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Hello Lazy Pup,
> I am in the process of replacing a galvanized pipe
> with PVC for a drain.
> I am replacing one sink in a bathroom with dual
> sinks, and will need a "cross" instead of just one
> pipe.
>
> Could I cut the galvanized pipe with a
> reciprocating saw and then replace a small part with
> the PVC? And how do I fit the PVC to the existing
> galvanized pipe?
>
> Thank you very much for your time!
>
> Fredrik
I originally received this question and the photo from Fredrik via email but I felt that this topic would be of interest to all so with his permission I am posting it here in the forum.
To the novice this project would appear to be simple, just install a tee on the end of the waste arm and attach the two sinks, however there are a number of code issues that must be considered here.
Under both the International Residential Code & the Uniform Plumbing Code a lavatory bowl is rated at one (1) DFU (Drainage Fixture Unit) and is rated for a 1-1/4” Drain & P-trap.
Back in the days of leaded joint cast iron DWV systems they primarily used cast iron pipe for all lines 2” or greater, while they commonly used GIP (Galvanized Iron Pipe), lead pipe or DWV grade Brass or Copper pipe to for the 1-1/4” & 1-1/2” lines. Although 1-1/4” still remains the proper size for a lavatory drain we seldom use 1-1/4” pipe and fittings today because the codes allow an exception, which permits us to increase the trap or drain line by one nominal trade size. Understanding that the lavatory is the only fixture in the house that is permitted to have a 1-1/4” trap or line it quickly becomes apparent that it is not cost effective to maintain a separate inventory of pipe and fitting for just this one line when we can easily opt for the exception in the code and use 1-1/2” pipe. The practice of increasing to 1-1/2” is now so common that most hardware or home supply centers no longer carry 1-1/4” DWV fittings.
In the upper right corner of Fredricks photo it appears that there is an 1-1/2” GIP connected to the cast iron stack. The 1-1/2” runs to the left to a 1-1/2” riser that is dropping to the floor, then immediately to the left of that riser in the second stud bay there is a 1-1/4” x 1-1/2” reducer bushing. The horizontal vent then continues as 1-1/4” to the left to the point where it drops down to the waste arm, then the 1-1/4” continues down as the drain for the waste arm.
A lavatory bowl is rated at one DFU and an 1-1/4” pipe is rated to carry a maximum of one DFU so this present configuration is fine for one sink, however if we now install a second lavatory bowl the combined load on the drain line would now be 2DFU’s.
INTERNATIONAL RESIDENTIAL CODE:
If we are under the International Residential Code we must now increase the waste arm and drain size to 1-1/2”, which is rated for a maximum of 3DFU’s.
To do so we could cut the vertical vent line at any convenient point which is 6” above the flood level rim of the highest fixture served by that vent, which in this case would be at any convenient point which is 6” higher than the blue line marked “finished sink elevation” We could then attach a 1-1/4” x 1-1/2” rubber “Fernco” coupling to connect our new PVC to the existing GIP. From the Fernco we would then use 1-1/2” PVC to drop down to a “Sanitary Tee” (DWV grade tee, a Wye is prohibited here). From the bottom of the Tee we would then need to continue an 1-1/2” line through the floor and continue 1-1/2” until we tie into the building main drain or a branch drain line.
UNIFORM PLUMBING CODE:
The UPC requires that the vent must also be 1-1/2”. In this case we would need to cut out all the existing 1-1/4” pipe all the way back to the reducer bushing at the 1-1/2” tee on top of the 1-1/2” riser. We could remove the reducer bushing and install a 1-1/2” PVC male thread adapter in the Tee, then continue 1-1/2” to make the horizontal vent and the vent riser down to the sanitary Tee at the waste arm, then continuing 1-1/2” down through the floor and to the branch or main drain as described above.
When we install the new sinks if the total horizontal distance when measured from center to center on the drain openings will be 30” or less we may connect both sinks with a “Center Waste” or “End Waste” kit such as used for a kitchen double sink, then we could install a single 1-1/2” p-trap from the waste kit to the fixture waste arm.
If the horizontal separation will be greater than 30” we must install a “Double Wye” on the end of the waste arm. (A sanitary cross or double Tee would be prohibited here). We then install an 1/8th bend in the side openings of the Wye and we can then extend the side inlets to a trap adapter and a separate trap on each sink, however, the maximum distance when measured on a line on the top of the pipe from the vertical riser in the wall, coming out the waste arm and horizontally to a trap may not exceed 3’6” under the UPC or 6’ under the IRC.
In the center opening of the Wye we then install a female thread adapter and a cleanout cap as illustrated.
> I am in the process of replacing a galvanized pipe
> with PVC for a drain.
> I am replacing one sink in a bathroom with dual
> sinks, and will need a "cross" instead of just one
> pipe.
>
> Could I cut the galvanized pipe with a
> reciprocating saw and then replace a small part with
> the PVC? And how do I fit the PVC to the existing
> galvanized pipe?
>
> Thank you very much for your time!
>
> Fredrik
I originally received this question and the photo from Fredrik via email but I felt that this topic would be of interest to all so with his permission I am posting it here in the forum.
To the novice this project would appear to be simple, just install a tee on the end of the waste arm and attach the two sinks, however there are a number of code issues that must be considered here.
Under both the International Residential Code & the Uniform Plumbing Code a lavatory bowl is rated at one (1) DFU (Drainage Fixture Unit) and is rated for a 1-1/4” Drain & P-trap.
Back in the days of leaded joint cast iron DWV systems they primarily used cast iron pipe for all lines 2” or greater, while they commonly used GIP (Galvanized Iron Pipe), lead pipe or DWV grade Brass or Copper pipe to for the 1-1/4” & 1-1/2” lines. Although 1-1/4” still remains the proper size for a lavatory drain we seldom use 1-1/4” pipe and fittings today because the codes allow an exception, which permits us to increase the trap or drain line by one nominal trade size. Understanding that the lavatory is the only fixture in the house that is permitted to have a 1-1/4” trap or line it quickly becomes apparent that it is not cost effective to maintain a separate inventory of pipe and fitting for just this one line when we can easily opt for the exception in the code and use 1-1/2” pipe. The practice of increasing to 1-1/2” is now so common that most hardware or home supply centers no longer carry 1-1/4” DWV fittings.
In the upper right corner of Fredricks photo it appears that there is an 1-1/2” GIP connected to the cast iron stack. The 1-1/2” runs to the left to a 1-1/2” riser that is dropping to the floor, then immediately to the left of that riser in the second stud bay there is a 1-1/4” x 1-1/2” reducer bushing. The horizontal vent then continues as 1-1/4” to the left to the point where it drops down to the waste arm, then the 1-1/4” continues down as the drain for the waste arm.
A lavatory bowl is rated at one DFU and an 1-1/4” pipe is rated to carry a maximum of one DFU so this present configuration is fine for one sink, however if we now install a second lavatory bowl the combined load on the drain line would now be 2DFU’s.
INTERNATIONAL RESIDENTIAL CODE:
If we are under the International Residential Code we must now increase the waste arm and drain size to 1-1/2”, which is rated for a maximum of 3DFU’s.
To do so we could cut the vertical vent line at any convenient point which is 6” above the flood level rim of the highest fixture served by that vent, which in this case would be at any convenient point which is 6” higher than the blue line marked “finished sink elevation” We could then attach a 1-1/4” x 1-1/2” rubber “Fernco” coupling to connect our new PVC to the existing GIP. From the Fernco we would then use 1-1/2” PVC to drop down to a “Sanitary Tee” (DWV grade tee, a Wye is prohibited here). From the bottom of the Tee we would then need to continue an 1-1/2” line through the floor and continue 1-1/2” until we tie into the building main drain or a branch drain line.
UNIFORM PLUMBING CODE:
The UPC requires that the vent must also be 1-1/2”. In this case we would need to cut out all the existing 1-1/4” pipe all the way back to the reducer bushing at the 1-1/2” tee on top of the 1-1/2” riser. We could remove the reducer bushing and install a 1-1/2” PVC male thread adapter in the Tee, then continue 1-1/2” to make the horizontal vent and the vent riser down to the sanitary Tee at the waste arm, then continuing 1-1/2” down through the floor and to the branch or main drain as described above.
When we install the new sinks if the total horizontal distance when measured from center to center on the drain openings will be 30” or less we may connect both sinks with a “Center Waste” or “End Waste” kit such as used for a kitchen double sink, then we could install a single 1-1/2” p-trap from the waste kit to the fixture waste arm.
If the horizontal separation will be greater than 30” we must install a “Double Wye” on the end of the waste arm. (A sanitary cross or double Tee would be prohibited here). We then install an 1/8th bend in the side openings of the Wye and we can then extend the side inlets to a trap adapter and a separate trap on each sink, however, the maximum distance when measured on a line on the top of the pipe from the vertical riser in the wall, coming out the waste arm and horizontally to a trap may not exceed 3’6” under the UPC or 6’ under the IRC.
In the center opening of the Wye we then install a female thread adapter and a cleanout cap as illustrated.
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