Builder has fixed 9.5 boards to stud walls/ceilings

[tfish]

My builder has fixed 9.5mm handy boards to the stud walls in my extention.. i thought 12.5 was normally used for this, he says he always uses it... iv read it can be prone to saggin on ceilings at this thiness.

Should i cause a fuss and get him to remove it (i didnt specify him to use 12.5 but didnt think i had too) and replace it or should i just board over it with another 9.5 and skim?

or is 9.5 ok for internal stud walls?

 

[Richard C]

My builder has fixed 9.5mm handy boards to the stud walls in my extention.. i thought 12.5 was normally used for this, he says he always uses

Yes its standard practice to use 12.5mm minimum on stud walls; sometimes thicker or specialist boards are required depending on where the stud wall is located or if a new loo is involved. Whatever he normally does is irrelevant & I would be a bit concerned about the rest of what he’s doing for you; what size timber has he use for the stud partitions? I much prefer to use blockwork for internal walls but on stud partitions, I would only ever use 4”x 2”. I would never use 9.5mm boards & none of the guys I know would either unless there were extenuating circumstances.

Should i cause a fuss and get him to remove it (i didnt specify him to use 12.5 but didnt think i had too) and replace it

I wouldn’t accept it &, IMO, you shouldn’t have had to specify 12.5mm & I can’t really fathom why he’s done it. The price difference is marginal & I, along with all the others I know, only use 12.5mm on ceilings as well now; either he’s not very strong & has a problem lifting them or he’s got a few pallet loads he got “on special” tucked away somewhere!

or should i just board over it with another 9.5 and skim?

Personally, I wouldn’t accept that either.

or is 9.5 ok for internal stud walls?

IMO, no it's smacks of cheap & nasty!

 

[gregers]

just gota agree with richards comments here.
ive never heard or seen anyone using 9.5mm board on a stud???
especially handy boards,wouldve thought you would get more cracking over time because of the extra joints used?.

 

[tfish]

Is there anywhere in building regs that says this is so, I can confront him a lot easier if I can produce something other than "its normal practise" to him. Thats basically what I said but iv got nothing to say it is???

I checked my plans and theres no spec for the stud walls either..

Thanks for the replys


Edit: Is there anything in fire regs to mention plasterboard thickness on ceilings?

 

[Richard C]

especially handy boards,wouldve thought you would get more cracking over time because of the extra joints used?.

Sorry I completely missed that bit; makes him look even more suspect. This is a good source industry standard reference;
http://www.british-gypsum.com/pdf/WB09_Non-loadbearing_timber_stud_02.pdf
You won’t find any reference in there to using 9.5mm wallboard on a stud wall.

In addition, building Regs. require minimum acoustic insulation standards under certain circumstances which, in turn, affect which boards you can use, which you will also find I the above link; sorry to say it sounds as if he’s either doing it on the cheap, doesn’t know or conform to industry standard or is just a complete muppet. It’s rather late now but I will have another dig around tomorrow to see what I can find but in the meantime, can advise what rooms (use) does your extension comprises?

 

[tfish]

lounge area, bedroom (stud wall sep this from the lounge area so sound would be a issue... and............ on suite with shower, loo AND extention to old bathroom which will include a bath, all done in this 9.5...

Iv got a good relationship with him and the rest of the work is spot on, its only cos i know a little AND i he isnt doing the plastering iv noticed this... so i am reluctant to make him take them off/replace them out of his own pocket. hence it will be a lot easier if i can produce something on paper.

would the inspector pick up on any of this? obv not normally cos the place would be skimmed by the time he got round..

 

[dextrous]

I take it that he's insulated the stud walls prior to sticking the board up (which I concur should be 12.5mm). If he hasn't then the inspector would pick this up and may provide you with a good reason for him to remove the boards anyway. I may be in error here, but studwork should be made from 4 by 2 timber to allow for adequate insulation plus a minimum distance from the face of any plasterboard to any cables running within it. Preferably treated timber should be used where a bathroom is involved.

In the ensuite and bathroom, this should be Moisture Resistant board as a minimum specification (and preferably aquapanel or equivalent around wet areas such as the shower). 9.5mm board is unlikely to be strong enough to support tiles.

 

[neds]

I've only ever used 9.5mm boards when I dot n dabbed. 12.5mm for everything else.

 

[tfish]

hes only boarded one side of the walls i asked him to do this so i could use my own sparky at a later date

but i did ask him if he insulated on normal jobs and he said no

Ok... the .pdf on stid walls richard has provided is great i can quote from that or show him it if ness... now is there anything in fire/building regs that states 12.5 is standard too that would be the nail in his coffiin..

The walls are defo coming down but i am undecided about the ceiling.. the stud is fitted over the ceiling now...

so should he replace the boards and refit them?

 

[Richard C]

There is definitely a requirement for sound insulation in a wall separating a room containing a w/c & another habitable room. What I am unsure about is BR requirements for stud walls in new builds which includes extensions. I was previously under the impression that all stud walls & floors in a new builds now had to be sound insulated but as far as I can establish from Buiding Regs Part E;
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADE_2003.pdf
& other searches, this doesnt seem to be the case; perhaps others can confirm

To meet the required standard, stud walls must use a minimum Wallboard 10 (12.5mm thick)
http://www.british-gypsum.com/produ...ies/gyproc_acoustic/gyproc_wallboard_ten.aspx
& in many cases Soundblock is used;
http://www.british-gypsum.com/produ...ssories/gyproc_acoustic/gyproc_soundbloc.aspx
In addition, mineral wool sound insulation must be used within the stud.

Here is another useful link
http://www.customaudiodesigns.co.uk/articles/1.2.htm

Dex also has some useful pointers on plasterboard & tile backer boards you should follow but in particular you need to be aware that your new electrics will need to comply with 17th edition regulations; this may involve additional costs in upgrading or possibly replacing your existing consumer unit but in the worst case (as I had) more or less a complete rewire!

 

[noseall]

We never use diy boards...er..9.5mm boards, unless we absolutely have to.

As for using them on a stud partition...

 

[Chukka63]

ditto to never using less than a 12.5 mm boards and except in extreme cases always use 8'x4' boards.he sounds like a DIY builder to me.

 

[gregers]

just a thought for him to overcome his cock up.......
get him to over board the lot again with another sheet/s of 9.5 mm board (full boards),and tell him to make himself some dead men.
and maybe get him to overboard in the bathroom with 9mm?wpb ply.


OR JUST GET HIM TO DO THE JOB PROPERLY.

 

[Richard C]

OR JUST GET HIM TO DO THE JOB PROPERLY.

I totally agree with that.

just a thought for him to overcome his cock up.......
get him to over board the lot again with another sheet/s of 9.5 mm board (full boards),

On reflection, I was probably being a bit harsh about not letting him double board; it would be a suitable solution & would exceed the minimum standard.

and tell him to make himself some dead men.

and maybe get him to overboard in the bathroom with 9mm?wpb ply.

Personally I wouldn’t do that; I never use WBP in a bathroom as tile base, other than for the floor. The problem is that even WBP is dimensionally unstable in moist environments unless it’s tanked & if you’re going to tank it, you might as well use a decent tile backer board & be done with it.

Although I could find no definitive confirmation regarding sound insulation in new builds this morning, I just got this from the British Gypsum website;

Gyproc WallBoard TEN
Standard board product with specifically engineered weight of 10kg/m2.
Engineered to meet the guidance given in the national Building Regulations Part E (transmission of sound), that states plasterboard, where used, must have a minimum mass of 10kg/m2 for internal and separating constructions in all residential projects, both new-build and refurbishment.

It’s seems pretty conclusive to me but it would be advisable to get confirmation for at least one other source?

 

[dextrous]

Op, could you clarify what the written specifications for the extention and stud wall actually said? It must be in writing somewhere that it satisfies an appropriate regulation. In fact, it may be worthwhile ascertaining what other regs are involved (eg fire-rating for walls and doors, insulation, drainage etc) within the written specs.

Since all this work has no doubt been approved and fees paid to LABC, you are entitled to phone them to ask for advice and for details of their next visit. At which time, all will be suitably clarified.

I must admit, for the life of me I cannot fathom why he used 9.5mm board. I can understand that, if he is a sole trader and general builder with no other employees, he would use 1800 by 900 boards for ease of manhandling. I fear that his knowledge base may be limited, or that he's trying to minimise his costs. The trouble is, you can't be sure where else he has used inappropriate materials - had he done any work on the roof for example, which may have involved lead work?