How to get rid of roaches?

I am living with my boyfriend at his grandpas house and he has a roach problem. moving is not an option right now. his grandpa is sensitive to sprays, so we cannot use insecticides. roach traps are not working. ive heard boric acid and sugar works. does anyone know the success (or failure) rate of boric acid and sugar or of other solutions? we have no pets or children, so open poison is ok. i am terrified of them. please help!