Mould/Damp forming in attic

zt-OctaviaN

Hi Folks,

Firstly Happy new year to you all!

My question is as follows:
Following the pumping of cavity walls with bead and insulation applied in the attic.
I first had the attic joists increased in height before the additional rockwool material was layed and then it was then covered with a 12mm ply.
Note there was no compression of the rockwool material at all.

I was just up returning the Christmas decorations into the attic i could smell the mouldy dampness however on closer inspection the boards near the roof joist are showing signs of a greyish green dust forming on them extending inwards about 1.5 to 2 feet.

The rockwool material is actually placed into the joists! some have a 3x3 inch gap pressed into them. This is occurring next to joists.

http://dl.dropbox.com/u/49781843/photo.JPG

http://dl.dropbox.com/u/49781843/photo%20(1).JPG

http://dl.dropbox.com/u/49781843/photo%20(2).JPG

http://dl.dropbox.com/u/49781843/photo%20(3).JPG


Is this normal? Is it just a case of a little more venting required you think?

The house was built in 2003/2004 and is a 1.5 story dormer.
Any steps I can take to enquire about the installation of the attic layer i.e. should I call back the insulators (a large well known insulation company) and enquire if its actually been done correctly etc, any advice would be great.

Thanks in advance
Nick

muffler

Im sure there were vents in the soffit before you had the attic insulated and from looking at the pics it seems those vents have been blocked which shouldn't happen. If you go into your attic a lot you would probably find that its not as cold or drafty now compared to before and it really should be the same.

get the company back again to sort that and anything else that needs done....water tanks and pipes lagged, trap door insulated and sealed etc if they haven't already been done.


Edit/ if you're not sure yourself whether vents have been blocked or not get a local arch. technician in to have a look and give you a written report. There's no point in asking the firm who done the work if its right or not as they will only give you the one answer.

yellow50HX

neighbour had similar problem with dampness, his breathable membrane was not as breathable as he thought. Anyway he hired a core drill and cored out a hole in the east and west gables as high as he could go and put a vent on the outsides to let air pass through the attic. 4 years later and the attic is still perfectly dry. ceiling below is sealed so no draughts

engineermike

Hi,
Ensure all soffits vents are clear, putting vents at high level isn't going to allow for cross ventilation of timbers / purl ins etc.
See the image for the requirement for your roof design.

https://www.dropbox.com/s/0v5upjsl1ean6bh/Condensation_in_roof.jpg
Also check that your background vents in walls haven't been blocked by bead.
Rgds,
Mike f

Eastside

Iv got the same problem!! Happy I'm not the only one. I was up before Xmas and everything was ok then went up Xmas eve after a week of very damp weather and found my suitcase had mould starting to form on it. Anyway went up again this week putting the Xmas stuff away and it was very damp, could see greyish mould forming on wooden chairs up there and boxes were damp aswell. The roof timbers seem to be ok. Had a good look around and inspected for leaks but nothing. The attic isnt badly insulated but it wouldn't be the best either so there should be some heat escaping in there. Going to get it done professionally this summer as I need to re felt the roof, the roof is approx 40 years old but all the felt is tore in numerous places so it needs to get sorted, could this be a problem resulting in dampness? I also noticed that there is a gap about half an inch in the corner of the soffit outside, again could this be leading to moisture getting in? The attic is ventilated as it's quite drafty up there. Any advice much appreciated as I'm slightly concerned and also iv alot of stuff stored in the attic I.e. books etc that could get damaged by this.

sydthebeat

yellow50HX wrote: »

neighbour had similar problem with dampness, his breathable membrane was not as breathable as he thought. Anyway he hired a core drill and cored out a hole in the east and west gables as high as he could go and put a vent on the outsides to let air pass through the attic. 4 years later and the attic is still perfectly dry. ceiling below is sealed so no draughts

breathable membrane DOES NOT mean you can push insulation right up against it... thats a misconception.

Dully

In an attic with no VCL installed on ceiling level it is all down to avoiding moist warm air from the living space entering the attic and as lined out before: ventilation, ventilation, ventilation
Check your attic hatch for draughts, install draught proof strips if necessary
Check around pipes and cables penetrating the ceiling, seal around them if there are obvious holes / leaks
Make sure you have a continous gap of 10mm along the eaves for ventilation and adequate soffit vents
You also must leave a 50mm gap between your insulation and the floor/platform/plywood sheeting for ventilation
Again, all above is for the case you have no designed vapour control layer installed on the ceiling. If so, details might change.
Breathable membranes do help avoiding moisture in the attic, but there is a little phenomenon: If the moisture load is so high that you get a water film on the breathable felt, most felts become diffusiontight as a water film does not allow evaporation of damp!

zt-OctaviaN

Thanks for the response folks.
Slight problem does anyone know if Ecoseal have gone wallop?????
http://www.ecoseal.ie/ 1800 number on the site is out of service and
this galway number is also out of service???
http://www.irelandlookup.com/3027147/Sales_Promotion_Consultants/Eco_Seal_Insulation/

zt-OctaviaN

Confirmed Ecoseal are indeed gone Guess I'll have to fix it up myself.

Frere Jacques

I have the same issue. There was a lad on AAM in a post from a few years back suggesting its the rapid temp swings causing this, ie, warm air entering a cool attic in the mornings and condensating. I see where he was coming from but I reckon for the main my problem is caused by the top up insulation reducing the air gap near the sofits.
I also have a 40 yld flat roof which I rammed full of rockwool before Christmas. I guess I better fish all of that out before the place rots to pieces.
Question though, is it better to core drill the gables or can I just get a 4" hole saw and put 3 vents into the sofits front and back.
Cheers,
J.

engineermike

Frere Jacques wrote: »

I have the same issue. There was a lad on AAM in a post from a few years back suggesting its the rapid temp swings causing this, ie, warm air entering a cool attic in the mornings and condensating. I see where he was coming from but I reckon for the main my problem is caused by the top up insulation reducing the air gap near the sofits.
I also have a 40 yld flat roof which I rammed full of rockwool before Christmas. I guess I better fish all of that out before the place rots to pieces.
Question though, is it better to core drill the gables or can I just get a 4" hole saw and put 3 vents into the sofits front and back.
Cheers,
J.

Hi,
Put vents in soffit front & back for cross ventilation. If you want to ensure full ventilation of moisture - put a vent tile mid way / or high up one of the pitches of the roof also. Puncture the felt / membrane and allow the flexible connection hose / pipe of the vent dangle into the attic space. (normally about a foot).
Tape your felt / breather membrane around the aperture of the vent to ensure a water tight seal is intact for your roof's secondary cover protection.
mike f

Frere Jacques

Cheers Mike.
I have a dehumidifier sorted for the weekend so I'll throw that up there for two days and also move all the top up insulation away from the eaves. I'm going to check the RH though this evening and Sunday evening too. I'll let ye know the readings monday morning.
Rgds,

J.

heavydawson

Frere Jacques wrote: »

Cheers Mike.
I have a dehumidifier sorted for the weekend so I'll throw that up there for two days and also move all the top up insulation away from the eaves. I'm going to check the RH though this evening and Sunday evening too. I'll let ye know the readings monday morning.
Rgds,

J.

Hey Frere Jacques, you can buy rafter vents to ensure the insulation never blocks the vents in that area. They're just plastic trays that provide a 25-50mm gap between the felt and the end of the insulation. You can push the insulation up tight against them and they'll ensure the ventilation gap remains.

Frere Jacques

Cheers HD. That's funny now, I was up there this evening moving back the top up lagging, thinking would I be better off getting a sheet of marine ply and cutting it into 16"x24" rectangles and putting one on the end of each of the rafters to maintain the air gap. I'll check out the rafter vents though in the morning, plastic is the way to go up there.
Cheers for the tip.

Frere Jacques

This summed it up for me;
from this link;
http://www.energyauditingblog.com/the-problems-with-attic-ventilation/


In older buildings, no insulation meant enormous amounts of heat flowed into the attic space. The gigantic boiler is chewing through hundreds of gallons of oil, keeping this sieve of a house warm. The warm air rises, carrying with it a heavy moisture load (the warmer the air, the more water vapor it can hold). This rising heat keeps the attic space relatively warm, ensuring that solid surfaces stay over the dew point (the temperature at which moisture condenses on a solid surface – think a glass of ice water).
When properly insulated the interior heat is cut off, chilling the attic space. The attic is colder and often falls below the dew point. Unless you’ve hire a bang up contractor, odds are good the attic floor is not airsealed well. This well insulated modern house is much tighter than an older home, so the air lingers 2 to 3 times longer and the modern boiler’s lower output does much less to dry out the house.
Moisture loaded warm air sloughs into the attic, dumping its water vapor onto the first cold hard surface. Usually your roof. After time (sometimes not much time), the roof system decays and possibly fails. So you call a roofer…who recommends more attic ventilation. Unless the attic ceiling is completely airsealed, poking a hole into your attic only causes the warm moist air to updraft faster. And more air movement means more moisture and probably more damage.
If done correctly, a vented roof assembly is one of the most effective approaches in building science. But attic vents can fail and are not a cure all.

Sridhar

Is anyone aware of any professional help available for preventing dampness & mold in attic. Need urgent help !

yellow50HX

Sridhar wrote: »

Is anyone aware of any professional help available for preventing dampness & mold in attic. Need urgent help !

Start with venting the attic and then seeing how it is in a few weeks rather then spending a lot in getting someone in now. If that doesn't improve the situation then starting looking at roofers for their suggestions