Floor Drain Vent Distance

Above roof plumbing vent diameter.

Floor drain vent distance.

If the drain lines in your home have poor venting as in figure a for example water rushing down the drains will pull water from nearby p traps. Figuring out your drain waste vent lines if you have to make plumbing repairs around your home it helps to understand your drain waste vent system dwv. The general rule is that smaller drainpipes 1 1 4 inches for bathroom sinks and 1 1 2 inches for kitchen sinks for instance lead to larger branch drains. As water goes down a drain air is needed to equalize the pressure in the drain line.

Because the main stack is also vertical it will rarely clog. When installing your vents it s highly recommended that you plan out your drain lines to minimize the risk of clogging. Floor drains are plumbing fixtures and they must be provided with a trap the trap to vent distance must meet the requirements of table 1002 2 r fd i i i i i i incorrectly vented 1 incorrectly vented r i i i i i flat i i vent flat vent j l. Vent terminals shall not terminate under the overhang of a structure with soffit vents.

When builders look only at the table without reading the text they find that a 2 inch diameter drain can run a maximum distance of 8 feet to the vent. This is the purpose of a venting system. Drain and vent lines must be positioned precisely so you should install them before the supply pipes. The fat pipes in your house make up the dwv carrying wastewater to a city sewer line or your private sewer treatment facility called a septic tank and field.

You must slope the drainpipe at 1 8 to 1 4 inch drop per foot. It may be possible to simplify supply runs by moving a vent pipe over a few inches. If you must run drainpipes across a floor carefully calculate the amount of vertical space available. In areas exposed to snow or freezing or temperatures below 0 degf that can block a plumbing vent the vent pipe should be at least 2 in diameter beginning at least one foot inside the building in an insulated space before the vent passes through the roof.

Both kitchen 1 1 2 inches and bathroom 1 1 4 inches are smaller than the rest of the drain system on purpose. They may also see that the slope column references 1 4 inch per foot but they are likely to assume that it s just reiterating the minimum allowable slope for a 2 inch drain. These in turn lead to the main stack which is the largest pipe of all typically 4 inches. 2014 fbc plumbing 5 th edition 9 vents 909 fixture vents 909 1 distance of trap from vent jump to full code chapter each fixture trap shall have a protecting vent located so that the slope and the developed length in the fixture drain from the trap weir to the vent fitting are within the requirements set forth in table 909 1.