Ceiling hole too big for new extractor fan

[Kinso89]

The previous homeowner has taken their extractor fan and I've bought a replacement.

The hole in the ceiling is now too big - see picture.

How would I go about fixing this or best getting a professional plasterer in?

Thanks

 

[JohnD]

is that an extractor fan? Or a cooker hood with chimney?

What size is the duct, above, that you have connected to?

Is there a room above that ceiling?

 

[Kinso89]

Its a chimney of a cooker hood.
The hole is in a recess that holds an RSJ, there is a room above yes.
The white piping - duct? That fits in the chimney.
I'm guessing a strip of plasterboard, slightly longer than the hole glued to the otheride of the original plasterboard and then plastered?

 

[JP_]

wouldn't it be better to board and plaster the whole hole, then make a new circular hole just for the vent? And change vent for metal too (I have plastic, daft builder didn't buy metal!)

 

[Kinso89]

The chimney needs to extend into the hole though - the reason being due to the RSJ recess which has removed head height from the ceiling.

 

[JohnD]

If it was me, I would cut a square "collar" of plasterboard that would fit closely to the ceiling and fit round the chimney or duct. Painted to match the ceiling I think it would look neat. You may not keep that hood for ever.

However I might have shortened the chimney by adjustment or by cutting so it didn't need to penetrate the ceiling.

I don't know how you'd fireproof the hole to prevent smoke or flame erntering the void and setting fire to the room above. Plaster ceilings are quite a good fire barrier, if they don't have holes in them. If there is an RSJ it must have fire protection as it will soften and give way when hot.

 

[bobasd]

fwiw, i agree with johnD and jonbey suggestions:
ref. coming at it from the room above - remove a floorboard
and jonbey's blank the hole and then re-hole .
OP, i dont understand your objection "reason" about the RSJ and head height? the metal chimney is supposed to stop at the plasterboard.

as mentioned, definitely replace the Pvc flex duct - they retain moisture and food particles and are a v. bad fire risk.
replace best with Alu semi-rigid ducting or similar rigid ducting.