BITESIZED CPD – CORRECT INSTALLATION OF AN MF PLASTERBOARD CEILING
In this Bitesize CPD we will be looking at a basic (non-acoustic) MF plasterboard ceiling installation.
These are the most common defects picked up by FCM’s Clerks of Works during their site inspections.
Grid to hanger fixings
Fixings through thicker, stronger section into thinner, weaker hanger.
There is a likelihood that the fixing will come loose allowing movement and cracking to the ceiling.
Correct fixing method shown below.
Steel angle hanger to soffit fixings.
Incorrectly cut and fixed strap hanger.
Here the steel angle has been cut, bent and fixed without the required care.
The ends have been bent but do not lap correctly and not pre drilled before fixing. This has caused the laps to open and only one half has been fixed to the soffit.
Under load it will probably come loose causing the ceiling to drop slightly. More cracking at joints.
Correct fixing of MF ceiling hangers.
As you will have noticed above there are 2 methods of fixing the hangers to the soffit.
On most sites you will notice that the fixers want to use the cut, fold and direct fix method rather than the proprietary angle cleat.
This is an alternative, method that reduces the load allowed to be fixed to the grid.
BG state that the direct fixing method must not be used if there is likely to be soffit deflection.
“Gypframe GA1 steel angles must not be fixed direct to the soffit if the ceiling is likely to deflect..”
The ceiling hangers must be fixed with the correct angle cleat.
When the ceiling grid is complete the boards are fixed with screws with centres of 230mm maximum in the board and 150mm max at board ends.
Not 300mm centres as on the walls.
Boards are also fixed at right angles to the framing grid as shown above for strength and stability.
Watch the video below for the whole sequence.
Incidentally – this video is the most watched on YouTube with over 1m views. See how many errors you can spot. No wonder we pick up so much on site!
Fox Curtis Murray are a building consultancy specialising in providing Clerks of Works services and Quality Control inspections.
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