I knew a guy who was hasseled entering the US with some tools because he planned to do renovations on his own house that he owned outright.
The border guards said that unless he was a citizen or had a work visa then he was not allowed to work on fixing up his own house, and would have to hire a local to do it.
tl;dr working for "just food and a place to live" is still technically working, and unless you have permission to do so it would be risky for all parties involved.
There's a grey area. Making your own bed is ok. Renovating a series of houses to sell on isn't. It's not totally clear where the boundary is but I think the guards have some discretion.
The border guards said that unless he was a citizen or had a work visa then he was not allowed to work on fixing up his own house, and would have to hire a local to do it.
tl;dr working for "just food and a place to live" is still technically working, and unless you have permission to do so it would be risky for all parties involved.