Water drops on under side of breather membrane

[iTRYer]

Hi any help apreciated, I have drops of water underside of my breather as seen on photo, the inuslation leaves a gap as seen but still water in this cold weather which then soaks insulation, how do I stop this?

Thanks

 

[Alastairreid]

Ventilation at high and low level.
Make sure extractor fans are connected to outside. Moisture in attics is quite common in this cold weather, the attic space should be cool and airy with insulation at ceiling level.

 

[iTRYer]

Hi Thanks for reply, this is a small office extension on floor level with tile roof then the Easytrim Master 112. If I fit roof vents removing a tile on both slopes and add one of these will that sort?

https://www.amazon.co.uk/dp/B01FUYLHOI/ref=twister_B01FUYLHHU?_encoding=UTF8&th=1

or are you saying eaves as well so this too:

https://www.amazon.co.uk/10mm-Over-Fascia-Vent-Ventilation/dp/B07B4NTBC5/ref=asc_df_B07B4NTBC5?tag=bingshoppinga-21&linkCode=df0&hvadid=80195721626759&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583795266897400&th=1

 

[Mr Chibs]

Is that all the insulation you have in the roof? what is the tickness 50mm?

It should be, say, 100mm in-between the rafters, and 50mm under the rafters, and all properly gap filled and tape'd up, to make it air-tight.

It might be warm air (presume you have heating in there) rising and condensing on the underside of the breather membrane.

 

[iTRYer]

It might be warm air (presume you have heating in there) rising and condensing on the underside of the breather membrane.

Yeah I think it is this as I dont think I have leaks above the membrane, 50mm insulation leaving 50mm, so if thats case do I need better vents above the membrane or fit a Water Vapour barrier over top of insulation then plaster or ply?

 

[Mr Chibs]

Think I would go down the eaves vents route firstly.

Then I would get a foam gun and foam the gaps for the insulation that is in-between the rafters.
Tape all the joins with aluminium duct tape.

I would then overboard the whole roof with more insulation, as thick as you can take.

I'm presuming your joists are 100mm? would have thought they should be deeper?
With a 50mm air gap that would explain why the insulation is 50mm.

If everything is taped this should stop moisture making it's way into the roof.

Have you got a pitched roof? if so, perhaps a dry ridge ventilation would be a good idea.


Good luck

 

[JohnD]

CONDENSATION IN LOFT (ANSWERS)

This seems to be the time of year for condensation in lofts, so instead of replying to lots of queries I though I would write this "one-size-fits-all" post. Please also see http://www.diynot.com/wiki/Building%3ACondensation-in-Houses Condensation in lofts occurs when the amount of water...

www.diynot.com

 

[tony1851]

Yeah I think it is this as I dont think I have leaks above the membrane, 50mm insulation leaving 50mm, so if thats case do I need better vents above the membrane or fit a Water Vapour barrier over top of insulation then plaster or ply?

Any vapour barrier should be on the warm side of the insulation.

 

[iTRYer]

Think I would go down the eaves vents route firstly.

Then I would get a foam gun and foam the gaps for the insulation that is in-between the rafters.
Tape all the joins with aluminium duct tape.

I would then overboard the whole roof with more insulation, as thick as you can take.

I'm presuming your joists are 100mm? would have thought they should be deeper?
With a 50mm air gap that would explain why the insulation is 50mm.

If everything is taped this should stop moisture making it's way into the roof.

Have you got a pitched roof? if so, perhaps a dry ridge ventilation would be a good idea.


Good luck

Thanks Mr Chibs, so the joints, gaps in the insulation between rafters foam and tape for tight seal. Overboard on top, can I use foil backing there and tape as could still screw boarding then to the rafters. Joists are 100mm, yes pitched roof both sides, eves first make sure flow goes over...

 

[Mr Chibs]

Morning, yes you can and should use foil backed... and tape.
Use as long screws as you need to to anchor into rafters, they don't need to be anything special.

You can use Wedi washers to anchor insulation/plasterboard in place, it will stop the head of the screw pulling through.

Good luck

 

[iTRYer]

Morning, yes you can and should use foil backed... and tape.
Use as long screws as you need to to anchor into rafters, they don't need to be anything special.

You can use Wedi washers to anchor insulation/plasterboard in place, it will stop the head of the screw pulling through.

Good luck

Morning, agh good advice thanks, so you wouldnt recommend aliminium roll on top as oppose to thicker kingspan...?one daft question I thought the eves insulation was the air flow above the membrane and not under it too as that would be inside the build that correct, so just above?

 

[Mr Chibs]

Aluminium roll? Are you talking about the space blanket foil quit malarkey? If so, I wouldn't.

Eaves vents, go under the membrane. When you make the insulation air tight, warm air from the roof will not be able to reach the underside of the membrane and condense into droplets. The eaves ventilation will allow any moisture to be carried away.

Have your ridge tiles been mortared on? Can you take a pic if unsure. A ventilated ridge might help, along with the eaves vents.

 

[iTRYer]

Hi yes ridge tiles mortared on I know there is air flow over the ridge above the membrane. I think I am mixed up with eves and soffits lol, so you mean put vents in the eves as in up the sides/slope of the roof both sides and below the membrane to allow air flow, but thats ok as inside will be sealed so no draft will come down inside the room, that correct? or is it soffit under rood edge hang need vents for under membrane and above membrane. Sorry for questions thanks for all your help.

Agh like this: https://www.bing.com/videos/search?q=eves+ventilation+&&view=detail&mid=E0547AB8CCC800E982B8E0547AB8CCC800E982B8&&FORM=VRDGAR&ru=/videos/search?q=eves+ventilation+&FORM=HDRSC4

Same tiles as me too, so without taking tiles back off can I drill thru and stick a different vent on? if so can you advise what would work thanks again.

 

[Mr Chibs]

Take a photo of your current fascia, so we can check what you currently have i.e. soffit vents?

One or the other, you don't need both.

You don't need any ventilation for above the membrane.

 

[iTRYer]

Hi I think I see the issue now you have pointed it out that the membrane has no air under on the edges, so clear out under there and add some vents, same for both sides that about right?