New Ducting advice please

[Arnold9801]

I'm due to start fitting the ducting to the roof vents installed by the roofers on our new build for the bathroom and another for the en suite. The run from the vents to the showers is approx 15 feet. 

 

I'm concerned that if I fit flexible ducting it will develop sagging and with condensation, be a trap for water to build up. As its up in the attic the long term effect of this (as we won't be going up there very often) concerns me. 

 

Could anyone advise me whether I'm being overly concerned or would it be best to avoid flexi ducting and install rigid ducting instead? Any other advice would be appreciated. 

 

Thank you. 

 

Arnold9801 

[JohnMo]

Avoid flexible, unless pulled taught.  Use hard pipe and elbows, will give a better performance from fan and less noise.

[Arnold9801]

Many thanks. 

[James94]

Might be worth insulating all ducting too if its a cold roof space, this might prevent some condensate.

[Iceverge]

There's 2 types of flexible ducting. 

 

Floppy:

 

 

 

Best Avoided. 

 

 

 

And Semi Rigid:

Which lots of us have used to good effect. 

[Conor]

Semi ridgid all the way. The fully flexible is OK if you support it fully. But that can be a pain if it needs to be elevated.

 

Keep an eye on the market place here or post a request as the amount you need is likely laying around unused at somebody's site.

Edited June 28, 2022 by Conor

[Arnold9801]

May Thanks everyone for your advice. Greatly appreciated in an area I know nothing about. 

 

 

Arnold9801 

[Arnold9801]

8 hours ago, James94 said:

Might be worth insulating all ducting too if its a cold roof space, this might prevent some condensate.

What insulation is best? 

[Iceverge]

 

 

This would work. 

 

If you can get extract fans that run constantly at a low level. You'll have better internal air quality and less noise. 

[Arnold9801]

Many Thanks