Within irc s chapter 9 section r908 reroofing addresses reroofing.
Irc roof drains.
Where required for roof drainage scuppers shall be placed level with the roof surface in the wall or parapet.
Scuppers shall not have an opening dimension of less than 4 inches 102 mm.
The imc dictates a 1 minimum pitch of the drain which is equal to 1 8 fall for every 12 foot of horizontal run.
In irc 2015 and its previous editions roof assemblies are addressed in chapter 9 roof assemblies.
Overflow drains having the same size as the roof drains shall be installed with the inlet flow line located 2 inches 51 mm above the low point of the roof or overflow scuppers having three times the size of the roof drains and having a minimum opening height of 4 inches 102 mm shall be installed in the adjacent parapet walls with the inlet flow located 2 inches 51 mm above the low point of the roof served.
A ponding instability check is to be made assuming the primary roof drains are blocked.
When scuppers are used for secondary emergency overflow roof drainage the quantity size location and inlet elevation of the scuppers shall be sized to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by section 1611 1.
The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures.
Take the roof s total square footage and divide by the total square footage handled by one drain.
Section 2003 irc r903 4 roof drainage states.
The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.
The result is the number of drains needed.
Ings that do not have secondary roof drainage provisions such as overflow drains and overflow scuppers.
In practice it is safer to use 1 4 of fall per foot to ensure proper drainage and provide some wiggle room for error.
R903 4 1 addresses overflow drainage.
In such situations an ice barrier is required to prevent dammed meltwater from penetrating through the roof assembly and into the interior spaces.
Therefore the irc also recognizes scuppers as being an acceptable method of roof drainage.
50 000 4 400 11 36.
In these instances new secondary drain.
For some roof assemblies in cold climates ice may form along eaves which may impede the drainage of meltwater from higher up on the roof surface.
The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.
From a practical standpoint it makes sense as in my.
