How do I keep my cats safe during a home renovation?

I have two cats. One is a 6 year old and the other is 8 months old. They both like to wonder around the house. Starting in two weeks, we are going to be completely renovating our first floor and basement leaving us with only our second floor and third floor (which has a guest bedroom and bathroom). How can we keep our cats from going into the construction area? Is there any like plywood thing we can use to block the stairway and balcony? Should we lock them in our bedrooms connected with a shared room and bathroom? Is there anything we can do? People who have been in this situation please help! I don't want my cats to get hurt or lost.