How to treat mould on eaves?

lilnikoy82

Can you please tell me what causes this, how to fix it and prevent it? Also happening at the front

EricL

It's possible that water has settled onto the top part of the soffit and has caused mould to start growing. You'll notice that it is only happening where the down spout is, and it could be an indicator of a leak in that section. The only way to tell if there is a leak is to remove that section of the soffit and doing a thorough investigation. Because the mould has been there for a while it has started to travel towards the metal gutter.

Once the leak has been addressed, I recommend changing the soffit and not reusing the old one so that you will not run the risk of mould spreading further. The gutters outer surface can be cleaned using 30 Seconds 1L Mould Off. Please make sure to rinse the surface with clean water once the mould has been cleaned off.

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you need further assistance, please let us know.

Eric

Dave-1

Good Evening @lilnikoy82

My thoughts are a little bit different from @EricL 's but still end up with mould appearing from moisture.

At first I thought that the water was curling under the gutter and onto the eve area due to the shadecloth (Still think that this is helping with the issue of mould. ) I am not sure as to the front of the house mould point but maybe the gutter is full and the water is curling over the gutter and under the edge to end up back under the eve. With the Photo you have shown I think I can see an instantaneous hot water tank up near the eve, if thats the case then potentially warm air rises from that, travels along to that point and working with the moisture/collecting because of the shade cloth helps form mould.

I do like @EricL's suggestion as well. Both come back to a water coming from somewhere.

Dave

Nailbag

Hi @lilnikoy82

It's my experience that you have rainwater leaking in to your Soffit, which has been occurring for some time due to the spread and extent of the mould. A common cause could be from blocked downpipe/s and/or gutters overflowing in to the Soffit due to being filled with debris. The other scenarios will be from leaking guttering and pipes due to ages, from the roof with a damaged tile or metal flashing that has failed.

As @EricL mentioned, this needs to be identified and fixed first before the repair work. The suggested 30sec mould killer, will barely make a dent in that level of mould, which will be well engrained within the cement sheet. Your choices are to replace the sheets or as they appear to still be in good condition, would be to paint them first with a specialty primer sealer. I use this one by Zinsser which is an excellent product. Just follow the preparation steps on the label. Then apply 2 coats of matt ceiling white to finish the job.

The photos below show an example of an eve I restored with this process a few weeks back.

Hope that helps. Nailbag

lilnikoy82

Thanks for replying, just a few things, there is a down pipe right where the mould is forming. I got up last year and looked but couldn't see anything blocking the down pipe and even ran the hose down it with no issues, the shade cloth has only been up for this summer and the unit in the background is the air con unit in a terrible spot.

So I'm at a loss as to what's happening. The house is only 10 years old. The front one is really bed and it settles in a corner spot which I think is because there is no downpipe there? I can add photos for that tomorrow as it is pretty bad.

Just will let you know, I get completely lost when you talk about soffits and other words as I'm still learning how to do these things myself. I don't even know how to take one off. 😕

EricL

Hello @lilnikoy82

Please post the other photos of your gutters and eaves so that our members can assess their condition. We can then make recommendations on how to proceed.

Eric

Nailbag

Hi @lilnikoy82

Firstly I also often don't know the terminology, but my mate Google is a lifesaver. Simply type in "what does "Soffit" mean and like magic the answers appear. Sofitt is typically e US term for an eve and often used by Australians. It's basically the overhanging area of the roof past the external wall. I don't use the term, except when its part of a conversation started within the community such as this case by @EricL. Its not uncommon for overseas terminology and names to be used here.

Now back to the issue. If water is lying in the guttering at the mould end, then the fall of the guttering needs to be rectified by your plumber. It could also result in heavy rains over filling that end flowing into the roof space/eve/sofitt.

Noting the downpipes goes straight into the roof space/eve then if there is any issue within with a leak, that needs addressing. Is your roof tiled or colourbond (steel corrugate)?

My recommendation would be to get a licensed plumber over to check the following:

Check gutter falls are correct
Check there is a enough downpipes
Check internal of the damaged eve boards for signs of water ingress and possible cause.
Quote on relocating AC compressor unit.

Nailbag

Dave-1

Morning @lilnikoy82

I really suspect there is water getting into the area above the eave lining/soffit

I just googled terms and came across this pic in the building code that shows what I suspect is happening.

https://ncc.abcb.gov.au/ the diagram is right at the bottom of the page

You can see an example of the eves profile on the left. For mould to form I would be thinking water is gaining entrence from maybe a leaky tile, water curling under the gutter from gutters being overfull in storm instances. @Nailbag explanation works really well for breaking down the issue.

If water is entering via the tiles or curling then a likely spot for it to pool after running down the timber trusses is on top of the eaves/soffit. This moisture then migrates through the material and can introduce mould. Alternatively, if water curls under from the facia (I know mine does in extreme storms) it can also introduce that wet area and then mould is quiet happy to make a home.

First check the area for leaks (if you are not confident with heights then a roofer or plumber) Check the state of the tiles, look for cracks slippage or holes. You will need to folow up the roof line from the mould area to the top of the crest. as the water could be traveling down a ceiling truss.

Once you have it sorted, I would paint it with a paint that kills mould and coats the area more then trying anything else.

Dave