Foam and Cement method


Many methods may be employed to seal the connection between a new Flout and old siphon outlet.  One method is the “foam and cement” (F&C) method. It is most easily used when a smaller size Flout can be used with a larger existing outlet, for example 3 inch into 4 inch or 4 inch into 5 or 6 inch. If pipe size must stay constant the old hole must be enlarged or use mechanical couplers to the old siphon stubs.


A bell siphon typically has two passages into the floor. Under the bell is the trap and closer to the outlet wall is the vent. Either may be used for the new Flout. Whichever is used, the other must be plugged. It is easiest to use the vent and plug the old trap. Fill old trap mortar or stuff with a backer and use the F&C method. If the trap is used, be careful not to plug the line when sealing the old vent!


Step 1:   Cut old siphon outlets flush to the floor and dry area as much as possible.

Step 2: Cut a 45 degree angle from one end of the new pipe and place in the old outlet until it bottoms. Angle keeps pipe from settling and blocking the flow.

Step 3:   Mark the pipe at the desired height. Remove pipe and cut off at mark.

Step 4:   Reinsert the pipe into hole and rotate so angle faces direction of flow.

Step 5:   Apply “Great Stuff” foam in a can or equivalent liberally around pipe.

Step 6:  As  the foam sets up, keep pushing it down around the pipe, forming a 2-3 inch deep recess around the pipe. After a few minutes the foam should stabilize the pipe. 

Step 7:   Mix up some fast curing water stop cement or anchoring cement and trowel into recess.

Step 8:  Check bottom of pipe for excess foam. Remove any if found.

Step 9:  After a 20-30 minutes of curing the new pipe stub is ready for the Flout.

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