How to Use the 3 4 5 Rule to Build Square Corners

How is square calculated?

To “square” means to calculate the value of a number multiplied by itself. A simple example is three squared, or three times three. Mathematically the problem looks like this: 32 = 3 × 3 = 9. The exponent 2, written as superscript 2 (N2), says to multiply a number (N) by itself, like so: N2 = N × N.

How do you lay out the building?

For simple building layouts, such as rectangles, the outline of the building is given by line tied to corner post – Nails at the top of the posts can be used to attach wires. Theodolites, site grids, or building grids are used to close the 90-degree corners of the remaining corners.


How to calculate the area in square meters?

Multiply length and width. After converting the two measurements to meters, multiply them to get the area measurement in square meters.

How High Should A Foundation Be Above Ground?

The building code, which happens to be a set of minimum standards, states that the top of the foundation must be no less than 4 or 6 inches above the ground that touches the foundation. But wait, there’s more! The ground must then slope away from the foundation a minimum of 6 inches within the first 10 feet of horizontal distance from the foundation. Confused?

What this means is that your foundation should sim

What this means is that your foundation should simply mimic the top of a hill where all the ground around the foundation slopes away so you have great water drainage and surface water doesn’t flow towards the house. Remember, the numbers above are minimum requirements. You can create more fall if you want.

Learn how to do every step yourself

Here at Western Interlock, we’re on a mission to take the hard out of hardscaping. That’s why we publish DIY tips, tricks, and step-by-step tutorials at and host a live DIY seminar every month during the summer at one of our manufacturing or distribution facilities.

If you have any questions, you can visit our Paving Stone Display at our Manufacturing Facility in Rickreall, OR. Or, give our team of hardscape experts a call at 503-623-9084.

Why is it so important build things perfectly square?

Building things like walls, floors or decking perfectly true, plumb and square is when possible essential. It will help you avoid problems and save lots of time later on and is also the strongest way to practically form structures. 

Sometimes like in old houses for example exceptions have to be made. Sometimes you need to ‘split the difference’, or accept the lesser of two evils and do what you can. In these instances I always imagine what I would do if it were my own place or, which is the least noticeable/most pleasing to the eye. 

<p>Building walls square will ensure sheet materials like plasterboard are fast and easy to install. Wall plates need to be square and level in order for the roof rafters to work. Garden decks and floor joists built perfectly square will be much easier to lay flooring/decking on. The list goes on and on, but an extra 10 minutes checking everything’s square in the early stages could save you hours or even days later on.

Failing to build things level and true will only lead to headaches and extra work later on. Doors will swing open or closed on their own if you don’t install door linings level and square. Miters will be a bastard to get right, and more scribing will need to take place meaning extra work, headaches – and time/cost.

Whilst there are lots of carpentry squares available to check for 90°, when building a large stud-work wall or a garden deck for example these are usually much too small to accurately ensure the structure has perfect 90° corners.

There are two simple and easy to remember methods I use.

Squaring A Section using the 3 4 5 method

3 4 5 method or multiples there off

This is based on that 3 squared plus 4 squared = 25 take the square root of that = 5. Squaring this way works and most people will be able to remember the required measurements.

At times it will be more efficient and more accurate to square an L shape using the total available lengths. Not as easy as using 3 4 5 as the measurements and it will take a calculation to get the diagonal length.



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