Garage Felt shingles leaking / mould on inside

[Badger40]

Hello,

First year in this house and noticed some yellow mould on the inside of the garage roof either side of the truss running all the way down. I’m assuming the felt shingles on the other side of the ply are letting water through. I got on the roof for a look and they look ok although there is some moss growth in places. Nothing seems loose.

What can I look for / what can be repaired? Never had felt shingles before so this is all new to me.

Thanks for any input.

 

[Wayners]

Kill Moss.

Ventilation either end of garage so you don't get condensation.
You might need some insulation to stop the mould...
Need more information to get you a better answer

 

[Badger40]

I’ve sprayed with wet and forget the worst of the moss isn’t quite where the worst of the mould is but not a million miles away.

 

[Badger40]

Does anyone think blackjack or similar over the top of the leaking area all the way the roof in a strip would help?

 

[ree]

OP,
The colored Fungi and dead Tendrils could suggest perhaps a more serious defect than condensation?
Why not clean off all traces of fungi & tendrils - then probe the truss timber for softness, and then force spray fungicide between the trusses & the roof sheathing.
Remove all moss from the asphalt shingles by painstakingly lifting/flapping up each individual shingle.
the bottom three courses of asphalt shingles are repair courses or roof extension courses - is there a flat roof below the shingled roof eaves?

 

[Badger40]

Thanks for the replies. I assumed as the damage is located in line with the truss and not widespread it was water coming in from outside. And that’s where I should focus on looking for a leak / damage or apply some sort of repair. I will look for condensation.

Is wet and forget suitable for hitting this stuff with?

I will get a picture but the felted part is a lean to type shed built on the back of the garage.

 

[ree]

If you post pics of the ridge, & anything irregular or damaged that's exposed when you flap the shingles up, it would help.
Look for wet areas under the shingles.
Is there a membrane under the shingles?

 

[^woody^]

That looks like water penetration from the shingle nails and or poor overlap. It may be moss related.

 

[Badger40]

Managed to get up there today all the shingles look to be nailed and glued down, couldn’t really flap any up a couple of areas it seemed the shingles were not adhered to the ply as a section would move when I walked on it. Couldn’t see any tears or anything else like that.

 

[Badger40]

It looks like it was felt underneath and then they have put shingles on top.

 

[Badger40]

Any ideas of what I can look at next or anything I can do to stop the damage.

 

[Badger40]

That looks like water penetration from the shingle nails and or poor overlap. It may be moss related.

If it is this what can be done about it?

Under the shingles is felt. It looks like it was felt for a while and then they went over the top with shingles.

 

[Badger40]

Hello there was a reply on here but it’s disappeared?! Please re post if you can.

From the replies above and the missing post I’m going to make a start with lifting and re sealing some shingles above the worst effected areas.

Is sika roof and gutting sealant suitable for this?

I will see where I can install some 6 inch vents to create some air flow, maybe some soffit vents also.

 

[^woody^]

That pattern is indicative of moisture penetration and mould feeding on it. However, it does look like its small amount, so potentially is not allowing constant or persistent moisture to get in - unless you know otherwise?

So that tends to be either directional rain, or a specific set of circumstances that allows a very small amount of moisture to get around the shingles. In these cases, you are looking for gaps, loose shingles, excess moss, poor overlap issues up at the ridge and suchlike that is allowing rain to get in or be blown up and under the shingles.

The location looks like it's on a board edge, so you would be looking directly above the mould or vertically up the roofslope above it, say about 500mm either side and up to the ridge.

If there is nothing wrong there, then one other possibility is condensation - damp air and a cold spot on that board joint causing it to condense on the felt underside and seep back in and appearing like small amount of penetrating moisture.

This would be feasible, but when this happens it tends to occur in many places, but it may well be appearing in just one place if the local conditions are just right there

So,
- First thing check the roof again to confirm there are no obvious issues. If there is, deal with those, but avoid ripping the shingles off unless there is an obvious problem
- Clear all that mould, sterilise the board for 500mm either side and the timber truss. Let that dry properly and then give the area a light sand to expose clean timber so you can see if it gets damp again.
- Monitor and see if anything reoccurs
- If it does, determine if its after rain or not. Is it after particular weather - cold, windy etc. If it does get worse after raain then its a shingle issue
- If not worsening after rain, then the likelihood shifts to condensation
- See if you can seal any board joints with a mastic and coat the underside with an oil like decking oil or fencing oil, or clear preservative. This should at least prevent mould coming back there.

 

[Badger40]

Thanks for the reply.

I couldn’t see any issues when I was up there other than a patch half meter square which seemed to be floating / not adhered down it moved when I walked on it. Besides that it looked fine. Should this floating area be sorted also?

Bought some vents from screwed fix will get some air flow going and give the underside another wet and forget then just up on the roof for another inspection and seal any edges. I will as you say start looking at the lap. The moss isn’t near when the issue is but I will get that off also. To me the roof looks very neat and tidy when I’m up there.

I suspect it’s as you say occasional rainfall at a certain angle causing it and lack of air flow not helping.