Electrical

Is it okay to have shower extractor fan vented to eaves?

Anonymous user 03/03/2024 - 3.44 PM

I was wondering why the shower fan in our 1996 townhouse was absolutely rubbish, especially after we just had a bathroom refit and the plumber replaced the old one (inline fan replaced via bathroom, not attic). Turns out the extractor fan exhaust pipe in the attic doesn't actually vent anywhere, it was just tossed to the side of the roof, over the eaves... face down, which explains the lack of suction - but luckily means it didn't flood the attic with damp air.... I can't find any eaves vents or vent tiles in the roof bathroom side that it would have ever connected to so my assumption is given the bathroom was there when the house was built in 1996 it just didn't have an extractor fan as there's a window in the bathroom. Previous bob the builder owner then decided to have a go himself at some point but thought just venting to the side of the attic was enough.... it's obviously not so looking to get that corrected now.... Ideally it would go via the roof but we don't currently have any tiles and I can't imagine it would be that cheap getting a roofer up 3 stories to get one fitted, I'd also need to find a reliable roofer thats not going to cause a leak which is a task in itself. I'll be getting an electrician out to do this but it sounds like the alternative is to get a vent fitted to the eaves next to the bathroom and use a decent inline fan within the attic. The bathroom window provides easy access to the eaves so should be easy enough to get that part fitted and attic access is easy for the fan. Since the eaves vents seems like quite a common solution my question is.... Since we have tiny slots running continuously around the edge of the eaves for ventilation would the hot damp air not get pushed directly back into the attic? Or is the amount not a concern? Block them directly around the vent 3ft either side? Thanks! Edit: I forget I can't reply to comments on here. It's a semi detached house so the slots are around the whole house. A little research online suggests covering the "slots" 3ft either side to stop hot air rising back in. This should still leave a large amount free around the house. I can physically touch the eaves from the bathroom window and feel like I could easily reach out with a drill to make the hole near the window. I'd be happy to do that if the electrician is not - if it's the correct location for it.

Anonymous user

Hi Adam. You need to keep the 'slots' in the eaves unblocked. The purpose of those is to vent the roof space so blocking them would cause problems. All you need to do is get positive venting from the fan. Your idea to put a vent in the eaves is sound as long as you can get the vent hose from the fan fitted to it. Three stories is quite a height so using a ladder is probably not an option. I would not like to work off a ladder that high. Alternatively hire a scaffold tower for a day or two. Its not that expensive and allows the work to be done properly and safely. Access through the window may be possible but can you comfortably get a drill and 100mm diameter holesaw through it and cut the hole and fit the vent grille? The vent hose is usually pulled in to the hole by inserting your arm in through the eaves soffit and grabbing hold of it. It may not be possible to do this hanging through a window? You will be the best judge of that. Good luck. Edit: Once air exits the fan vent it will quickly dissipate and mix wifh the outside air. Its not going to go back up in to the loft. I would not block any existing vents its not necessary.

Answered29 November 2022

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StrangLX

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It’s always best to vent directly to the outside atmosphere. There was a time when venting a bathroom extractor into breezy attic spaces was considered acceptable if the attic had sufficient air flow and was large enough that moisture was unlikely to condense before naturally exiting the space via ventilation spaces around the soffits. This isn’t ideal in my opinion but it’s not unheard of, my parents in law have had this set up for 20+ years and I’ve found their attic to be nothing but bone dry and no signs of rot or damp anywhere… saying that you have described a good solution where you can safely access through a window to fit the external vent which sound reasonable. If you’re planning on getting an electrician in I’m sure they’ll advise on a safe way of getting venting directly outside safely within their skills and abilities. If there’s currently no signs of damp or condensation in your attic then I recommend getting it done to a standard you’re happy with and to be glad no damage was done.

Answered18 December 2022

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