7 posts / 0 new
Last post
pilgrimtj
roughin plumbing

I am helping my daughter and son-in-law build their own house and we are doing the rough in plumbing. The house is 1600 sq ft on a crawl space. It has 2 full baths, washing machine, kitchen sink and a dishwasher. I am running a 4 inch waste line but I am not sure what size vent to run up through the roof. Sure would appreciate any help !

dj1
Re: roughin plumbing

3" for the kitchen, 2" for each bathroom, 2" for the washing machine. Large vents (7" or 8") for the gas range, 3" for the gas water heater.

Not sure? call your building department. Or ask your friendly building inspector. Smile.

HoustonRemodeler
Re: roughin plumbing

Some vents can be tied together all into one vent, depending on the local codes. You'll need to check on that.

enigma-2
Re: roughin plumbing
pilgrimtj wrote:

I am helping my daughter and son-in-law build their own house and we are doing the rough in plumbing. The house is 1600 sq ft on a crawl space. It has 2 full baths, washing machine, kitchen sink and a dishwasher. I am running a 4 inch waste line but I am not sure what size vent to run up through the roof. Sure would appreciate any help !

The size is usually governed by one of two different plumbing codes, the International Residential Code or the Uniform Plumbing Code. (Check with your local building department to see which code you should use).

In the IRC, the code section is P3113.1 which requires the vent is to be 1/2 the size of the drain served (i.e. 2-inch for a 4-inch drain). Vents which exceed 40 ft. in developed length to be increased on size larger. So you could run a 2-inch diameter vent up to within 12-inches of the roof, where you may need to increase it to 3-inches for frost closure protection, if the winter design temperature in your area is 0° F or less. Terminate at least 6-inches above above the roof or 6-inches above the anticipated snow accumulation (whichever is greater).

In the UPC, Section 904.1 also requires the vent to be not less than 1/2 the drain size and and sized to the total number of fixture units connected. Based on what you stated was connected, we can assume you have 17 fixture units. Table 7-5 allows 24 fu for a 2-inch vent so that would be the minimum acceptable. The UPC allows 2-inch pipe to terminate outside with a winter design temp of 0° F, but required you extend a minimum of 10-inches above the roof (or more if req by the AHJ).

In either case, keep the vent termination at lease 10-feet from, or not less than 3-feet above, any window or air intake.

pilgrimtj
Re: roughin plumbing
dj1 wrote:

3" for the kitchen, 2" for each bathroom, 2" for the washing machine. Large vents (7" or 8") for the gas range, 3" for the gas water heater.

Not sure? call your building department. Or ask your friendly building inspector. Smile.

thank you...

pilgrimtj
Re: roughin plumbing
HoustonRemodeler wrote:

Some vents can be tied together all into one vent, depending on the local codes. You'll need to check on that.

thank you....

pilgrimtj
Re: roughin plumbing
enigma-2 wrote:

The size is usually governed by one of two different plumbing codes, the International Residential Code or the Uniform Plumbing Code. (Check with your local building department to see which code you should use).

In the IRC, the code section is P3113.1 which requires the vent is to be 1/2 the size of the drain served (i.e. 2-inch for a 4-inch drain). Vents which exceed 40 ft. in developed length to be increased on size larger. So you could run a 2-inch diameter vent up to within 12-inches of the roof, where you may need to increase it to 3-inches for frost closure protection, if the winter design temperature in your area is 0° F or less. Terminate at least 6-inches above above the roof or 6-inches above the anticipated snow accumulation (whichever is greater).

In the UPC, Section 904.1 also requires the vent to be not less than 1/2 the drain size and and sized to the total number of fixture units connected. Based on what you stated was connected, we can assume you have 17 fixture units. Table 7-5 allows 24 fu for a 2-inch vent so that would be the minimum acceptable. The UPC allows 2-inch pipe to terminate outside with a winter design temp of 0° F, but required you extend a minimum of 10-inches above the roof (or more if req by the AHJ).

In either case, keep the vent termination at lease 10-feet from, or not less than 3-feet above, any window or air intake.

appreciate that.....you were a big help.

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.