How to build a timber screen
You'll need to start with a level base to support your timber screen. To make one, attach a plinth board to your frame using a nail gun. Just make sure the board is level when you attach it. You can also pack some dirt underneath the board to help you get it level.
You'll need to measure and cut a check-out in your load-bearing vertical post. This is so it can sit in your hole directly above your frame. Place your post in the hole and mark it at the top of the plinth. You'll also need to measure the thickness of the frame you're making the cut-out for – in this case it's 50mm. Use a circular saw to make cuts down to your required thickness and then knock these out with a hammer and chisel. Then use a chisel to clean up your checkout.
You need to use horizontal rails to support your pickets. That means you'll need to make notches in your post for these rails. After deciding the heights your rails will be, mark out the notches on your post. Use an offcut from your rails to make your marks.
Now you're ready to cut your post to the height you have measured out. This should be above the notch you have made for the top rail.
Mark your post about a third of the way up and a third of the way down for your bolts. Drill a hole through your post with a spade bit. Then with a 11mm drill bit, drill through the hole you've made for the bolt to go into.
Then, using a 10mm masonry drill bit and a hammer drill, make your holes in the brickwork for your bolts to go into.
Hammer your bolts into the holes you have made. Then use a 1/2inch socket set to tighten the bolts to the wall.
Using a nail gun, attach your railings to your posts. Make sure that the nails go in at a slight angle so they don't pull straight out. You need to put in up to four nails at each notch to make sure the railing is secure enough to hold the pickets.
Attach the pickets to the frame using the 50mm galvanised timber screws. After screwing in your first screw on each picket, make sure you use a spirit level to keep your pickets straight before screwing in the second screw.