Ive got mould forming in the ceiling.....why??

[67restoproj]

I was up in the loft cleaning today and noticed mould and ice forming on the inside of the open ceiling. The nail heads have ice on them as well. This isnt good. The roof is on the north side so it doesnt get much sun. The other side (south facing)appears to be ok for now.
Anybody know why,and how to get rid of the mould. Thanks in advance.

 

[fireman]

It's most likely from condensation due to poor ventilation.

 

[SteveU]

Probably not too much to be done now but when the weather warms up I would look at putting in a ridge vent or other form of ventilation and increasing insulation while up there.

 

[ddawg16]

A bigger issue is that you have water on that nail....your roof could be failing....how old is it?

 

[lh4x4]

Agree with the vents as a solution.

 

[67restoproj]

The upstairs looks pretty much the same as the pic right now other than the windows are in. The ceiling and walls are not closed in yet so should there be lots of ventilation? I noticed the windows were iced over this morning also....

 

[67restoproj]

A bigger issue is that you have water on that nail....your roof could be failing....how old is it?

The roof is about 4 months old..

 

[67restoproj]

It's most likely from condensation due to poor ventilation.

I installed 3 vents on that same side........is that sufficient enough or do also need a ridge vent? Thanks!

 

[idoine in toronto]

Depending on how tight your building envelope is you may need to add soffit vents for intake or supply ventilation.

Also check to make sure your roof vents are working and not blocked by snow or ice.

Here in Toronto the amount of roof ventilation typically used is open vent area = 1/300th of roof square footage. Making sure to balance the amount of soffit vent area with roof vent area. You may need more in BC.

Also try to eliminate or minimize the source of moisture by looking for things like poorly vented dryers and showers.

Is this roof over a heated garage? if so there shouldn't be much moisture supply unless it's like my garage and full of slushy cars.

Good luck, hope you find a solution.

 

[67restoproj]

Depending on how tight your building envelope is you may need to add soffit vents for intake or supply ventilation.

Also check to make sure your roof vents are working and not blocked by snow or ice.

Here in Toronto the amount of roof ventilation typically used is open vent area = 1/300th of roof square footage. Making sure to balance the amount of soffit vent area with roof vent area. You may need more in BC.

Also try to eliminate or minimize the source of moisture by looking for things like poorly vented dryers and showers.

Is this roof over a heated garage? if so there shouldn't be much moisture supply unless it's like my garage and full of slushy cars.

Good luck, hope you find a solution.

Right now there are no soffits installed. Its wide open. There is no power in the building to heat it. Pretty much an empty building...

 

[walrus]

Part of the moisture is new wood, new concrete. If its heated downstairs, warm moist air is escaping up stairs and going thru dew point. The warm moist air hitting a nail at outside temps, causes ice. Happens in attics all over in northern climes.

 

[kbs2244]

I fully agree you need ventulation.
Have you been heating with an unvented heater?
They put out huge amounts of moisture.
You can overload your vents with their moisture.
Maybe a lot of melting slop from under the cars?
If you are not heating, have roof vents but no way for replacement air to get in, you might want to leave a door cracked a little bit.
Moisture will follow heat.
But the warmer air needs to be replaced.

 

[67restoproj]

The attic is open to the garage below (see pic) and with no soffits, maybe could it be drawing in to much moisture?

 

[kesselect]

Could you have purchased the board with mold already on it? All indications are that there hasn't been enought time, even without ventilation for the mold to get that far along.

steve.

 

[Vicegrip]

what are you using for heat? never mind saw a later post.

 

[idoine in toronto]

My guess based on you saying there is no heat or interior moisture source is that the open soffits and other drafts (or perhaps wet cars) are letting moisture in and the inside temp is warmer than the outside temp. The sun or hot cars may be warming up the interior and vapor is rising and as others have said, hitting the cold roof and nails and freezing over. If your not worried about anything freezing in your garage this winter you can try cracking the gable windows and letting some of the moisture/vapor escape and at the same time cooling the interior temps to help balance out your interior/exterior temps.
I wouldn't worry to much about the moisture now, as the conditions will change once you've finished off the exterior of the building.

 

[kbs2244]

That is about as much soffit vent as you can get!
As long as the air has a way out, you have plenty of ventlation.
kess has a point abaout your getting it moldy in the first place.
OSB will **** up rain if it isn't stored correctly.
You may just have to wait for it to dry out.

And to answer your question, it is not very likely you are bringing in moisture through the soffits. Cold air is dry air. Moisture follows heat. So the cool air comes in the soffit, warms and absorbs moisture, and flows out the ridge vents.

 

[wrigh003]

Since your building envelope isn't enclosed or heated, cool air will condense on the relatively warmer roof/ceiling structure, since the sun's heating it. If your 4-month-old roof isn't leaking (I'd hope not!), this problem may correct itself once you close in your walls. At that point, even if you don't actively heat the structure, passive heat gain from the sun coming in will keep the whole building warmer than ambient, and then this won't happen.

In short, close in your walls. I bet you don't see any further condensation after that, and then your mildew/mold problem goes away.

 

[pattenp]

The roof is about 4 months old..

I had aproblem with my roof which looks alot like yours. I had a new roof installed and two nail heads in one spot were not covered totally by the next course of shingles and slowly leaked. I had dropplets of water forming on the points of all the nails that were down stream and had spotted mold forming on the underside of the roof sheathing. It was unreal how large of an area was affected by just those tow nails leaking over a period of 2 months before I discovered it.

 

[Vicegrip]

Since your building envelope isn't enclosed or heated, cool air will condense on the relatively warmer roof/ceiling structure, since the sun's heating it. If your 4-month-old roof isn't leaking (I'd hope not!), this problem may correct itself once you close in your walls. At that point, even if you don't actively heat the structure, passive heat gain from the sun coming in will keep the whole building warmer than ambient, and then this won't happen.

In short, close in your walls. I bet you don't see any further condensation after that, and then your mildew/mold problem goes away.

sounds backwards to me. Warm moist condenses on cold. some source of warm water carrying air is getting to the roof and condensing after sundown. Perhaps a damp cement floor that has ground heat and snap cold nights.

if this is the only place you are having an issue spray the wood with a weak clorox solution to kill the mould and set a fan up in the space during condensing conditions. Closing in with no insulation might exacerbate the problem. Hard to tell what is happening without knowing local conditions.

 

[67restoproj]

Looking closer, It appears both of the roof sides are doing this. The concrete floor below is 2 months old and is dry. It has been sunny here with mild temperatures in the day, but soon as the sun goes down it cools of real fast. Frosty mornings also. The air is quit humid right now....very damp.
I dont have power wired in the building yet, maybe a propane heater at night??

 

[wrigh003]

Vicegrip is right, I had that backwards. I still think there's moisture condensing on your ceiling somehow, though I'm not really sure how- being winter everything should be pretty dry, and if you're not artificially heating the space, everything should be roughly the same temperature, so you shouldn't have problems like that. Looks just like the ceiling of my open carport at my old house used to look. High relative humidity, always in the shade- boom, mildew.

Wouldn't hurt to go up there and look and make double sure there's not a tiny leak around those nailheads, though (are they all like that, or was that the only one?). Could be that one of the shingles has a tear in it, or somebody got careless with the roofing nailer and there's a nail through the exposed surface of a shingle somewhere.

 

[Vicegrip]

Propane heater will make more moisture from combustion. Can you run a long extension cord and run a fan?