Thread: posts for patio

1 Set out your three footing holes using a tape measure, string lines and building profiles.

2 Dig holes to suit the weight of the structure (450 X 450 X 600 deep would probably be plenty)

3 Drive a long stick down the edge of each footing hole and make sure that it's plumb with a plumb bob or spirit level (You can make a plumb bob by tying a piece of string to a rock).

4 Buy a water level (cheap 10mm clear plastic tube) a bit longer than half the diagonal dimension of your work area.

5 Fill a bucket with water and place it in the middle of your work area.

6 Put one end of the water level in the bucket, under a brick.

7 Siphon water out of the bucket until it starts running then put your finger over the end, and ensure that there are no bubbles in the tube.

8 Hold the tube against one of the sticks, a bit higher than the level of water in the bucket.

9 Remove your finger and wait for the level of water in the tube to settle, then mark the level on the stick.

10 Don't allow any of the water to escape as you mark the other two sticks, and a reference mark on the wall of your house, adjacent to where you're measuring your existing patio ground level/slab level/roof height.

11 Double check all of your marks again for accuracy.
(With two people, you could use just the tube as a water level. One person holds the tube, and adjusts its height against the reference mark, whilst the other marks the stick at the footing hole, after the water level has steadied.)

12 Measure down from your reference mark on the wall, and transfer the measurements to your sticks.

13 Drive a nail in your sticks, and pour your concrete to the level of the nail.

14 When the concrete has cured, mark the exact position of the posts using your builders profiles, string lines, tape measure, plumb bob (or spirit level).

15 Bolt down the posts, and plumb them up using a plumb bob or spirit level, and hold them in position by using stakes driven into the ground, and braces nailed to them, and clamped to the posts.

16 Install beam, rafters, guttering and roofing.

17 Open stubby of Coopers Ale and skull.


For greater accuracy: -
13 Pour the footings 15mm below desired level.

15 Lay a small 15mm packer in the centre of where the post base plate will be, then bolt down the posts, and plumb them up using wedges driven into the ground, and braces nailed to them, and clamped to the posts.

15a Double check height of posts with water level, and adjust packers to compensate for any errors.

15b Using a non-shrink grout, or just a strong (3:1 sand/cement) cement grout with clean sharp renderers sand, mixed fairly dry, pack under the base plate using a stick to ram the grout in, and taper the outside edges away from the base plate.

17 Open two stubbies of Coopers Ale and skull them consecutively.

A water level and a plumb bob are more accurate than any laser/ dumpy or spirit level. You can trust Isaac Newton and the laws of gravity, and unlike a laser, they compensate for the curvature of the earth. This might not be too important for a patio, but I recall that it was a concern when building Hong Kong's new airport. The terminal is quite long

Originally Posted by pawnhead

..................A water level and a plumb bob are more accurate than any laser/ dumpy or spirit level. You can trust Isaac Newton and the laws of gravity, and unlike a laser, they compensate for the curvature of the earth. This might not be too important for a patio, but I recall that it was a concern when building Hong Kong's new airport. The terminal is quite long

Apparently the two towers of the golden gate bridge, San Francisco are perfectly plumb, but due to the earth's curvature aren't parallel.

Mick

advice on concreating metal posts

Are they metal posts, or timber posts on stirrups?

thanks all for the help

No worries.

I forgot to mention that for greatest accuracy, ensure that the same amount of air is above the level of water when you make each mark. In other words, if you're marking something close to the bucket, don't keep lifting up the tube draining the water back into the bucket. It would slightly raise the level of water that you're marking, depending on the size of your bucket, and diameter of your water level.

You could go so far as marking the level on the tube with a small piece of duct tape, but I wouldn't be that fanatical about it. Your pencil mark would probably be thicker than any discrepancy you'd get from being a bit out.