Author Topic: NHBC standards for chipboard floors on I-joists?  (Read 53509 times)

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new_home_17

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #30 on: September 26, 2019, 10:14:40 am »
Hi, hopefully resurrecting this old thread will be ok...

I bought my Redrow home 18 months ago and have been dogged by the cracking sounds from the ceiling/floor structure since around 2 weeks into the ownership. Initial barrier was the absolutely appalling customer service which explains most of the reason it is still not sorted.

We have a 4 bed detached and the noise is happening in the living room (below bed 1) and kitchen diner (below bed 2, directly behind bed 1 (same joists). We don't seem to have it in the diner part of the kitchen/diner which is below the bathroom and bed 4.

Like others, the initial work was to screw the ceilings back in both rooms, hundreds and hundreds of screws and the initial result was positive. For a couple of weeks all was quiet, great! Then little pops/snaps appear, then more, then more, then its multiple loud cracks under every footstep again.

Recently we had the living room ceiling pulled down and refitted with resilient bars in between. I'd say that about 90% of the cracking sounds have gone but I'm not convinced it will stay that way. Now when someone walks above you can hear like a twist noise. Its hard to explain but I imagine that the joist movement is still there but now its fighting against the bars. I suspect the noise will return.

Kitchen/bed area needs attention and I'm wondering if there is any progress on this and what the correct repair should be. It seems quite clear Redrow Homes don't understand what the problem is. This thing that also surprises me is that they seem to be convinvced its the ceilings yet there's no visible cracking or nail pops or anything. If it was moving and causing the sound it must show signs of it??

In a previous post it suggests resilient parts are not the solution. For me it is not addressing the root cause. One thing we immediately noticed (and bought to Redrow's attention) was how springy the bedroom 1 floor seemed. When in bed and someone walks past it shakes. We had a little vase on top of a chest of drawers that would wobble when we walked past it... they dismissed this as normal.

The other question is whether I should get NHBC involved?
Redrow Homes are engaging the issue now but should I log it with NHBC anyway?

Thanks in advance.





New Home Expert

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #31 on: September 27, 2019, 10:32:40 am »
Please do log it with the NHBC.

Then read what is in this link which details what is causing the problem.
http://www.gpda.com/uploads/Joint_statement_on_cracking_sounds_from_ceilings.pdf

The NHBC are aware of this so should be able to tell Redrow Homes what they have to do.
Resilient bar isn't the answer.

I would also question the deflection of your floor joints, if you notice it, it certainly isn't "normal" whatever any housebuilder tells you, which most of the time is an outright lie to avoid doing expensive extensive remedial works.

Make sure your joists aren't bodge stiffened like these!
The strength against deflection is in the web not the top or bottom flange so any extra timbers should have been full depth!  Clearly no manufacturer would sanction this work.

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new_home_17

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #32 on: September 30, 2019, 07:45:11 am »
Thanks a lot for the reply.

The noise is awful but to my absolute amazement when the Constriction Director visited last week he said he would not be sanctioning any work in the kitchen as he felt what was done in the living room (resilient bars) had improved it to an acceptable level. He told us to contact the NHBC and he'd only do the work if they told him too. The arrogance is off the scale.

There's a number of issues with that. 1) He said all along he'd repair both ceilings 2) the kitchen is absolutely no different following work in the living room. 3) There's no technical reason why the living room work would affect the kitchen.

So today we'll contact NHBC to get them out.

What exactly is the repair for this? At the start of the this thread it was suggested that replacement of the floorboards. I know someone else who had the same issue and he had a combination of herringbone fixings to reduce joist deflection and extra screws in the plaster board.

Attached is a short snipped of the issue, when walking in the bedroom (bed 2) just above). Is there any scenario in this world where someone sane could listen to that and conclude its acceptable? I really wish there was a mechanism for house builders to be fined for frivolous referrals.

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #33 on: September 30, 2019, 09:14:55 am »
What is needed is the statutory New Homes Ombudsman, but this government looks like it is giving control to the industry to crate their own voluntary new homes ombudsman - like that will work!

If you read the pdf what is required is the plasterboard and adhesive cut back below the floor joists.
In addition, stronger (deeper) joists or more joists fitted closer together, or existing joists properly stiffened to manufacturer's requirements may also be required.
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new_home_17

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #34 on: September 30, 2019, 10:16:59 am »
This shows the situation with the new ceiling partially installed.
Did you have a watch/listen to the video? What did you think. It seems worse than a lot that I’ve seen which makes it very surprising they think it’s acceptable.

new_home_17

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #35 on: September 30, 2019, 12:22:26 pm »
Sorry to add another question before the last one was answered, but its about upstairs partitioning/stud wall.
Before replacing the ceiling in the living room the builder suggested cutting the downward fixings from the wall into the floor that separates the upstairs 2 bedrooms that have the problem. They removed the skirting board and then with a hammer and bolster cut through the fixing by bashing under the lower stud beam against the floor. Not only did this not have any positive impact on the cracking noise , they managed to slice through the power supply of the plug socket that was staring them in the face.
Is it a building regulation that the partitioning wall be fixed down into the floor? Have they now made it non-compliant?
In terms of a stiffness/flexing root cause taking out these fixings will be reducing the rigidity of the upstairs structure and increase the likelihood of the cracking noise.

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #36 on: October 02, 2019, 09:18:27 am »
You are dealing with idiots! 

The stud wall partition needs to be fixed top and bottom otherwise it will move out of plumb.

So many bodges attempted to avoid doing the more expensive remedial works required such as I have suggested before.
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new_home_17

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #37 on: October 03, 2019, 09:30:07 am »
Would I be right in assuming that a proper solution to the problem looks something like this?



I found it on another forum and the poster confirmed that it resolved the same issue I have.

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #38 on: October 04, 2019, 06:59:02 am »
Yes this would be a solution to stiffen joists spaced too far apart and/or not deep enough and greatly reduce the deflection in the middle third of the span. Done properly in conjunction with manufacturer's design and instructions - with glue and screws too.

It would be better if these I-joists were all mandated in warranty standards to be at 450mm centres and perhaps this would then mean no further issues like yours in new homes.

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new_home_17

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #39 on: October 04, 2019, 08:53:54 am »
Mine are actually 450mm spaced, I measured them when the ceiling was down.

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #40 on: October 05, 2019, 10:05:02 am »
Then perhaps the joists have been weakened by cutting and drilling the flanges or holes in the web in the wrong place?
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Eggy12

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #41 on: December 03, 2019, 05:21:05 pm »
Just reading through this as I've been put to task to resolve this issue in new build site I'm working on.

I'm the making good man for the plastering company and we are getting blamed for it!!!
From first time I looked into it I said screw down floorboards from above, they have not and instead asked me to add screws across the ceiling, made no difference. Then got me to cut away 150mm of ceiling right along the edge and 100mm of the dabbed wall along the length (no dabbing compound touching underside of joists as ceiling board stopped it)and has made no difference. They did get a chippy in and took up a small area of flooring and added a couple of X style noggings and still no difference.

Noise comes from centre of room, no screw pops and no joint cracks in ceiling so I'm going along with wet when installed and just shrunk when home heated up. One thing I did notice was one joist seemed around 640mm centre from others so could well be this one as in centre of where the noise is?

They want to rip ceiling out and install resilient bar and I'm saying if the noise is from above ceiling (ie floor boards) resi-bar won't fix it as said in this thread also. Joists are built into the wall.
Will post up if it gets resolved and I'm still thinking it's the joists moving

Eggy12

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #42 on: December 04, 2019, 11:53:20 am »
It is almost certainly caused by too wide centres for the joist spacing, causing excessive deflection in the centre of the span (middle of the room)
NHBC requirements are 600mm maximum anyway but unless the joists are very deep, I would suggest 450mm centres is what was designed.

Try to get hold of the manufacturer's design drawings and check joist centres before ripping anything down or out!

There is no point in adding resi-bar to ceilings until all possible causes have been investigated.
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Eggy12

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #43 on: December 04, 2019, 12:00:44 pm »
Joists move at ends around blockwork that's supposed to hold them, noggings easily moved/wriggled with hand. It's the glue cracking under pressure either from floorboards to joist or where joined on above and under I bit of joist. Get the same crack when pushed up from below mostly near wall end. Needs new noggings and glue, screw together in my opinion but I'm just the making good guy 😎

gdavies07

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Re: NHBC standards for chipboard floors on I-joists?
« Reply #44 on: December 09, 2019, 11:22:14 pm »
Apologies for hijacking this thread!

I have a very similar issue where weeks after moving in I noticed the upstairs had creaking and knocking noises on both bedrooms and the landing. I reported this to Croudace Homes the developer and got fobbed off a few times saying its normal etc.

Croucdace then attempted to screw the floorboards down and this failed to resolve the issue so they looked at screwing from the ceiling downstairs which also failed to resolve this issues.

The next attempt they cut holes in the floorboards in the different rooms and they started to say the strongback wasn't fixed tight to the joist as you can see they did a really bad job on the floorboards and the hatch was just glued back.

NHBC have approved a schedule of works however both the Croudace Homes and NHBC are refusing to do the work and want me to find a contractor to carry out the repairs. My issue is here we don't know what the issue is and the first contractor has suggested the floorboards have been laid incorrectly in the same direction as the joists which is most likely causing the issue and would be very difficult to lift the floorboards and relay due to the stud walls being in place.

Sorry as you probably can tell I have very little knowledge on this so I'm struggling to find the best way forward!

Appreciate any help/advise.

Thanks
 ;)