How Much Slope On An 18 Ft Roof

As a rule of thumb there are 3 bundles to a square assuming that you are using three tab strip shingles.
How much slope on an 18 ft roof. Determine the minimum slope of the roof based on the roofing material. Commercial buildings with a slope like this are considered low slope. In these instances a system of drains or gutters is necessary to channel the water away from the roof. You write the pitch assuming a run of 12 inches thus the ratio would describe how much a roof rises for each foot of the run.
Drains are usually located at the low points or valleys of the roof. A square of shingles is the number of shingles needed to cover 100 sq feet of roof area. It is often compared to slope but is not exactly the same. Roof pitch or slope is a measure of vertical rise to horizontal run expressed in inches per foot.
Thus a moderate 6 in 12 roof pitch means the roof rises 6 inches for every 12 horizontal inches it runs. A roof slope of 7 12 is also good and can provide the additional benefit of helping minimize the effects of wind driven rain. However shingles are packaged in a way that they are light enough for the average person to carry around. This means that for every foot of the roof it must slope downward by at least one quarter inch.
How do you calculate the slope of a roof. The roof pitch is important in determining the appropriate installation method and how much roofing material will be needed. There are also 29 standard sized shingles. The minimum pitch for shingles is 1 6 which is equivalent to 4 inches rise to 24 inches run.
The rise is the distance from the top of a stud wall to the peak of the roof. But the most commonly used pitches range between 4 12 and 9 12. The minimum pitch for a. The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7.
Roof pitch is used to describe the slope or angle of the roof. As aforementioned there is no standard pitch of a roof. A 12 in 12 pitch is a steep 45 degree angle roof. However from the wind uplift mitigation perspective a 7 12 roof slope can be considered as a two story building due to the higher overall steepness and profile of the roof.
This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. In the united states a run of 12 inches 1 foot is used and pitch is measured as the rise of the roof over 12 inches. Outside of the u s a degree angle is typically used. There are advantages and disadvantages to having a steep pitch versus a shallow or low pitch the most obvious of which is the roof s ability to shed or withstand.
A 4 12 pitch being 4 inches of vertical rise over one foot or 12 inches of horizontal run. When referring to roofs the term pitch means two.