Serious Attic condensation problem

gombeen01 · 17-01-2013 8:07pm #1

I have a serious condensation problem in my attic that I am not able to solve without actually stripping the roof and replacing the roofing felt or cutting it
out altogether.
There is plenty of vents at eaves level and at the top.
My house was built in 03/04 and the felt that was used is non breathable (very similar to polythene)
I found this link its identical to my condensation problem http://www.youtube.com/watch?v=KU7TKI3fmt0
There is no condensation on the inside until we get frost, zero or minus 1 and the inside is wet.
Have you ever seen this and if so what can be done?

Certified · 18-01-2013 9:21am

What type of roof have you got, is it a traditional simple truss/cut roof over a bungalow or two-storey house? Can you see all the roof when inside the attic and is it possible to get access to the wall plate?
If you have a similar amount of moisture/water forming on the membrane there is maybe something else that is significantly contributing to the moisture levels up there.
By any chance is there a bathroom, kitchen or tumble dryer extractor venting into the attic space?
If not, is there an attic hatch located in the bathroom or utility?

gombeen01 · 18-01-2013 12:34pm

Yes it is a cut roof and it is a bungalow.Im almost sure there is 800sq feet of conversion space but only one room is complete so I have access to all of the roof except for about 12ft by6 ft area where the slab is nailed to the rafters. This room is not at the end of the attic space but probably two thirds of the way along the length of the house if you know what I mean.I can still get at this space in a limited way if I have to.Example I can see that the insulation is not too near the felt in this area.There is no extractors vented into the attic and there is no attic hatch there is an opening for a stairs and at the top it was temporaily (few years ago) closed off to see if it would cure the condensation problem.Even with it closed off I still have access to the room upstairs.I didnt finish the rest of the rooms until I get this fixed.The worst part is the north facing and east facing end.First my engineer told me it was a ventilation problem so I put lots more vents in the soffit and a few slate vents
on the front about 6 or 7 feet from the eaves level and I put 5 more at the apex on the back of the house and to be honest I noticed no difference at all.The last time he looked at it he told me he didnt know the cause of it more or less telling me Im on my own.This is going on for a few years as its only wintertime and after frost it shows up the time for trying something is somewhat limited.There is lots of vents all around my house would it make any sense to cover the ones on each end and just have them on the front and back

YouThere · 18-01-2013 12:45pm

any chance that an extractor downstairs might be accidentally venting into the wall cavity - eg. back of tumbler without 4-in wavin to bridge the cavity?

Certified · 18-01-2013 12:50pm

The more ventilation the better for an attic such as this, so I would not recommend closing any vents. If your attic is as bad as the video I would not be convinced a new breathable felt would completely solve the problem, because the real problem is an excess of moisture up there in the first place and this is what must be lowered. Moisture may be getting in through a leak in the roof or a small pipe leak. Believe it or not your problem may be quite simple to solve so don’t be going taking the roof off just yet.

Certified · 18-01-2013 12:58pm

gombeen01 wrote: »

The worst part is the north facing and east facing end.

I would focus my attention around this area first. What rooms are under this area?

gombeen01 · 18-01-2013 6:31pm

YouThere wrote: »

any chance that an extractor downstairs might be accidentally venting into the wall cavity - eg. back of tumbler without 4-in wavin to bridge the cavity?

I have checked the extractor vents including the tumbledryer vent and all is fine.

gombeen01 · 18-01-2013 6:49pm

Certified wrote: »

I would focus my attention around this area first. What rooms are under this area?

There are four bedrooms under this area and my ceilings do not have foil backed
slabs and to add more fuel to the fire so to speak there are seven people occupying these rooms at night so thats a lot of vapour.The ceilings are skimmed and have got two coats of ceiling paint.
I did think about this and was going to repaint them again and mix some sealer through the paint to see if it had any effect but I didnt do it yet maybe theres no point what you think?Each of these rooms have a vent and they are positioned about 18ins down from the ceiling but still above the top of the windows and they are open.Hope this info helps.

scwazrh · 18-01-2013 10:59pm

Attic condensation is usually quite easy to solve.The main points to check are

-Is the air in the attic too warm and thus causing condensation when hitting the cold felt , if this is the cause place a min of 400mm fibreglass at ceiling joist level to keep the heat below ceiling level.

- is there excessive moisture in the attic , possible causes being a roof leak or leaking pipe .These should be easily found

- Are extract vents fitted incorrectly and venting to the attic space , again easy enough to check out.

-Is the insulation fitted incorrectly ? Any insulation fitted at ceiling joist level should finish a small amount back from the wall plate.If insulation is fitted in rafters there should be at least 50mm air flow between insulation and felt .

- Does you water storage tank have a lid and is it insulated ? Also is all pipe work lagged.

- is the insulation correctly fitted over the hot press? Missing insulation here allows a lot of warm air into the attic.

Unless your problem is very unique the above should help you to narrow it down to the cause.

gombeen01 · 19-01-2013 1:05am

Scwazrh in ans to your questions.

Although there appears to be no breeze in it the attic is very cold and I have already got the insulation installed to the top of the 9x2 and I realise now that it probably needs to be done better cos the 9x2 spacing is a little wider than the pre cut roll of insulation so there is room for heat to escape.Also over the hot press is not completely covered the reason for this is because the water storage tank is directly over it and a bit of heat goin up will stop the tank from freezing.Looks like I should get some bags of loose fill insulation and fill up any spaces that is there.The hot press and tanks are not near the troublesome side.

There is no leaks from pipework or through the roof this condensation only shows up when theres frost and I have no proper covers on either of the water tanks,I do have a piece of a ceiling slab over them just in case a mouse falls in :-)
Believe it or not the time we got -16 deg c a few years ago there was ice on the inside of the felt from the apex to the wall plate for best part of a week.

I have 12 of these downlights in the kitchen there has to be a lot of heat escaping up at these points as well but the kitchen is on the west side of the house........

martin46585 · 19-01-2013 1:19pm

Is the access hatches between the new conversion and the crawl space completely sealed at this point, as the warm air from the house may be creating a dew point on the inside of the felt.
Also just a though, is the felt the same type as the transparent fibre woven type, as these do seem to cause ecessive condensation during the drying out of construction....

gombeen01 · 19-01-2013 6:34pm

martin46585 wrote: »

Is the access hatches between the new conversion and the crawl space completely sealed at this point, as the warm air from the house may be creating a dew point on the inside of the felt.
Also just a though, is the felt the same type as the transparent fibre woven type, as these do seem to cause ecessive condensation during the drying out of construction....

There are no access hatches between each end its open so the air/heat can travel around the new room if you know what I mean.
I know the felt that was used on my roof is non breathable, black in colour and it is woven type as you can see the threaded squares all over it.(its French made I dont know if I can say the name of it here or not)
This is not a new build I have been in the house since 04 and the room is finished a few years ago.We noticed this problem a long time ago but seeing that it only shows up when there is frost it tends to get forgotten about after the winter.

My so called "engineer" who is well known countrywide......unfortunetly not for his engineering skills looked at it a couple of years ago and said he dosent know whats wrong.I did ask a few carpenters and they all say its the felt because its not breathable.(Maybe they are looking for work)

muffler · 19-01-2013 6:44pm

gombeen01, you've mentioned earlier that you have loads of vents but have you checked to see if they are obstructed in any way?

You also mentioned that it was cold in the attic but necessarily drafty. I would expect any ventilated attic to have some form of light "breeze" blowing through it.

Re: Insulation absent below water tank. Do not insulate this area.

Builderfromhell · 19-01-2013 6:57pm

Have read all this thread and I suspect the insulation between the rafters may have been fitted tight against the roof thereby blocking ventilation flow.
You really need to get in some type of an expert to take a look

gombeen01 · 19-01-2013 7:08pm

muffler wrote: »

gombeen01, you've mentioned earlier that you have loads of vents but have you checked to see if they are obstructed in any way?

You also mentioned that it was cold in the attic but necessarily drafty. I would expect any ventilated attic to have some form of light "breeze" blowing through it.

Re: Insulation absent below water tank. Do not insulate this area.

Yes all the vents are clear of obstructions and the fiberglass is pulled away from the felt inside.I have these 3 inch round vents every 3 ft or less all around the house and the house is 65 feet long so thats a lot of openings.
Yes there appears to be no breeze or its not noticable in my attic.There are a few trees on the east side about 50yrds away the other 3 sides are open.

Yes no insulation below water tank.

gombeen01 · 19-01-2013 7:29pm

iceonfelt.jpg

Some of my attic looked like this during the heavy frost
we got a couple of years ago.

Victor · 19-01-2013 7:29pm

The biggest problem would appear to be the lack of a vapour barrier. Solve that and your problem should go away.

martin46585 · 20-01-2013 12:04am

Might be an idea to make sure that all the roof vents have unobstructed air flow and that they are indeed cut in to the felt, as they serve little or no purpose if not, especially on heavy bitumen type felt

esox28 · 20-01-2013 12:59am

Check your water tanks/tank in attic are not getting heated by the central heating or a faulty immersion heater.

I've seen attic spaces flooded with condensation due to over heating the hot water cylinder, the excess heat then gravity feeding or pitching into the attic water storage tank heating it and excessively evaporating the water which in turn condensing on the cold felt.

Certified · 20-01-2013 2:17pm

gombeen01 wrote: »

I have 12 of these downlights in the kitchen there has to be a lot of heat escaping up at these points as well but the kitchen is on the west side of the house........

Would these downlights be the turnable/twisty types? These types are brutes for heat/vapour loss and much worse than the fixed spots.

If these bulbs are 50 watt halogens, thats a lot of heat pumping into the attic and with them being in the kitchen, possibly a good deal of moisture also.

Either way, if not done already, you should replace the halogen bulbs with LED bulbs and get them fitted with suitable covers in the attic.

In the bedrooms, what heats these rooms and would condensation be much of a problem on the windows?
Is there any paraffin or gas heaters used during cold periods?
Just wondering beacuse, one gallon of water is produced by one gallon of gas or paraffin burning.

gombeen01 · 20-01-2013 8:40pm

None of the water tanks get warm as far as I know but I will double check the next time the cylinder is hot at the bottom as it does everyday.

Yes Certified they are 50w halogen turnable/twisty types and they get fairly hot but they dont be switched on very often however there is a three inch hole in the ceiling for each of these downlights so any steam from the kettle or cooking and heat probably is escaping up here.I dont know if thats is a contributing factor or not cos the kitchen is at the opposite end of the house and theres no condensation over it.

There is a radiator in each room but they are not on too aften.During the day its cold in the rooms as there is no heat on in that zone.
They are heated with an outdoor oil boiler and come on for half hour before bedtime and come on for about 2hours altogether during the night in 15 minute intervals.
There is a very small trace of condensation in the morning just on the bottom of the glass where it meets the pvc frame.

YouThere · 21-01-2013 2:15pm

some disjointed brainstorming ideas - each with a healthy pinch of salt:

condensing boiler? where is the steam from that headed? any of your attic vents nearby?

to the excellent vapor barrier comment earlier - my own house has tongue+groove ceilings - and vapor barrier immediately above - and insulation above that again and finally the void attic space - and bare felt between rafters overhead. what's the sequence of layers in your house?

your "ice on felt" photo is interesting (yours or borrowed?) - it shows no ice near wall plate - where there would be no rising warm vapors - and also presumably great air circulation near soffit.

The fact that only your north face is affected might be an artifact of the sun helping to dry everything out on the other sides of house. At this time of year - in my own house - the angle of the sun and the angle of my roof means the north side gets zero sunshine - seldom melts the morning frost.

again in my own house - I would imagine I'd get condensation on the north face right now - whereas I just reached out through a velux a moment ago and the slate on south is warm to touch - yet it's only 4C outside here today.

btw - wondering if your insulation is now so saturated from dripping condensation - that you're in a circle - insulation trys to dry out a little - only to cause further condensation - more dripping - leading to wet insulation again.

better stop with the brainstorming - else not enough pinches of salt!

Certified · 21-01-2013 2:16pm

It may be very possible that your condensation in the attic is being caused by these spotlights in the kitchen.
Moisture from the kitchen and possibly a utility (?) is rapidly escaping through the 12 holes bored in the ceiling. The kitchen and this part of the house is the warmest part of the building and most lived in, hence the air is carrying a good deal of moisture. As the warm air rises it escapes around the spots into the attic and it is naturally migrating down to the colder area of the attic, over the bedrooms and when the air temp in cold spells gets too low for the air to carry it, the moisture condensates on the coldest part of the roof, the felt.
The problem will be only exaggerated when the 600w halogen lights/heaters are on.
Lack of noticeable air circulation in the attic is a concern but the coldest days and nights are generally when there is little or no wind and this may be adding to your problem.

You should either remove the lights or up grade the bulbs along with the amount of insulation you have in the attic.
Or alternatively, have the whole house heated to the same temperature, by doing so the moisture will dissipate and condensate evenly on the attic felt and it may not be noticeable.
I would recommend the former.

Out of curiosity, why are there pieces of electrical conduit inserted between the layers of roofing felt?

muffler · 21-01-2013 2:26pm

Certified wrote: »

Out of curiosity, why are there pieces of electrical conduit inserted between the layers of roofing felt?

Good spot. That to me looks like a very very poor attempt at a bit of DIY ventilation and if that is the case then it leaves a lot of questions to be asked why the standard soffit vents aren't working.

In saying all that maybe the OP will tell us that they are for cabling from a sat dish or rooftop aerial.

gombeen01 · 21-01-2013 3:16pm

YouThere:
My boiler is against the back wall of the house and I have no idea where the steam/fumes go as there is just the standard flu on it which directs the fumes down towards the ground.

Heres the sequence of layers in my house half inch slab,insulation and felt.

"""your "ice on felt" photo is interesting (yours or borrowed?) - it shows no ice near wall plate"""
You need to have a closer look, it starts at the wall plate and goes all the way to the top.If you have any doubt this pic is ((borrowed)) I have 9 pics altogether each one is under 2mb and were taken on the 21/12/2010 if your email address will hold that much I will send them or can they be uploaded somewhere without having to resize them.

North and East is the worst and its worst over the bedrooms but during the heavy frost we got a few years ago there was condensation all over the attic
and on the worst area there was ice from top to bottom which is the area in the pic.

No the insulation is not wet there may be a droplet here and there but its nothing.

gombeen01 · 21-01-2013 3:24pm

You are right muffler the electrical conduit inserted between the layers of roofing felt was an attempt at a bit of DIY ventilation and not for cabling.......
I wouldnt say it was a very very poor attempt at D.I.Y vent........more like a desperate attempt at D.I.Y vent :-)

PaleRider · 21-01-2013 7:11pm

Hi
Can you email or post more photos. Need to see attic room/attic door details etc. insulation detail. draw a simple sketch of layout.

There should be no warm air reaching attic area. Of course you can't stop warm heated air from rising up. but you must seal attic from this heated air. Attic door/existing floor/ceiling insulation must be fitted correctly.

gombeen01 · 24-01-2013 12:03am

I found this its the tech document on the felt I have.

http://www.laydex.com/laydexdocs/Griltex%20ATX%20IAB.pdf

nunu123 · 22-01-2021 1:13pm

gombeen01 wrote: »

I have a serious condensation problem in my attic that I am not able to solve without actually stripping the roof and replacing the roofing felt or cutting it
out altogether.
There is plenty of vents at eaves level and at the top.
My house was built in 03/04 and the felt that was used is non breathable (very similar to polythene)
I found this link its identical to my condensation problem http://www.youtube.com/watch?v=KU7TKI3fmt0
There is no condensation on the inside until we get frost, zero or minus 1 and the inside is wet.
Have you ever seen this and if so what can be done?

Hi,

Just wondering if your problem got fixed. We're having the same issue like the one in the video. Its only happening on the north side of the house and fully dry on the south side of the house. We do have a bathroom in the attic and not sure where the extractor fan is leading to. The person who did our attic cheated us and never did the work properly. Any help/suggestions would be appreciated.

Thank you.

cgaie · 02-01-2023 12:44pm

My house is in tyrrelstown built 20 years ago and the felt in the roof is not breathable

I’m having the same problem in the attic when it gets really cold under 1 degree, lots of condensation and start dripping water.

Already got 6 new vents on the roof few weeks ago for the attic airflow

My main concern is in the en-suite I get water sweeting on one corner of the ceiling, this is just happening in the en-suite but I’m afraid it expands across to the bedroom. This stopped few days ago and it came back again today because it was very cold last night

This problem started last year after I put more insulation on the attic and I think it could be blocking the airflow because the soffit are blocked, hard to know because it’s difficult to get there

who can I get to have a look at this problem in my attic?

Not sure who to contact, the roofers don’t look after this issue

SC024 · 02-01-2023 12:55pm

What is the reason for the plastic electrical conduits shoved down behind the felt in your photo? The roof vents you installed are they cut through the velt so that are actually ventilating the attic space?

Serious Attic condensation problem

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