Frank Pattern Roof Drains-bottom and side outlets


  • choose a bottom or side outlet roof drain
  • add a sump pan to your order
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Frank Pattern 8-1/2″ Roof Drains

The Frank Pattern roof drain side outlet model numbers are 852SN, 853SN and 854SN. The Frank Pattern roof drain bottom outlet model numbers are 852N, 853N and 854N.


  • Has an 8-1/2″ diameter bowl and is available in 2″- 4″ outlet, no-hub pipe sizes.
  • Each roof drain has a combination protective gravel stop/membrane clamp (flashing ring) which compresses to make a water tight seal.
  • Corrosion resistant Duco coating.
  • Each roof drain has a dome or leaf grate that prevents debris from entering the roof drain. It twist locks into the membrane clamp for a secure connection.
  • Dome height is 6″ and will filter out debris.
  • 100% cast iron construction
  • Add a sump pan to make a watertight connection and to prevent standing rainwater. See below

What is a common application for this roof drain?

Frank Pattern 853SN roof drain side outlet is ideal for residential and light commercial roof drain installations such condominiums, apartment buildings, restaurants etc. It is precisely adapted to be used where space is limited. There are couple of reasons for this:
  1. Flat roofs often do not have an attic space. As such, the only space that can be utilized for the installation is between the roof and the ceiling.  This can be 8″ to 12″ commonly. This s the primary reason
  2. Also, the bowl size is smaller, generally 8-1/2″ or so as compared to the medium and heavy duty commercial roof drains which are either 12″ or generally 15″ or 16″.  These are used on warehouses, manufacturing plants etc. Whenever you have a large surface to be drained, the demand to convey (move) increases and becomes more critical. For this reason, the larger bowl and larger pipe sizes are used.

PIPE PITCH – Correctly sloping your roof drain pipe is VITAL

  1. It is important to factor in the length of your pipe run from the roof drain to the final termination point.
  2. You should factor in 1/4″ per foot pitch on the piping if possible. In some cases, 1/8″ per foot slope may be acceptable. Refer to your plumbing code.
  3. Make sure there will be enough slope on the piping and that it will not be back pitched.
  4. If you plan on using this roof drain in a walkway, be advised that the dome will extend above the roof or deck surface.
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Roof drain sump pan – should you use one?

  1. A true roof drain sump pan should be used to make sure that your roof drain is lower than the surrounding flat roof surface.
  2. There are a number of factors that go into making that evaluation but the thickness of the roof plays a big part. A thin roof membrane will be lower than the inlet on the roof drain and will actually create standing rainwater. A thicker roof will be the opposite. If it’s uncertain, err on the side of caution and use the sump pan.
  3. You can add it your purchase below or click here for more info
A side outlet roof drain and it's related components

What Does The Membrane Clamp Do?

  • It is intended to seal the roof as it attaches to the roof drain. It clamps the roof membrane to the roof drain body in three places. When cutback sealant is applied to the membrane prior to the clamping step, it will provide the necessary seal.  There are many You Tube videos that show this process. SEE AN EXAMPLE HERE
Weight N/A
Dimensions N/A
Pipe size

2", 3", 4"


bottom, side


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