top of page

Frequently Asked Questions

All About Culwell Flange

Should I worry about the Flange Ring breaking in the future?

Absolutely NOT! 

The unique Blue Nylon Clamping Ring was designed with superior strength and durability. It was engineered to withstand over 1000lb, to prevent the flange from breaking with the use of repeated heavy transfers.

We challenge you to take a sledgehammer to it! It will not break.

Culwell Flange models are backed by an exclusive Limited Lifetime Warranty for the lifetime of the property. We will replace the product.

Getting Started

Common Terms & Abbreviations

DWV pipe = Drainage Waste and Vent pipe

Closet Flange = Toilet Flange

Wet room = Area where the toilet and shower are in same wet area. Popular in small spaces and with accessible designs for individuals with mobility challenges


What Culwell Flange model should I use: Glue-In or Compression?


All Culwell Flange models are designed with the same unique floor protecting/ sealing properties. The method in which the flange is attached to the sanitary pipe is standard in the industry.


    • All Hub Glue-In models are cUPC or UPC code approved and are primarily used for new construction or remodeling when there is a NEW Drainage waste vent (DWV) pipe installed where the flange meets the pipe. These flanges are typically installed over the DWV pipe. However, the 4 in. x 3 in. code approved flanges can be universally installed inside a 4 in. or over a 3 in. DWV pipe.

    • Compression models are NOT code approved for installing to DWV pipe in new construction (which is standard in industry). Although they are designed to replacement existing flanges, DIY’ers can and have used Compression flanges for new or replaced pipes provided there is no required code inspection in the jurisdiction for such applications. Feedback received from DIY individuals claim that it is quicker, and more convenient to install Compression (over Glue-In models) because solvent weld is not used with these models, making it is easier to replace and adjust if needed. NOTE: It is at the sole discretion and responsibility of the individual installer to verify what the requirements are in your area.

    • EXCEPTIONS: The Culwell Flange set a NEW Standard in the US and Canada for its one-of-a-kind floor sealing properties (that no other flange can achieve), therefore if your project is specified and/or requires that the floor be water-seal protected, there may be exceptions to the inspection approval. (ie: Culwell Flange 4in. Compression has been used in Hospital construction). Check with your local plumbing inspector.


    • Compression models are designed to replace or retrofit existing installed flanges that cannot be completely remove without destroying or altering the integrity of the DWV sanitary pipe system. Which size to use will determine the size of the pipe and how the existing flange was originally installed. Please see the FAQ–How the flange is attached to the sanitary pipe system.

    • 4 in. x 3 in. Hub Glue-In models can be installed INSIDE an existing 4 in. DWV pipe when an existing 4in. Hub Glue-In flange is attached OVER the DWV pipe. Note: the top portion of the existing flange that sits above the subfloor must be removed or cut off so that the existing pipe is flush to the subfloor.


How is the Culwell Flange attached to the sanitary pipe?

All Culwell Flange models attach to the sanitary piping system called the Dainage,Waste,Vent pipe (DWV) using conventional means that are standard in the industry.

  1. Glue-In flanges attach to the DWV pipe using a solvent cement (“glue”), with a primer applied first if required by code or otherwise. PVC flanges weld to PVC Schedule 40 DWV pipe. ABS flanges weld to ABS Schedule 40 DWV pipe.

    • 4in. x 3in. Hub serves as a universal fit, by either fitting inside a 4 inch DWV pipe or over a 3 inch DWV pipe.

    • 4in. Hub fits over a 4 inch DWV pipe.

  2. Compression flanges are inserted into the DWV pipe and do not require use of glue, but rather attach to the side walls by means of a firm compression.

    • 3 in. O-Ring fits into 3 inch Cast Iron, Schedule 30 or Schedule 40 DWV pipe. Two (2) O-Rings are provided to accommodate different inside pipe diameters. Choose the O-Ring that fits inside the pipe and still makes contact with the inside pipe wall. (Smaller size O-Ring generally fits inside 3 inch Schedule 30 DWV and most 3 inch Cast Iron pipes.

    • 4 in. Drop-Fit easily drops into 4 inch Cast Iron or Schedule 40 DWV pipe and can be used in the replacement of Cast Iron flanges. Hand-tighten the three (3) stainless steel bolts with a 3/16” Allen wrench until the gasket is firmly compressed against the side walls of the pipe.


What kind of Sealant should I use to seal the membrane to Culwell Flange?

100% Silicone Sealant/ Caulk is generally used. There are a variety of high quality sealant/ caulks on the market that adhere to specific types of water-proofing material, wood, and or concrete. We recommended that you select the one most suitable for your application.


What is the ideal size closet bolt to use?

5/16” x 2-¼”

Although 1/4" x 2-¼” bolts can be used, they do not stand securely upright as the 5/16” bolts do and they may be a little more challenging to manage when inserting the bolts into the Culwell Flange “BOLT” indicator slots and it's Blue Clamping Ring. The thicker diameter of the 5/16” Bolts provide a secure stable fit while also engaged with the sealing gasket(s). Check your Retail packaging- Culwell Flange Models are packaged with a 5/16” Closet Bolt Kit.


When I apply Silicone under the flat surface of the flange, will this "secure" the flange to floor?

NO! NO! NO! Silicone does not secure nor anchor the toilet.

Silicone is ONLY used to seal a membrane to the flange - when using an impermiable membrane liner or vinyl flooring. Or Silicone is applied under the flat base of the flange surface for added seal protection - when a membrane is not used.

**SCREWS Anchor the Flange to the Floor (concrete or wood). The Blue Nylon Clamping Ring has 8 counter sunk holes for attachment.

***CLOSET BOLTS Anchor the Toilet to the Flange. If the Flange is not anchored to the floor then the Toilet is not attached to the floor.

Dont let the flush flat sealing surface of the Culwell Flange throw you off. When the gaskets, membrane and clamping ring are all in place then drive the 8 screws through the compressed layers, penetrating through the bottom portion of the flange into the substrate.







If I am driving screws through the Culwell Flange blue nylon ring, gasket (s), membrane liner and body into the subfloor, will that break the water-seal?


No way! Culwell Flange's Blue Nylon Ring has counter sunk screw holes that were designed to draw/ pull up the liner and the elastomeric gasket when the screws are engaged- along with the use of 100% Silicone per manufacturer's instructions.

Culwell Flange passed lab testing while submergered in a flooded area for over 24 hours. This product inspired the creation of a new standard, IAPMO IGC 285, published by the International Association of Plumbing and Mechanical Officials (IAPMO) for US and Canada for it's revolutionary sealing property design.


Tools & Materials
New Installs:
bottom of page