My house is about 25yrs old and boy,are the floors noisy!!They also arent level .ie,big gap under the door when shut but small gap when open. I have tried screwing the floors down but little change.the flooring seems to go under the upstairs walls so the noise and movement are transmitted room to room.no chance of sneaking home unheard!! I cant afford to get a builder in ,so what can i do myself to fix it??any help appreciated! 
