Daughter had raindrops coming in corner of kitchen. West-facing wall
in Scotland so very wet.
Traced to the cooker hood vent. Rectangular section with good cowl on
outside.
Remove flexible trunking for hood to this final section and noted that
the *inside* of the duct was completely dry but the *upper* surface
was wet. Checked and re-sealed external cowl to wall.

Could this be coming from inside the cavity - since the duct bridges
the cavity (which has been insulated in the last year with woolly
stuff).
Perhaps dripping from wall ties above?
If so - how to cure - duct is only a couple of mm from ceiling.
https://www.flickr.com/photos/13629865@N03/16078423477/

The outer wall is saturated (like the rest of Scotland just now).

"Geo" wrote in message
...
Daughter had raindrops coming in corner of kitchen. West-facing wall
in Scotland so very wet.
Traced to the cooker hood vent. Rectangular section with good cowl on
outside.
Remove flexible trunking for hood to this final section and noted that
the *inside* of the duct was completely dry but the *upper* surface
was wet. Checked and re-sealed external cowl to wall.

Could this be coming from inside the cavity - since the duct bridges
the cavity (which has been insulated in the last year with woolly
stuff).
Perhaps dripping from wall ties above?
If so - how to cure - duct is only a couple of mm from ceiling.
https://www.flickr.com/photos/13629865@N03/16078423477/

The outer wall is saturated (like the rest of Scotland just now).

Might well be.
Check for overflowing gutters, gaps in pointing and holes/gaps in roof.

Water can run down through the cavity insulation.

There are roof repair products you can use on wet surfaces.

Strong winds can blow water across cavities.

Is the horizontal duct installed with a slight fall to the outside so that
water runs that way?
Even if it is strong winds can blow water uphill.

Try some sealant along top surface of the outer cowl/wall joint.

"Geo" wrote in message
...
Daughter had raindrops coming in corner of kitchen. West-facing wall
in Scotland so very wet.
Traced to the cooker hood vent. Rectangular section with good cowl on
outside.
Remove flexible trunking for hood to this final section and noted that
the *inside* of the duct was completely dry but the *upper* surface
was wet. Checked and re-sealed external cowl to wall.

Could this be coming from inside the cavity - since the duct bridges
the cavity (which has been insulated in the last year with woolly
stuff).
Perhaps dripping from wall ties above?

More likely to be water running down the outerwall and then across the top
of the ducting

The wall ties cannot drip water if you have cavity wall insulation


If so - how to cure - duct is only a couple of mm from ceiling.
https://www.flickr.com/photos/13629865@N03/16078423477/

The outer wall is saturated (like the rest of Scotland just now).

That ducting slopes downwards towards the inside of the house. So two
options

1. aim the vent downwards towards the outside
2. Silicone


--
Adam

On Mon, 12 Jan 2015 16:44:39 -0000, "harryagain"
wrote:


Check for overflowing gutters, gaps in pointing and holes/gaps in roof.

OK

Water can run down through the cavity insulation.


Strong winds can blow water across cavities.

Certainly had some of them - but judging by state of the piece of
hardboard below the duct it has been a long-standing fault.

Is the horizontal duct installed with a slight fall to the outside so that
water runs that way?

No - it slopes inwards

Try some sealant along top surface of the outer cowl/wall joint.

Yes - took the cowl off the wall and put new silicone all round.

Also - as test - put duct tape across the cowl opening (which is at
the bottom) so will see if that makes any difference.

On Mon, 12 Jan 2015 18:53:15 -0000, "ARW"
wrote:

"Geo" wrote in message
.. .

Perhaps dripping from wall ties above?

More likely to be water running down the outerwall and then across the top
of the ducting

The wall ties cannot drip water if you have cavity wall insulation

OK

If so - how to cure - duct is only a couple of mm from ceiling.
https://www.flickr.com/photos/13629865@N03/16078423477/

The outer wall is saturated (like the rest of Scotland just now).

That ducting slopes downwards towards the inside of the house. So two
options

Well spotted guv...

1. aim the vent downwards towards the outside
2. Silicone

Thinking 2 - and/or expanding foam?

"Geo" wrote in message
...
On Mon, 12 Jan 2015 18:53:15 -0000, "ARW"
wrote:

"Geo" wrote in message
. ..

Perhaps dripping from wall ties above?

More likely to be water running down the outerwall and then across the top
of the ducting

The wall ties cannot drip water if you have cavity wall insulation

OK

If so - how to cure - duct is only a couple of mm from ceiling.
https://www.flickr.com/photos/13629865@N03/16078423477/

The outer wall is saturated (like the rest of Scotland just now).

That ducting slopes downwards towards the inside of the house. So two
options

Well spotted guv...

1. aim the vent downwards towards the outside
2. Silicone

Thinking 2 - and/or expanding foam?

You need to stop the water where it's coming in.
Expanding foam will likely only divert it to elsewhere.

"Geo" wrote in message
...
On Mon, 12 Jan 2015 18:53:15 -0000, "ARW"
wrote:

"Geo" wrote in message
. ..

Perhaps dripping from wall ties above?

More likely to be water running down the outerwall and then across the top
of the ducting

The wall ties cannot drip water if you have cavity wall insulation

OK

If so - how to cure - duct is only a couple of mm from ceiling.
https://www.flickr.com/photos/13629865@N03/16078423477/

The outer wall is saturated (like the rest of Scotland just now).

That ducting slopes downwards towards the inside of the house. So two
options

Well spotted guv...

1. aim the vent downwards towards the outside
2. Silicone

Thinking 2 - and/or expanding foam?

You should also chip away the hole below the duct in the outer leaf and bend
it down so any water runs outwards.
Stupid person that done the installation as it is in the first place.

On 13/01/2015 06:16, harryagain wrote:
wrote in message
...
On Mon, 12 Jan 2015 18:53:15 -0000, "ARW"
wrote:

wrote in message
...

Perhaps dripping from wall ties above?

More likely to be water running down the outerwall and then across the top
of the ducting

The wall ties cannot drip water if you have cavity wall insulation

OK

If so - how to cure - duct is only a couple of mm from ceiling.
https://www.flickr.com/photos/13629865@N03/16078423477/

The outer wall is saturated (like the rest of Scotland just now).

That ducting slopes downwards towards the inside of the house. So two
options

Well spotted guv...

1. aim the vent downwards towards the outside
2. Silicone

Thinking 2 - and/or expanding foam?

You should also chip away the hole below the duct in the outer leaf and bend
it down so any water runs outwards.
Stupid person that done the installation as it is in the first place.


I notice there 2 pipes there hot/cold? Could that be causing
condensation, just guessing.

"Geo" wrote in message
...
On Mon, 12 Jan 2015 16:44:39 -0000, "harryagain"
wrote:


Check for overflowing gutters, gaps in pointing and holes/gaps in roof.

OK

Water can run down through the cavity insulation.


Strong winds can blow water across cavities.

Certainly had some of them - but judging by state of the piece of
hardboard below the duct it has been a long-standing fault.

Is the horizontal duct installed with a slight fall to the outside so that
water runs that way?

No - it slopes inwards

Try some sealant along top surface of the outer cowl/wall joint.

Yes - took the cowl off the wall and put new silicone all round.

Also - as test - put duct tape across the cowl opening (which is at
the bottom) so will see if that makes any difference.



That's where you are going wrong. The water is running down the inside skin
of the outer wall and then across the ducting (as it slopes the wrong way).

You need to remove the rectangular ducting and put a bead of silicone across
the top of it just where it sits itside the outer skin. That silicone (when
cured) will then push the water back to the front of the ducting and back
down the front of cavity.

--
Adam