If a roof s various drainage areas call for different size gutters go for the biggest one k style.
Gutter drainage work estimate needed.
Size downspouts to fit the gutter.
Then use the chart below to see what size gutter you need.
Working out gutter slope as a general rule gutter slope is set at 1 4 inch per 10 feet of guttering.
Doubling the number of downspouts halves the required capacity for each.
Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage.
This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end.
A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.
Multiplying by 15 minutes leaves you with the amount of gallons to be stored.
To calculate the volume of water that needs to be stored multiply the amount of runoff from each drainage zone by 15.
5 inch 5 520 square feet.
These estimates are for basic work performed in serviceable conditions by qualified trade professionals using mid grade materials.
Seamless aluminum gutters costing around 10 linear foot are the cheapest and best performing option while copper gutters are the most expensive at 25 per foot and vinyl gutters are easiest to install for diy homeowners.
Using the table below will help calculate the volume of water to be stored.
The runoff for each zone was in gallons per minute.
For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e.
6 inch 7 960 square feet.
Work not mentioned on this page and or work using master craftsman premium materials and project supervision will result in higher costs.