Boric acid powder is one of the cheapest and most effective ways to roach proof your home and deal with a cockroach infestation.
A bottle of roach powder can be purchased for around five dollars and it will provide many months of protection from roaches.
Boric acid is an odorless, fine white powder and when cockroaches come in contact with it, it gets lodged in the joints of their exoskeleton, causing them to become dehydrated and die.
The way to effectively use boric acid is to spread it around your home in locations where cockroaches tend to frequent such as under the kitchen sink, in the cabinets, and in the bathroom.
If you have a lot of cockroaches you can spread it throughout your house along the walls to give maximum protection. Be sure to put it in cracks and crevices and other locations were cockroaches like to hide.
It will take a day or two before the dehydrating action of the boric acid takes effect, but you should soon start to see dead cockroaches around your home which will let you know that the product is working.