Condensation

sinnerboy

I received this by PM from a poster who has difficulty posting dierct to forum ......

I,m sorry to have to send you a P/M as i cant seam to use the fourm on the boards.ie site. (dont know how to yet, petty as i wanted to get as meny answers as possible from as many viewers?

I have a two bed bungalow the front is north facing & the back is south facing ,
we got an attic conversion done two years ago, we use it as our main bed room now & the probliem is everything we have in storage up in the enclosed storage aera to the north facing side is getting damp & is getting destroyed by wet dripping condesation. it only seams to happen on days/nights of minus degrees of weather conditions. strangly it can handle mild conditions. even though it is really well ventalated in the soffits 5 soffit vents to the front & 4 to the rear & one velux vent always left open?
builder has 3 roof tile vents & changed ridge vent tiles to a special breathabtle type. still no good

It only happens to the north facing side, directly under this aera is our kitchen cum dining (sitting room)
and bathroom. (sitting room vented,cooker hood & bathroom fan very well secure & sealed)

the south side of the conversion over looks the back garden & has two velux windows & this is the side the water tank is stored also, the other half of the storage area is used to store household items in storage.

all foil back plaster board used in attic, kingspan tp-10
used in ceilling,only 35mm gap between kingspan & original old roof felt,(ment to be 50mm building regulations) this leads to terble condesation in storage aera. any ideas welcome please as a charterd suvayour could find nothing wrong after a 2 hr inspection last week, baddly need to get to the end of this?
thanks mini cooper Dublin 22.

sinnerboy

firstly - eaves vents -

vents should be provided as a CONTINUOUS 25MM STRIP . providing vent openings randomly as you describe is not sufficient

perversely . leaving the "velux vent" open ( i assume this means velux which open into storage are only - not into bedroom / living space ) is adding to the problem

1. it is reducing the temperature in the storage space - which is "assisting" the condensation affect - condensation occurs when warm climate meets cold
2. for this kind of venting ( i.e. inlets at eaves , outlets at apex ) a velocity needs to be allowed to occur . i.e. don't vent space except at these locations . leaving the velux open is having the affect of slowing the ventilation path . I hope this makes sense to you , best i can describe it .

i would remove your soffits and install a CONTINUOUS 25MM STRIP

i would ensure that the felt is OPEN below the ( must be continuous ) ventilated ridge tile - to provide a continuous 5mm strip . MAKE SURE that you have in fact had installed a purpose designed ventilated ridge system - this will include continuous pvc ventilation strips the the ridge tile sits onto together with "system" fixings

gsxr1

sinnerboy wrote: »

firstly - eaves vents -

vents should be provided as a CONTINUOUS 25MM STRIP . providing vent openings randomly as you describe is not sufficient

perversely . leaving the "velux vent" open ( i assume this means velux which open into storage are only - not into bedroom / living space ) is adding to the problem

1. it is reducing the temperature in the storage space - which is "assisting" the condensation affect - condensation occurs when warm climate meets cold
2. for this kind of venting ( i.e. inlets at eaves , outlets at apex ) a velocity needs to be allowed to occur . i.e. don't vent space except at these locations . leaving the velux open is having the affect of slowing the ventilation path . I hope this makes sense to you , best i can describe it .

i would remove your soffits and install a CONTINUOUS 25MM STRIP

i would ensure that the felt is OPEN below the ( must be continuous ) ventilated ridge tile - to provide a continuous 5mm strip . MAKE SURE that you have in fact had installed a purpose designed ventilated ridge system - this will include continuous pvc ventilation strips the the ridge tile sits onto together with "system" fixings

this sounds scarry.

this is what I have...




im guessing it not going to be enough either.

ircoha

...(sitting room vented,cooker hood & bathroom fan very well secure & sealed) ...

You need to see where they are venting to and if they are to the outside are they finding there way back in through the open velux.

Just a thought

sydthebeat

gsxr1... what you have is standard, i wouldnt worry..... these would approx equal a 25mm continuous strip.....

sinnerboy

will still need to vent at or at least close to apex

amount you need will vary depending on vent tile free area

eg you need to divide free area by 5000mm2

these tiles 20000mm2 each / 5000 = 4m spacings

so if your frontage is say 8m , I would OVER provide ( to be safe ) and locate 3 tiles to each slope either side of the apex ( staggered )


http://www.ubbink.co.uk/roof_vent/slope/tiles.htm

if your felt is breather type - leave it

if it is not - you need to attach a smalll vent pipe THROUGH the felt and seal the felt externally to it

got any roofer mates gsxr 1 ?

mini cooper

ircoha wrote: »

You need to see where they are venting to and if they are to the outside are they finding there way back in through the open velux.

Just a thought

hello & thanks to all who replyed to this thread so far, i'm only new to computers & could not get up and running on line last week, thanks to sinnerboy for getting me started.

so first off ircoha ( when i spoke about the velux window being open i ment it is open a slight bit you cant bearly even feel the air comming in ,it is an in-built in vent in the window you are able to open the vent in the window without opening the window) so dont think this has anything to do with whats going on as the attic room is open planed no door downstairs only our hallway that leads you up to this room.)

but i think you may be on to something but do you have a good expelation of how this may come about, only of days of minus degrees in weather?, someone else has also pointed out this to me,but it dosent make make much sence to me?

the cooker hood vents go through the storage space through a ducting in the attic & carries on out through a vent to the soffit board to the back of the house (south side) , there are 4 other large air vents cut out allong the leinth of that same soffit cut in diffrent spaces, underneath one of them but halfway down the back outside wall a gas flue pipe stickes out from the wall, but when the gas is on & hot air is venting from it, it is blowen away, strait away to the right or left side it never seams to travel upwards, so i dont think it can be either of those two forms of warm air re entering the attic through the vents? if it were anything to do with hot air blowing up this side of the attic the south side (that by the way neaver gives us any bother) it would really need to be a lot of hot air blowing up through the soffit vents & having to travel up a really long way up and over the vented ridge tiles & then dropping down to the north facing side which is the side that is only giving us this condesation.

the bathroom is to the north facing side (the front of the bungalow) it has a fan in the bathroom that is secure & vents through the attic storage aera through a ducting & goes out through a roof vent tile on the north facing side, so it cant be that either,

a survayour spent two hours inside & outside my home last week & cant find anything wrong, he said all our ventalation is sufficent & builder seams to have built it to standard insulation wise & structure wise, but we have friends up the road from us on the same road who used a diffrent builder, he made much the same attic room for them & their velux windows are in the same place as ours on the south facing side exept their in storage space the builder used this type of expanding foam insulation in the roof space & fibre glass & foilbacked plaster boards, now they have no probliems on days of minus degrees their storage area is bone dry when ours resembles a wet soggy mess, they have no extra roof tile vents on their roof, we have 3 over the northfacing side, our soffit boards to the front & back of the house have vents & we have ridgetile roof vents,
so any idea what gives? two houses on the same road done by diffrent builders done with diffrent building insulation metairals, two diffrent rusults one dry & one wet? why
hope some one out there can help, mini cooper D.22

ircoha

MC: what follows is just a guess: given that you seemed to think there was some merit in my first comment, I have put the attached sketch together: however it could be all rubbish.

My quess is that the kingspan is acting as a barrier to the damp moist air getting out of the attic space. The surveyor has told u the external ventilation is okay but the source of the damp is inside the house and it is not getting out past the kingspan.

I have not figured out how it is getting in yet but have u another window in the room other than the velux? 2 sleeping adults create a lot of moisture at night, not to mind Tina Turner/Steamy windows:)

What access is there from bedroom to attic space?

Have u recessed lighting in the ceilings below?
Is there a tear in the duct from the cooker hood or bathroom fan where they pass through the floor?
It there a leak somewhere in the flashing or poor render on the gable end that is making the end wall damper than normal?
Is there any pipework in the attic space that is seeping a slow leak ?

mini cooper

Hi Ircoha thanks for reply,

that drawing is spot on of the type of attic conversion & how it is put together.
I will try to answer your questions to help you build up a picture of whats going on.

(1) the attic room has two velux windows, on the south facing side (one of the windows over the stairs always has that slight vent open)

(2) access to our attic bedroom comes by a stairway in our hallway(no door leading from hallway leading up to the open plan bedroom).

(3) the only thing not able to be fully sealed up there is the 5 spot lights in the attic room ceilling ) as the builders have to leave a small space around/between each for fire regulations. builder thought this might be causing it all-right but is directly under the ridge vent tiles so the hot air from around each light should escape through the ridge vent tiles. these spot lights do never be on long .only really enough time to allow you to walk up stairs & switch on our bed side lights on our lockers,which are regular lights & shades & then switch off the spot lights.

(4) in the bathroom under the north facing side there are two philips slender tone spot bulbs in a fitting called an eyelid socket the revolve/can be turned to diffrent angles.

(5) cant see any visable signs of a tear in cooker hood or batheoom fan ducting.

(6)no leak in flashing or any sign the gable wall is damp.

(7) i do think like you the king span is some how acting as a barrier to allowing damp -warm air getting away (mabe it's to thick? or the original roof felf should have been changed at time of attic conversion if it was knowen not to work with this type of old none breathable feld) does new tecnogioly (kingspan t-p10 work with old tecnogionly ( the black roof felt?

ircoha

Looks like just you and me on this:)

I don't see a problem with the felt as the ventilation which has been 'certified' by the surveyor is for the air path between the kingspan and the felt so that is not the issue.
If u had breathable 'felt' then the roof would breath without the soffitt and ridge vents.{this is a conceptual idea to help the OP as opposed to being a definitive spec for breathable roofs}

The focus should be on where the source of the damp is from within the house that cant escape from the attic space.

meant to add, if u can get someone to modify the sketch in paintbrush I will update it if it helps

sinnerboy

ircoha wrote: »

Looks like just you and me on this:)

I don't see a problem with the felt as the ventilation which has been 'certified' by the surveyor is for the air path between the kingspan and the felt so that is not the issue.
If u had breathable 'felt' then the roof would breath without the soffitt and ridge vents.

The focus should be on where the source of the damp is from within the house that cant escape from the attic space.

meant to add, if u can get someone to modify the sketch in paintbrush I will update it if it helps

not true ircoha - in this case you must vent above felt - and use counterbattens to acheive 50 vent space between felt and underside of tiles or slates - soffits and apexes must always be vented in "ceiling slopes with rafter" condition

sinnerboy

mini cooper wrote: »

Hi Ircoha thanks for reply,

that drawing is spot on of the type of attic conversion & how it is put together.
I will try to answer your questions to help you build up a picture of whats going on.

(1) the attic room has two velux windows, on the south facing side (one of the windows over the stairs always has that slight vent open)

(2) access to our attic bedroom comes by a stairway in our hallway(no door leading from hallway leading up to the open plan bedroom).

(3) the only thing not able to be fully sealed up there is the 5 spot lights in the attic room ceilling ) as the builders have to leave a small space around/between each for fire regulations. builder thought this might be causing it all-right but is directly under the ridge vent tiles so the hot air from around each light should escape through the ridge vent tiles. these spot lights do never be on long .only really enough time to allow you to walk up stairs & switch on our bed side lights on our lockers,which are regular lights & shades & then switch off the spot lights.

(4) in the bathroom under the north facing side there are two philips slender tone spot bulbs in a fitting called an eyelid socket the revolve/can be turned to diffrent angles.

(5) cant see any visable signs of a tear in cooker hood or batheoom fan ducting.

(6)no leak in flashing or any sign the gable wall is damp.

(7) i do think like you the king span is some how acting as a barrier to allowing damp -warm air getting away (mabe it's to thick? or the original roof felf should have been changed at time of attic conversion if it was knowen not to work with this type of old none breathable feld) does new tecnogioly (kingspan t-p10 work with old tecnogionly ( the black roof felt?

(3)
The spot lights directly connect your internal warm climate to the external cold climate - causing condensation on your non breathable felt . how often these lights are switched on , or not , is not relevant .
I recomend to
a-remove these lights .
b-repair the ommision of insulation .
c- install surface mounted fittings


(4)

Same as (3) - even more so , as bathroom genarates warm humid internal climate

Question - has the non breathable felt been cut back below vented apex tiles to allow ventilation path to function here ?

Off topic but very important

(2)

your open plan bedroom ought to have a door to access onto the stairway - your veluxes ought to be sized and located to serve as means of escape or rescue

mini cooper

ircoha, ment to say one one thing about your drawing that might have some relevience or not? in your drawing you have the kingspan starting up at the ridge which it does & ending right down in the eves area where it does not, it would stop around where you have noth side written in picture, as that is where the storage space doors are & it just is cut & stops there & dosent go any further so the condesation dosent dribble of it & strait out the soffit vents . which might be a good idea if it did?

sinnerboy , thanks for your views but cant see why we
cant keep our spotlights as the other 500 attic conversions this guy did for other customers get to keep theirs with no probliems? anyway we have very little head room just about able to stand up strait, only now that the ceiling has been lowered & the floors raised up, so trying to put a flosient strip lighting up there would be very hard at this stage & very unatractrive also.

we will most deffently look into changing the bathroom lighting .
when this attic conversion guy was selling us his great sales pitch he told us to leave it open plan even though we wanted it closed off with a fire door, he told us we dont need one, it's optonal and would only give less space & block off light from the window over the stairs & block off light to downstairs hallway, havent got any spare money now to get center hung fire escape windows now in hindsight, he's probley laughing all the way to the bank with our 20k (nothing but a headache since it was done)

sinnerboy

I understand your reluctance MC - but I believe the recessed lighting is at least part of your problem

In the absence of ( required ) fire seperation ( doorway ) to the attic - the velux is big enough to escape out of ? you have extended the smoke detector system up there ?

hope so

sinnerboy

mini cooper wrote: »

ircoha, ment to say one one thing about your drawing that might have some relevience or not? in your drawing you have the kingspan starting up at the ridge which it does & ending right down in the eves area where it does not, it would stop around where you have noth side written in picture, as that is where the storage space doors are & it just is cut & stops there & dosent go any further so the condesation dosent dribble of it & strait out the soffit vents . which might be a good idea if it did?

It would be better if the kingspan extended from soffit of eaves to apex- but not for the reasons as you appear to understand it . the soffit vents are not meant to drain off condensation - they let air in to move up the vent slope and out at the apex . I suspect the the high level vents that you say are installed are in fact in-active . By that I mean that , like in the advice i gave to GSXR1 earlier - the vent tiles have to ventilate to the B]underside[/B] of the felt - into the 50mm wide vent cavity over the kingspan - yours is only 35mm you say - a small section of vent pipe has to connect to the vent tile , and penetrate and to seal to the felt

ircoha

mini cooper wrote: »

ircoha, ment to say one one thing about your drawing that might have some relevience or not? in your drawing you have the kingspan starting up at the ridge which it does & ending right down in the eves area where it does not, it would stop around where you have noth side written in picture, as that is where the storage space doors are & it just is cut & stops there & dosent go any further so the condesation dosent dribble of it & strait out the soffit vents . which might be a good idea if it did?

Thanks for this as it adds a great deal to the reason for the condensation.

The warm damp air from within the house is being cooled by the cold air in the attic space which is there by virtue of there being no insulation all the way down.

The fact that the insulation is not there will make the functioning of the 35mm gap very difficult.
I note your comments re not having funds to do remedial work, however even if you were able to put a layer of [X] from where the kingspan ends down to the eaves and tape the joins with eaves and kingspan with duct tape , u will stop the cold air mixing as freely as it is now with the warm air and also 'encourage' the 35mm gap to work as it should . I have my own ideas on what X would be but in the interest of correctness I hope someone with more professional knowledge will suggest what it would be.
Hope this helps.
ps amended sketch added

mini cooper

thanks guys everything helps at this stage, sorry only getting back on line now.

ircoha thanks for sketch but again the kingspan is even shorter as you have it here , & i think you might be spot on with you say about the functioning of the 35mm air gap doing a vary hard job as the kingspan doesent go all the way down & there being just so much felt where i think like you it should be all covered in & sealed up?

are you a builder or an arichect? i'm only asking because that sketch is great & if you were able to describe in builders terms & not lay-mans terms as you so kindly have be doing on this fourm for me i could e-mail that sketch & relevent information to builder to see if he will agree to put your your idea in to action for me to sort out my probliem once & for all? and some along the lines you propose as everything else has been tried now i think? (roof vent tiles, ridge vent tiles, bathroom extractors,insulation,ventalation,suvayours) i have all this on camcorder & dvd if you'd be intrested in looking at the probliem first hand otherwise everything we've spoke about is the way it is with no resolve in sight on behalf of my builder. if you want to see the amount of condesation from this attic conversion p.m. me with you address & i will forward you on a copy of a d.v.d. thanks to all for every valubale bit of information recived, i will try to put it all to gether & send it to my builder to get a headache over hopefully his will be bigger than mine! regards mini cooper