Carpentry & Joinery Question

New build - floor boards installed with only 3 nails per board (!?)

I am looking at buying a new build property and when looking around, the (un-carpeted) upper floors are boarded with tongue and groove chipboard floorboards.

However the alarming thing, in our mind is that they have only been fixed with a few nails - in many cases only 3 nails per rectanglar board (not even 1 per corner!) .

After quite a lot of probing and asking, the sales woman tells us they install them using a 'no nail system', sticking them down with a mastic type adhesive, and thus only using minimal nails.

Common sense and best practice makes me think that you'd use the mastic AND then use planty of nails to secure the boards. When I've researched it everything I've found says have fixings spaced with gaps of no more than 300mm along the joists.

What I'd like to know is is this correctly installed? Should we be worried? They claim they have the NHBC, but I'd appreciate any comments you have on this.

The 2nd thing, and this is the reason we are concern about the floorboards, is because in the lounge (middle floor of 3) across the width of the room and about 6 feet deep, all of the boards have been ripped up and replaced with big ply wood sheets. The sales woman doesn't know why its happened, we think because of levelling, but the way they have put the ply wood back in is ropey at best. Firstly they haven't replaced with the chipboard unit, but much bigger ply sheets, and to one side they have then put the ply down, and then had to cut holes out of it (obviously didn't get it levelled out) and it has been nailed back in place. Looks like a patch work quilt. Plus one long very thin piece, which I don't think is good, plus a couple of the boards move when you put weight on them. Finally, they have a few big gaps where the ply meets the rest of the chipboard, and the large gaps have a mastic looking material filling it in - about 3/4 of an inch wide in some places.

I'd appreciate your comments on this - why would it be ripped up? How should it be replaced - is ply ok, or a quicker, easier way to get the job finished and move on?

Is all of this typical of a large nw build housing developer?


Thanks Steve, really great advice. In terms of installing the floor boards generally - I am awaiting a response from their Technical Dept to tell me the exact method they use. However, if using a mastic or no nail system, surely when running a bead of glue down the T&G joint, when joinedt the glue would be sqeezed out a bit so you could see it had been glue. When we looked around and looked at the floor we couldnt see any sign of glue whataoever - surely wthis means they've neither not glued it at all or not done it correctly?!

8 Answers

Best Answer

Hi in answer to your questions.
There is a new mastic/clue on the market which if you put a bead on the floor joist before you lay the floor board it is supposed to stop squeaks and also stick the board done. Perhaps they have used this, but personally would fix the boards down with ring nails or better still screws at 4 fixings across joist per board width.

If some of the floor boards have been removed it is more than likley that they have had a leak. But it doesnt make sense why they had fitted plywood instead of putting new T&G chipboard back.To use plywood is more work as you should put perimeter noggins between the floor joists around the edges of the chipboard flooring.
I would advise if you are serious about buying this new build you should insist that the flooring has more fixings and that the plywood is removed and replaced with T&G chipboard also get a qualified person to check the work after they have finished.
If they refuse to carry out your request and loose the sale of the property for a days labour and a few materials, I would walk away and look for another property.

Hope this helps and good luck

Andover Interiors
kitchens,Bathrooms and Carpentry.

Answered 12th Apr 2011

Andover Interiors

Member since 17 Feb 2011

On our new build contracts we use the 'weather deck' system in which the boards have an adhesive that is gun applied similar to mastic, all the boards then have pva applied to the t&g joints, with this system only the perimiter requires nailing. This system was adopted by most of the main house builders as it elimates the squeaking caused by board movement on the nails when the joists shrink slightly as they dry out on new build.

Answered 15th Apr 2011

D.S.Lewis Building and Carpentry Contractors

Member since 21 Nov 2008

Hi this is not a new thing I've been doing it for the last 7 + yrs it's basically a floating floor but the mastic stop squeeking. Good luck on your purchase. Brian

Answered 18th Jul 2012


Member since 28 Mar 2012

Like the others have said, it is a system commonly used with man made tji joist systems it is a resin glue which foams up to guarantee no squeaking. The other plywood is only ever used in wet areas but this does appear from your description that it is a ill fitting repair job

Answered 13th Apr 2011


Member since 18 Sep 2010

I agree with Andy, if this is the standard of finish on what's visible! I would ask myself what's the standard of work like that can't be seen? It's all down to mindset, some people take pride in what they do. This firm clearly don't. I'd walk away.

Answered 3rd May 2013

D2 Plumbing & Heating

Member since 18 May 2011

that is fine its a silent floor system the nail in there are just to stop them moving untill glue gone off

Answered 12th Apr 2011


Member since 31 Oct 2008


What a load of C**p

8' x 2' boards fixed at a minimum of 600 c/s (spanning across joists)
300 c/s along joists.... basically 15 screws per board, glue or no glue.

Low end market housing ring nailed, high end market screwed.

a Mastic is applied to joists to prevent squeeking but this is nothing new, this was introduced well over 10 years ago but not every build company used it due to cost. When used it still needs to be fixed down.

What can I say....

Depends on the tradesman/company..... handyman, craftman or master craftman!!!!

Wow 3 fixings.............

Kindest regards

Aura Carpentry

Answered 24th Apr 2012

Aura Carpentry

Member since 9 May 2011

Hi there,
The floor boards. At all construction sites cross country, they use the glue which stops leaking and moving boards, and actually they stick 4 nails, just to stop moving boards, untill the adhesive action will apply. And this technology is definetely according to actual NHBC standards.
What about the replaced chip board with the ply wood. It's hard to explain their actions, I suppose it could be a leak, or any kind of the damage that forced them to strip off the sheet of chip board... However replacing with plywood is definetely not according the NHBC standards (probably they have ran out their stock of boards, and replaced with what they had)
I would recomend you to chase them up for the reason of replacement, and insist to replace this ply with propper floor board.
Otherwise, just turn around and look for another offer. It is more likely that in such cases they've done more doggy jobs than just this issue you are worried about.

Answered 14th Jan 2016

S & Q Solutions

Member since 7 Oct 2015

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