Uneven joists - can they be fixed

rampantbunny

First floor ceilings installed yesterday. Installer rang me when done to tell me that some of the ceilings were very uneven. I got up on a ladder and looked across the plasterboard...looks like waves across the ceiling in place...very bad.
I personally never checked that joists were even at any stage. Please, no one post back that I should have done, because I'll lose all faith in local tradesmen.

I expect plasterer to be able to flatten out some of the ceiling, but there is half to 3/4 inch diff in one spot which I've asked him to take a look at it.

In meantime, what are my options?
Only thing I can think of is to take down plasterboard and plane down or shim underneath affected joists.

Armchair Andy

Was on a job where this happened and the builder ended up counter battening with 2*2s.Set up the laser level and he spent an age cleating out the humps and hollows. Was in a foyer so he had headroom to play with.

sydthebeat

A sign of insufficient bridging?

You could always acro them up, include more stiffeners, floor across, then remove acros and slab

rampantbunny

sydthebeat wrote: »

A sign of insufficient bridging?

You could always acro them up, include more stiffeners, floor across, then remove acros and slab

Joist are 9" at 400mm centers. What centers for bridging timbers?
I think they are in at over 1m.

The joists are bedded into the blockwork at the external walls (I should have used hangers). Will acrowing them up just put a bow in them Syd?

rampantbunny

Armchair Andy wrote: »

Was on a job where this happened and the builder ended up counter battening with 2*2s.Set up the laser level and he spent an age cleating out the humps and hollows. Was in a foyer so he had headroom to play with.

I'd consider a variation on this approach and maybe get some metal ceiling work done below the joists. Will have to check if have room for a drop though.

sydthebeat

rampantbunny wrote: »

Joist are 9" at 400mm centers. What centers for bridging timbers?
I think they are in at over 1m.

The joists are bedded into the blockwork at the external walls (I should have used hangers). Will acrowing them up just put a bow in them Syd?

Depends on what's causing the waves.

Were the joists sized from is444?

rampantbunny

sydthebeat wrote: »

Depends on what's causing the waves.

Were the joists sized from is444?

Had to look that up.
Joists were specced and roof structure subsequently checked by engineer so I have to assume they are fit for purpose.

Would a 9" joist have that much flex in it? There is no load on the joists where the largest waves are.
In the most problematic ceiling there are 16 joists, 3 of which are doubled. Just checked the engineers drawings and bridging is shown at 1350mm. Seems to match with what has been installed. Room width is 4460mm long (the joists span this length).

Drift

Where did the timber come from rampant bunny? Has it got a strength grade stamped on it?

It would be unusual to see a 4.5m, bridged, 225 joist "wave" so much under it's own weight. Also if it was purely undersizing alone I would expect to see a gradual deflection from the sides to a max deflection in the middle of the span. Not waves.

rampantbunny

Drift wrote: »

Where did the timber come from rampant bunny? Has it got a strength grade stamped on it?

It would be unusual to see a 4.5m, bridged, 225 joist "wave" so much under it's own weight. Also if it was purely undersizing alone I would expect to see a gradual deflection from the sides to a max deflection in the middle of the span. Not waves.

Timber came from local hardware. They're a busy outfit and their timber comes from a munster based timber stockist. It was stamped so I'm confident it's decent quality.

The deflections don't appear along the length of the joists, but from one joist to the other i.e. perpendicular to the joists. So I think the root of the problem is more that the joists were not installed evenly rather than them sagging etc.
I can see that the slabber had to start a new slab on some of these joist as the plasterboard probably wouldn't bend around.

Bonzo Delaney

We're the joists not all put in high side up then all you would have is a hollow in the ceiling often heard plasterers comment "it's easier to straighten a hollow than a hump"
Just putting it out there ,would a good plasterer bond out all the hollows to straighten the ceiling then skim all in straight.
Once of course the ceiling structure is solid.

rampantbunny

Bonzo Delaney wrote: »

We're the joists not all put in high side up then all you would have is a hollow in the ceiling often heard plasterers comment "it's easier to straighten a hollow than a hump"
Just putting it out there ,would a good plasterer bond out all the hollows to straighten the ceiling then skim all in straight.
Once of course the ceiling structure is solid.

Don't know what way the joists were put in bonzo. Fella was hired based on recommendations by two housebuilders and I saw two finished roofs he did. I didn't talk to the slabber to see how the ceilings worked out though. At some stage you have to put your faith in the tradesman.

I've plasterer coming in to see if it is something he'd straighten out with skim etc. I wouldn't like a thick layer of plaster on the ceiling to become an excuse though for there to be dimples/rough skim finish.

Drift

It does sound like an installation problem.

I'm not an carpenter so I don't know what the installation procedure should be but what Bonzo says sounds like sense. Maybe your carpenter didn't size/shape match the joists prior to installation?

It sounds like the slabbing is complete?

If the slabbing isn't done a metal suspended ceiling would solve the problem provide you have a few inches headroom to spare.

rampantbunny

Drift wrote: »

It does sound like an installation problem.

I'm not an carpenter so I don't know what the installation procedure should be but what Bonzo says sounds like sense. Maybe your carpenter didn't size/shape match the joists prior to installation?

It sounds like the slabbing is complete?

If the slabbing isn't done a metal suspended ceiling would solve the problem provide you have a few inches headroom to spare.

Plasterboard is in already. Will see what plasterer says. If he thinks it's too much to remedy with plaster, I'll ask metal ceiling guy what the minimum drop he can install is. If it's 1-2inch I'll go with that.

893bet

rampantbunny wrote: »

Plasterboard is in already. Will see what plasterer says. If he thinks it's too much to remedy with plaster, I'll ask metal ceiling guy what the minimum drop he can install is. If it's 1-2inch I'll go with that.

An expensive fix! That will 9+ euro per m2 for the metal grid, plus cost of reslabbing and plastering.

rampantbunny

893bet wrote: »

An expensive fix! That will 9+ euro per m2 for the metal grid, plus cost of reslabbing and plastering.

Not plastered yet. Might be able to isolate to one room.
Sound proof slabs used already which are more expensive than standard. Might leave them in place, metal ceiling underneath and standard plasterboard for finished ceiling. The hollow between the two might cause a drum effect with noise though..not sure.

Mahogany Gaspipe

In any stack of timber there is invariably a couple of lengths of timber that are bowed to such an extent that they should be left aside and not used. The remaining straight, or acceptably straight, lengths are then distributed through out the building, stood on edge, spaced and held in their position by the temporary nailing of a lathe on, and perpendicular to, the upper edge of the joists.

The joists should then be leveled throughout the building with a straight-edge lifting and shimming joists found to be low; planning joists found to be high and in some extreme cases building down the underside of those joist found to be high by adding rips of ply to their underside edge. Only now bridging should be installed.

The solution to your problem is to first clarify using a long straight-edge if the undulating ceiling is due to an anomalously high or low joists, it may by both.

I don't want to be too scathing with my language when I haven't seen the work first hand but from what you have described the problem stems from poor workmanship/installation of the joists and they are the components in need of correction.
Once you have established this have a chat with the Carpenter and get him to return and rectify the problem.
The plasterboard is easily removed to facilitate this.

rampantbunny

Mahogany Gaspipe wrote: »

In any stack of timber there is invariably a couple of lengths of timber that are bowed to such an extent that they should be left aside and not used. The remaining straight, or acceptably straight, lengths are then distributed through out the building, stood on edge, spaced and held in their position by the temporary nailing of a lathe on, and perpendicular to, the upper edge of the joists.

The joists should then be leveled throughout the building with a straight-edge lifting and shimming joists found to be low; planning joists found to be high and in some extreme cases building down the underside of those joist found to be high by adding rips of ply to their underside edge. Only now bridging should be installed.

The solution to your problem is to first clarify using a long straight-edge if the undulating ceiling is due to an anomalously high or low joists, it may by both.

I don't want to be too scathing with my language when I haven't seen the work first hand but from what you have described the problem stems from poor workmanship/installation of the joists and they are the components in need of correction.
Once you have established this have a chat with the Carpenter and get him to return and rectify the problem.
The plasterboard is easily removed to facilitate this.

Thanks MG. Not seeing your post until now but I actually used a straight edge across the joists on the attic side yesterday evening. Joists are 'up' in places on the attic floor but unless i measure the depth of these joists I can't tell if they are high on the underside. Can't use straight edge underneath unless I remove plasterboard, a 2 man job.

The tradesman in question will not be on site again. There were other untidy finishes. This latest issue confirms the quality of his work. I'd rather do the work myself than go through the torture of trying to get him to fix.

Not to go on a rant, and not trying to tar everyone with the same brush, but I'm still waiting on that one trade to come onsite and do a job properly. From the early stages I began to expect fcuk ups. That's probably why I'm not hugely disappointed or angry with this latest turn of events.

Mahogany Gaspipe

rampantbunny wrote: »

Thanks MG. Not seeing your post until now but I actually used a straight edge across the joists on the attic side yesterday evening. Joists are 'up' in places on the attic floor but unless i measure the depth of these joists I can't tell if they are high on the underside. Can't use straight edge underneath unless I remove plasterboard, a 2 man job.

The tradesman in question will not be on site again. There were other untidy finishes. This latest issue confirms the quality of his work. I'd rather do the work myself than go through the torture of trying to get him to fix.

Not to go on a rant, and not trying to tar everyone with the same brush, but I'm still waiting on that one trade to come onsite and do a job properly. From the early stages I began to expect fcuk ups. That's probably why I'm not hugely disappointed or angry with this latest turn of events.

I actually failed to mention in my post that it is acceptable to use joists that may have a bowed. I think it may have been mentioned by a previous poster that the joists are sighted along their length and then positioned crowned up. Say for example in a 10 foot run if a joist was a 1/4" bowed that would be acceptable to use.

You can still use the straight-edge underneath the plaster board.
You need to establish whether the joist are bowed up or down. If they are bowed up the plaster can bond them out. He may make it out to be a big job but it isn't really negotiate a price say per bag of bonding it takes.

If the joists are bowed down the best remedy would be to remove the plasterboard is covering those joist and plane off the required timber to true up the ceiling. It is the job of the Carpenter to do that.

ht9zni1gs28crp

rampantbunny wrote: »

Not to go on a rant, and not trying to tar everyone with the same brush, but I'm still waiting on that one trade to come onsite and do a job properly. From the early stages I began to expect fcuk ups. That's probably why I'm not hugely disappointed or angry with this latest turn of events.

I feel your pain...Its frustrating as a self builder and this sums it all up. You end up accepting a lot of sub quality stuff and questioning your own beliefs. A lot of the trades have their main eye on main contractor builds and self builds are a bit of a holiday for them. I had one decent trade on site which was a blessing. You couldn't stress him, he evoked a sense of calm in the whole whirlwind of finishes. Anyone want a recommendation for plastering then PM me.

PROJECT K

+1
I had high expectations at the start of my project which due to unbelievable incompetence, were reluctantly lowered. As above I eventually came across an 'unlikely' local builder who turned out to be the saviour of the project - not that he was particularly up to speed on low energy building etc but was willing and eager to learn, took his time and did things right. Has restored my faith a little bit but I find myself doing more and more of the work myself just so I know its done right...how long will it take for builders to realise the days of botching and covering up are over! If anyone performed at the same level in any other industry they wouldn't last long, how do these guys get work I don't know! Ok rant over, good luck with the remedial work RB hopefully you find a simple solution, draw a line under this one and hope its your last!

rampantbunny

PROJECT K wrote: »

+1
I had high expectations at the start of my project which due to unbelievable incompetence, were reluctantly lowered. As above I eventually came across an 'unlikely' local builder who turned out to be the saviour of the project - not that he was particularly up to speed on low energy building etc but was willing and eager to learn, took his time and did things right. Has restored my faith a little bit but I find myself doing more and more of the work myself just so I know its done right...how long will it take for builders to realise the days of botching and covering up are over! If anyone performed at the same level in any other industry they wouldn't last long, how do these guys get work I don't know! Ok rant over, good luck with the remedial work RB hopefully you find a simple solution, draw a line under this one and hope its your last!

I'll be drawing a line under it (and it'll be a straight one) in the same fashion as has been done with other jobs. I don't want to think about what these lines are costing me overall. This must be what the 10% contingency in the budget is for..not for my overspend on better products but for remedial work.

ht9zni1gs28crp

I think you also need an 'argument' or tipping point early on with tradesmen to set out who is boss. Otherwise they will keep telling you how to do things and that they are the expert. When in reality they all have a lot to learn, ESPECIALLY on low energy or Passive builds. yet you would think they would be keen to learn!

One of my trades got an awful shock when I counter billed him for resulting extra work that they had done wrong. Okay it never went to full fruition but a warning was laid down. Some of the arguments that came out of their mouths were unbelievable. I think 95% work best under full supervision only from main contractors, and they happy to clock in and clock out...

Armchair Andy

Any outcome yet OP?

rampantbunny

Armchair Andy wrote: »

Any outcome yet OP?

Haven't tackled it yet. Put ply on attic floors yesterday and it didn't seem to rock or sink too much on the joists. Will hopefully have it remedied this week.

rampantbunny

Armchair Andy wrote: »

Any outcome yet OP?

Haven't tackled it yet. Put ply on attic floors yesterday and it didn't seem to rock or sink too much on the joists. Will hopefully have it remedied this week.