There are basically two variations of Sawn post and rail. Each can have as many rails as needed, usually between two and four. The post and rail sizes can vary depending on the specification. Netting for stock or pets is easily added, especially to option 1/.
1/ Where either external woodscrews or galvanised nails attach the rails onto the face of the posts. The rails form a continuous line along the front of the fence. The usual bay size is 1.8m (the centre of a post to the centre of the next post). Joints in the rails are staggered so that all the rails are not joined on the same posts. This variation is easy to put up and repair.
2/ Where the posts are mortised to take the rails. The ends of the rails are usually scarfed (cut at about a 45-degree angle), which enables the joint to be inside the mortise. Bay sizes can vary from 1.8m to 3m. Bays over 1.8m usually have what is known as a prick post (a 1.8m length of rail) attached in the centre of the bay. This type of post and rail takes more effort to install and is much more difficult to repair.