Bathroom plasterboard

[Svensl]

I'm replacing an old bathroom extractor fan and am wondering what kind of plasterboard this is. The bottom layer (brown) is almost sand like, you can rub it away with the finger. Any comments are greatly appreciated. Thanks

Ps It's a 1930s bungalow

 

[cross thread]

It may be asbestos in the middle layer

 

[JohnD]

i think it's gypsum plaster that has got wet, for example with condensation from a steamy bathroom.

where is the duct taking the steam outside

I see nothing to suggest asbestos.

1930 is a bit early for plasterboard but it might be a later replacement ceiling. photograph it from above please.

the fluffy stuff is yellow fibreglass loft insulation.

 

[Svensl]

Here's a picture from above. Total thickness of the board is approx 12mm with the white middle bit being about 6 to 7mm.

The steam is meant to be vented vertically outside. But the fan was not very powerful and there was no condensation trap meaning the water would drip back down.

The house only has had 2 owners. The previous owners had the bathroom decorated but I don't think the ceiling was redone.

 

[Deleted member 292770]

looks like some sort of fibre ‘sandwich’ .
the middle could be asbestos.

 

[JohnD]

In a house of that age, I'd expect to see L&P ceiling.

yours may have been replaced, especially if it was shaken about during WW2 bombing.