Yes, brick slips can be used externally.
We have supplied many projects where brick slips have been used externally ranging from decorative garden walls to full on reskinning of houses.
Brick slips can be a great way to improve or completely change the exterior look of a property and add some kerb appeal.
Brick slips are perfect for using externally. The only area we would not recommend using them is on the floor externally.
They can be used as flooring internally but when used externally, they are likely to experience frost damage during the cold winter weather. When placed on a floor externally, rainwater has nowhere to go other than to soak into the surface of the brick slip. If the temperature then dropped to freezing levels, the water within the surface of the brick slips will freeze, expand and can crack the face of the bricks. Over time this will result in the brick slips crumbling away.
If you are wanting to acheive a similar look, we would recommend going down the line of a brick paver. These pavers are specifically designed to be used over external flooring and come with frost rating protection.