+0

These sentences are correct, it seems

To get to my house from yours is a three hour walk.
My house is three hours' walk from your house.

but my general question is when should I use the pattern " three hour's walk or five days' trip" and when to use the pattern " a three hour walk/ a five day trip". Thanks.

+0

To get to my house from yours is a three-hour walk.
My house is three hours' walk from your house.

They are both rather formal, and not really conversational. The first is probably used more.

In a conversation, you night hear this:

It will take me three hours to walk to your house and another three hours to get back.