Norwalk Roofing: Article About Downspouts For Rooftop Drainage
One of the essential functions of a roof is to drain rainwater into the gutters and away from the home's walls and foundation. In order to do this, the roofing system must have enough downspouts. Calculating the necessary number of drainpipes is based upon the roof area and the average amount of rainfall the location receives every year. Homeowners can calculate this number on their own or work with a local Norwalk roofing service to have it done for them.
Before installing a new set of downspouts, a few calculations must be made in order to ensure adequate drainage. To do this, a few basic tools are needed, including a ladder, tape measure, pencil, paper and a calculator. If the homeowner needs to climb the roof to take measurements, this should be done on a dry, cool day.
With the measuring tape, measure the length and width of one face of the roof. Multiply the length and width to determine the area in units of square feet. Do this for each face of the rooftop to get the total area.
Next, find out the annual average amount of rainfall in inches for the area. A home needs a drainage rate of 1 gallon per minute, which corresponds with 96.15 square feet of rooftop surface and a rainfall rate of 1 inch per hour.
A roofing contractor from Sound Renovation of Norwalk CT can answer any question you have about gutters or siding.
Downspouts are sized to indicate how many gallons per minute they are able to handle. This allows the roofer or homeowner to select the proper circumference of downspout.
To determine the number of necessary downspouts, divide the total roof area by 4. For example, a roof measuring 8800 square feet will require 4 downspouts that are each capable of draining 2200 square feet of surface area. Then divide this number by the circumference of the downspouts to determine how much rain it can handle. Once the size needs have been estimated, the homeowner or roofing technician can make a shape and style selection, such as round corrugated or smooth and rectangular. It is best to plan for the maximum rainfall rate, as the roof may need to drain the water from occasional storms that deliver 1 inch or more of rain per hour.
The final essential measurement is the downspout length. Measure the distance from the opening in the gutter to the ground. Add about 10 percent to this total for measurement errors. Multiply figure by the number of downspouts that the roof will have, such as 4 or 8. This provides the property owner with the total length of downspout to purchase.