@Mar***
, renovating your own or gf/wife home is the absolute tiniest of risk when we talk about working without a work permit.
Going to a school to volunteer and be publicly facing poses a risk. This is a job. A regularly scheduled commitment.
However, that doesn’t mean you’re not allowed to do other charitable deeds.
For example, there’s a Chiang Mai Clean City movement and foreigners can and do show up to their events to help beautify the city with trash removal.
After the flood in October, many foreigners were helping locals with cleaning and other tasks.
This is not “work” that would get someone arrested in a group photo, fined, possibly jailed and deported.