bathroom extractor flat roof installation for loft conversion

[pr1970ster]

Hi all

we are having a loft converted currently and have a bathroom in the dormer area. The builders have put in a 100mm hole up through the ceiling , waiting for the ceiling extractor fan to go in. But i`m querying to them where the ducting is as cant see anything apart from obs board above. There doesnt seem to be any extractor vent on the outside, so i assume if it is there, its going into the soffit. I`ve checked back on some photos of the build and i couldnt see any allowances in the joists of the roof for a 100mm ducting pipe. The builder said the ducting is up there so i`m taking his word for it.

Question is, I need to check properly to see whats up in the ceiling. But could at worst the vent go straight up onto the flat roof , obviously its better to go out the side and avoid having to put a flat roof vent in. But surely you cant put a 100mm hole through a joist. There must be two at least as the extractor is in the middle of the bathroom ceiling.

Trying not to cause hassle with them as they are nearly finished and done a good job but i`m just suspicious.

Thanks

 

[Taylortwocities]

You are right to be suspicious. INSIST where it is. It must be on the plans?????
You should see the ducting coming through the ceiling. Also there must be an external extract grill is for the ducting.
Probably they forgot, put down the OSB and hoped you wouldnt notice.
Or the ducting run is tooooo difficult because the option is not in the direction of the joists. Always a tricky thing to sort..

I have been in several houses where the bathroom fan just vents into the loft space. That gets the work signed off by LABC because the inspoector never looks up in the loft, but he can see the fan so ....tick in the box... approved.

Do report back. We love builders around here, little treasures.

 

[pr1970ster]

Thanks. Just went up and had a look whilst they’re out at lunch and I can just see the flexible ducting with my phone camera. But there isn’t anything externally, and even the soffit is solid, no vent slots.
So I might ask if they just can put a vent into the side.

 

[BS3036]

My son has a new old house. As the toilet ceiling fan didn't seem effective they decided to put a new fan in. On taking out the old fan they found it went into a duct , ran a meter towards the other end of the ceiling, and came down through a vent again.

 

[SimonH2]

Thanks. Just went up and had a look whilst they’re out at lunch and I can just see the flexible ducting with my phone camera.

You should be able to clearly see the ducting - there should be a section that the tail of the fan will sit into. My suspicion is that they just stuffed a bit of flexible ducting in and it doesn't go anywhere. You really do not want to dump a load of damp air into the roof space where the only thing it will do is cause condensation and make your timbers rot.