Sagging MDF Ceiling?

[pmdpmd]

I am planning to use MDF to form a ceiling to my basement home cinema. The MDF will be painted black and have fibreoptic "stars" poking through from the top.

I plan to use 2m x 1.2m sheets of MDF, with a thick batton and hinges along one 2m edge. There will be another batton and key-bolt fixing at the other 2m edge, but the panel will be unsupported for the 1.2m width.

My question is, what thickness of MDF will I need to prevent the panels from sagging? It only has to support its own weight.

I am thinking of using moisture-proof MDF to improve the situation.

Thanks,
Paul.

 

[Jasonb]

Over that span any thickness of MDF will sag, its bad enough leaving a sheet of 18mm up against a wall for a week or two let alone hanging it horizontally (and thats MR)

You will be better off making a frame with 3x2 PAR or CLS with intermediate supports at say 400cts and then you could get away with 12mm thick board.

Jason

 

[pmdpmd]

That is true - I could support the MDF with a frame. Just need to make sure the struts don't interfere with my stars.

Also, I would not want to fix the MDF through the front, as this would be visible from the room. What do you think - some glue and precise length screws from above?

 

[Gary_M]

Hi,

What about using tongue and groove, over a frame? I have used this in several rooms - it is easy to put up, easy to cut to size and very cheap (depending on the thickness you use) - however, if you have a decent frame then you should get 5 x 2.4m 'planks' (giving about 450mm width per pack) for about £3.00. Also, it looks great when finished

 

[Jasonb]

Glue and screws from the back will be OK or countersunk screws filled with epoxy wood filler and well sanded don't show under paint.

Depending on the number of stars you would need to ensure the Grid of the frame didn't show as unlit straight lines, you could always space the frame under each screw to allow the loghts to go where you want.

Jason

 

[^woody^]

MDF will burn nicely (and quickly) in a basement or any other room, and will offer no protection to the ground floor or rest of the house from fire spread.

I would look for other alternatives, denser plasterboard or Fermacell come to mind - peace of mind

 

[Jasonb]

Or a sheet of FR(rire resistant) MDF.

Jason