Would like to clean the outside of your playhouse building? Maybe it’s got ground dirt or dust on it or maybe it’s covered in bird shite. Then you need one soapy water and a sponge. Don’t use anything hard. Don’t use any hard brushes or anything like that. Sponge is perfectly fine. That will get rid of the dirt from the outside. On the inside, if you haven’t already used anything like teak oil or Danish oil or beeswax or wax on the inside to make it a wipeable surface. Then what you need to do to get rid of any dirt that’s on the timber is just a light fine sandpaper, and that will get rid of that.