Advice on buying a brand new home > Snagging and defects

NHBC standards for chipboard floors on I-joists?

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Mugen:
I bought a 4 bed detached from Redrow Homes (big mistake) around 2 years ago and like many, I have had numerous problems with the workmanship and have had to endure some appalling customer service!

One of the main problems we have is with creaking/cracking noises from floors/ceilings. Basically, when someone is walking around in a room on the first floor you can hear some kind of creaking within the room but at the same time these noises produces cracking type noises in the room directly below (appears to be from ceiling).

The floor construction is 22mm thick chipboard set on 240mm deep x 45mm TJI style timber joists set out at 600mm centres. It has been discovered that the boards have not been fixed down properly e.g. random patches of glue on joists, glue on the boards but completely missing the joists and like the odd screw somewhere. Limited presence of noggins, noggins too short, and overall poor workmanship.

Does anyone know what the NHBC standard/specification for fixing chipboard floors?
They should be glued and screwed?
Noggin requirements?
Any other information that I should be aware of?

New Home Expert:
The relevant NHBC standards regarding chipboard flooring are:
"6.4 - S14
Flooring shall only be fixed when the dwelling is substantially weathertight
6.4 - S15
The length of nails should be 2½ times the thickness of the decking.
The ends of adjacent boards should be square. Joints should be staggered and supported on noggings or joists.
Temporary wedges and packings at the perimeter should be removed after the floor decking is complete.
6.4 - S18
Chipboard flooring shall be of the type and thickness specified
Only moisture-resistant, Type P5 chipboard to BS EN 312 should be used for flooring. Joist centres should not be greater than 450mm for board thickness of 18/20mm and 600mm for boards 22mm thick.
6.4 - S19
Chipboard flooring shall be securely fixed
Chipboard should be supported and fixed in accordance with manufacturers' instructions, using either
flat-headed ring shank nails minimum 3mm diameter and of length 2½ times the thickness of the chipboard, or screws.
Edges at room perimeters should be supported on joists or noggings.
Fixing centres to joists should be:
200mm - 300mm centres around the board perimeter
400mm - 500mm centres on intermediate supports.
Expansion gaps should be not less than 10mm wide where boards abut a rigid upstand. For larger areas of boarded floor a wider gap may be needed at upstands and intermediate expansion gaps equal to 2mm per linear metre of floor provided.

Tongued and grooved chipboard:
Boards should be laid with long edges at right angles to joists
Short edges should be supported on joists or noggings.
Projecting ends of boards should be cut back to form a butt joint on a joist.
To reduce squeaking, tongued and grooved joints between boards should be glued and the boards should be glued to the joists. A suitable polyvinyl acetate (PVAC) adhesive should be used."


The standards say "should" be glued not "must" be glued.
TJI joists must be installed strictly to the manufacturers' guidelines and design.
It may be that the joist spans are too large or joist section is too small, meaning you get excessive deflection in the joists of the larger rooms 
It would also be useful for you/your engineers can get to see a copy of the TJI floor joist design.

Mugen:
Thanks for the reply.
I know the joist manufacturer is Steico so will need to check out the specifications!

Regarding "TJI joists must be installed strictly to the manufacturer's guidelines and design"

I am just wondering would it be possible to post the extract along with the section numbers as it will come in handy when I argue with Redrow and the NHBC?

New Home Expert:
The NHBC standards state:
"SITEWORK STANDARDS
6.4 - S1 All sitework shall:
(a) meet the Technical Requirements
(b) take account of the design
(c) follow established good practice and workmanship"

6.2 - S1 (with regard to timber frame components) states:
"All relevant information in a form suitable for the use of site operatives should be available on site before construction starts including:

* full set of drawings
* materials specification
* fixing schedules
* nailing details
* manufacturers' recommendations relating to proprietary items."
You shouldn't need to quote specific NHBC standards as the industry knows that manufacturer's designs and recommendations must be strictly followed.

TaylorWimpeyDidThis:
Hi Mugen

We have exactly the same issue with our Taylor Wimpey House - all of the issues with the floors were noticeable when we moved in 2 months ago and have got significantly worse as the house has "settled"

When someone is walking around upstairs, the noise is a very distinct and loud cracking sound and when walking on the thresholds of the rooms upstairs, the cracking and creaking is deferred a few feet away.

One of the smaller rooms has Amtico installed and you can physically feel the movement in the floor, as well as hear it! Interestingly, we have been advised that to sort the other rooms upstairs, the carpet can be lifted and fixed from above. But where Amtico is laid, rather then remove and reinstall the Amtico (at additional cost) - Taylor Wimpey will remove the ceiling underneath and go in from the ground floor and then redecorate the ceiling - although I'm scratching my head as to how they will fix the boards down from underneath?

Within a week of moving in, the outlines of the floorboards could be clearly seen through the plaster ceiling in the living room, even though the room above is not used!

We know that our house was exposed to very wet weather before the roof went on and also that it was rushed - so I guess only a closer look will determine what lies beneath.

I'd be very interested to hear how you get on, please keep us posted

http://www.youtube.com/watch?v=1Zr8s7gsrKs


 :)

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