Discussion:
new bathroom fan in loft - no room at the eaves
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Silent Ice
2024-06-09 22:09:48 UTC
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Hi, DIYers

We're having the bathroom done, I wanted to install an inline fan in the
loft and was planning to do the work ourselves to help the budget a bit.
Thankfully this timely video
surfaced which pretty
much covers what I wanted to do.

The plan was/is to exit via the soffit. What the video doesn't show is
actually getting the ducting out the eaves, I can only assume his was
straight forward. Having got up there and found my exit point there is
hardly any clearance and no way enough to push ducting through; if I did
it would be squashed flat.

Pictures:
https://ibb.co/MDc2QJc
https://ibb.co/C1z6346

At the top is the sarking, just about where the eaves begin is there's a
batten above so no way to stretch that up. Then you can see a pad of
mortar and the first row of bricks, the grey area is the bathroom
ceiling. The wire is a PoE cable leading outside. The rafters are
roughly 7.5cm but the notching at the wall means much less of a gap.

For some reason I thought I had more room and a clear row of bricks at
the eaves so I originally thought I could chop out a brick and might
have enough clearance. Aside from not wanting to disturb the rafters
there is no headroom and I don't think I could have much control over
tools (powered or otherwise) in that space. Don't want a brick falling
out onto the soffit either.

I'm wondering if I still have any options to go that way?


The alternative would be to run the ducting to the gable end, I didn't
favour this for a few reasons;
* 2x longer run of ducting than soffit exit. I've bought flexible
insulated duct but would prefer solid for that run
* wanted to install the fan as close to the exhaust as possible for
performance but if I do so it's harder to access for maintenance, needs
longer cable run, it will be located above bedrooms rather than the
bathroom itself in case of unwanted noise
* The wall is SW facing and we have had issues with penetrating damp


New to newsgroups so apologies if I commit a faux-pas. I'll later have
some related electrical questions; should I start a new post for those
or continue this one?
Jeff Layman
2024-06-10 07:47:57 UTC
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Post by Silent Ice
Hi, DIYers
We're having the bathroom done, I wanted to install an inline fan in the
loft and was planning to do the work ourselves to help the budget a bit.
Thankfully this timely video
http://youtu.be/z8958NYzpwg surfaced which pretty
much covers what I wanted to do.
The plan was/is to exit via the soffit. What the video doesn't show is
actually getting the ducting out the eaves, I can only assume his was
straight forward. Having got up there and found my exit point there is
hardly any clearance and no way enough to push ducting through; if I did
it would be squashed flat.
https://ibb.co/MDc2QJc
https://ibb.co/C1z6346
At the top is the sarking, just about where the eaves begin is there's a
batten above so no way to stretch that up. Then you can see a pad of
mortar and the first row of bricks, the grey area is the bathroom
ceiling. The wire is a PoE cable leading outside. The rafters are
roughly 7.5cm but the notching at the wall means much less of a gap.
For some reason I thought I had more room and a clear row of bricks at
the eaves so I originally thought I could chop out a brick and might
have enough clearance. Aside from not wanting to disturb the rafters
there is no headroom and I don't think I could have much control over
tools (powered or otherwise) in that space. Don't want a brick falling
out onto the soffit either.
I'm wondering if I still have any options to go that way?
The alternative would be to run the ducting to the gable end, I didn't
favour this for a few reasons;
* 2x longer run of ducting than soffit exit. I've bought flexible
insulated duct but would prefer solid for that run
* wanted to install the fan as close to the exhaust as possible for
performance but if I do so it's harder to access for maintenance, needs
longer cable run, it will be located above bedrooms rather than the
bathroom itself in case of unwanted noise
* The wall is SW facing and we have had issues with penetrating damp
Anything here (or from similar suppliers) worth considering:
<https://www.aboutroofing.com/pitched-roofing-materials/roof-and-wall-ventilation/roof-tile-vents>

Many of the new builds round here seem to have two or three ventilated
tiles in their roofs.
Post by Silent Ice
New to newsgroups so apologies if I commit a faux-pas. I'll later have
some related electrical questions; should I start a new post for those
or continue this one?
It's up to you. It could be best starting a new thread for your
convenience if you want to keep it all under one obvious subject that
you might want to refer to later. Anyway, the way threads drift off
subject here and elsewhere means it probably won't matter in the long run!
--
Jeff
Silent Ice
2024-06-10 16:44:35 UTC
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Post by Jeff Layman
<https://www.aboutroofing.com/pitched-roofing-materials/roof-and-wall-ventilation/roof-tile-vents>
Many of the new builds round here seem to have two or three ventilated
tiles in their roofs.
I think it's worth considering, yes. I've discounted it so far and it's
my least favourite option as I assume the roof is original and don't
really want to disturb things if I can help it. It will need doing at
some point.
SteveW
2024-06-11 10:01:45 UTC
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Post by Silent Ice
Post by Jeff Layman
<https://www.aboutroofing.com/pitched-roofing-materials/roof-and-wall-ventilation/roof-tile-vents>
Many of the new builds round here seem to have two or three ventilated
tiles in their roofs.
I think it's worth considering, yes. I've discounted it so far and it's
my least favourite option as I assume the roof is original and don't
really want to disturb things if I can help it. It will need doing at
some point.
I don't know if it is an option for you, but facing a similar problem, I
dropped the vent pipe through the ceiling, into the airing cupboard and
then through the wall lower down.

My cupboard goes up to the (suspended) ceiling, but if I'd not put that
in and still just had the original ceiling above, I could have used a
piece of enamelled steel tubing to bridge the gap, like you often see
for a vent or boiler in a kitchen.
Andy Burns
2024-06-10 07:50:40 UTC
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my exit point there is hardly any clearance and no way enough to push
ducting through; if I did it would be squashed flat.
Xan you transition to rectangular ducting for the exit, either rigid or
flexible type?

<https://www.manrose.co.uk/product/10212-rectangular-pvc-flexible-ducting-l3000mm-110-x-54mm/>
fred
2024-06-10 09:09:44 UTC
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Post by Andy Burns
my exit point there is hardly any clearance and no way enough to push
ducting through; if I did it would be squashed flat.
Xan you transition to rectangular ducting for the exit, either rigid
or flexible type?
<https://www.manrose.co.uk/product/10212-rectangular-pvc-flexible-ducti
ng-l3000mm-110-x-54mm/>
Or indeed super slim versions eg. 234x29:

https://www.fastlec.co.uk/ventilation-ventilation-ducting-flat-ducting-
225mm-slim-flat-ducting-polyvent-225

Yes, rigid but that may actually aid placement in the tight space
concerned.

Plenty of useful adaptors/corners in the range.

For the o/p, short runs best to avoid condensation in the duct and dripping
back or smelling.
fred
2024-06-10 09:17:00 UTC
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Post by fred
Post by Andy Burns
my exit point there is hardly any clearance and no way enough to
push ducting through; if I did it would be squashed flat.
Xan you transition to rectangular ducting for the exit, either rigid
or flexible type?
<https://www.manrose.co.uk/product/10212-rectangular-pvc-flexible-duct
i ng-l3000mm-110-x-54mm/>
https://www.fastlec.co.uk/ventilation-ventilation-ducting-flat-ducting-
225mm-slim-flat-ducting-polyvent-225
Yes, rigid but that may actually aid placement in the tight space
concerned.
Plenty of useful adaptors/corners in the range.
For the o/p, short runs best to avoid condensation in the duct and
dripping back or smelling.
Worth shopping around for "225mm flat ducting", the Manrose version
appears significantly cheaper from some sources:

https://www.plumbingforless.co.uk/ventilation/ducting/flat-channel-
ducting-225mm
Silent Ice
2024-06-10 20:50:50 UTC
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Post by fred
Post by Andy Burns
my exit point there is hardly any clearance and no way enough to
push ducting through; if I did it would be squashed flat.
Xan you transition to rectangular ducting for the exit, either rigid
or flexible type?
<https://www.manrose.co.uk/product/10212-rectangular-pvc-flexible-duct
i ng-l3000mm-110-x-54mm/>
A few mentions for rectangular ducting. I had seen it in the TLC
catalogue and I'll have to look into it some more. Wasn't sure if I
could make it fit either. And fiddly work as I'd have to probably go for
a few in series
Round-to-rectangle converter ==> 135 degree angle ==> rectangle-to-round
... connecting some of it from the loft and trying to fit the rest/
fiddle around with it all from the soffit side without it coming apart.

With any of the rectangle profiles I assume the adaptors and bends won't
interface directly and need a joining piece so it adds up.
Post by fred
https://www.plumbingforless.co.uk/ventilation/ducting/flat-channel-
ducting-225mm
Thanks for highlighting the super slim ducting. This is interesting and
looks worth further research. These thinner ones may well do it.


Sorry I'm still trying to work out how replying and quoting works, not
sure how this is going to come out
Silent Ice
2024-06-10 16:48:10 UTC
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Post by Andy Burns
my exit point there is hardly any clearance and no way enough to push
ducting through; if I did it would be squashed flat.
Xan you transition to rectangular ducting for the exit, either rigid or
flexible type?
<https://www.manrose.co.uk/product/10212-rectangular-pvc-flexible-ducting-l3000mm-110-x-54mm/>
Thank you I'd seen rectangular solid duct but didn't know this flexible
rectangular existed!
Andy Burns
2024-06-10 16:59:13 UTC
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Post by Silent Ice
Thank you I'd seen rectangular solid duct but didn't know this flexible
rectangular existed!
Wasn't sure if you were using the round insulated ducting as per the
video, if it's important for noise reduction to keep to a similar ducting?
Silent Ice
2024-06-10 17:27:15 UTC
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Post by Andy Burns
Post by Silent Ice
Thank you I'd seen rectangular solid duct but didn't know this
flexible rectangular existed!
Wasn't sure if you were using the round insulated ducting as per the
video, if it's important for noise reduction to keep to a similar ducting?
I've bought round insulated, swayed a little by the video - I know
technically it's sound insulation but I suspect the foil ducting is
louder than solid even with the insulation. I was hoping it would
instead offer some element of thermal protection and then reduce the
amount of condensation (hopefully better than nothing).
Theo
2024-06-10 09:17:28 UTC
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Post by Silent Ice
At the top is the sarking, just about where the eaves begin is there's a
batten above so no way to stretch that up. Then you can see a pad of
mortar and the first row of bricks, the grey area is the bathroom
ceiling. The wire is a PoE cable leading outside. The rafters are
roughly 7.5cm but the notching at the wall means much less of a gap.
For some reason I thought I had more room and a clear row of bricks at
the eaves so I originally thought I could chop out a brick and might
have enough clearance. Aside from not wanting to disturb the rafters
there is no headroom and I don't think I could have much control over
tools (powered or otherwise) in that space. Don't want a brick falling
out onto the soffit either.
As it happens I came across a similar problem yesterday. What I thought was
the back of the soffit was actually the inner skin of blocks, and there's
then the cavity and outer brick skin. In my case there was insulation (and
a bird's nest) in the gap so I could access the soffit, but need very long
arms.

Looking at a diagram (of a soffit ventilated roof, but bear with me):
Loading Image...

it looks like your brick skin goes right up to the sarking, without leaving
any kind of gap.
Post by Silent Ice
I'm wondering if I still have any options to go that way?
Have you thought about doing it from the outside? ie take the soffit off,
drill whatever hole in the bricks you need to get access to the loft.

You could use rectangular ducting to get through this gap, perhaps adapting
back to circular ducting:
https://www.bpcventilation.com/rectangular-straight-adaptor

How much height do you have? From the picture it looks like about a brick,
which isn't much, but I can't see what the grey thing in front of the brick
is. I think the small rectangular duct is 110x54mm so that might just fit.
Post by Silent Ice
New to newsgroups so apologies if I commit a faux-pas. I'll later have
some related electrical questions; should I start a new post for those
or continue this one?
Looks fine to me. I'd start a separate thread as a new title it may attract
those who know about electrics.

Theo
Silent Ice
2024-06-10 20:48:23 UTC
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Post by Theo
Have you thought about doing it from the outside? ie take the soffit off,
drill whatever hole in the bricks you need to get access to the loft.
There's a certain faff factor that kicks in. The soffit panel in
question is one long piece, possibly 4-5m. I don't think I could remove
this from a ladder so I'd need a tower - I also suspect whoever put it
up there, "did the job" with a view that when it comes down it'll be at
the end of its life... so maybe it won't come cleanly.

However, I'm considering if, once I have a 4" hole in the soffit, I
could get enough access through it to make the hole. Maybe?
Post by Theo
You could use rectangular ducting to get through this gap, perhaps adapting
https://www.bpcventilation.com/rectangular-straight-adaptor
How much height do you have? From the picture it looks like about a brick,
which isn't much, but I can't see what the grey thing in front of the brick
is. I think the small rectangular duct is 110x54mm so that might just fit.
Yes possibly a brick's worth, if the area visible were to be removed.
The grey is the ceiling plasterboard. It goes almost all the way to the
brick. Using an inspection mirror there is insulation beyond the edge.
The white cable just visible in the centre is the 12v feed to the
existing wall mounted extractor beneath. That wall has additional boxing
and the fan duct goes through the lot to outside. I'll see if I can
check if that cable is coming into the wall cavity or the boxing cavity.
Tim Lamb
2024-06-11 08:42:11 UTC
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In message <v47oqn$jmkb$***@dont-email.me>, Silent Ice
<***@example.null> writes
Snip
Post by Silent Ice
Post by Theo
You could use rectangular ducting to get through this gap, perhaps adapting
https://www.bpcventilation.com/rectangular-straight-adaptor
How much height do you have? From the picture it looks like about a brick,
which isn't much, but I can't see what the grey thing in front of the brick
is. I think the small rectangular duct is 110x54mm so that might just fit.
Yes possibly a brick's worth, if the area visible were to be removed.
The grey is the ceiling plasterboard. It goes almost all the way to the
brick. Using an inspection mirror there is insulation beyond the edge.
The white cable just visible in the centre is the 12v feed to the
existing wall mounted extractor beneath. That wall has additional
boxing and the fan duct goes through the lot to outside. I'll see if I
can check if that cable is coming into the wall cavity or the boxing cavity.
I suppose you could utilize the existing wall outlet if it is close to
the ceiling. Round duct across the loft and re-enter near the wall...

Alternatively, cut a large enough hole in the soffit to work safely from
your ladder. Cover with a rectangular sheet, pre-bored to suit the
extractor outlet. You are only trying to keep Sparrows out:-)
--
Tim Lamb
Silent Ice
2024-06-12 17:21:12 UTC
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Post by Tim Lamb
Alternatively, cut a large enough hole in the soffit to work safely from
your ladder. Cover with a rectangular sheet, pre-bored to suit the
extractor outlet. You are only trying to keep Sparrows out:-)
The exhaust will be at the front of the house and the soffit is profiled
UPVC so a more aesthetically pleasing solution I think will be to make a
bigger hole as you say and either fit it with a blanking plate of the
type used to hide blowout, or make a square hole and fit an access panel
with the outlet mounted directly in the door if it's strong enough (I
think 3mm should be but the latch might not), or next to it if not.
https://www.toolstation.com/100-wall-plate/p79588
https://www.tlc-direct.co.uk/Products/FXAP88.html

Tricky Dicky
2024-06-10 10:41:44 UTC
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Post by Silent Ice
Hi, DIYers
We're having the bathroom done, I wanted to install an inline fan in the
loft and was planning to do the work ourselves to help the budget a bit.
Thankfully this timely video
http://youtu.be/z8958NYzpwg surfaced which pretty
much covers what I wanted to do.
The plan was/is to exit via the soffit. What the video doesn't show is
actually getting the ducting out the eaves, I can only assume his was
straight forward. Having got up there and found my exit point there is
hardly any clearance and no way enough to push ducting through; if I did
it would be squashed flat.
https://ibb.co/MDc2QJc
https://ibb.co/C1z6346
At the top is the sarking, just about where the eaves begin is there's a
batten above so no way to stretch that up. Then you can see a pad of
mortar and the first row of bricks, the grey area is the bathroom
ceiling. The wire is a PoE cable leading outside. The rafters are
roughly 7.5cm but the notching at the wall means much less of a gap.
For some reason I thought I had more room and a clear row of bricks at
the eaves so I originally thought I could chop out a brick and might
have enough clearance. Aside from not wanting to disturb the rafters
there is no headroom and I don't think I could have much control over
tools (powered or otherwise) in that space. Don't want a brick falling
out onto the soffit either.
I'm wondering if I still have any options to go that way?
The alternative would be to run the ducting to the gable end, I didn't
favour this for a few reasons;
* 2x longer run of ducting than soffit exit. I've bought flexible
insulated duct but would prefer solid for that run
* wanted to install the fan as close to the exhaust as possible for
performance but if I do so it's harder to access for maintenance, needs
longer cable run, it will be located above bedrooms rather than the
bathroom itself in case of unwanted noise
* The wall is SW facing and we have had issues with penetrating damp
New to newsgroups so apologies if I commit a faux-pas. I'll later have
some related electrical questions; should I start a new post for those
or continue this one?
Squashing the ducting is the answer. The duct diameter is not altered hence
the area enclosed though a different shape is the same, as long as you do
not completely squash it flat. I did that with my inline fan and no
problems it clears the vapour in the bathroom in a matter of minutes in
fact by the time I am out of the shower and jumped into some clothes all
glass panels and mirror are completely clear.
The Natural Philosopher
2024-06-10 14:59:05 UTC
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Post by Tricky Dicky
Squashing the ducting is the answer. The duct diameter is not altered hence
the area enclosed though a different shape is the same,
Christ in a bike,
Some needs to go back to school
--
Microsoft : the best reason to go to Linux that ever existed.
Silent Ice
2024-06-10 12:36:56 UTC
Reply
Permalink
Post by Silent Ice
Hi, DIYers
We're having the bathroom done, I wanted to install an inline fan in the
loft and was planning to do the work ourselves to help the budget a bit.
Thankfully this timely video
http://youtu.be/z8958NYzpwg surfaced which pretty
much covers what I wanted to do.
The plan was/is to exit via the soffit. What the video doesn't show is
actually getting the ducting out the eaves, I can only assume his was
straight forward. Having got up there and found my exit point there is
hardly any clearance and no way enough to push ducting through; if I did
it would be squashed flat.
https://ibb.co/MDc2QJc
https://ibb.co/C1z6346
At the top is the sarking, just about where the eaves begin is there's a
batten above so no way to stretch that up. Then you can see a pad of
mortar and the first row of bricks, the grey area is the bathroom
ceiling. The wire is a PoE cable leading outside. The rafters are
roughly 7.5cm but the notching at the wall means much less of a gap.
For some reason I thought I had more room and a clear row of bricks at
the eaves so I originally thought I could chop out a brick and might
have enough clearance. Aside from not wanting to disturb the rafters
there is no headroom and I don't think I could have much control over
tools (powered or otherwise) in that space. Don't want a brick falling
out onto the soffit either.
I'm wondering if I still have any options to go that way?
The alternative would be to run the ducting to the gable end, I didn't
favour this for a few reasons;
* 2x longer run of ducting than soffit exit. I've bought flexible
insulated duct but would prefer solid for that run
* wanted to install the fan as close to the exhaust as possible for
performance but if I do so it's harder to access for maintenance, needs
longer cable run, it will be located above bedrooms rather than the
bathroom itself in case of unwanted noise
* The wall is SW facing and we have had issues with penetrating damp
New to newsgroups so apologies if I commit a faux-pas. I'll later have
some related electrical questions; should I start a new post for those
or continue this one?
I'll get back later to all your questions and suggestions. Just wanted
to exclaim that while it's fiddly to have to use the computer to reply
it's already worth the effort to get this set up. So much better than a
certain forum I will not ;-) be using again.
David
2024-06-10 12:47:28 UTC
Reply
Permalink
Post by Silent Ice
Hi, DIYers
We're having the bathroom done, I wanted to install an inline fan in the
loft and was planning to do the work ourselves to help the budget a bit.
Thankfully this timely video
http://youtu.be/z8958NYzpwg surfaced which pretty
much covers what I wanted to do.
<snip>

Not the question that you asked, but have you considered putting a non-
return flap in your ducting run?
Our bathroom fan duct (in line fan) in the loft is waiting for one to be
fitted, because there can be quite a strong draught back through the duct.
OK in summer but can lower the bathroom temperature in winter by several
degrees.

Cheers



Dave R
--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 10 x64
Silent Ice
2024-06-10 17:37:39 UTC
Reply
Permalink
Post by David
Post by Silent Ice
Hi, DIYers
We're having the bathroom done, I wanted to install an inline fan in the
loft and was planning to do the work ourselves to help the budget a bit.
Thankfully this timely video
http://youtu.be/z8958NYzpwg surfaced which pretty
much covers what I wanted to do.
<snip>
Not the question that you asked, but have you considered putting a non-
return flap in your ducting run?
Our bathroom fan duct (in line fan) in the loft is waiting for one to be
fitted, because there can be quite a strong draught back through the duct.
OK in summer but can lower the bathroom temperature in winter by several
degrees.
Cheers
Dave R
I didn't buy one but thanks for mentioning it, I'm keen to hear any real
experiences. I'm not against it, wanted to see if it's an issue. Does
yours vent through the soffit? I was thinking the wind blowing across
the soffit would create more of a suction effect if anything - and cause
knocking if it were blustery. Have you gone for a straight forward type
with a round disk and offset pivot?
David
2024-06-11 18:21:56 UTC
Reply
Permalink
Post by Silent Ice
Post by David
Post by Silent Ice
Hi, DIYers
We're having the bathroom done, I wanted to install an inline fan in
the loft and was planning to do the work ourselves to help the budget
a bit.
Thankfully this timely video
http://youtu.be/z8958NYzpwg surfaced which
pretty much covers what I wanted to do.
<snip>
Not the question that you asked, but have you considered putting a non-
return flap in your ducting run?
Our bathroom fan duct (in line fan) in the loft is waiting for one to
be fitted, because there can be quite a strong draught back through the
duct.
OK in summer but can lower the bathroom temperature in winter by
several degrees.
<snip>
Post by Silent Ice
I didn't buy one but thanks for mentioning it, I'm keen to hear any real
experiences. I'm not against it, wanted to see if it's an issue. Does
yours vent through the soffit? I was thinking the wind blowing across
the soffit would create more of a suction effect if anything - and cause
knocking if it were blustery. Have you gone for a straight forward type
with a round disk and offset pivot?
The vent is directly above the bath, and goes up into the loft and out to
the soffit via an in line fan and bendy tubes.

The flap is a standard one (we have them on the downstairs extractors) but
I can't recall where it pivots.

Cheers



Dave R
--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 10 x64
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