Find here the detailed instructions for laying concrete footing and subsequently pouring below:
Laying out a brickwork footing
If the footing is for a free-standing wall, it must be 100mm deep and 300mm broad. If the wall being built is a retaining wall, the footing should be extended to 150mm deep and 450mm wide. A structural engineer may need to be consulted for assistance on larger retaining walls.
First, use pegs and a string line to mark the location of the footing. Drive the pegs into the ground along the trench’s edge, digging a shallow trench to the appropriate footing depth. To show where the finished surface of the footing will be, the tops of the pegs should be level. The levelness of the pegs can be determined by running a spirit level along the tops of adjacent pegs.
Tools
Spirit level / Leveling hose
String line
Shovel
Wooden float
Plywoods
Wheelbarrow
Cement mixer
Timbers or 2×2, 2×3 Lumbers
Setting out Post for Fences and Pergolas
You must first determine the locations of your first and last posts before determining the distance between the remaining posts. Check the height of each post before using string lines and spirit levels to line and plumb.
The depth will vary depending on the post’s length; typically, 230mm of footing must extend into the ground for every third of the post’s length. The diameter of the footing should be three times that of the post being set.
Each post should be inserted into a hole and wedged into place. Verify that the posts are the proper height, plumb, and parallel to the other posts.
Concrete Requirements for Bigger Jobs
Multiply the footing’s length, width, and depth to determine its volume. You will receive a concrete quantity in cubic meters after doing this.
Concrete Mixing
On clean and clear smooth, hard surfaces, such as a board or an existing concrete slab. If one is available, you can also utilize a cement mixer. Place your measured amount of sand first, then add the right amount of cement. These ingredients should be carefully combined to achieve a uniform color.
When the color is consistent, add the coarse aggregate and thoroughly combine the first three ingredients once more. When the mixture is uniform in color and texture, add the water to the calculated amount. Sprinkle the water over the mixture gently while pausing regularly to turn it over. Avoid making your mix overly wet by not using too much water.
Wet concrete is weak concrete. The weight of the water should be about 50% that of the cement.
A concrete mix for footings consisting of 1 part cement, 2 parts sand, and 4 parts coarse aggregate (by volume) should be used.
Pouring the Concrete
After mixing, concrete must be poured within 30 minutes.
Brickwork: Fill your trench with concrete. Utilizing a shovel, work the concrete into tight spaces and corners. Put down enough concrete to slightly overfill the formwork. By drawing it firmly across the concrete surface with your wooden float, compact the concrete. Spread the extra concrete using a sawing motion and a straight edge to level it off to the pegs.
Smooth the concrete’s surface with a wooden float to obtain a uniform mortar finish, which will guarantee that the concrete is tightly compacted.
Before beginning any brickwork, the footing must be covered with plastic and given at least seven days to cure.
Fence Posts and Pergola Posts
Create a hole for your post and make sure there are between 50 and 80 millimeters between the sides of the hole and your post. For posts that will be buried, make sure the hole is dug deep enough so that 25% of the post is buried. This will provide the post with enough strength. As an alternative, you might buy a metal stirrup or shoe made expressly for posts.
Pour the appropriate amount of concrete into the hole right away after completely saturating it (as directed on the bag). Completely combine. By pounding down on the concrete with your boot or another similar-sized object, you must compact it.
The post must then be held in place with a wood brace until the concrete has dried.
For up to 20 minutes following the concrete pour, posts that have just been put into concrete may be pushed into a different position.
Before any braces are taken off or anything is added to your posts, they should be kept standing for at least three days.
tags: how to lay concrete footings, concrete post footings