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Floor bounce - PosiJoist Floor Vibration checks


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well I've just re-secured all our strong backs - its made Q a difference.  Also added 18mm ply either side of the metal web joists - also a positive impact.

 

After reading on this forum - I also secured the ends of the joists again so they are rock solid.  All helps me sleep at night and hopefully has a positive impact on the floor as well!

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  • 1 year later...

Hi Dave,

 

Yes i believe so the builders cut hatches isn't it supposed to be fixed upright and against the top of the joist!

 

I think the flooring or ceiling needs removing to inspect in full!

 

A carpenter had a quick look on the landing and the flooring is unlevel by around 10mm using a 6ft level. The ceiling below is the even worse!.

 

Thanks

Gary

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20 minutes ago, Gary Davies said:

...

I am having an absolute nightmare with a new build home the flooring making awful cracking/clicking noises and just cant get the builder to resolve.

...

 

First post: welcome, therefore.

.... you beat me to it, cross  post    - could you show us how out of level it is....?

10mm over 2000mm .... Ouch!

I haven't got a clue how to remedy it simply... our carpenter's here, so I'll go and ask him now.

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Thanks!

 

The NHBC confirmed it was a fault however they didn't look in the hatch or check the floor level they just listened to the noise. There schedule of works says to cut a strip of floorboard up across the center of the house and then install noggins across the joists!?

 

Both NHBC and the Builder are refusing to do the repairs and NHBC will only cash settle and by the above i think they are just guessing!

 

Thanks

Gary

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13 minutes ago, Gary Davies said:

...

Both NHBC and the Builder are refusing to do the repairs and NHBC will only cash settle

...

 

If the cash settlement is a complete and satisfactory repair, then thats the best of a bad job. But what  might satisfactory mean?

To my inexpert eye, just putting noggins across the centre of the house would not be satisfactory.

 

Maybe this is a case for an independent surveyor's report and recommendation?

 

 

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Yes its a tricky one £300k for a 2 bed semi you would expect it to be of some quality!

 

Its not the only issue either! I have spoke with a Solicitor who advised breach of contract is definitely on the cards.

 

Would you recommend a structural survey? Will they need the flooring up to do the survey? Sorry i am a First time buyer so not to clued up with this stuff!

 

Cheers

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Noggins will not fix this - sounds like the strongback has been missed from the floor joists (assuming metal web) or the joists themselves are not installed correctly.

 

I would be taking ceilings down, not floors up, as the floors should be glued or bonded to the joists as they form part of the structure.

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Hi Peter,

 

Yes metal web posi joists the builders cut hatches in the flooring which has created more creaking and clicking noises.

 

The flooring is moving quite badly upstairs and bounces when not even jumping shakes the wardrobe and drawers etc. (I'm not saying it should be solid and not flex!)

 

One carpenter has quoted to lift the floors and when i asked how he would do that he said cut around the stud walls!! I know the floorboards don't look fitted correct some appear to not have the glue and looks like they used ring nails which some have missed the joists below!

 

His suggesting the following

 

Take up floorboards

Replace and fit with correct glue

Take down ceiling 

Clip up loose pipes 

Raise Joist

Re board and plaster

 

Thanks

 

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thats a lot of cost and work there.  The quality of a lot of new builds is bad - normally down to poor trades + poor management.  I'd want all those strong backs securely attached to those pozi joists to start with - that will help.  No pipe insulation & no sound proofing either.  Are you sure the joists are properly secured at the ends of the joists?  I had to go back and sort ours out - after some on here suggested it, and it did help.  Sad that neither the builder or NHBC want to sort it out.  Good luck.

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1 hour ago, Gary Davies said:

...

not 100% sure if the joists are secured correctly at the ends is the best way to check this to get the ceilings down?

 

Unfortunately , yes.

You might get away with cutting an inspection hole for a random sample of joists , making a generalised judgement about how adequately  they are fastened and then making good as necessary.

 

In the preceding posts, I smell aggro.

It might be as well to get an independent surveyor (RICS ?) to write a proper report, and then present that to whoever needs to see it. It'll take away all the you-said-she-said-thats-not-needed nonsense that you appear to be facing. And get the surveyors fee added to the bill.

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3 hours ago, Gary Davies said:

 

One carpenter has quoted to lift the floors and when i asked how he would do that he said cut around the stud walls!! I know the floorboards don't look fitted correct some appear to not have the glue and looks like they used ring nails which some have missed the joists below!

 

 

Pulling up the D4 foam glued floorboards would damage the joists, don't do this. Glue plus nails is standard practice, a few nails that missed the joists is fairly typical providing 95% found their target. The absence of sound proofing material between the floors looks like a significant transgression of building standards.

 

My advice would be to:

 

Find a surveyor who is experienced at NHBC disputes. He will help clarify what build anomalies are acceptable and what you should pursue e.g. whinging about a few off target ring nails will undermine the credibility of your claim with NHBC.

 

If the surveyor thinks the problems are substantial get a plasterer to quote for pulling down and reinstating the ceiling.

 

With the ceiling down you can spend a week cataloging the noise sources and then the surveyor can produce a fix list.

Edited by epsilonGreedy
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I would start buy cutting an exploratory trap in the ceiling to have a better look.  Squeaking and creaking boards, even with a missing or not secured strongback says to me not glued, just laid dry and nailed.  If that is the case the boards need to come up, which would allow you to fix the strong back, and then re lay the boards glued and screwed.

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You need to take action against NHBC.  Their tolerances for floors are poor and there is a fair bit of allowable deflection.  If they are acknowledging it as defective, the remedy will be very disruptive or impossible depending on the ground floor walls / first floor joist layouts.

 

Explain that you are unwilling to accept a cash settlement.  You need to go in hard with them and keep going.  Come back to us as many times as you like until you get it resolved to your complete satisfaction.

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16 minutes ago, Mr Punter said:

You need to take action against NHBC.  Their tolerances for floors are poor and there is a fair bit of allowable deflection. 

 

 

I wonder if @Gary Daviescould obtain a copy of the technical floor design from the joist supplier shown in the photos?

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Gosh! I know how must be feeling. I'm still trying to teach my 8 year old boy after nearly 3 years living in my house to try and walk gently on the first floor as it flexes so much. Not ever checked the level though, not to worried about that, more concerned about sag - dare not check that.

 

Got no where with the builder, floor joist supplier, floor joist software developer all passing the book. Still peeves me I'm just glad my home office is in a different part of the house and we are rarely upstairs except for sleeping

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  • 8 months later...

Reading this thread is making me regret switching from regular joists to posi joists in my spec. The only reasons for the switch were various people on this blog praising the ease of installing MVHR ducting through posi joists, but that was when I wasn't expecting my builder to say that he had never worked with posi joists before. Given I will be using mainly 75mm diameter radial ducting, query whether I should just switch back to traditional joists. Won't those be thick enough to withstand 75mm holes? I really hate springy floors and want it to feel rock solid.

 

Maybe I should have done what @joe90 did which i think was go for JJI joists, with those metal frames for hole supports, but that just seemed like extra work and at over £20 plus VAT for the metal hole support, seemed expensive.

 

I just feel like I'm damned if go for Posi joists and damned if I don't. So given builder is more comfortable with regular joists, perhaps reverting to that is the answer. Or maybe the answer is to ensure builder studies the installation detail of posi joists and follows it religiously. He is very capable, so there is no rational reason for me to be worried I think. Is this something a Building Regs officer would monitor, or do i need to do it myself? I would ask my architect, but he hasn't got experience with posi joists either. The SE was obviously familiar with them, but not sure that sort of supervision comes under his remit.

 

I don't think anything has been ordered yet, but it's happening this week, so not much time to decide.

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Only my personal opinion, but i would go for posi everytime. I usually up the spec width wise, rather than depth. Ie; go above minimum spec. Floor above , glue and screw. Rock solid floors. Most of the timber i find, is wet, shrinks like hell, twists like hell, and is generally crap. Engineered timber all day long for me.

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19 minutes ago, Big Jimbo said:

Only my personal opinion, but i would go for posi everytime. I usually up the spec width wise, rather than depth. Ie; go above minimum spec. Floor above , glue and screw. Rock solid floors. Most of the timber i find, is wet, shrinks like hell, twists like hell, and is generally crap. Engineered timber all day long for me.

Thanks @Big Jimbo. By upping the spec do you mean laying them at 400 centres rather than 500 or 600, or do you mean going for wider joists, or both?

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1 minute ago, Adsibob said:

Thanks @Big Jimbo. By upping the spec do you mean laying them at 400 centres rather than 500 or 600, or do you mean going for wider joists, or both?

A bit of both, i tend not to increase the height of the joists, as height always seems to be an issue. I usually work out what size wood i beams i need for the spans. This will give me the minimum acceptable for building control to pass. I usually purchase the next width up in size (for very little extra cost) and look at my layout as sometimes moving a few of the joists closer together can make work to come after easier. So in effect if i was using 15 joists, i might end up using 17 joists. When i sent them off to the joist companies for confirmation, i always get told that i have over engineered it. (I'm happy with that, i don't like just minimum) Always screw and glue the floor above, and joking aside i have ended up with better floors than some block and beam, and with less bounce.

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3 minutes ago, Adsibob said:

Thanks @Big Jimbo. By upping the spec do you mean laying them at 400 centres rather than 500 or 600, or do you mean going for wider joists, or both?


Can do both but tbh the quickest way is just close them down to 400mm centres with the same depth; secure the ends of every hoist properly; ensure all floor and ceiling noggins are installed with z-clips; ensure all boards are glued with D4 to every joist and every joint. 
 

That will give you the most solid floor with the components properly installed. 

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I used JJI joists which are engineered timber using osb as the web, these will take holes cut fir MVHR (as long as you put the holes where they stipulate, which is not difficult. ) We had joists specced as 600mm centres but put them In at 400 ctrs (as I don’t like bounce either). Engineered timber anyway is straighter, less twist/warp, dead flat. 
 

here you go, all you need to know (point your builder at this) https://www.jamesjones.co.uk/assets/downloads/subdir/Technical manual 5th edition.pdf

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