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I was hoping someone may have experienced similar condensation issues as I have. I’m in a 1 yr old new build and have managed to sort out a baseboard ready for a new O Gauge layout. I just get to the bit where I’m going to lay track and see what fits where and I enter the attic to find it’s been raining in there. Clearly a condensation issue.  I get that I’ve probably allowed warm moist air into the attic and allowed it to condense on the underside of the cold roof but has anyone any ideas on what I might be able to retro fit that will prevent the condensation dripping onto the baseboards? I get that as we enter warmer times this will resolve itself but for the cold spells I cannot risk this issue from damaging my expensive fleet.  Any suggestions are welcome, thanks

 

Simon

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You don't appear to have any insulation between the rafters.   You need it; but you must also ensure that there is an ait gap between the insulation and the felt to allow the rafters to breathe and dry out from condensation.

You need to ensure that the roof space is ventilated and that may mean that you need to change a few of the roof tiles.  

 

I suggest you search this site for "loft" and "attic".  You will find lots of threads about the pros and cons.  You have just found one of the cons.  There will be some suggestions about what you can do to minimise problems but the majority (small perhaps) would seem to be in favour of not using the loft.

 

Edit:  That should of course have been air gap and not ait gap

Edited by Andy Hayter
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Without seeing all of the detail of your roof, you need to be very wary as it looks like you have a tar based roofing underfelt which will not allow the loft space to breath if you add insulation to the underside with insufficient airspace. The amount of moisture you have on the boards gives me the impression you have a lot of moist air entering the loft and condensing on the underside. The timber gables suggest this is a timber framed house so you should avoid large amounts of condensation forming and running down to the eaves

 

Unless converted properly I am not in favour of utilising lofts. I did note you are in a 1 year old house which will be covered by either an architects certificate or NHBC. Before going further I would check whether your cover will still be valid if works which should be subject to building regs approval are carried out without it. NHBC especially will ignore any faults or snagging which they can attribute in any way to such works.

Sorry for being negative but the loft is just the void between the bedroom ceiling and the roof, it's not habitable and isn't sold as habitable.

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Sounds like a fundamental issue.  Something you should sort before your roof ( and wall) structures rot.

I would stick a dehumidifier or four in the roof space to dry it out, run the pipes outside the loft , don't use the internal tanks, and then get some air flowing.  We dried our band room out with a dehumidifier running 24 /7  and later 8 out of 24 hours on a timer.  We also fitted 2 small computer tower fans running 24/7 to shift air out the underfloor void,  Its made a massive difference.  Normally  I would complain to the builder, ut they wil say you shouldn't have put the layout up there, the roof structure clearly isn't designed for it, there would be an RSJ along the apex  instead of the forest of trusses if it was designed to he a habitable space.   

However you are going to need some ventilation if you get breathing our warm moist air up there, maybe duct air from the apex of the roof out through the eaves with fans connected to the lighting circuit?   Also maybe make the dehumidifiers a permanent fixture,  Run them whenever you are in the loft and a few hours after.  Light circuit plus timer to run on for an hour or so after the lights go off   Maybe several small ones not one monster.    Otherwise gardens are a great place for O gauge.

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I’ve struggled with a similar problem in a garage converted to hobby room. The bottom line is you need to prevent warm, moist air from reaching the cold underside of the roof. Just insulating between the rafters will not be sufficient. As already mentioned, you need an airtight barrier below the insulation. The space above this needs to be ventilated. Installation of a dehumidifier alone will ease the problem but is not a guaranteed solution. It will simply lower the temperature at which the water vapour in the air will condense. 

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Posted (edited)

This is really difficult. You seem to have no insulation between the rafters so inevitably when the warm air from downstairs gets in and meets the cold roof, then it will condense. 

Air bricks and soffit vents will help.

However, unless you insulate between the rafters. Your loft will be unbearably hot in the summer and cold in the winter. Lofts are not ideal spaces for model railways unless you can do the work first.

You also need to make sure that the ceiling joists can bear the extra weight. If you leave it as it is then it is never going to work properly. Get some professional advice and see what they say.

People do make lofts work, but it does need a lot of prep and work to do so. 

Edited by ikcdab
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Rather than trying to run dehumidifiers to cure the problem, just empty the loft of any euipment and close the loft hatch. That'll cure it.

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 think that you should realise that chipboard is not an ideal baseboard material for an environment that is damp. It will expand and break up very quickly in this environment. I know this from experience.

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4 minutes ago, Mick Bonwick said:

 think that you should realise that chipboard is not an ideal baseboard material. It will expand and break up very quickly. I know this from experience.

 

There, I've corrected your post for you!

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1 hour ago, chris p bacon said:

Rather than trying to run dehumidifiers to cure the problem, just empty the loft of any euipment and close the loft hatch. That'll cure it.

Regardless of there being a model railway up there, I'd be horrified if that was happening in my loft. Surely there is some fundamental problem there, & just ignoring it is storing up a lot of trouble.

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As an a temporary exercise leave a (big) room fan on for a couple hours up there and see if there's any reduction. Circulation and ventilation is more effective at condensation management than heat or dehumidification.

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39 minutes ago, F-UnitMad said:

Regardless of there being a model railway up there, I'd be horrified if that was happening in my loft. Surely there is some fundamental problem there, & just ignoring it is storing up a lot of trouble.

It looks like exactly what I'd expect: warm, damp air from the house meeting cold underfelt.  Under normal circumstances people don't go into the loft very often and/or for very long especially when it is cold so not only would you not see it but the warm damp air wouldn't get up there.  Added to that, most lofts don't have boards to catch the water droplets and damp insulation is less visible.  When I was converting our loft I had a few days when I had similar amounts of condensation visible on the newly-laid flooring.  In fact on days when I was working hard sawing timber, cutting insulation etc. it could be worse.  As soon as it was insulated the problem went away.

 

FWIW I would never consider using a loft space for anything other than storage. :bomb_mini:

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Hi Simon, Your loft was clearly not designed to be a habitable space, so if you want to use it as a railway room, I.e. inhabit it for more than an hour or so at a time, you need to do the work to make it habitable first. That needs professional input to do it correctly and safely.

Heating and/or dehumidifying an uninsulated space is not sustainable.

The forest of truss timbers is another problem for a model railway.

Sorry.

I hope you can find a better solution.

 

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I'm with Harlequin and the others, build it somewhere else even if it's smaller, leave the loft to the boxes of Christmas decorations and spiders. 

 

Apart from anything else it's a lot harder to fall out of a spare room/shed/garage/conservatory and a lot harder to void your house insurance/NHBC guarantee doing something silly in there. 

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Agree with above, having built houses including timber frame, for 30 years the roof void is designed as a cold space, when the wind blows it should be like a gale up there, lots of ventilation, in one photo looks like the fixings to one gable iron strap are missing.

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8 hours ago, F-UnitMad said:

Regardless of there being a model railway up there, I'd be horrified if that was happening in my loft. Surely there is some fundamental problem there, & just ignoring it is storing up a lot of trouble.

 

It's pretty much as @teaky posted. If the poster didn't go up there, there wouldn't be a problem.

 

As the property is 1 year old, this is a link to NHBC policy exclusions.

https://www.nhbc.co.uk/binaries/content/assets/nhbc/homeowners/find-your-policy/au-or-av-policy-booklet.pdf

 

Having had some experience of arguing with them for a client, the clauses  that are used to excuse themselves of any responsibility, which in the case of the property above would not be unreasonable.

 

m)  Anything done to your home or the land after the completion date, even if carried out by the original builder, except for work we or the builder have done to meet the responsibilities we or they have under this policy

 

r)  Damp, condensation, shrinkage, thermal movement (expansion and contraction as a result of temperature changes) and movement between different types of materials that is not a result of the builder failing to meet the
NHBC requirements

 

t)  Work done by anyone other than the builder

 

 

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Ventilation is the key here - I have built layouts in 3 different lofts, in houses from 1-100 years old, and have never insulated them, although a fleece and a fan heater come in useful at times!

 

The only time I ever had a condensation issue was in the old house, which was provided with no ventilation. I added soffit vents and made sure I always kept the vent in the Velux window open and there was no more trouble.

 

I am surprised that a modern house has this problem, as they are provided with good ventilation, normally at both soffit and ridge. Often the insulation can cover up the soffit vents so make sure they are visible or they won't do their job. It should be perfectly possible to use a loft that hasn't had a world of work done to it but definitely sort the ventilation as this sort of thing is very bad for your house,  and that's more expensive than a wet train set !

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A few years ago, my neighbour had their loft insulation 'topped up'

under the government scheme. Later in the year they went up to

get their Christmas decorations down, and every cardboard box

was soaked through and ruined, the muppets that did the work

had just stuffed it into every space, and blocked the ventilation!

I would be very concerned about airflow and ventilation in your

loft, there is no way that it should have that much condensation.

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If that amount of condensation was present every time there was a cold snap then it would definitely require investigation.  If it only happens after someone has spent time up there, probably with the hatch open too, then that would be the most likely cause.

 

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Thought I'd go and check our loft as I wasn't sure what out set up was. Our  loft is cold in the winter and hot in the summer, but absolutely bone dry and no sign at all of any condensation. The house was built 30 years ago and is traditional construction. There is 6" thick rock wool insulation between all the ceiling joists which extends right across the loft and stops short of the eaves to allow ventilation. I thought this was the case, but there is no insulation under the sloping eaves, just the back of the roof felt behind the battens and tiles.

 

The principle appears to be to stop all heat getting into the loft via the ceilings and to that end the 6" rock wool that has been there 30 years does an excellent job. The mere fact the loft is dry with no sign of condensation whatsoever confirms that.

 

I still wouldn't want a layout up there without a complete conversion as the temperature variants through the eaves is considerable between summer and winter.

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2 hours ago, Barclay said:

I am surprised that a modern house has this problem, as they are provided with good ventilation, normally at both soffit and ridge. Often the insulation can cover up the soffit vents so make sure they are visible or they won't do their job. It should be perfectly possible to use a loft that hasn't had a world of work done to it but definitely sort the ventilation as this sort of thing is very bad for your house,  and that's more expensive than a wet train set !

 

I'm not, The loft void is not meant to be accessed on a regular basis or subject to the humidity that we breath out.  To re-iterate, there is nothing wrong with the house or its design it is not being used as designed.

 

As a word of caution to those that are a little blasé about the use of lofts. The agent that is curently selling 2 houses for me has one on his books which is proving to be a headache. The owner had boarded the loft so that they could use it as a playroom but they have made it unmortgageable in the process. They are now having to have major works done to put the house into a structurally sound state and to deal with the mould that has built up where it can't be seen. It seems their child has had serious asthma issues for a couple of years and testing has looking like the mould is the problem.

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Posted (edited)
5 hours ago, chris p bacon said:

 

I'm not, The loft void is not meant to be accessed on a regular basis or subject to the humidity that we breath out.  To re-iterate, there is nothing wrong with the house or its design it is not being used as designed.

 

As a word of caution to those that are a little blasé about the use of lofts. The agent that is curently selling 2 houses for me has one on his books which is proving to be a headache. The owner had boarded the loft so that they could use it as a playroom but they have made it unmortgageable in the process. They are now having to have major works done to put the house into a structurally sound state and to deal with the mould that has built up where it can't be seen. It seems their child has had serious asthma issues for a couple of years and testing has looking like the mould is the problem.

 

We have just had our main house roof replaced, replacement of the loft insulation at floor level next on the list as we have had condensation issues. However, point of the post, our garage has an uninsulated flat, felted roof, it gets ridiculously hot in summer and cold in winter; although air can get in it is not particularly well ventilated for through circulation.

 

We have to use it for storage, being at a coastal location within 800 yards of the rocky beach the ambient air is regularly laden with sea spray, the mould (in our case usually white in the garage) as mentioned above is a serious issue. I always wear a heavy duty face mask when working in there for more than a few minutes nowadays as I had correlated previous asthma/hay fever like issues to periods spent tidying and box shifting in there.

 

A lot of occasional use stuff that was stored previously between usage bursts in the garage now lives on our spare room beds, only going out to the garage, when the family come to stay and the beds are actually needed for sleeping in!

 

Edited by john new
Punctuation corrected
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Sounds like our garage and position, currently being assaulted by a 40mph easterly off the beach.

The asbestos roof was dripping in the mornings, In the workshop area I've now put glassfibre insulation beneath the roof held up by OSB board screwed to the beams, which has made that section much better to be in.. I've decided now to do the rest of the garage...

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