Blessing and anointing the outside of the home (the property) is the same way as inside of the home. Go outside and anoint with oil. Bless the main land marks within your properties borders.
If you live in an apartment you won't have to do this, but if you have a small porch or sitting area outside, then bless it also.
If your property is large, walk around the yard surrounding your home that you maintain. As you pray dedicate everything within the boundary lines of your property from corner to corner unto the Lord. You might go out again at different times, such as working in the yard, or out to walk your property, you can take some anointing oil with you and bless it as you go.
With your anointing oil walk the property boundaries (front and back yard) and bless some of the landmarks in that path. Speak out your blessings and read scriputre if you like. Item examples could be a fence post, tree, the garage, telephone pole, storage building etc. Some like to make a boundary stake with written scripture and put them in the ground at the corners or various locations. After walking the property lines, you can now anoint some of the objects/ landmarks that are in the center. You don't have to bless everything, as long as you're at peace.