Builder using 10mm plasterboard instead of 13mm

Hello,

Our house renovation drawings specify 13mm plasterboard for all internal walls, however, I noticed our builder has used 10mm instead without telling us. It very much seems like a cost-saving for the builder as 13mm is double the price of 10mm. I know there are 10mm plasterboards suitable for walls but isn't this going against the contract to substitute products without notifying the client?

Thanks in advance!

My understanding is plasterboard has been 10mm for at least 25 years, 13mm is normally for special purposes like fyrcheck. Ceiling products are all 10mm too like supaceil, span10 etc are some product names, all 10mm spanning 600 in a ceiling.

Maybe they thought the drawing were old standard specs, can’t see any real benefit in using 13mm, could be an innocent mistake.

10mm is standard. However if your drawings specify 13mm and the builder has priced based on supplied drawings then they should be installing 13mm.
Who did the drawings for you?

If its been specified it should be 13mm, its very unusual to have 13mm on internal walls though.
The only place we use 13mm (I work for a builder) is external ceilings

Hi Doozer

I hope you are living the dream, building custom homes in beautiful COVID free WA.

Over here, we mainly use 10mm in new builds with lightweight frames unless the clients have a particular acoustic requirement, but often we use 13mm in the older renovation homes/apartments or in any direct stick situation.

In the area that we are in,( North Shore Sydney) we often come across double brick homes & apartments with structural cracks in the double brick walls.

After stitching the bricks back together we like to recommend gyprock as opposed to render on the internal walls as we think the finish is much better, and the 13mm direct sticks to the walls better.

For new builds where a client has a particular acoustic requirement ( such as a home theatre or master bedroom), we recommend using a double layer of 10mm gyprock combined with acoustic insulation and acoustic sealant. Those seem to be a good combination and are pretty cost effective.

Anyway, have a great day

Cheers

Simeon

Thanks everyone!! I am a qualified draftsman and I did the drawings for our house renovation. 10mm PB for ceilings and 13 or 12.5mm for walls is what I was taught at TAFE a few years back. Since graduating I have been working mostly on commercial projects where 13mm is standard, and for the few residential jobs I have done I have always specified 13mm PB for walls. The situation at our renovation has prompted me to research this. Not sure if this makes any difference but we are in the Top End where we get high humidity and extreme weather in general. We would never use plasterboard outside.

The biggest problem for you is that the builder is not following specification, either deliberately as cost saving or through lack of quality control. This should rise red flags and the builder should be closely monitored during your build.
There is no excuse, builder signed off on 13 mm plaster and that is what you should get. Unless you have specific requirements 10 mm for walls should be OK but the builder should give you a credit for difference in cost saving on labour and materials.
Unless the builder knows you are onto him and unless builder pays he will do it again.

Hi bc89


You might want to consider whether or not the works breaches section 18B of the Home Building Act.

It may or may not be a defect, depending on the particulars of your contract. You may want to reach out to a specialist construction lawyer in your area and let them examine your contract and other documents related to the build, so that they can advise you on possible next steps.


Cheers
John