6 in 12 roof pitch is a common roof inclination that translates to degrees as approximately 26.57 degrees. 6 in 12 roof pitch means that for every 12 inches of horizontal run, it has a vertical incline of 6 inches. Any roof with pitch more steep than 6/12 is a steep roof and then it becomes harder to walk on such a roof.
Table of Contents
- What is a roof pitch?
- 6 in 12 Roof pitch
- Procedure for calculating the angle of roof
What is a roof pitch?
Pitch is a slope of the roof, and it is defined as the fraction obtained by dividing the total rise of roof from horizontal plane by the span of a building. Here span is a horizontal distance between the outside of one wall top plate to Another.
There are different types of roofs which are used for covering the house and to roof prevent the other members of structure and inhabitant from adverse weather conditions. The roof also ensure the privacy of the inhabitants. The pitched roof is one of them. This roof is very common in European countries and USA in hilly regions.
The areas which face heavy rainfall and severely affected by climatic conditions it is recommended to construct pitched roof to ensure adequate drainage of rainwater and removal of snowfall.
The pitch of roof can be expressed in different ways it can be ratio, fraction or degrees. There is no single standard to measure the pitch of roof it depends upon some factors which include the type of material, intensity of rainfall and location of building.
Also Read: How to Plan for a Roof Remodeling Project
For normal rainfall areas flat roof is constructed with slope of 10 degree. Similarly in moderate to high rainfall areas pitched roofs with slope of 15 to 20 degrees is constructed. For very high rainfall areas pitched roofs with slope of 20 to 30 degrees is recommended.
6 in 12 Roof pitch
The 6 in 12 slope is the most common pitch used in construction of roofs. Here 6 in 12 means for every 12 units horizontal distance there is a rise of 6 units. It is a ratio of two same units, so its final parameter is unitless. This pitch can also be expressed in other ways such as 1 in 2 or 26.56 degrees.
This slope is more and enough to remove water quickly as possible. The pitch 6 in 12 is preferred for very high intensity rainfall areas and snowfall regions because ponding of water can damage the roof and structure of house. The severe damage can also results in loss of life, so it is very important to account the climatic factors while selecting the roof.
In gable type pitched roof there is a ridge at the middle of span with slope on both sides in opposite direction. This type of roof is constructed by providing sloping rafter from ridge board to eaves in both the directions of ridge.
For high rainfall regions slope of 6 in 12 is used. Here 6 in 12 means that rafter will rise 6 units for 12 horizontal units. For example, if we have a 30 ft span of house then ridge board will be provided at 15ft horizontal distance and vertical height will be according to the pitch of roof.
If recommended slope is 6 in 12 then it means that for every 1 ft horizontal distance a rise of 6 inch will be provided or we can also say that a total of 7.5 ft rise of rafter will be provided for 15 ft horizontal distance exactly at the middle of span.
Also Read: What Is the Standard Roof Pitch?
The pitch of any roof is very easy to calculate. It can be calculated by the simple mathematical trigonometric calculation. The concept is simple which is rise/run method. Here rise is representing the y value which is in vertical direction and run is representing the x value in horizontal direction.
Rise is defined as vertical change in height per unit of horizontal length or run.
Run is defined as the distance from the outside of wall top plate to a point directly below the center of the Ridge or hip.
Slope ratio = Rise/Run
Slope ratio = y/x
The slope percentage and slope angle is also sometimes used to represent the slope or pitch of roof which can be calculated by the formulas given below
Slope ratio = (Rise/Run) ×100
Slope angle = tan^-1(Rise/Run)
Procedure for calculating the angle of roof
- The first step is to calculate the vertical rise of rafter and horizontal distance up to middle of span exactly below the ridge.
- The second step is to divide the vertical rise by horizontal distance value which will give a pitch of 6 in 12 for this case.
- Then find the inverse tangent of slope ratio to get the angle in degrees
= tan^-1(Slope ratio)
Roof slope angle = 26.56°
This simple mathematical procedure can be used to calculate the pitch and angle of any pitched roof and any other sloping member.
The pitch of roof is an important factor which depends upon the many factors such as climate and material of building. The pitch of roof can be expressed by different ways it can be a slope ratio, slope percentage or roof slope angle. The roof angle of any roof can be calculated by using simple trigonometric method. The roof pitch 6 in 12 can be written as 6/12 or 1/2. It means that a rise of 6 units will be provided for every 12 horizontal units. The 6 in 12 pitch is equal to 26.56 degrees angle of roof slope. This pitch is best for residential houses where rainfall is more than normal climate.