I don’t think this is a good idea…

…what say you?

My elderly parents have a joiner/builder chap round building a wooden lean-to. They’ve got round to talking about their shower extractor fan, which currently doesn’t work because the duct was venting straight into the loft, making everything damp. The joiner reckons he can connect the extract fan duct into the boiler flue, which passes straight up above the bathroom to a ridge tile vent. I’ve told them under no circumstances to allow him to touch the flue. Is this a thing these days? They hadn’t considered the potential of boiler gases coming back down and into their bathroom; they’re elderly and very trusting of anyone who’s a self-styled ‘expert’. Whaddya reckon? I’m sure it must contravene a building regulation somewhere, but couldn’t state exactly which one. They’re in England, fwiw.

Sounds genuinely deadly. What other daft things will that builder do that you never see?

Your instincts are correct. Leave the boiler alone.

Is there scope to take a flexi or rigid trunking from the bathroom vent horizontally across the loft to the eaves then vent downward, cutting a hole and putting a grille if cutting int eaves boards?

Are they on the Gas Safe Register?

Your reasoning seems very sound to me. The guy sounds like an archetypical cowboy builder who needs reporting to trading standards.

Hell no.

is this flue/ridge vent still in use? Is it a historic boiler flue vent left if place as it was part of ridge, if so can’t see why not.

If boiler is still “live” in that flue absolutely not

Are they on the Gas Safe Register?

Almost certainly not.

is this flue/ridge vent still in use?

Yes, the boiler is in a cupboard right next to the bathroom.

What other daft things will that builder do that you never see?

The mind boggles, they have a track record of employing dodgy people who are the best thing since sliced, and then rapidly become the devil incarnate when everything falls apart. Bathroom’s been done twice, two patios, this is now the third lean-to, all in about 10 years.

The issue is they’re 200odd miles away from me, and only tell me these things after the event. Luckily a chance conversation this evening revealed Dr Death’s plans for their flue.

Is there scope to take a flexi or rigid trunking from the bathroom vent horizontally across the loft to the eaves then vent downward, cutting a hole and putting a grille if cutting int eaves boards?

That’s my exact plan when I’m next up with them.

Are your parents cyclists and if so, can I have their bikes afterwards?

When WCA can see it’s plan certain death then I think the debate is over