Ceiling - gypsum sheet thickness

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ajarnudon
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Ceiling - gypsum sheet thickness

Post by ajarnudon » October 4, 2019, 9:04 am

I am getting close to ceiling installation and perhaps some members can give me the benefit of their experience. I have set the roof frame up with rafters at 1.2m centres, and transverse steel ceiling purlins at 60cm centres. I am sure that in Oz we used 12mm thick Gyprock sheets. However the thickest sheeets carried by my local stockist (who will be providing the labour) are 9.5mm thick. Does anyone have experience with ceilings of the 9.5cm thickness? Are these sheets rigid enough for the 60 cm batten spacings, or do I need to source 12mm sheets from elsewhere?
Regards, John



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Re: Ceiling - gypsum sheet thickness

Post by ajarnudon » October 4, 2019, 10:54 am

Have found the answers I needed by downloading a plasterboard design and installation guide from Boral Australia. The two standard Boral thicknesses in Oz are 10 mm and 13 mm (equating approx. to 9.5 mm and 12 mm in Thailand). Firstly, only 10 mm board can use 60 cm batten spacings - thicker board must use 45 cm max. spacings. Further, Boral produce a special ceiling board (they don't recommend general purpose board for ceilings). This ceiling board is only made in 10 mm thickness. So, local 9.5 mm ceiling board is the go for two reasons - the second of which is that battens have already been fixed for the entire roof at 60 cm centres.

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kopkei
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Re: Ceiling - gypsum sheet thickness

Post by kopkei » October 5, 2019, 5:55 pm

the 9mm is ok , in bathrooms they advise to use the green ones...(water resistant)
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laksnrub
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Re: Ceiling - gypsum sheet thickness

Post by laksnrub » October 5, 2019, 10:14 pm

ajarnudon wrote:
October 4, 2019, 9:04 am
I am getting close to ceiling installation and perhaps some members can give me the benefit of their experience. I have set the roof frame up with rafters at 1.2m centres, and transverse steel ceiling purlins at 60cm centres. I am sure that in Oz we used 12mm thick Gyprock sheets. However the thickest sheeets carried by my local stockist (who will be providing the labour) are 9.5mm thick. Does anyone have experience with ceilings of the 9.5cm thickness? Are these sheets rigid enough for the 60 cm batten spacings, or do I need to source 12mm sheets from elsewhere?
Regards, John
In Oz you can use 10-13mm sheets @ 600 ceiling batten spacing, the 13mm sheets usually stick direct to the Truss, no battens, the 10mm sheets can also use direct stick fix to truss , but as some trusses are not true straight on the bottom cord the 10 mm tends to show up more deflections, but still the most popular method used.

25 odd years ago Gyprock/ Boral developed the 10mm sheet for ceiling, aerated core FIBRE reinforced board, making is lighter easy to fix and able to span 60mm, the most popular truss center used in tiled roofs is 600mm, the 13 mm sheet is still used as it does not show up the imperfections in the truss deflection, has 3 mm extra insulation value.

Ceiling battens on truss is the rolls royce way of reducing ceiling stress from truss deflection in hot climate, high winds and humid environments, or when the ceiling has a floor above it.

If your using 10mm Thai board it will need to be fibre aerated core designed for 600mm centers.
Glue spacing and screw spacing is also very important for the design use of the ceiling, {poorly done in Thai}
Ceiling battens need 30mm face width { Thai they use 25mm face width} 30mm is available
Back blocking the sheets is a must { not seen it in thai domestic construction} if you have 3 sheets or more wide back block the sheets
Ceiling load on 10mm sheets is very low, 2kg a M2. we use battens at 450mm centers, not worth the saving to use 600mm spacing, as the quality control in OZ is high all the problems that have been encountered over the last 50 years with plaster sheets is a fine art design system to last the life of the building which is 50 years.

Some ceiling insulation in the roof space will go over 2kg m2, down lights the same, fluo lights, any thing that uses the plaster board to support the fixing, wiring also. so be careful with installing all these items, make sure ceiling nogging is installed to support down lights fluors ETC.
If you follow the Australian installation method then you will have a life time of no problems, and very few if any cracking, remember 50 years of experience reducing the problems, do it right the first time.

If truss direction or sheet direction changes you may need a control joint, like a large room and hall meet, do it wrong and you will have a crack there for ever, if the room is bigger than 6m x 6m or close to it, put a control joint in to allow expansion.

From about a east west line north of the tropic of Capricorn in OZ, Rockhampton in QLD north of that and just south when a ceiling is installed there are different conditions of installation, due to wind loading and MOISTURE. Udon is similar to Cairns Darwin, MOISTURE is a killer for Plaster, it softens the sheet, on high class buildings we either spray the back of the sheet with a good quality paint to reduce moisture or use Moisture resistance Sheets, very few in OZ would spray a sheet now, cheaper to use MR sheet,, make sure you have good ventilation in the ceiling ,we usually install 1 whirly Bird in the ceiling per 80 Mt2 most homes will have 2 or gable vents, plus soffit vents, it is a must to ventilate to keep the moisture out of the roof space, stop sheet deflection sag.

Read the Gyprock manual ceiling if you design it to that you will have a trouble free ceiling, in QLD 6 year guarantee, and 10+ year service life for a ceiling, if it fails cracks in that time, the builder is required to fix, if all of the fixing methods comply to the manufacture requirements, the owner pays, but if one component is not installed, wrong spacing, not enough glue ETC the builder pays, no such quality here.

Up to you pay the cheap price and you may regret it 5 years down the track, 600 batten spacing with 30mm facing, I would pay the extra and make it 450 centers, check to see if the facing width is 30mm, if 25mm pay the extra and redo the job to 450c.

Would you buy a car and in 5-7 years time the door sills and lower panels rust, they did as little as 30 odd years ago, the consumer wanted a better quality, so the manufactors gave a better coating, Buying a house is a lot more expensive than a car, give it the same quality.

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Barney
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Re: Ceiling - gypsum sheet thickness

Post by Barney » October 6, 2019, 9:54 am

Now that's a very comprehensive report from laksnrub, all good info by the way.
My personal experience when building was, as mentioned by laksnrub, to use a good experienced installer. Levels, cracking etc will create unwanted problems down the track. We have gyproc walls and ceilings throughout the house so it was essential to get it correct. It was found that our steel frame roof trusses were slightly out and the gyproc guy picked it up and rectified the problem. Tying in the 10mm ceiling and 13mm walls was done professionally. Left the cornice area square.
Others have mentioned the wet areas of the house, it is essential for bathrooms, toilets and laundry which should have the water resistant gyproc.
So use a very good installer. Non level ceilings will certainly show up once painting is complete. It is to late to fix later.
You have most likely thought of it but make sure you have a good think about what you need and your electrical wiring and anything else in the ceiling space in place prior to the ceiling being placed.
I know you have a supplier and just saying we purchased our gyproc and all associated products from the main gyproc supplier on the ring road up from Tesco and near the Suzuki dealer towards Nong Samrong lights. They also supply glass. The subcontract installer was recommended by them.

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Re: Gypsum Ceiling

Post by ajarnudon » October 6, 2019, 1:07 pm

A lot of great information there - thank you so much guys. My bathroom walls are only as high as privacy demands. There a couple of more metres to ceiling height. There won't be any moisture problem here.
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Ensuite
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Main bathroom
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Re: Gypsum Ceiling - labour cost

Post by ajarnudon » October 6, 2019, 1:09 pm

Does any have any recent experience as to labour costs to fit and finish a gypsum ceiling. I am being quoted 100 baht per square metre - how does this compare? Regards, John

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Re: Ceiling - gypsum sheet thickness

Post by laksnrub » October 6, 2019, 1:50 pm

FAILED Installation!

You can see in the first photo the ceiling battens running the length of the room,

Sheets are always to be fixed at RIGHT angles to the batten run, hence the sheets should have been run across the room

Now you have a ceiling joint running the length of the room 8mt?? or so long with no support for the set joint
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laksnrub
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Re: Gypsum Ceiling

Post by laksnrub » October 6, 2019, 2:03 pm

It's not the moisture from inside that is the main problem, as the sheets are painted,

It's the moisture in the air Humidity, that is in the ceiling space in the roof, coming from out side,

If this space in not ventilated with air flow the moisture forms and forms droplets, then drips down to the ceiling, hits the insulation and with enough moisture trapped under the insulation is absorbed into the ceiling sheet causing deflection sag over time, the many problems researched by Boral/ Gyprock and solving

Keep the ceiling space well ventilated
ajarnudon wrote:
October 6, 2019, 1:07 pm
A lot of great information there - thank you so much guys. My bathroom walls are only as high as privacy demands. There a couple of more metres to ceiling height. There won't be any moisture problem here.IMG_20191006_124913.jpgIMG_20191006_125135.jpg
Quality is best done first

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Barney
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Re: Ceiling - gypsum sheet thickness

Post by Barney » October 6, 2019, 3:06 pm

ajarnudon wrote:Does any have any recent experience as to labour costs to fit and finish a gypsum ceiling. I am being quoted 100 baht per square metre - how does this compare? Regards, John
Sorry John to long ago to remember the install rate.
But just check and confirm from him is the 100 bht rate for him to supply just labor and tools or does it include other items other than the gyproc
sheets. Tape, screws, plaster mix? etc.


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Re: Ceiling - gypsum sheet thickness

Post by ajarnudon » October 7, 2019, 8:55 pm

"FAILED Installation!
You can see in the first photo the ceiling battens running the length of the room,
Sheets are always to be fixed at RIGHT angles to the batten run, hence the sheets should have been run across the room. Now you have a ceiling joint running the length of the room 8mt?? or so long with no support for the set joint"

If you click on the first picture to enlarge it, you will see that at the 2.4 metre point from the side wall there are double battens. Of course the sheets will be run across the room! And moreover, even the ends of both adjoining sheets will all be supported.
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Re: Ceiling - gypsum sheet thickness

Post by ajarnudon » October 7, 2019, 9:04 pm

Thanks Barney and Kopkei. Sometimeswoodworker (over on Coolthaihouse) concurs that the 100 baht/sq m seems reasonable, so I am going down the track with this installer. However, I don't agree with his estimate of 90 sheets. I will get him back and we will measure up together, then go together to buy the material (yes, I have to supply all the extras - screws, tape, adhesive etc.). Hope to have the job underway in the middle of next week. Regards, John

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Re: Ceiling - gypsum sheet thickness

Post by ajarnudon » October 7, 2019, 9:21 pm

"You have most likely thought of it but make sure you have a good think about what you need and your electrical wiring and anything else in the ceiling space in place prior to the ceiling being placed."

Yes Barney, we have about 2-3 days work in the ceiling void before the ceiling crew starts.

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Re: Ceiling - gypsum sheet thickness

Post by ajarnudon » October 7, 2019, 10:08 pm

'It's not the moisture from inside that is the main problem, as the sheets are painted,
It's the moisture in the air Humidity, that is in the ceiling space in the roof, coming from out side,
If this space in not ventilated with air flow the moisture forms and forms droplets, then drips down to the ceiling, hits the insulation and with enough moisture trapped under the insulation is absorbed into the ceiling sheet causing deflection sag over time, the many problems researched by Boral/ Gyprock and solving"

As others posting in this thread have already mentioned, both Boral and Thai manufacturers have special sheets for bathtroom ceilings. My point was that I don't have a normal bathroom ceiling. BUT - Watch this space! viewtopic.php?f=42&t=43232&p=555923#p555923

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Re: Ceiling - gypsum sheet thickness

Post by kopkei » October 8, 2019, 7:40 am

my only advice would be , do not necessary over complicate things ....
in our first home build 18 years ago , we did have ceramic roof tiles (excella) and we put the special foil under from chang , we used normal gypsum board even to close the eves on the outside and bathrooms , and all this is still perfect after all these years ... , media always inventing stories to make a buck (mostly)...;)

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