extractor fan duct running.

[Greig222]

Quick question to the sparkies/joiners out there.

Looking to fit a ceiling fan above my shower can anyone shed some light on drilling 4" holes for running ducting through the joists running adjacent for about 2m to reach the outside wall. Are the joists strong enough to handle being bored out? The supporting wall either side would be 4m and 2m either side of the bore.
Would I have to put extra support to the joists.

What fan would you recommend?
Bathroom space 2.5 x 2 x 2.5
shower is mains fed

Cheers G

 

[EFLImpudence]

http://niceic.com/Uploads/File3777.pdf

 

[Gutterball]

NO YOU CAN'T
can you not go through the wall

 

[JohnD]

What is above the ceiling?

 

[Greig222]

Can't go thru the wall as there is a window runs the full length of the room and the lintel obstructs where the fan would go if wall mounted.
Above the bathroom is a floored attic which I'm planning a conversion at some point in the near future.

 

[Gutterball]

you could mount it in the window.

 

[bernardgreen]

Above the bathroom is a floored attic which I'm planning a conversion at some point in the near future.

Use your imagination.

With creative planning you could bring the duct up vertically to then run on top of the floor of the attic to where it leaves the building.

Then box it it in as part of a storage unit, under a bed or as part of a childs play castle.

Or take it vertically up and out through the roof. Box it in and make it a feature in the room. A long vertical run will need a condensation trap and drain.

 

[JohnD]

consider rectangular rigid exposed duct. You can paint it to match the ceiling. You can run it in the angle between wall and ceiling.

What is the room next to the bathroom? Has it also got a full-width window?

What is above the bathroom? Is it in the middle of the loft or is any part of it towards the eaves or of limited height?

Or you could put a duct up through the ceiling and immediately turn it to vent through the loft wall. Presumably the loft does not have full-height full-width windows. This would give you space for an inline fan which can be quieter and more powerful.

Or you can run the duct downwards and vent it through the wall below the window.

Or buy a new glass pane with a fan hole in it.

 

[Greig222]

I've thought about window mount bit assumed high costs having replace window with customers made item?

Unfortunately directly above is centre loft space not in the eves.

Does the fan have to be put above shower to work properly or can it be put in opposite corner of the ceiling closer to the outside wall.

I do have the flu for the toilet waste pipe boxed in in the corner of the bathroom closest to the outside wall going out thru the roof could this be incorporated somehow?

 

[JohnD]

it does not have to be directly above the shower.

Steam rises, so if the extract is in the ceiling, the steam will reach it.

Unless it is more than 2250mm high, do not put an electric fan directly over a bath or shower

//www.diynot.com/wiki/Electrics:bathroom_zones

 

[bernardgreen]

I do have the flu [vent pipe] for the toilet waste pipe boxed in in the corner of the bathroom closest to the outside wall going out thru the roof could this be incorporated somehow?

You cannot use the vent pipe but you could run a separate pipe inside the same boxing and out through a second vent.

You cannot use the toilet vent as that would allow sewer gas to enter the bathroom when the fan was NOT running.

 

[Greig222]

I vaguely read something about the length of ducting effecting the performance of the fan is there a rule of thumb when calculating length of ducting from ceiling vent to fan and fan to exit property.

 

[Greig222]

I'm thinking now to take ceiling vent to fan and run parallel to joists and out at the eves exiting downward from the venting facia which runs the length of the house by the guttering.

The ducting would be roughly 4.5m from ceiling vent to exit

Is this an option?

 

[JohnD]

yes

get an inline fan, which will have enough power to blow up the duct.

for example http://www.screwfix.com/p/100mm-mixed-flow-fan/26867

Read the db noise and the cubic metres per hour extract rate.

As a guide, a cheap, ineffective builders fan has a rate of about 85 cu m which is weak. Look for double.

Use rigid plastic duct (or soil pipe which is the same thing) tilted downwards slightly towards the outside so that any condensation runs out. Wrap the duct in mineral wool. This will keep it warm this minimising condensation, and will also muffle any vibration.

 

[EFLImpudence]

Don't bother - open the window.

If your house is airtight open a window somewhere else as well.