is there a snap to wall button to avoid gaps inbetween walls?

as the question states in the title. I know that there's snap to floor and align to floor in the transform section(left clicking the object -> transform) but it doesn't seem to help much for ceilings / walls on second floors or first.

I've got lots of gaps in my map and would like to fix it and i don't think I'm doing it the most efficient way possible. At the moment I'm selecting the mesh that's out of place and trying to fix it in coordinates in the properties section. If that doesn't work then I guess by moving it up and down side to side on grid snap 1.

So if there is a button that snaps two or multiple walls/cielings/floors/meshes together or a better way to do this please tell me, thanks.

is there a snap to wall button to avoid gaps inbetween walls?