Hi @LorenClayton,
Thank you for your question about a hole in your soffit/eave.
This hole doesn't appear to serve a purpose as there is a vent right next to it that would promote airflow in the ceiling cavity. It is likely just damage from previous work, the location of a previous fitting or a lazy way of allowing airflow to the eaves before a vent was installed.
If there is a ceiling cavity above this that you can access through a manhole, this would be a way of confirming this. Alternatively, if you have a tiled roof, it might be possible to shift a tile, or with a corrugated metal roof, a roof sheet, to see what is behind the hole, but I'm fairly confident it doesn't serve a purpose at this time.
A simple temporary solution would be to stick an adhesive screen patch over the hole to prevent insects and rodents from entering the hole.
A more permanent solution is to fill the hole with James Hardie Base Coat Compound.
You'll need to "back-block" the hole, so the compound has something to stick to. The scenario is vastly different, but my colleague @MitchellMc's technique in Step 3 of How to repair a hole in an internal door is a good option.
Use some Liquid Nails to glue pieces of Timber Paint Stirrers to the back of the eave sheet. You can use a screw through the centre of the paint stirrer so you can pull it down to compress the glue against the back of the eave sheet.
Once they have dried, apply the James Hardie Base Coat Compound with a 100mm Sharp Edge Paint Scraper to fill the hole. Do your best to get it as smooth as possible while wet, as the base coat is not easy to sand.
Once dry, paint the patch with an external paint to match.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
