A well-built building starts with a good foundation. A good foundation layout has to be straight from the word go.
So the main focus when constructing your building should be how to square the foundation layout. This is important because any slight alteration and the whole building will be off. This means if the foundation is not square, then the walls won’t be either. Same way, any process to have additions on the building walls will be hard to carry out, and fittings may not fit properly.
What do I need to square my foundation? This is the question you may keep asking yourself.
There are many ways to go about this. To square off the foundation layout of a building doesn’t require specialised knowledge or skills. Just putting into practice the right methods is enough to give you that square foundation you need for a perfect and durable structure. The following methods can be used.
- Square triangle rule 3-4-5
- Equal diagonals method
Either of the above methods can be used to square the foundation layout of any rectangular building. They work almost the same way, and they give the same results.
Let’s see how the methods work when finding the square of a foundation layout.
The Square Triangle Rule Method
This method uses a right triangle rule to establish the square of the foundation layout of any rectangular building plan. The right triangle has a length A corresponding to 3 units, and length B corresponding to 4 units and the diagonal side C corresponding to 5 units. The angle between the two sides is a right angle and measures 90o.
After establishing the site dimensions, you need to cover the whole area with crushed stones. These should cover a large area than the intended space for the foundation where you want your building to stand. Therefore, if you choose to use the triangle rule method to establish the square of the foundation layout, you will start by marking the corners with a big nail marked by a string.
At one of the proposed corners, measure a straight line then attach a string from the reference corner to the next adjacent corner. This should be according to the planned measurements of the building plan. This corner should be the starting point, and all the measurements will be made from it. Measure the distance from this corner to the adjoining corner as you desire the building to be. Your measurements should come from the outside of the wall to the outside of the wall.
After measuring the length of the string, use the triangle rule to square the angle at the corner. The triangle rule 3-4-5 states that the length of the triangle 3 squared plus the width of the triangle 4 squared is equal to the diagonal length of the triangle 5 squared. This translates to 32+42=52. The figures can be applied in 3-4-5 or multiples of the same as 6-8-10, 9-12-15, or 30-40-50.
With the rule 3-4-5, the angle at the corner of the triangle is exactly 90o. This gives you a square corner of the foundation layout. Fix this corner with a stake and should not be moved. Move to the adjoining corner to the base corner, then measure the length of the width as per the building plan. After measuring the length, mark the endpoint with a stake attach a string from the corner stake at the base corner.
Use the triangular rule to make the corner square as you did in the first corner. Measure the distance between the corner stake and if it fits the building dimensions, then use the triangular rule to make the adjoining angle a right angle of 90o. You now have two square corners. All you need to do is measure the required dimensions from these two front corners to the rear corners.
If the two opposite lengths of the edges are equal, the other two angles at the corners should be equal as well. Check the angles if they are square before staking the corners with more permanent marks.
If they are not right angles, try adjusting the measurements using the right triangle rule to obtain the right angles. After doing this, you should have a square, rectangular foundation layout for your building. This means you can move to the next step as per the building plan.
The Equal Diagonals Method
This method is used where the site is slightly gentle and requires a few people to assist you with the task. To square up the foundation layout of your building, measure the distance of the diagonal lengths of the rectangular building layout. This is done consistently until they equal each other and establish the square of the corners.
So how does this work? It is pretty simple, and the only accuracy is key.
When the site has been leveled and where the structure will be constructed designed, you need to lay down the dimensions where the outside walls of the building will be. The corners of the rectangular layout are always marked by visible stakes driven into the ground at each of the four corners. Strings are then attached along the edges according to dimensions of the building. To square the layout using the equal diagonals method, you’ll start by measuring the diagonals of the rectangular layout.
At one corner mark one stake as the reference corner stake. Then, measure the distance from the reference corner post to the corner perpendicular to it. Next, measure the distance of the other diagonal length and mark at the end as per the building dimensions. This means you need to measure from the front left corner to the rear right corner and from the right front corner to the rear left corner.
If the two distances are equal, then you’ve got a right rectangle and the corners of the foundation are square. If, however, the two distances are not equal, then the angles are not right, and as such, the rectangle is not square at the corners.
Using the base corner, adjust the dimensions, and repeat the process until the two diagonal lengths are equal.
What If My Building Is Not Rectangular?
What if my building is not rectangular but indeed, say, L-shaped? This is a common scenario in the building field. It happens as buildings’ foundation layouts may differ from one place to another. But the interesting part is that even in such cases, finding the square of the foundation layout should not be hard. The methods discussed in this guide can be used and achieve the same brilliant results.
Though it might be technical to work with an L-shaped foundation, the steps followed will almost be similar to the ones applied in the above two methods. The only difference could be while dealing with an L-shaped foundation; the process is a bit long and involving and may require the extra workforce. The materials needed will also be slightly more than in a normal rectangular foundation.
To find the square of a foundation layout using the triangle rule 3-4-5, you’ll need to subdivide the foundation into smaller rectangles first. After establishing the mini rectangular foundations, then you can apply the triangular rule as shown earlier in this guide. Going from corner to corner and establishing the right triangles one after another. You’ll need to square one rectangle at a time then move to the other until the whole foundation is square and all angles are right.
If you decide to use the equal diagonals method, the process will be much less the same as the one used with the 3-4-5 triangle theory. Divide the whole foundation into a few rectangular shapes, then measure the two diagonals of these rectangles and square the corners. Establish the reference corner points and then work from one small rectangle to the other until the whole L-shape is square and all corners are right angles.
The two methods are preferred over others because they use trigonometry aspects and applications. This makes them reliable in giving you the right angles of 90o and giving accurate results of a square rectangle foundation for your building.
They’re also easily and widely applicable. For instance, the triangle rule 3-4-5, also known as the Pythagoras theory, can be used with multiples of the formula 3-4-5 like 15-20-25, which makes it flexible. Experts also advise on using the triangle rule with big numbers as it gives more accurate results in such cases.
The two methods are quite useful in determining the square of a foundation layout. It is however advised you stick to only one method and do not use them together. This is because when you use one method throughout, the results are likely to be consistent. It is also likely to raise the degree of accuracy in the measurement of distances and angles as well.
Besides, whichever method you use in the process of finding square for the foundation of your building, always use one corner as a home base or the reference wall from which you measure the lengths of the edges. It is also from this corner where the angles are square and made right angles for the overall foundation to be a right rectangle.