How To Remove Mould Under Eaves

Will Sugar Soap remove mould from eaves under a verandah?

Yes — with one important qualification. Selleys Original Sugar Soap is excellent for cleaning mould and mildew from surfaces both indoors and outdoors before repainting. But it cleans the visible mould off; it does not kill the mould spores. If the conditions that produced the growth are still there, the mould may return.

So Sugar Soap is the right product for the cleaning stage of the job, and it needs a second step behind it if you want the result to last.

Cleaning off versus killing off

This distinction is the whole answer, and it is worth being clear about because it explains why a wall that looked clean is spotted again a few months later.

Cleaning removes the growth you can see. It also removes what feeds it — grime, dust and organic film that collect on a sheltered soffit. Spores, though, are not removed by cleaning; they are microscopic and they sit in the surface. Under eaves and verandahs they have ideal conditions to start again: shade all day, no direct rain to wash the surface, and still, humid air trapped against the lining.

That is why Selleys' advice pairs the two steps. Clean first, then treat the surface.

How to do the job

1. Clean with Selleys Original Sugar Soap. Dilute half a cup into 5 litres of water for most jobs, and dilute to suit the task. A Selleys Super Cloth soaked in the solution and wrung out is ideal. Work from the highest point down, so runs go over surfaces you have not cleaned yet rather than over ones you have.
2. Then kill the remaining spores. Selleys' advice for this job is to use a bleach or white vinegar solution after cleaning, to kill any existing mould spores on the surfaces.
3. Rinse off thoroughly. Apply, then rinse well. Do not leave either product sitting on the surface.
4. Let it dry completely before repainting. Painting over a damp soffit traps moisture in exactly the place you are trying to keep dry.
5. Consider an anti-mould additive. If you are repainting, one can be added into your paint to help prevent future mould.

Never mix the two products

This must be said plainly, because the two-step sequence invites the shortcut. Do not add bleach to Sugar Soap. Selleys does not recommend adding any other product to Selleys Original Sugar Soap, and where a bleach-based cleaner is used it must be a separate step with the surfaces rinsed thoroughly in between. There is more detail on whether you can add bleach to Sugar Soap — that answer also names Selleys Rapid Mould Killer as a follow-up for effective eradication of mould.

Safety when you are working overhead

Eaves and verandah linings mean working above your head, with solution running back down towards you. Selleys' advice for this job specifies disposable gloves and protective eyewear.

Selleys Original Sugar Soap's own safety directions reinforce it: the product causes serious eye irritation. Keep it out of reach of children, avoid contact with skin and eyes, use rubber gloves if you have sensitive skin, wash your hands after use, and if it does get in your eyes, rinse thoroughly with water.

Add the obvious physical risk. Ladder work with a wet cloth and a bucket of solution is where these jobs actually go wrong.

Limitations to keep in mind

• Sugar Soap does not kill mould spores. Treat this as the defining limitation for this job.
• Wipe it off immediately from aluminium and brass surfaces. Eaves work usually means aluminium gutters, downpipes, fascia capping and window frames within splash range.
• Rinse it well from glass before the product dries, or it leaves a hard salts deposit. Windows under a verandah are directly in the firing line — see removing Sugar Soap marks from glass if it happens.
• Test an inconspicuous area for compatibility and colourfastness if the solution will reach blinds, outdoor fabric or cushions.

Why the mould came back — the part no product fixes

Selleys' answer is explicit that the mould may return if conditions are conducive to mould growth. Under eaves those conditions are shade, still air and moisture, and no cleaner changes them. Where you can improve airflow, clear vegetation back off the wall, or fix the source of moisture, you get a longer result from the same cleaning work. Where you cannot, expect to repeat the job periodically — and the anti-mould paint additive becomes more worthwhile.

For the broader problem across a house, see how to eliminate mould in your home.

Common questions

Does Sugar Soap kill mould?

No. It cleans visible mould and mildew off the surface but does not kill the spores.

What do I use after cleaning?

Selleys' advice for this job is a bleach or white vinegar solution applied after cleaning, then rinsed off thoroughly, to kill existing spores on the surface.

Can I mix bleach into the Sugar Soap to save a step?

No. Never mix the two. Use one, rinse thoroughly, then the other.

What dilution of Sugar Soap should I use?

Half a cup into 5 litres of water for most jobs, diluted to suit the task. Neat use is reserved for stubborn or in-ground marks with a non-scratch scouring cloth.

Do I need to rinse if I am repainting?

For this job Selleys advises applying and then rinsing off thoroughly. See preparing ceilings for painting for how the rinse question differs when you are repainting straight away indoors.

What safety gear do I need?

Disposable gloves and protective eyewear. Sugar Soap causes serious eye irritation, and you are working overhead.

Will repainting stop the mould coming back?

Not on its own, but an anti-mould additive can be added into your paint to help prevent future mould.

What if the mould keeps returning anyway?

The conditions are still favourable. Cleaning treats the symptom; shade, still air and moisture are the cause.

Is there a Selleys product specifically for killing mould?

Yes — Selleys Rapid Mould Killer, named in the answer on adding bleach to Sugar Soap. Spot test an inconspicuous area first; it is not for use on fabric, mirror tiles, metallic surfaces, or older baths and basins.