That is dry vent piping carrying only air sewer gas or moisture to above the roof line is unrestricted.
Venting sewer in attic.
There are 3 vents in one area and 2 venting into attic plumbing contractor talk.
The first would be a bathroom or kitchen in that part of the house and the other would be a.
Local building codes that regulate the materials used in the dwv system have changed over the years so most older homes have a combination of materials.
The other pipes are probably vents too its very common to have multiple vents enter the attic and converge into one stack through the roof or have multiple stacks through the roof depending on how far apart they are from each other and which is more feasible.
Cut the pipe and connect a reducer tee fitting.
Is unusual although it may be required by your local plumbing code.
Vent pipes look like sewer pipes only two plumbing set ups could require sewer pipes in the attic.
Another not so common way the vent can become clogged is when a horizontal section of the venting system itself inside the attic is sloped the wrong way.
As long as the sink drain connects to the main drain of the building within a few feet then it is vented.
During maintenance you ll want to be assured the top of the vent is kept open.
Your sink drain will connect to the pipe going up through your roof.
Vent pipes supply fresh air to each plumbing fixture in the house which helps the system move water through the drainage pipes each time a toilet is flushed or a sink is drained.
A blocked vent can be caused by leaves dead animals and ice dams in very cold climates.
The drainpipes are made of cast iron galvanized pipe copper or plastic.
The vent pipes remove or exhaust sewer gases and allow air to enter the system so that the wastewater flows freely.
Transition coupling either plastic like this or banded rubber to join a 3 in.
In the attic tap into a conveniently located vent pipe.
Someone took a shortcut.
Use no hub fittings to connect a pvc fitting to cast iron or abs pipe.
I have a customer that we are doing some work in the attic for and i noticed yesterday that the plumbing is vented up into the attic phew and not thru the roof.
However the piping does need to be protected from nails use nail plates to protect vent and drain piping both where where piping passes through studs joists or rafters.
Plumbing air vents also prevent sewer gases from entering the home and allow wastewater gas and odor to escape.