Whether your outdoor steps are concrete or wood, providing a handrail adds safety and may be required by building regulations. This procedure will be for steps coming off a wooden deck between posts. Some handrail systems can be very elaborate with balusters and decorative ornaments. Once you have established the top handrail as described here, you can easily add these other items.
Using the post hole digger, dig two holes at least 45 cm (18 inches) deep directly in front on both ends of the last step. These holes should be perpendicular to the existing posts on the walking deck and be equally spaced from those posts. Use the framing square laid in line with the upper post, the long side projected toward the last step indicating proper alignment with upper post.
Stand a 1.5 m (5 foot) long 10 cm x 10 cm (4 x 4 inch) post in each hole. Mix water and the concrete in the bucket to the consistency of toothpaste. Carefully pour about half the contents into each hole containing the wooden post. Use the level to stand the posts perfectly vertical in both directions so that the posts are in line and parallel with the upper existing posts. Do not proceed until the concrete has set, usually the next day.
Lay the handrail material on top of the stairs so that the handrail is alongside the upper and lower posts. Place the angle divider on top of the handrail. Slide it down to the lower post and extend the metal arm outward to match the vertical post. This will establish the angle of the stairs. Move the set angle divider to the upper post and again lay the angle divider on the rail to compare the two posts. If the angle is the same you will not need the second angle divider. If it is not the same, use the second divider to establish the angle of the upper post. Set the handrail and angle divider(s) aside for future use.
Measure up from the leading edge of the lowest step 90 cm (35 inches) and mark the post on the outermost edge. Repeat this step at the upper post from the walking deck. This will establish the parallel height for the handrail. Lay the speed square on the post and transfer that mark to the other side of the post. Repeat for the other side of the stairs.
Using the appropriate angle divider, mark the same angle onto the post on both sides being careful not to move the angle. Set the circular saw to its deepest setting. Cut through the post on those lines leaving the top of the post with the angle exposed.
Lay the handrail on top of the newly cut posts so that the handrail extends about 10 cm (4 inches) beyond the posts. Manually adjust the placement so that the edges have equal spacing all around. Secure the handrail with 5 7.5 cm (3 inch) deck screws into each post.
Set the speed square on the handrail 7.5 cm (3 inches) beyond the post and draw square a line. Place the angle divider on the speed square and note the angle that it projects on the compass degree settings. Adjust the table on the circular saw to the angle noted on the speed square and cut the line. Repeat on the upper post and the other side of the stair system.
Sand the handrail to eliminate any splintering and roughness.
Ballasters and lower rails can be added to dress up the rail system.
When working with power tools, always insure that guards are working properly.