Welcome to our flat roof drain installation page!
Here is the information to walk you through the product selection process...
1) In order to have a successful flat roof drain installation project, it's important to select the right products for your application.
2) Follow the numbered steps below to find out which roof drain assembly works best for your project
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Designing a roof drainage system
  • These flat roof drain installation instructions apply to just about any roof drain installation project. They are however geared toward using the sump pans shown here.
  • When done, you will be able to select the correct roof drain and sump pan for your project.
  • Further, these roof drain installation instructions can be used as your “pre-construction” checklist. These are the steps the pro’s use.
  • Your “due diligence” will pay off big time!  
Plumber installing a model LSP roof drain sump pan and a Zurn z100 roof drain

STEP 1: MEASURE THE DISTANCE BETWEEN YOUR ROOF JOISTS

  • For joists that are 16″ on center you must 14″ of clear space between them.

  • For joists that are 24″ on center you must 22″ of clear space between them.

  • If you have a concrete or metal roof, you probably have joists much further apart.

Model SSP roof drain sump pan sumps the Frank Pattern bottom and side outlet roof drain.

STEP 2: MEASURE THE VERTICAL DISTANCE BETWEEN YOUR ROOF AND CEILING

  • If you have at least 13″ of space or more, use a bottom outlet roof drain.

  • If you have a maximum of 8″ or 10″, use a side outlet roof drain.

  • If you do not have access to this space, you will either have to create an opening or use your best guess.

  • REVIEW THE LINK BELOW

STEP 3: SELECT YOUR PRODUCTS

  • Based on the information in step 2, select the roof drain pan and drain that go together:  

If your joists are 16″ on center: 

  • Use model SSP sump pan and a bottom or side outlet Frank Pattern flat roof drain.
  • Or, use model SCP sump pan and a bottom outlet combination Frank Pattern flat roof drain.
  • SCP will also accept two single side outlet Frank Pattern roof drains.   

If your joists are 24″ on center:     

  • Use model LSP roof drain sump pan and a bottom outlet Zurn flat roof drain.
  • Or, use model LCP double roof drain sump pan and bottom outlet combination Zurn  flat roof drains.
tech support for roof drains sump pans

We Have Great Tech Support

  • Send us your specs/plans/drawings. We’re plumbing contractors and may be able to assist. 
  • Visit our installation page, blog or FAQ pages.
  • Call and speak to our trained techs. 
  • Review our videos on our YouTube channel. 
  • available from 8:00 am – 5:00 pm PST, USA
  • 949 297-8689….Toll free (888) 900-9145