BlackRat Posted December 6, 2012 Share Posted December 6, 2012 Oh dear, condensation in loft, mainly on one side only! Had a fan running up there for 3 days, no change. Any ideas? Poss ventilation?? HELP! :help: Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted December 6, 2012 Share Posted December 6, 2012 To have any condensation means water vapour (probably in warm and therefore humid air) is getting into the loft, and then condensing on which ever part is being most actively cooled by the chilling blast from the North. If this hasn't been a problem before, I would go looking with a torch or other portable light to provide an easily moved backlight to spot any visible vapour entering the loft , most easily seen when the temperature is below zero. Also check the header tank to the Central Heating if that is in the loft. An open system that's poorly regulated for boiler heat output, such that it can begin to boil, can push hot water from the primary circuit into the header tank, and there's plenty of water vapour entering a cold space, ready to condense out. More ventilation through the loft may fix the condensation - or may freeze it on - and also means any header tanks up there are getting even better chilled. I would definitely want to start from the source of the water, unless that is you have blocked up the ventilation significantly during the past summer... Link to post Share on other sites More sharing options...
RMweb Gold 30801 Posted December 6, 2012 RMweb Gold Share Posted December 6, 2012 Also check the header tank to the Central Heating if that is in the loft. An open system that's poorly regulated for boiler heat output, such that it can begin to boil, can push hot water from the primary circuit into the header tank, Watch out for that one. I recall reading about an horrific accident where this happened and the hot water softened the plastic tank such that it dumped boiling water into the room below. Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted December 6, 2012 Share Posted December 6, 2012 One of our neighbours near our previous address had this event during the cold winter of 83. I think it was a frost protection stat fell off the pipe, and since the boiler was in an unheated garage it stayed on full bore. The occupants were away, so the rest may be imagined... Link to post Share on other sites More sharing options...
BlackRat Posted December 6, 2012 Author Share Posted December 6, 2012 Thanks all for the replies so far. new boiler 2 years ago so no tank. Its only on on side to, as if warm moist air is circulating and condensing on there. I have notice a few rusty nails coming through the bitumen (the roof is tiled over bitumen felt) and I am wondering if water is tracking down via these. A right pain as there are hundreds of empty stock boxes now wet!!!!! Link to post Share on other sites More sharing options...
BlackRat Posted January 16, 2013 Author Share Posted January 16, 2013 Was wondering if replacing some of the tiles with vent tiles is worth it or drilling two holes in the wall and putting in a couple of tumble dryer vents? Anyone any suggestions re these poss solutions? Link to post Share on other sites More sharing options...
Silver Sidelines Posted January 16, 2013 Share Posted January 16, 2013 The 'rules' for lofts seem to change by the year. But basically sounds like ventilation or rather lack of. Mother's timber frame house from the 70's was dire. Yes there was the problem with the central heating header tank being insufficiently high for the pump pressure. After that it was a case of putting as many ventilators as possible into the eves and the peaks. The modern approach seems to be to use the pitched roof to keep rain water out and to place all the heat insulation on top of the ceiling (mind the wires) such that the loft space is kept at much the same temperature as outside. In our current house we are plagued with continuous eves ventilators all around the periphery of the roof. No chance of anything keeping warm plus the fact that all the smoke and soot from the stove get blown on top of the fibre glass insulation. Five years ago we had to rush up into the loft with buckets and washing up bowls to scoop up all the snow that had blown in - before it started thawing. My opinions of the Building Regulations are not printable. Yes we have a a few drops of water up there right now. After a prolonged period of frost there is a build up of ice on the nails that hold the slates on - when the temperature rises the frost thaws and drips on to the fibre glass or anything else stored up there. As one of the early contributors noted - condensation becomes worse as the supply of moist air increases. Gaps round loft hatches, pipes and electrical wiring will all provide a path for super heated air from the living space below. Just some observations Good luck Ray Link to post Share on other sites More sharing options...
Anglian Posted January 16, 2013 Share Posted January 16, 2013 I'm of the view that you need adequate ventilation in the loft. In my house the loft has poor ventilation and having more stuff up there made this even worse. As mentioned above the issue is warm moist air condensing on the cold surface just as it may with windows. The loft should have soffit vents mine doesn't. Built 1991. Veting tiles can be fitted, it's about £400 or so I'm advised. The solution I've come up with that works for my house is to run a dehumidifier when cooking and showering. I used to get condensation on the north face of my roof right above the trap door but not around the water tank etc. At one point I had an issue with my central heating being semi blocked up and that was causing over runs and hot water and steam to be released into the over flow tank, this of course made matters worse. The central heating system was modified to a more recent design to avoid a possible design fault where the cold water entered the system. The entire system was flushed which took a day and a Magna clean fitted. This has resolved any central heating issues but it remains a fact that moist warm air still enters the loft from the house below. As the winter draws in I run the dehumidifier for a few days to dry the air a little. Too dry and it irritates my throat. I also use it in my old car from time to time. I paid about £180 for the dehumidifier from Eco Air. I haven't noticed that it's terribly expensive to run so I'm not worried from a power consumption point of view. If I were you I'd buy one and have it running 24 hours a day in the loft for a few days until you resolve the issue. It might be that you've got too much stuff up there and have reduced the circulation. Link to post Share on other sites More sharing options...
RMweb Gold 30801 Posted January 16, 2013 RMweb Gold Share Posted January 16, 2013 I paid about £180 for the dehumidifier from Eco Air. I haven't noticed that it's terribly expensive to run so I'm not worried from a power consumption point of view. If I were you I'd buy one and have it running 24 hours a day in the loft for a few days until you resolve the issue. That won't work unless there's a monster leak of warm air into the loft. The moisture will condense out in the cold loft before it hits the dehumidifier and the dehumidifier itself will freeze solid in cold air. I had an experiment with a dehumidifier in the garage and they are flat out useless in the cold. Having a dehumidifer in the house to dry the air before it gets to the loft would help some, but the underlying cause of the condensation will still be there. Link to post Share on other sites More sharing options...
Black Sheep Posted January 16, 2013 Share Posted January 16, 2013 another reason to move the loft hatch from the bathroom... Link to post Share on other sites More sharing options...
Anglian Posted January 16, 2013 Share Posted January 16, 2013 It works for me but as a preventative measure, as you write you really have to get the moisture out of the air before it condenses in the loft and I agree with you that I don't think you can entirely. Mine makes a massive difference in my house itself. I run it before and whilst I cook, shower and dry clothes. The best thing really is to ensure adequate ventilation in the loft. Both the builders I spoke with said that's the real issue and I can't understand how my house has been built in 1991 without adequate loft ventilation. I must sort it out one day. If it gets too cold the dehumidifier doesn't stand a chance as it can't cope playing catch up but if you use it to prevent things getting bad in the first place from my experience it's been a huge help. Soffit vents, venting tiles and clearing out the loft would be the real answer. The other thing is to open your window vents if you have them. Edit: Well that's interesting I've been back in the loft and have discovered that I do have soffit vents but whoever laid the insulation pushed it right into the edges blocking the vents. I have no idea why I never checked this before, I just assumed the builders who built the property knew what they were doing. Link to post Share on other sites More sharing options...
BlackRat Posted January 16, 2013 Author Share Posted January 16, 2013 It could be that e heat from the boiler (which is in the loft) is causing the issue, combined with the ventilation. Builder has sugested drilling two holes and fitting a grill like a tumble dryer vent but I want to try and avoid drilling the walls if I can! I have rigged a bathroom extractor to the flue from the gas fire which vents out through the roof ridge tiles. No issue as the flue isn't connected to a fire as we no longer have a gas fire or a fire place. This may help. Link to post Share on other sites More sharing options...
RMweb Gold chris p bacon Posted January 16, 2013 RMweb Gold Share Posted January 16, 2013 This should be a simple one. Forget dehumidifiers and the like and work on the basic principle that you have warmer air in the loft than outside, hence the condensation. Make sure you have a complete covering of insulation over the ceilings, the standard at the moment is 4 inches laid between the joists and 7-8 inches laid at 90 degrees. the area where the roof intersects the ceiling joists should be clear so that air can pass from the soffit (even if it is not a modern vented one) up to the ridge. if you have the boiler in the roof space then a ridge vent above it, or a couple of vent tiles to let the warm air escape. pretty basic but works. A note on dehumidifiers, they are sold as a cure but are pretty useless, most moisture we have in houses comes from our breath, if the house is vented then there is not a problem. I have seen many houses with condensation mould in kitchens and bathrooms, you ask the simple question do you have a fan/open the window when you shower or cook and the answer is "no", but someone sells them a dehumidifier to cure the problem which it doesn't. You can't beat an extraction fan with overun timer. Link to post Share on other sites More sharing options...
BlackRat Posted January 16, 2013 Author Share Posted January 16, 2013 I suspected the boiler I must admit, will look at a roof vent so thanks!! Link to post Share on other sites More sharing options...
RMweb Gold Donw Posted January 16, 2013 RMweb Gold Share Posted January 16, 2013 You may find that where the cables in ceiling light pass through the ceiling the whole is quite large and in cases like some bathroom light they are spaced off the ceiling creating a nice route for warm moist air. Similarly where pipes from a boiler and to rads pass through ceilings these can aslo allow warm air through. For those with header tanks you can get problems wehere the cold feed from the header joins the main pipe getting scale deposited. In bad cases the water gets forced up into the tanks and then runs back down the the cold feed avoiding the blocked length. Thus the header tank becomes hot causing lots of evapouration. when I moved into the present house this was happening you could hear it running. Reasonably easy to fix just replace the blocked pipes. But I have worked as a plumber. Don Link to post Share on other sites More sharing options...
Anglian Posted January 16, 2013 Share Posted January 16, 2013 This should be a simple one. most moisture we have in houses comes from our breath, if the house is vented then there is not a problem. I have seen many houses with condensation mould in kitchens and bathrooms, you ask the simple question do you have a fan/open the window when you shower or cook and the answer is "no", but someone sells them a dehumidifier to cure the problem which it doesn't. You can't beat an extraction fan with overun timer. I'm not sure I agree that most moisture comes from our breath but if it does then fair enough. My kitchen never gets condensation on the windows unless I'm boiling a kettle or vegetables. If my breath produced more moisture than cooking my kitchen would get condensation on the windows all the time when I was in there wouldn't it? I do agree that dehumidifiers aren't the answer but they do help. As I mentioned before I run mine while cooking and I don't get condensation on the windows so it's got to be of help surely? I also run mine to dry my clothes inside in the winter, without it I struggle to get them dry but then I don't have a hot house with blazing central heating pumping out to maintain an over high room temperature. Perhaps if my house was warmer I'd get less condensation? Anybody? Question: having identified that I have wet felt, but have now cleared all soffit vents how do I get rid of the wet and get the loft dry again? Link to post Share on other sites More sharing options...
RMweb Gold chris p bacon Posted January 17, 2013 RMweb Gold Share Posted January 17, 2013 I'm not sure I agree that most moisture comes from our breath but if it does then fair enough. My kitchen never gets condensation on the windows unless I'm boiling a kettle or vegetables. If my breath produced more moisture than cooking my kitchen would get condensation on the windows all the time when I was in there wouldn't it? Question: having identified that I have wet felt, but have now cleared all soffit vents how do I get rid of the wet and get the loft dry again? You don't notice it but the air is moistened by our breath, 99% of visible condensation though comes from items such as kettles & showers and the way to stop that is to vent the room. drying the air is a very power hungry and inefficient way of trying to deal with the problem. Also if you are creating condensation when you are cooking then it means the kitchen has insufficient ventilation. Have to admit that the charcoal filters you get in extraction units are worse than useless (partly because we don't change them often enough) so the best is extract to exterior. Do you mean the underside of the felt is wet ? is it just moist to the touch or are there droplets forming ? if it is the latter then you have too much warm air escaping into the loft. maybe add a layer of wool, places like B&Q/Wickes have rolls of insulation this time of the year that are subsidised by the power companies for as little as £3-4 a roll (8-10M2), don't forget to do above the hatch. If you have tanks etc in the loft, the area beneath the tanks should be bare to allow the tanks to "warm" then a blanket cover needs putting over them. We find the big issues building inspectors look for nowadays are ventilation and insulation, getting those 2 right stops endless other problems. Link to post Share on other sites More sharing options...
MichaelW Posted January 17, 2013 Share Posted January 17, 2013 Condensation in the loft is generally caused by warm, humid air escaping from within the thermal envelope of the house, and meeting the cold surfaces of the roof and rafters, where the moisture condenses out. The best way to prevent condensation is to stop the warm humid air escaping from the house (which has the added benefit of reducing heat loss, and therefore your gas/oil/wood/electric bills). How to do this? As others have mentioned, make sure that there are no holes in the ceilings that this air can escape through - so seal round pipes, electicity cables etc. Consider replacing any ceiling mounting downlighters with less draughty lighting - e.g. a traditional pendant fitting, or units that seal to the ceiling, and don't leave a massive open path for heat to escape. The loft hatch is a big problem - you need to make it seal as well as you would a window - so plenty of draught-proofing strip, and a latch to hold the hatch tight against it. In the loft itself, make sure your eves are clear (at least a 1" gap between the insulation and felt) all round, any tanks are covered (covering them also makes insulating them easier), and your insulation is continuous (except for under the tanks). Ultimately, you could put in a vapour barrier, which stops moisture travelling through the fabric of the building - unfortunately this needs to be fitted on the warm side of the insulation, and be continuous - which would mean taking down ceilings and walls to get it in. Perhaps not Link to post Share on other sites More sharing options...
Anglian Posted January 17, 2013 Share Posted January 17, 2013 Yes, I've got droplets forming on the felt. I'd say in the last 24 hours since I've pulled the yellow insulation back from the soffits to clear the vents that it hasn't got any worse but the droplets are still there. I guess I need to mop them up. The floor of the loft is covered all over with the yellow insulation and it's deep. Only about 1/3 of the loft is boarded. This evening I cooked with the window open and two external extractors going and the steam and condensation did clear. No dehumidifier though as an experiment. My loft hatch is heavy with a rubber seal around it but how good a seal it is I don't know. Both tanks are well covered. All very worrying as last year I didn't have any issues at all and thought I'd solved the problem. Link to post Share on other sites More sharing options...
MichaelW Posted January 18, 2013 Share Posted January 18, 2013 Don't forget that this year the cold temperatures have been accompanied by still, (relatively) humid conditions (and in Yorkshire at least, freezing fog most of the time) - both of which will reduce the rate at which the loft can dry. You may find once it gets windy and the humidity drops, it'll dry on its own... Link to post Share on other sites More sharing options...
Anglian Posted January 18, 2013 Share Posted January 18, 2013 That makes me feel better. Today for the second day I woke to find the windows totally clear. I've unblocked an unused gas fire flue and am going to drill a pattern of holes in the board I cover the hole with so that this can vent directly from downstairs to the outside. I'm going to replace the rubber seal on the loft trap door as well. Link to post Share on other sites More sharing options...
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