Floor joists - extending them
Discussion
Question for a surveyor/structual engineer.
Existing house. The entire front and back wall had to come down. New walls will be set out 15 cm further out than old walls so the floor joists need extending. The extended bit will then sit on the block wall.
This will be done by adding wood to the existing joists and bolting them together.
The work has already been done but before I get it checked over I wanted to see what people thought were required in terms of
a) how much overlap should there be between new and old wood
b) how many bolts used to connect them together
Concern at the moment is that the new wood is not connected to the old wood solidly enough but builder saying its fine and more than strong enough, I think problem is visually it doesn't look like much but stricturally it may be fine.
Existing house. The entire front and back wall had to come down. New walls will be set out 15 cm further out than old walls so the floor joists need extending. The extended bit will then sit on the block wall.
This will be done by adding wood to the existing joists and bolting them together.
The work has already been done but before I get it checked over I wanted to see what people thought were required in terms of
a) how much overlap should there be between new and old wood
b) how many bolts used to connect them together
Concern at the moment is that the new wood is not connected to the old wood solidly enough but builder saying its fine and more than strong enough, I think problem is visually it doesn't look like much but stricturally it may be fine.
Its a complicated situation........
I would say the span is approx 4 or 5m without measuring - one end is sat on an RSJ type thing which is in the centre of the house - there are then joists going the other way to the back. So RSJ on one end and blocks on other.
Builder one - the overlap is about 30cm on some (some are longer) with 3 bolts close together.
This builder was sacked for various reasons including poor workmanship and time delays
Buidler two - he came in to carry on the work - he says the above is OK but he also had to do some joists and he did them about 100cm overlap with 2 bolts.
Whilst I was getting quotes to have other unrelated work done a couple of buidlers who came on site mentioned that they thought builder ones work was maybe not ideal (i.e not long enough).
A strutural engineer has looked at builder ones work. His view is that it is fine. He mentioned something like the overlap just has to be twice what the extension is - so if the extension is 15cm then 30cm is enough. (but bear in mind visually 30cm overlap over 4m looks like nothing)
Builder two has a vested interest in not going back and altering builder ones work as it will cost him time/money.
The surveyor - although he is OK I am not convinced he is totally impartial as he is paid for by the company I contracted with (they sub contracted teh building work out and organsied the surveyor). So again he may not wnat to create hassle by asking them to go back and change something.
My doubts are for the following reasons
1) what other buidlers have said (who are definitley independent)
2) visually it doesn't look amazingly solid (but I am not expert)
3) quetsions over whether builder and surveyor are happy to do the bare minimum.
Essentially I just need to know what has been done is OK even if it is not belt and braces over the top quality.
My own way of doing it owuld probably to have used 100cm overlap with 3 bolts - so not far off above poster)
I do trust the surveyor but my mind is saying to get a second opinion.
I would say the span is approx 4 or 5m without measuring - one end is sat on an RSJ type thing which is in the centre of the house - there are then joists going the other way to the back. So RSJ on one end and blocks on other.
Builder one - the overlap is about 30cm on some (some are longer) with 3 bolts close together.
This builder was sacked for various reasons including poor workmanship and time delays
Buidler two - he came in to carry on the work - he says the above is OK but he also had to do some joists and he did them about 100cm overlap with 2 bolts.
Whilst I was getting quotes to have other unrelated work done a couple of buidlers who came on site mentioned that they thought builder ones work was maybe not ideal (i.e not long enough).
A strutural engineer has looked at builder ones work. His view is that it is fine. He mentioned something like the overlap just has to be twice what the extension is - so if the extension is 15cm then 30cm is enough. (but bear in mind visually 30cm overlap over 4m looks like nothing)
Builder two has a vested interest in not going back and altering builder ones work as it will cost him time/money.
The surveyor - although he is OK I am not convinced he is totally impartial as he is paid for by the company I contracted with (they sub contracted teh building work out and organsied the surveyor). So again he may not wnat to create hassle by asking them to go back and change something.
My doubts are for the following reasons
1) what other buidlers have said (who are definitley independent)
2) visually it doesn't look amazingly solid (but I am not expert)
3) quetsions over whether builder and surveyor are happy to do the bare minimum.
Essentially I just need to know what has been done is OK even if it is not belt and braces over the top quality.
My own way of doing it owuld probably to have used 100cm overlap with 3 bolts - so not far off above poster)
I do trust the surveyor but my mind is saying to get a second opinion.
Do you have to use spiked washers? Or just belt and braces?
I have seen that the new builder (buidler two) has used them
As for the old stuff done by builder one, i can see one or two joists where the has used them but only because the wood hasn't totally joined together as you can kind into the gap and see the joist conenctor in the middle - but they are bolted together solidly. The others are together so I assume they were used but wont know unless we take em off.
I have seen that the new builder (buidler two) has used them
As for the old stuff done by builder one, i can see one or two joists where the has used them but only because the wood hasn't totally joined together as you can kind into the gap and see the joist conenctor in the middle - but they are bolted together solidly. The others are together so I assume they were used but wont know unless we take em off.
BC have been but I am not sure whether his view is on the joists as I ahvent seen him face to face myself yet. AFAIK he has not raised any cocnerns.
My contract is with company A and they have hired builder one and buolder two - to be fair when buidler one caused problems they binned him and bought in builder two (at a lot of cost two them) - buidler two has been fine in terms of block/brickwork but I still have niggles about the joists.
I don't he wants the hassle of putting new joists in - yes he could do it and get paid but I don't think he wants to.
At this stage as the builder and surveyor both say it is OK then unless I get another surveyor I will not be able to convince company A to change it.
The blockwork is almost up to the heigh of the joists - and it will be built around the extensions - but I spsoe if in the future they need to come out the old ones could be taken out and the new ones slot in?
My contract is with company A and they have hired builder one and buolder two - to be fair when buidler one caused problems they binned him and bought in builder two (at a lot of cost two them) - buidler two has been fine in terms of block/brickwork but I still have niggles about the joists.
I don't he wants the hassle of putting new joists in - yes he could do it and get paid but I don't think he wants to.
At this stage as the builder and surveyor both say it is OK then unless I get another surveyor I will not be able to convince company A to change it.
The blockwork is almost up to the heigh of the joists - and it will be built around the extensions - but I spsoe if in the future they need to come out the old ones could be taken out and the new ones slot in?
C Lee Farquar said:
That's firmly in the remit of a structural engineer, but you say you've already had one look?
Yea, and he is an old hat. This is the only concern I have amongst all the work that is going on.
He said what I have is already more than what is needed!
Maybe there is a conflict thre visually between what looks like enough and what is enough - i.e mayb 1m makes me feel more comfortable but isn't needed. Of course as a customer I want it belt and braces not bare minimum.
Again though unelss there is guidance on it it could come down to structural engineers opinion?
Does building cotnrol guidance/legislation cover this? If not is the building control person also an engineer?
New joist can't cost £10?
I presume you are talking about the whole actual bit of wood that goes from one side to the other. The house has about 20 in total (although they split in the middle of the house as they are held on a steel) - I imagine it would cost a fortune to repalce them.
I presume you are talking about the whole actual bit of wood that goes from one side to the other. The house has about 20 in total (although they split in the middle of the house as they are held on a steel) - I imagine it would cost a fortune to repalce them.
OK just to bump this.
Engineer is saying it is OK.
I had 2 builders look at it and whilst they say they would have made it meatier they say if the SE OK's it then they wouldn't argue.
BC has asked for drawings but generally the BC isn't showing much concern. I think he is just trying to keep his nose out of it - but he said the drawings will be checked out by the councils own engineer.
All of the work has now finished and whilst I am generally happy in the main I have noted that some of the joists are not level - this means the floor above is not flat. I have just raised this with the buidlers so will wait to hear back. BTW I don't mean a slope - I mean like a bump where one/two are too high. One of the joists is above a downstairs wall and has always been the same height - I suspect some of the new joists have fallen below this level.
I do wonder if new joists will now be needed as I cannot see how they can easily remedy this! The joists have all been set into the blockwork.
I think what has happened is that whilst the joists were being extended they have sagged and the floor now is not totally flat - although the joists did look level from outside when set in the blockwork. They look reasonably level from the underside until you go upstairs and see the way the floor is - when you come back and look at the joists from underneath you can see the problem.
I can't see how the uneven floor I have is acceptable though.
Problem is my upstairs walls are all built on the floorboards so it would be a hassle to take the (block) walls out and the floorboards - do it all and put it back. That said I iamgine 2 brickies could put all the walls back up within a day or 2.
What a faff!
How hard is it to put new joists in? I spsoe they can re-use the notches in the blockwork.
What about joist hangers - do they do the same thing but let you put it into the block directly?
Engineer is saying it is OK.
I had 2 builders look at it and whilst they say they would have made it meatier they say if the SE OK's it then they wouldn't argue.
BC has asked for drawings but generally the BC isn't showing much concern. I think he is just trying to keep his nose out of it - but he said the drawings will be checked out by the councils own engineer.
All of the work has now finished and whilst I am generally happy in the main I have noted that some of the joists are not level - this means the floor above is not flat. I have just raised this with the buidlers so will wait to hear back. BTW I don't mean a slope - I mean like a bump where one/two are too high. One of the joists is above a downstairs wall and has always been the same height - I suspect some of the new joists have fallen below this level.
I do wonder if new joists will now be needed as I cannot see how they can easily remedy this! The joists have all been set into the blockwork.
I think what has happened is that whilst the joists were being extended they have sagged and the floor now is not totally flat - although the joists did look level from outside when set in the blockwork. They look reasonably level from the underside until you go upstairs and see the way the floor is - when you come back and look at the joists from underneath you can see the problem.
I can't see how the uneven floor I have is acceptable though.
Problem is my upstairs walls are all built on the floorboards so it would be a hassle to take the (block) walls out and the floorboards - do it all and put it back. That said I iamgine 2 brickies could put all the walls back up within a day or 2.
What a faff!
How hard is it to put new joists in? I spsoe they can re-use the notches in the blockwork.
What about joist hangers - do they do the same thing but let you put it into the block directly?
Edited by Mojooo on Monday 17th November 03:59
I spose my only problem is that they built my house and left holes specifically for joists to go into - so better off using them as I sort of have a bloc / half a block gap / block / half a block gap - scenario - so at the first floor level the blocks do not go all the way across the house - so best off using the holes already there as much as possible.
Anyone recommend an engineer in south Hampshire? I may need a 2nd opinion on this!
Anyone recommend an engineer in south Hampshire? I may need a 2nd opinion on this!
OK so I have spoken to a builder friend. We discussed the floor and we reckon some of the joists are not totally level. The issue is what to do about it.
I am not really happy going for some bodge job fix - but the alternative if taking out all the joists is pretty extreme as it would involve taking of floorboards and possibly the upstairs walls!
I am not really happy going for some bodge job fix - but the alternative if taking out all the joists is pretty extreme as it would involve taking of floorboards and possibly the upstairs walls!
http://1drv.ms/1Hr8Xbb
First two pics show the short joists I was on about
Third pic shows longer joists by builder 2. a 3rd bolt has been added in the middle due to building inspector asking for it
That also shows the curviature of the joists
Photo 3 is room above with dodgy floor
We put a spirit level to the curved joists and they are not level.
First two pics show the short joists I was on about
Third pic shows longer joists by builder 2. a 3rd bolt has been added in the middle due to building inspector asking for it
That also shows the curviature of the joists
Photo 3 is room above with dodgy floor
We put a spirit level to the curved joists and they are not level.
It is still like that.
As per my OP I have had 2 buidlers. In the interim between them I suspect the floor has sagged (no acro props and the floor wasn't extended properly) and the 2nd builders haven't checked it before putting blocks up.
I think the new wood is roughly level with the old wood - problem is both together are slightly too low in some places.
I am not sure if I even want more tampering and more bolts going in - its starting to get silly with so many holes as further on up I have holes for electrical wires and notched joists for pipework!
As per my OP I have had 2 buidlers. In the interim between them I suspect the floor has sagged (no acro props and the floor wasn't extended properly) and the 2nd builders haven't checked it before putting blocks up.
I think the new wood is roughly level with the old wood - problem is both together are slightly too low in some places.
I am not sure if I even want more tampering and more bolts going in - its starting to get silly with so many holes as further on up I have holes for electrical wires and notched joists for pipework!
All our upstairs walls are made of clinker blocks - which are sat on the floorboards
Plus of course they are packed with furniture and we often have a lot of people in.
I probably woudl have lived with them had the floor been flat but I am now somewhat psised off as they have been as issue for a while.
Plus of course they are packed with furniture and we often have a lot of people in.
I probably woudl have lived with them had the floor been flat but I am now somewhat psised off as they have been as issue for a while.
Yea
I rang a Structural engineer earlier - they said I needed a Building surveyor. Will get in touch with one soon. I am waiting to hear fro mthe buidlers what their view is one it.
I seem to have 2 options - jack up the existing joists and make the floor flat or just change them completley which resolves both problems - although as far as the buidlers are concerned the short joist bit isn't a problem.
I rang a Structural engineer earlier - they said I needed a Building surveyor. Will get in touch with one soon. I am waiting to hear fro mthe buidlers what their view is one it.
I seem to have 2 options - jack up the existing joists and make the floor flat or just change them completley which resolves both problems - although as far as the buidlers are concerned the short joist bit isn't a problem.
Picture 3 is the key one.
Where the orange wall is there is a joist above that which has obviously always stayed still as it is fixed.
Where the white door is - above that is a clinker block wall - which has probably pushed down the joist.
If you go to the left of the orange wall I think they are also slightly lwoer on that side as well but will need to check again.
In picture 4 where you see the 'hill' that is where the orange wall is underneath I think.
Where the orange wall is there is a joist above that which has obviously always stayed still as it is fixed.
Where the white door is - above that is a clinker block wall - which has probably pushed down the joist.
If you go to the left of the orange wall I think they are also slightly lwoer on that side as well but will need to check again.
In picture 4 where you see the 'hill' that is where the orange wall is underneath I think.
TA14 said:
You could jack up the joists at mid span but then what? When you release the jacks the floor will just spring back down?
I think you would have to take off the extensionsJack up the old (dark brown joists) and then insert the extensions again but level - which may involve messing around with the hole in the wall which I don't want to do.
Then that should keep them in place?
Problem is the floorboards may be twisted now. Will they go down flat? They have prob been liek that for weeks.
Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff