shouldn't be getting wet.
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Haha ! I've just built a roof held up with lots of joist hangers, and I was wondering about their lifespan. There is not much steel bearing the weight (two bands of steel around 12mm x 3mm cross-section that bend alarmingly easily), but of course steel is strong in tension (think of steel cables). But, a nick or a rust spot and the quantity of weight bearing steel can be reduced a lot. And if the weight distribution is poor, more of the weight could be on one band. I wonder in a modern house, what the first thing to decay is ? I guess if the joist hangers are damp enough to rust, the wooden joists will be rotting too ! In practice, several joist hangers are usually used to bear a floor, and a failure of one would not bring the whole lot crashing down. Simon.
They're heavily galvanised, and if it's that wet, I think the timber would fail first.
Err, I think the OP's choice of name might be a clue.....
True. I have several leftover joist hangers in my garage used as hooks for various heavy items. They've been there for at least 25 years and they don't have a trace of rust.
steel in the absence of EITHER surface moisture OR oxygen, doesn't rust, and the plates are galvanised.
The wood, if surface moisture is present, will rot long before the hangers rust..
>
Well for a start there is water vapour in the atmosphere and there may be flooding in the house from time to time.
Here you can see a rusting galvannised corrigated steel roof.
Haha ! I've just built a roof held up with lots of joist hangers, and I was wondering about their lifespan. There is not much steel bearing the weight (two bands of steel around 12mm x 3mm cross-section that bend alarmingly easily), but of course steel is strong in tension (think of steel cables). But, a nick or a rust spot and the quantity of weight bearing steel can be reduced a lot. And if the weight distribution is poor, more of the weight could be on one band. I wonder in a modern house, what the first thing to decay is ? I guess if the joist hangers are damp enough to rust, the wooden joists will be rotting too ! In practice, several joist hangers are usually used to bear a floor, and a failure of one would not bring the whole lot crashing down. Simon.
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Thats what they said about the world trade centre!!
25 years is not a long time in the lifetime of a house though it it?
I mean there are plenty of houses standing which are almost 200 years old.
Anyway apparently you can get stainless steel ones.
In which case the wood will likely suffer first.
well neither is relevant. water vapour will only condebse where thngs are cold, and building regs ensure that cold things are well ventilated things.
A few days of flood wont affect things much either. Rot and rust require wet and air, not just wet. By the time the wet goes, which will have protected the rusting, to an extent, the things will dry out fairly quickly.
Rust accumulates via long term exposure to mild damp, not short exposure to wet. And there is a LOT of steel to eat through.
Not bad for a 60 year old roof, in full weather conditions.
No holes, just a surface layer.
No, there are not.
Most houses undergo major refurbishment every 60 years and a typical life span is 120. MOST properties older than that would actually be more cost efficient to be demolished. They are simply fixed up mainly for sentimental reasons.
And that fixing up involves a lot of wood replacement
Almost pointless. The wood will have gone long before the steel does.
Mine is some 120 years old and has none of the original structural timber replaced. Although it did have some repairs and modifications to how the ground floor joists were originally installed. And this on a house which was previously poorly maintained.
Only because most of the wood used these days is the wrong type.
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