Condensation in attic - possible causes

youtheman

Went into my attic this evening. Saw some damp patches on the insulated flooring section. The felt overhead was damp, and there was evidence of water staining on the roof trusses. Thought I might have a leak, but then it dawned on me that the damp was ONLY ON THE NORTH FACING section of the roof. So I assume its condensation from warm air entering the attic space (the North face will be colder, particularly in this weather).

I checked the pipe from the en-suite shower fan, there was a small hole, though I doubt it is big enough to be the source of the problem (though I maybe wrong).

Anyone experience a similar problem?.


See damp patches on floor, and beads of water on the fiber insulation



See the water damage to the roof trusses. The felt on the right is on the South face, perfect condition. The felt on the left is on the North face, note the different colour which looks like frost but is actually condensation. The water damage to the roof trusses is not just on the apex, which means it's not just faulty ridge tiles.

stephendevlin

Looks more like a leak to me rather than condensation. The area on that touches the roof seems to be saturated. You could be right about the damaged tile. or felt may have ripped. Is it ony on this one truss?

youtheman

Stephen, it's on several trusses, and on some it extends down almost all the way (though not to the bottom). But there is absolutely no sign of water on any of the South side trusses, even when the corresponding North one is damp. Hence my reason to think its condensation, not a leak.

stephendevlin

In that case then it way well just be condensation from the weather we are having. If the roof is ventelated it will clear up when the weather heats up a bit more.

youtheman

Stephen, several trusses are damp, and on some it extends down the slope, though not to the bottom. But there is absolutely no sign of damp on the South side of the roof, which leads me to believe it's condensation rather than a leak.

I must stick my hand under the felt - it the outside is dry and the inside is damp then this would rule out a leak and point to condesnation (am I right?).

wilson10

I have the same problem for the first time this winter.

The first thing to do in a case like this is figure out what you've changed, so in my case I reckon I know what's causing it.

In the summer we put down an extra layer of Rockwool and I reckon we went out a bit too far on the soffit and covered the air grills so there's not enough circulation of air.

It's going to have to wait till next summer for trimming to find out next winter, too bloody cold up there now.

byte

When the dry warmer weather comes in, would it be a good idea to treat your attic timbers so they don't rot?

youtheman

Point well made about the insulation blocking the vents. I too put down another layer of insulation, though I thought I didn't extend it out too far (worth checking).

cram1971

Completly down to the weather we are having. warm air hitting the cold surface = condensation I would say 80% of people would see the same thing if they went up into there attic tonite. The better your attic is insulated the less the condensation along with the outside temperature.

gsxr1

i would get up to your ridge tiles for a look. I know it is the north area, but that still does not dismiss the fact that your ridge may need pointing up. The sharp point of your truss can puncture the sarking felt at that point. If so . I needs lapped with new stuff.

Even with treatment. Your trusses will not stand much more of that soaking.

You really dont want to go into a re-roof situation. That needs dealt with this summer .

Joey the lips

i am sure you have checked this but just throwing it out there. Is there a chance that when you were upgrading the insulation or orig when the house was built that the bathroom vents and there ducting has become disconnected...

youtheman

Went up to the attic this morning. Condition was worse than yesterday, and given that there was no rain I'm inclined to think it's due to condensation. Went into the next door neighbours house a took some photos of the offending North side (see below). No obvious sign of a faulty roof. Apologies for the photos, the sun was shining directly into the lens, nothing I could do about it. The vent on the roof is from my WC waste pipe, they are all internal in my house (and I've checked to see if they are disconnected).

There is a small leak in the extract duct from my en-suite, but I don't think it's the cause.

gsxr1

maybe a vent tile into the attic high up would be in order.

paddy147

Quick question here.

can you patch up and repair damaged roofing felt from with in the attic?

My house is mid 1950s house with heavy black roof lining (tar like substance).

A small bit of it is damaged and has fallen away,can I use something to patch this up and make it water tight again??

Thanks.:)

daithi2011

Ive seen this. It involved a header tank in the attic.
If you have a tank and If you have the heating on or back boiler, just go up and see is the water getting warm in the header tank
.
What was happening in my case was that it warms up and steam comes out of it, condensing on the felt and then dripping down.

gsxr1

paddy147 wrote: »

Quick question here.

can you patch up and repair damaged roofing felt from with in the attic?

My house is mid 1950s house with heavy black roof lining (tar like substance).

A small bit of it is damaged and has fallen away,can I use something to patch this up and make it water tight again??

Thanks.:)

Paddy it is tricky to get a new piece up under the lap above from the inside or out. If you can get you hands on a bit of the breathable felt you will be doing your self a favor as it is much easer to work with. Its really important to get it under the piece above as this will prevent water leaking into your attic.

paddy147

gsxr1 wrote: »

Paddy it is tricky to get a new piece up under the lap above from the inside or out. If you can get you hands on a bit of the breathable felt you will be doing your self a favor as it is much easer to work with. Its really important to get it under the piece above as this will prevent water leaking into your attic.

It just so happens that I have a brand new unopened roll of Daltex Ultra FX breathable roofing membrane in my garage.:)

Would that do the job??

When you say get it under the piece above........do you mean get it under,as under from the attic side or under as from the tile side??

Thanks.

gsxr1

paddy147 wrote: »

It just so happens that I have a brand new unopened roll of Daltex Ultra FX breathable roofing membrane in my garage.:)

Would that do the job??

When you say get it under the piece above........do you mean get it under,as under from the attic side or under as from the tile side??

Thanks.

You only need 4 foot of the stuff. Might be worth finding a small bit and sell the brand new roll. That roll you have is quite expensive .

Felt has the be lapped so the rolling water from above, rolls onto the next piece and not under it(then onto the floor). Like the tiles. One bit the width of the rafter gap should do. Its only a patch but it has to be long.