Once you know the total square footage of drainage for each gutter you ll need to adjust for the following two factors.
How to determine gutter spread.
From this depth and cross section geometry the gutter spread is computed.
Q flow in gutter in cfs cms z reciprocal of the cross slope.
Ask gutter suppliers what size gutters will be needed to handle that amount.
Step 1 determine input parameters including longitudinal slope s cross slope sx gutter flow q and manning s n.
Make a mark with chalk and record the measurement.
A depressing depth.
S longitudinal gutter slope.
If you still do not see your gutter style then order sizing samples 3 sizes per box to determine which size gutterbrush best fits your gutter.
S longitudinal slope.
Divide the inch per hour watershed of the roof by the 5 minute rainfall intensity.
Kc 0 56 0 376 for compound cross slopes a trial and error procedure is used to compute d in the gutter sw and sx sections separately.
Carefully climb down the ladder and move it to the chalk mark.
T flow width.
Compute depth of flow and ponded width t in the gutter section at the inlet.
Find spread t given gutter flow q.
Step 2 draw a line between the s and sxscales and note where it intersects the turning line.
N manning s coefficient.
That is how much rain a roof can drain during the most intense rainfall.
If your gutter style and measurement matches one of the images click the corresponding button above to view more information and place your order scroll down to see additional gutter styles.
Compare calculated spread to the allowable spread.
E 0 ratio of depression flow to.
Adjusting for pitch and rainfall.
The following procedure is used to design curb inlets on grade.
Run the tape measure from 1 corner of the gutter as far as you can go toward the opposite corner.
That will show how much water a gutter will have to drain.
If relocating an intake recalculate q for the new drainage area s and calculate new values of spread.
Measure from the chalk mark to the opposite corner of the gutter making another chalk mark and moving the ladder again if necessary.
How do you calculate gutter size.
The steeper a roof s pitch the more windblown rain it can collect.
Determine the ratio of the width of flow in the depressed section w to the width of total gutter flow t using.
D flow depth at curb.
