Condensation - At wits End!!!

kycrout · 13 Dec 2008

Hi Guys

Firstly I have read all the post of condensation and have been following this for a few months. Let me explain

A few months ago I found condesation in my loft, and you guys gave me some great advise - install roof/tile vents - I got a roofer in, he did this and the problem seem to improve vastly (never went away completely but kinda accepted this was life ...)

Last night I went into the loft and was absolutely horrified - The felt was soaked again, but worse I have a mould growing on all the wood, and a few of the stored items.

Ironically this only appears on one side of the roof, the other side has none of this behaviour.

I just dont know where to go next ? Is there any expert on this board in the Essex area - I need help

Thanks

Ky

JohnD · 13 Dec 2008

Does this help?

//www.diynot.com/forums/viewtopic.php?p=1080717#1080717

Comments please

-----------------

if you have already read all the threads on loft condensation, please say which of the common causes you have investigated and resolved.

Xenon · 13 Dec 2008

Is there any expert on this board in the Essex area

What part?

I am just outside Romford.

kycrout · 13 Dec 2008

JohnD - Thanks for the link, I have read your post, and following most of it ... still to do are the downlighters (but in fairness we do not use them at the moment)

Xenon - Im in epping.

I had the local roofer over today, who took one look at the loft and said (what I expected) VENTALATION. I was a touch frustrated to say the least

He then went on to explain that the tile vents were the right idea but no enough, At the moment I have two each side, he has suggested it should be more like 6 each side given the size of the roof.

He also went on to suggest the mould would die once ventalation was fixed, so just to leave it for now.

I expect to have his quote on Monday . .. Xenon if you are keen to quote let me know

Thanks

Ky

^woody^ · 14 Dec 2008

6 vents each side

What has every other house near you got? Have they got 6 vents, have their roofs collapsed in a mould rotted heap?

Increase the ceiling insulation and then go along and put your hand through the joint where the felt is lapped to open them up - a small bit of timber can be put in to keep them open in various places. This will do the same job as vents, only better.

Bear in mind you need cross ventilation and airflow from eaves to ridge.

You get condensation on one elevation because that is the coldest elevation

There is no way I'd accept 6 monster tile vents. If need be, low profile ones would be better, but this problem can be sorted out without them

PerryOne · 14 Dec 2008

The solution to your problem is not adding more loft ventilation, but to stopping the water vapour at source.
Water vapour usually arrives from inside the home, due to lack of ventilation in the home.
We all wash and breath and create water vapour.
Warm wet air rises!
2.5 litres of water vapour can move through a 8 by 4 foot sheet of plasterboard in 24 hours. Masses of water vapour move into a typical loft every night as the temperature drops the warm air is attracted to the cold of the loft and condenses onto the cold surfaces.
Each of us breaths out saturated air, this water vapour needs to be vented to the outside, if it is not it builds up inside and rises through the loft trapdoor and any opening it can find, ably assisted by any passing wind that sucks it out.
Solve the moisture problem in the home.
Sometimes a badly placed boiler flue can lead to moisture laden exhaust being sucked into the loft by the passing wind.

kycrout · 14 Dec 2008

Hiya

Thanks for your input ... I'm afraid I do not understand the crucial sentence "Increase the ceiling insulation and then go along and put your hand through the joint where the felt is lapped to open them up - a small bit of timber can be put in to keep them open in various places. This will do the same job as vents, only better. "

Could you please eloborate?

Thanks

Ky

^woody^ · 14 Dec 2008

Increasing the insulation stops heat getting into the loft which then condenses. You want to keep the loft cold

Opening up the laps in the felt gives ventilation. Bitumen felt sticks together over time so adventitious natural ventilation is removed. Open these up a bit, or even just loosening them puts the ventilation back

kycrout · 15 Dec 2008

woody,

I get the increasing the insulation. As soon as it warms up a touch I will be boarding the floor of the loft, and at the same time renewing or touching up the insulation.

What I am missing is the "opening the laps - Bitumen felt sitcks together" bit. I have a tiled, pitched roof with a layer of black almost plastic/felt between the tiles and the wood work - Where do I need to open it up?

sorry if this is a stupid question.

thanks

SurreyRoofingEstimator · 15 Dec 2008

What Woody is saying is where the underlay below the battens lap (which is probably every metre along the slope line (sounds like you have monarfol or some such)) place a piece of timber between the lapped joints opening them up to allow air to come through the laps. Unless you have a fibre slated roof air moves quite freely through the laps of the roof tiles so use this to allow the roof to breathe.

The plastic felts do have this issue if a lot of moist air is rising into the loft space and there isn't the airflow to dissipate it (bit like if you put cling film over a bowl of warm food, there isn't anywhere for the steam to escape

htgeng · 17 Dec 2008

SurreyRoofingEstimator said:
What Woody is saying is where the underlay below the battens lap (which is probably every metre along the slope line (sounds like you have monarfol or some such)) place a piece of timber between the lapped joints opening them up to allow air to come through the laps. Unless you have a fibre slated roof air moves quite freely through the laps of the roof tiles so use this to allow the roof to breathe.

The plastic felts do have this issue if a lot of moist air is rising into the loft space and there isn't the airflow to dissipate it (bit like if you put cling film over a bowl of warm food, there isn't anywhere for the steam to escape

I had the ceiling mould issue earlier this year. I had the entire roof stripped, new breathable underlay put down and tiles put back. It cost about £2000 and the results are pretty spectactular. Before I could go up in the loft and it was very stuffy. Now its like being in a wind tunnel! The ventilation is, well the area of the entire roof.

Henryv · 23 Dec 2008

^woody^ said:
Increasing the insulation stops heat getting into the loft which then condenses. You want to keep the loft cold

Opening up the laps in the felt gives ventilation. Bitumen felt sticks together over time so adventitious natural ventilation is removed. Open these up a bit, or even just loosening them puts the ventilation back

Ky,
I can agree with Woody on this one.
What I did (advice from a great builder friend) was to buy 100ft coil of 1/2" bore pvc garden hose.
We cut it up into pieces (about 4" long I think) and shoved them up under the felt. One piece in each section - as many
as you can reach all the way up and all the way along the roof.
It works a treat!!

Henry.

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Condensation - At wits End!!!

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