Over the next couple of weekends I'll be working on creating a new back patio. In some cases an edging is not necessary, but I have started with some because it will act as a container for the base course and pavers, as well as a step from the lawn. Most paving projects require a certain amount of excavation but I've already had a hard base in place for the past five years, so digging it up, transporting it and dumping it just seems like a royal waste of time and money. Instead I've decided to go over the top and build the area up. I still have to introduce hard fill into the site but believe me, that's a heck of a lot less work than digging it out.
Sleepers provide a strong attractive frame and a solid look. They won't bow during compaction of the base course, which can happen with lighter timbers.
For me, making sure the corners are at 90 degree angles is important and getting this right starts with setting out the string lines correctly. There are a few ways to do this and number one is measuring your square or rectangular area diagonally from corner to corner. This method simply tells you when your whole area is square which will mean all the corners are at 90 degrees. All you need to do is make sure both diagonal measurements are the same and you're all square.
Second is the Pythagoras triangle or three, four, five method. This method is a measurement performed on each corner and is useful because you'll know specifically which corner is the problem. From the corner make a measurement of 300mm and mark it on the string line. Next, starting at the corner and measuring along the string line that is 90 degrees from the first, make a second mark 400mm from the corner. If the two lines are at exactly 90 degrees from each other (or square) then the distance between the two marks will be 500mm and you will have the perfect corner.
Lastly you could just break out the trusty old set square. In small areas this may suffice but in larger areas I recommend checking with the first two methods. The numbers never lie.
Set up a string line at the outside edge of the paving. The line represents the final finished height and slope of the paved surface. Consider water run-off and any obstacles in the way of the line. It's at this time that you square off the corners. Remember, this can be time-consuming so don't be surprised if it takes a morning to get right. It's worth the fuss - trust me, I've done the research.
Clear the way for your sleepers. Dig out any humps or other obstacles then dig a shallow trench along the line 50mm deep. Dig a deeper section of around 150mm and around a shovel-length wide where the sleepers join.
Square the ends of the sleepers with a skill saw, then sand or dress them as you wish.
Drive two 9-inch nails into the back of the sleeper near the bottom then bend them down. These will hold the sleeper and the concrete together.
Mix and place concrete along the trench and in the holes at the sleeper joins then place the sleeper in the concrete bed. Follow the string line carefully and check the sleeper with a spirit level.
Using concrete, haunch the back of the sleeper - this will hold it firmly in place. The haunching should not go any higher than 100mm from the top of the sleeper so you can still install some base course and the paver.
Cut in the corners and recheck the sleepers you have already installed. Once the concrete has set, drive a nail diagonally through the top or back of the sleepers to hold them together.