Went up to get the Xmas tree down and dismayed to see the amount of
water dripping down from the SW side.

https://flic.kr/s/aHBqjA8aE8

It is a gable roofed bungalow, approx 8m width.

Recent changes:

1) Original Soffits & Fascias replaced with PVC

2) Added 200mm insulation mainly to the SW side (the side with the
most problem)

3) Running the CH at a lower temperature

The roof already had has roof tile vents, and the attic was already
boarded as shown in the photos.

I didn't add much insulation to the NE roof as that is mainly boarded.
There is no sign of dripping on the side at first inspection.

Going by
https://nhbc-standards.co.uk/7-roofs/7-2-pitched-roofs/7-2-15-ventilation-vapour-control-and-insulation/
I may have been over-enthusiastic about using a rake to push the new
insulation into the eaves on the SW side.

I do not recall ever having any such problem in the previous 6
winters. There was a bit of interstitial condensation showing on the
sarking and rafters when the property was inspected at purchase hence
the 6 roof tile vents which appeared to fix the problem.

I know the weather is a bit extreme at the moment and I would like any
advice before I pull back the insulation on the SW roof.

--
AnthonyL

Why ever wait to finish a job before starting the next?

AnthonyL <nospam@please.invalid> wrote:
>
> Going by
> https://nhbc-standards.co.uk/7-roofs/7-2-pitched-roofs/7-2-15-ventilation-vapour-control-and-insulation/
> I may have been over-enthusiastic about using a rake to push the new
> insulation into the eaves on the SW side.
>
> I do not recall ever having any such problem in the previous 6
> winters. There was a bit of interstitial condensation showing on the
> sarking and rafters when the property was inspected at purchase hence
> the 6 roof tile vents which appeared to fix the problem.

By doing the works, did you perhaps block up any ventilation? For example
rotten wooden soffits might have had cracks which you sealed up replacing
with nice new PVC ones? I don't think pushing insulation into the soffits
would cause problems of itself, only if there was soffit ventilation
(deliberate or otherwise) which you have blocked.

Adding more insulation makes your roofspace colder, which makes condensation
more of a problem. The solution to that is better roof ventilation. Maybe
your tile vents aren't enough any more?

> I know the weather is a bit extreme at the moment and I would like any
> advice before I pull back the insulation on the SW roof.

I'm guessing you have confirmed this is condensation, rather than say
snowmelt coming in somehow? Does it feel 'muggy' up there?

Theo

On 15/12/2022 16:43, Theo wrote:
> I don't think pushing insulation into the soffits
> would cause problems of itself, only if there was soffit ventilation
> (deliberate or otherwise) which you have blocked.

Yup. I had water dripping off the windows here this morning. I opened
the windows a crack and it all cleared. Ventilation is the antidote to
humidity

Chances are some moisture laden inside air is leaking into the 'cold
roof'..so fix that or improve soffit ventilation

--
"Anyone who believes that the laws of physics are mere social
conventions is invited to try transgressing those conventions from the
windows of my apartment. (I live on the twenty-first floor.) "

Alan Sokal

In message <tnfk5p$34kco$1@dont-email.me>, The Natural Philosopher
<tnp@invalid.invalid> writes
>On 15/12/2022 16:43, Theo wrote:
>> I don't think pushing insulation into the soffits
>> would cause problems of itself, only if there was soffit ventilation
>> (deliberate or otherwise) which you have blocked.
>
>Yup. I had water dripping off the windows here this morning. I opened
>the windows a crack and it all cleared. Ventilation is the antidote to
>humidity
>
>Chances are some moisture laden inside air is leaking into the 'cold
>roof'..so fix that or improve soffit ventilation

During the conversion work on our timber frame chalet bungalow (built
1995) I was slightly surprised to discover a plastic membrane stapled to
the underside of the loft timbers and above the plasterboard.
As TNP says you don't want moisture laden warm air reaching a cold spot.
Elsewhere the soffit includes a slotted ventilation strip. Where we have
included original loft space for accommodation, I was careful to repeat
the arrangement. Building control insisted that additional insulation
should not fully block the air gap under the roofing felt.
>

--
Tim Lamb

On Thu, 15 Dec 2022 18:02:41 +0000, Tim Lamb
<tim@marfordfarm.demon.co.uk> wrote:

>In message <tnfk5p$34kco$1@dont-email.me>, The Natural Philosopher
><tnp@invalid.invalid> writes
>>On 15/12/2022 16:43, Theo wrote:
>>> I don't think pushing insulation into the soffits
>>> would cause problems of itself, only if there was soffit ventilation
>>> (deliberate or otherwise) which you have blocked.
>>
>>Yup. I had water dripping off the windows here this morning. I opened
>>the windows a crack and it all cleared. Ventilation is the antidote to
>>humidity
>>
>>Chances are some moisture laden inside air is leaking into the 'cold
>>roof'..so fix that or improve soffit ventilation
>
>During the conversion work on our timber frame chalet bungalow (built
>1995) I was slightly surprised to discover a plastic membrane stapled to
>the underside of the loft timbers and above the plasterboard.
>As TNP says you don't want moisture laden warm air reaching a cold spot.
>Elsewhere the soffit includes a slotted ventilation strip. Where we have
>included original loft space for accommodation, I was careful to repeat
>the arrangement. Building control insisted that additional insulation
>should not fully block the air gap under the roofing felt.

I don't recall seeing any ventilation strips on casual viewing. Did
the roofers miss something out? Are your strips obvious like this for
instance?

https://www.wickes.co.uk/Wickes-PVCu-White-Ventilated-Soffit-Strip---60-x-2500mm/p/162632

--
AnthonyL

Why ever wait to finish a job before starting the next?

On 15/12/2022 16:24, AnthonyL wrote:
> Went up to get the Xmas tree down and dismayed to see the amount of
> water dripping down from the SW side.
>
> https://flic.kr/s/aHBqjA8aE8
>

I had exactly the same. My semi has a 37 degree pitch roof
and the house is North-South aligned so the north side of
the roof never gets any sun at this time of year and that
side collects condensation under the 1976 sarking felt which
then freezes if the temperature goes below about -2C.

Then the next sunny day warms up the south side and all the
ice melts and you can hear it dripping which is alarming in
this weather because it sounds like a burst pipe dripping.

It only happens when we have a really cold spell immediately
after a mild, muggy spell and the last one was 2008/9 and
again 2009/10.

We had a *very* warm and wet November and all my temp+
humidity devices said it was 70percent humid inside the
house. Now they say 45percent humid, so all that humid
(effectively outside) air in the loft has dumped its
water content on the sarking felt.

A few houses on this estate (built between 1973 and 1978)
have had their marley modern tiles removed and the trusses
re-covered with breathable membrane + new tile battens.
Only two have gone the whole hog with new tiles as well.

Unless you have a warm roof structure this will happen
every time we transition from warm mild damp weather to
blocking high over Scandinavia and you have a cold roof
that is ventilated with damp outside air.

On 15/12/2022 17:06, The Natural Philosopher wrote:
> On 15/12/2022 16:43, Theo wrote:
>>   I don't think pushing insulation into the soffits
>> would cause problems of itself, only if there was soffit ventilation
>> (deliberate or otherwise) which you have blocked.
>
> Yup. I had water dripping off the windows here this morning. I opened
> the windows a crack and it all cleared. Ventilation is the antidote to
> humidity
>
> Chances are some moisture laden inside air is leaking into the 'cold
> roof'..so fix that or improve soffit ventilation
>

You can ventilate a cold roof all you like but if the air is
carrying a lot of moisture as it was during our unusually
warm November then a sudden change to -6 overnight is
going to condense out that water inside the loft onto
a convenient cold surface - the sarking felt.

On 15/12/2022 18:16, AnthonyL wrote:
> On Thu, 15 Dec 2022 18:02:41 +0000, Tim Lamb
> <tim@marfordfarm.demon.co.uk> wrote:
>
>> In message <tnfk5p$34kco$1@dont-email.me>, The Natural Philosopher
>> <tnp@invalid.invalid> writes
>>> On 15/12/2022 16:43, Theo wrote:
>>>> I don't think pushing insulation into the soffits
>>>> would cause problems of itself, only if there was soffit ventilation
>>>> (deliberate or otherwise) which you have blocked.
>>>
>>> Yup. I had water dripping off the windows here this morning. I opened
>>> the windows a crack and it all cleared. Ventilation is the antidote to
>>> humidity
>>>
>>> Chances are some moisture laden inside air is leaking into the 'cold
>>> roof'..so fix that or improve soffit ventilation
>>
>> During the conversion work on our timber frame chalet bungalow (built
>> 1995) I was slightly surprised to discover a plastic membrane stapled to
>> the underside of the loft timbers and above the plasterboard.
>> As TNP says you don't want moisture laden warm air reaching a cold spot.
>> Elsewhere the soffit includes a slotted ventilation strip. Where we have
>> included original loft space for accommodation, I was careful to repeat
>> the arrangement. Building control insisted that additional insulation
>> should not fully block the air gap under the roofing felt.
>
> I don't recall seeing any ventilation strips on casual viewing. Did
> the roofers miss something out? Are your strips obvious like this for
> instance?
>
> https://www.wickes.co.uk/Wickes-PVCu-White-Ventilated-Soffit-Strip---60-x-2500mm/p/162632
> There are also eaves vents that fit over the fascias

https://klober.co.uk/roof-ventilation/eaves-roof-ventilation/p/over-fascia-vent

If you have neither then the easiest thing to retrofit may be round
soffit vents to give the equivalent of 10mm per meter (assuming no
insulation in the loft over them). Eg

https://www.screwfix.com/p/circular-soffit-vent-white-70mm-10-pack/68936

--
Robin
reply-to address is (intended to be) valid

In message <639b63b5.159826984@news.eternal-september.org>, AnthonyL
<nospam@please.invalid> writes
>On Thu, 15 Dec 2022 18:02:41 +0000, Tim Lamb
><tim@marfordfarm.demon.co.uk> wrote:
>
>>In message <tnfk5p$34kco$1@dont-email.me>, The Natural Philosopher
>><tnp@invalid.invalid> writes
>>>On 15/12/2022 16:43, Theo wrote:
>>>> I don't think pushing insulation into the soffits
>>>> would cause problems of itself, only if there was soffit ventilation
>>>> (deliberate or otherwise) which you have blocked.
>>>
>>>Yup. I had water dripping off the windows here this morning. I opened
>>>the windows a crack and it all cleared. Ventilation is the antidote to
>>>humidity
>>>
>>>Chances are some moisture laden inside air is leaking into the 'cold
>>>roof'..so fix that or improve soffit ventilation
>>
>>During the conversion work on our timber frame chalet bungalow (built
>>1995) I was slightly surprised to discover a plastic membrane stapled to
>>the underside of the loft timbers and above the plasterboard.
>>As TNP says you don't want moisture laden warm air reaching a cold spot.
>>Elsewhere the soffit includes a slotted ventilation strip. Where we have
>>included original loft space for accommodation, I was careful to repeat
>>the arrangement. Building control insisted that additional insulation
>>should not fully block the air gap under the roofing felt.
>
>I don't recall seeing any ventilation strips on casual viewing. Did
>the roofers miss something out? Are your strips obvious like this for
>instance?
>
>https://www.wickes.co.uk/Wickes-PVCu-White-Ventilated-Soffit-Strip---60-
>x-2500mm/p/162632

Yes. Not quite that fancy but similar rectangular slots.

--
Tim Lamb

On Thu, 15 Dec 2022 18:39:19 +0000, Andrew
<Andrew97d-junk@mybtinternet.com> wrote:

>On 15/12/2022 16:24, AnthonyL wrote:
>> Went up to get the Xmas tree down and dismayed to see the amount of
>> water dripping down from the SW side.
>>
>> https://flic.kr/s/aHBqjA8aE8
>>
>
>I had exactly the same. My semi has a 37 degree pitch roof
>and the house is North-South aligned so the north side of
>the roof never gets any sun at this time of year and that
>side collects condensation under the 1976 sarking felt which
>then freezes if the temperature goes below about -2C.
>
>Then the next sunny day warms up the south side and all the
>ice melts and you can hear it dripping which is alarming in
>this weather because it sounds like a burst pipe dripping.
>
>It only happens when we have a really cold spell immediately
>after a mild, muggy spell and the last one was 2008/9 and
>again 2009/10.
>
>We had a *very* warm and wet November and all my temp+
>humidity devices said it was 70percent humid inside the
>house. Now they say 45percent humid, so all that humid
>(effectively outside) air in the loft has dumped its
>water content on the sarking felt.
>
>A few houses on this estate (built between 1973 and 1978)
>have had their marley modern tiles removed and the trusses
>re-covered with breathable membrane + new tile battens.
>Only two have gone the whole hog with new tiles as well.
>
>Unless you have a warm roof structure this will happen
>every time we transition from warm mild damp weather to
>blocking high over Scandinavia and you have a cold roof
>that is ventilated with damp outside air.

I'm not usually in the attic every other day and I wasn't here till
2016. Of course by the time I get round to going up there and
creating a bit of a gap the weather will have changed.

I've got a lot of stuff up in the loft which I don't want to get wet.
Fortunately, as I haven't yet put everything where I want it, most is
pushed up on the dry side whilst I've been waiting for it to be a bit
warmer to spend an hour or two sorting it out.

--
AnthonyL

Why ever wait to finish a job before starting the next?

On Thu, 15 Dec 2022 20:48:08 +0000, Robin <rbw@outlook.com> wrote:

>On 15/12/2022 18:16, AnthonyL wrote:
>> On Thu, 15 Dec 2022 18:02:41 +0000, Tim Lamb
>> <tim@marfordfarm.demon.co.uk> wrote:
>>
>>> In message <tnfk5p$34kco$1@dont-email.me>, The Natural Philosopher
>>> <tnp@invalid.invalid> writes
>>>> On 15/12/2022 16:43, Theo wrote:
>>>>> I don't think pushing insulation into the soffits
>>>>> would cause problems of itself, only if there was soffit ventilation
>>>>> (deliberate or otherwise) which you have blocked.
>>>>
>>>> Yup. I had water dripping off the windows here this morning. I opened
>>>> the windows a crack and it all cleared. Ventilation is the antidote to
>>>> humidity
>>>>
>>>> Chances are some moisture laden inside air is leaking into the 'cold
>>>> roof'..so fix that or improve soffit ventilation
>>>
>>> During the conversion work on our timber frame chalet bungalow (built
>>> 1995) I was slightly surprised to discover a plastic membrane stapled to
>>> the underside of the loft timbers and above the plasterboard.
>>> As TNP says you don't want moisture laden warm air reaching a cold spot.
>>> Elsewhere the soffit includes a slotted ventilation strip. Where we have
>>> included original loft space for accommodation, I was careful to repeat
>>> the arrangement. Building control insisted that additional insulation
>>> should not fully block the air gap under the roofing felt.
>>
>> I don't recall seeing any ventilation strips on casual viewing. Did
>> the roofers miss something out? Are your strips obvious like this for
>> instance?
>>
>> https://www.wickes.co.uk/Wickes-PVCu-White-Ventilated-Soffit-Strip---60-x-2500mm/p/162632
>> There are also eaves vents that fit over the fascias
>
>https://klober.co.uk/roof-ventilation/eaves-roof-ventilation/p/over-fascia-vent
>
>If you have neither then the easiest thing to retrofit may be round
>soffit vents to give the equivalent of 10mm per meter (assuming no
>insulation in the loft over them). Eg
>
>https://www.screwfix.com/p/circular-soffit-vent-white-70mm-10-pack/68936
>
>

I'm pretty sure I have neither and the work was only done this year so
I might go back to the roofers on this.

But ... I've only got the condensation dripping on the one side and
that is the side I added the insulation and used a rake to push it
into the edges. I think my first port of call is to retract it a bit
so that I can at least see daylight.

It'll have to be pulled back anyway if the vents are added.

The screwfix items look ideal though, thanks, and being a bungalow
it'll be a fairly easy job to put several in each side whoever does
it.

--
AnthonyL

Why ever wait to finish a job before starting the next?

I am in a similar situation to you. I went into the attic to get the xmas tree and noticed condensation droplets hanging of the felt and wet patches on the boarded section and water marks on the insulation. The majority of the condensation is on the north'ish facing roof but there is some on the south'ish facing side. I havent noticed it in previous years but then I may just have not been paying attention!

We have had a few changes recently.

Summer 2021 - Roof "muck work" redone on the edges and ridge tiles re-laid. Fascias and soffits fitted along with new gutters. We didnt have soffits before this. The ends of the roof trusses projected out beyond the tiles and the external wall (I assume a decorative feature). There is a plastic vent between where the underside of the roof meets the external wall which has insect mesh on the outside part. I am sure there is a name for this setup but I dont know what it is.

Summer 2022 - Solar panels and house battery installed. The inverter and battery are in the loft space.

Oct 2022 - H/W converted to unvented. Cold water tank removed from the loft. I insulated where the tank had been now that we dont need to keep it warm.

There are several downlighters in the bathroom and ensuite. These are just covered by a metal box and insulation laid over the top of them.

The solar inverter and battery will produce some heat but it doesnt seem to be very much so I dont think this is an issue. Having the south'ish facing side of the roof covered in solar panels may mean that the loft doesnt warm up as much as it did before so this may be a contributing factor.

These are the things I think need to be looked at/addressed:

I have been looking at the soffits that were fitted and I cannot see any ventilation in them so I assume that is one of the problems. I'll need to speak to the company that fitted them. Maybe removing the soffits would be a better option rather than fitting vents as this might allow more airflow?

We are having the bathroom and ensuite refurbished in a couple of weeks so I was going to ask them about removing the plasterboard ceiling and replacing it with plasterboard and a vapour barrier or foil backed plasterboard. There is no vapour barrier between any of the ceilings upstairs and the loft at the moment. I guess it wasnt the done thing in 1989. We were also going to use a standard light fitting in these rooms rather than downlighters to minimise the risk of damp air getting into the loft.

Where our H/W was converted, this has left several holes in the ceiling between the airing cupboard and the loft (from pipes no longer needed). I need to fill these in.

I have orderd some of these:
https://www.manthorpebp.co.uk/roofing/roof-ventilation-%E2%80%93-solutions-modern-day-problem/felt-lap-vent
Hopefully they will help improve the ventilation!

I am also wondering if I need to fit some ridge vents (currently there arent any vents on the roof) or gable end vents. I may see if the changes above help first.

Alan

Yes I have one unused room upstairs and in order to save on heating, closed
its door, the first time I went in I found the window frames frozen, and
water on the window sill, Sealing a room up is never a good idea.
What somebody seems not to realise is that warm air can hold a lot more
moisture than cold air, and thus it was predictable in my case that the air
as it cooled shed the water it carried.
Brian

--

--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"The Natural Philosopher" <tnp@invalid.invalid> wrote in message
news:tnfk5p$34kco$1@dont-email.me...
> On 15/12/2022 16:43, Theo wrote:
>> I don't think pushing insulation into the soffits
>> would cause problems of itself, only if there was soffit ventilation
>> (deliberate or otherwise) which you have blocked.
>
> Yup. I had water dripping off the windows here this morning. I opened the
> windows a crack and it all cleared. Ventilation is the antidote to
> humidity
>
> Chances are some moisture laden inside air is leaking into the 'cold
> roof'..so fix that or improve soffit ventilation
>
> --
> "Anyone who believes that the laws of physics are mere social conventions
> is invited to try transgressing those conventions from the windows of my
> apartment. (I live on the twenty-first floor.) "
>
> Alan Sokal
>

On 16/12/2022 11:28, AlanC wrote:

> The solar inverter and battery will produce some heat but it doesnt seem to be very much so I dont think this is an issue. Having the south'ish facing side of the roof covered in solar panels may mean that the loft doesnt warm up as much as it did before so this may be a contributing factor.
>
Your solar PV's will massively reduce the amount of heat energy from
the sun from warming your loft (and will also reduce the summer
temperature of your loft) assuming they are on south/south-west
facing roofs.

All the ventilation in the world won't prevent the problems that you,
myself and others are having. It is the result of an extremely
warm and humid November (so loft full of 'outside' air) followed
by temperatures down to -6 or lower and minimal/zero wind.

In years gone by a warm/wet September would be followed by cold
winds from the North West, but not below freezing. This would
blow the humid air out of a (ventilated) loft or cold flat roof
and replace it with much dryer air. Any subsequent really cold
snap would be less likely to cause significant condensation.

This transition from Indian summer in september to much colder
and dryer october doesn't seem to happen these days.

> We are having the bathroom and ensuite refurbished in a couple of weeks so I was going to ask them about removing the plasterboard ceiling and replacing it with plasterboard and a vapour barrier or foil backed plasterboard.

No need to remove existing PB. Just overlay with an extra layer of
foil-backed PB (or just staple a piece of polythene sheet over
existing ceiling and then add another layer of PB).

If you are really concerned with water vapour from the
bathroom getting into the loft then don't have any
downlighters.

On Friday, December 16, 2022 at 12:04:38 PM UTC, Andrew wrote:
> On 16/12/2022 11:28, AlanC wrote:
>

> > We are having the bathroom and ensuite refurbished in a couple of weeks so I was going to ask them about removing the plasterboard ceiling and replacing it with plasterboard and a vapour barrier or foil backed plasterboard.
> No need to remove existing PB. Just overlay with an extra layer of
> foil-backed PB (or just staple a piece of polythene sheet over
> existing ceiling and then add another layer of PB).

Ahh, good idea. I hadnt thought about just adding another layer. Thanks.

I had thought about adding a vapour barrier from the loft side by laying it over the joists, contouring it down to the back of the pasterboard (repeating over each joist) and then replacing the loft insulation. My concern with that method was that the joists are then on the warm side of the vapour barrier which might add a risk of them rotting?

We had our garage converted in 2014. The plasterboard that was fitted to the walls and ceiling had a vapour barrier behind it, basically sealing the whole room. The loft space above it has never had any signs of condensation. Given your weather statement above (which I am not disputing), I would have expected to see some condensation in the conversion loft. The same changes regarding fascias and soffits was also done on this part of the building too so I think it also has limited ventilation.

AlanC <alanc@mullen.demon.co.uk> wrote:
> I had thought about adding a vapour barrier from the loft side by laying
> it over the joists, contouring it down to the back of the pasterboard
> (repeating over each joist) and then replacing the loft insulation. My
> concern with that method was that the joists are then on the warm side of
> the vapour barrier which might add a risk of them rotting?

If the joists are the warm side, they are presumably warm (ie covered in
insulation) which reduces condensation? If there's no insulation over the
top of them, the vapour barrier would prevent condensation contacting the
joists but would just condense on the vapour barrier instead.

The problem though is that you can't cover all of the joists, because the
ends of them need to go into the walls etc. And that point might be where
you get problems - if the joist is warm but the end goes into a cold wall,
moisture can wick along the grain.

Theo

On Fri, 16 Dec 2022 22:37:34 +1100, Brian Gaff <brian1gaff@gmail.com>
wrote:

> Yes I have one unused room upstairs and in order to save on heating,
> closed
> its door, the first time I went in I found the window frames frozen, and
> water on the window sill, Sealing a room up is never a good idea.

Works fine for me to save heat because a sealed room would never
freeze inside, it doesnt get cold enough for that.

> What somebody seems not to realise is that warm air can hold a lot more
> moisture than cold air, and thus it was predictable in my case that the
> air
> as it cooled shed the water it carried.