Sewer Line Penetration of Foundation, Best Practices

Hi,
I’m in the process of replacing my 70+ year old sewer line. As part of the job, I need to replace some very rusty 3″ galvanized that runs through the poured concrete foundation. My guess it that at best I will be able to cut the pipe and chisel out the remains to have a rough 3″ opening. My city, Seattle, follows the IRC and I’m guessing that I will need to adhere to IRC 2603.5 and 2603.4. I’m having trouble finding a good photo, diagram or article that goes illustrates the best practice for making a foundation penetration with a sewer line. Any help would be greatly appreciated!
Thanks,
John
1. Pipes Through Footings or Foundations – Any pipe that passes under a footing or through a foundation wall shall be provided with a relieving arch; or there shall be built into the masonry wall a pipe sleeve two pipe sizes greater than the pipe passing through. (IRC P2603.5)
2. Sleeves – Annular spaces between sleeves and pipes shall be filled or tightly caulked as approved by the building official. Annular spaces between sleeves and pipes in fire-rated assemblies shall be filled or tightly caulked in accordance with the building portion of the code. (IRC P2603.4)
Replies
John
I've no diagram or photo.
Here, I would probably drill out around the still in the foundation but cut shorter pipe to the dimension of the pvc sleeve I'd be using.
This way, the pipe that remains will give me something to help guide a half inch or so drill bit through that foundation. Block wouild be easy. Poured, not so easy.
or
I'd call a concrete drilling company, have them mount and core drill around that pipe (cut flush with the foundation) to the size just a bit bigger than my sleeve O.D.
Seal in the sleeve, pass the new line through and seal that. Do a good job with your choice of sealant, I'd use a high grade Urethane. Pack with backer rod b/4 caulk.
P2603.4Pipes through foundation walls.
A pipe that passes through a foundation wall shall be provided with a relieving arch, or a pipe sleeve shall be built into the foundation wall. The sleeve shall be two pipe sizes greater than the pipe passing through the wall.
❖ Piping installed through a foundation wall must be protected from any small movement of the foundation wall that could cause loads to be imparted to the piping. Protection can be provided by either installing the piping under and through a relieving arch in the wall or by installing the piping through a pipe sleeve in the wall.
Where a pipe sleeve is used, it must be sized to be two pipe sizes larger than the pipe that passes through the pipe sleeve. For example, a 4-inch (102 mm) drainage pipe would require a 6-inch (152 mm) pipe sleeve. The annular space between the pipe sleeve and the pipe that passes through the sleeve will allow for some differential movement between the pipe and the wall. The pipe sleeve or relieving arch protects the pipe so that it will not be subjected to undue stresses that could cause it to rupture and leak [see Commentary Figures P2603.4(1) and P2603.4(2)].
In rare circumstances, it is necessary for a pipe to pass perpendicular to and through a footing. For example, the slope of a building drain might not be able to be changed to result in the piping passing under the footing. Although the code does not specifically address pipes passing through footings, the need for protecting pipes passing through footings is no different than for pipes passing through foundation walls. In these situations, protection of the pipe is not the only concern. The strength of the footing could be compromised by the installation of a pipe sleeve or relieving arch in the footing. Before any footing is to be altered, the proposed alteration should be reviewed by a design professional to determine what footing design changes might be necessary to maintain the required footing strength.
The plumbing system design for many buildings requires that the building drain and water line pass under the footing. In some cases, the required elevation of such piping places the top of piping just below the bottom of the footing. A commonly asked question is whether the piping is required to be installed with a pipe sleeve under the footing. It does not, because the footing acts in a similar manner to that of a relieving arch. The footing “spans over” the trench for the piping.
Footings are designed to be uniformly supported by undisturbed earth or compacted materials. A trench for piping passing perpendicular to and under the footing disrupts the uniform support for the footing. If the trench can be backfilled and compacted to the same level of compaction as the undisturbed earth or compacted materials, then the footing will be uniformly supported as intended by design. But if the trench cannot be compacted sufficiently, such as where a trench is dug after the footing is in place, then the footing will not be uniformly supported because there isn’t any way to compact the backfill materials. This will result in greater localized stress in the footing, potentially more stress than the footing was designed for. In actual practice, for buildings within the scope of the code, passing the typical sizes of building drain [e.g., 4 inches (102 mm)] and water service line [e.g., 1 inch (25.4 mm)] side-by-side and under a footing doesn’t seem to have created problems for prescriptive-designed footings that are placed on a stable base. Generally, such footing designs are known to have some reserve capacity for accommodating some loss of uniform support in a limited length of footing. However, where trench backfill surrounding piping passing beneath a footing cannot be compacted to the same level as the adjacent stable base, there are no “rules of thumb” indicating when a footing design should be analyzed for adequacy. Thus, installers and building officials must be aware of the possible detrimental effects to the footing and, where necessary, consult with design professionals regarding the footing design.
Another commonly asked question is whether the top of piping passing under a footing can be in direct contact with the bottom of the footing. The code doesn’t directly address this issue (except for where Section P2603.3 applies). However, given that this section is concerned with piping being protected from direct contact with foundation walls, it is reasonable to expect that the piping under a footing is not placed in direct contact with the footing. Because the code doesn’t provide any guidance for amount of separation, any amount of cover over the piping could be acceptable, including a backfill thickness that simply obscures the piping.
Commentary Figure P2603.4(1)
Commentary Figure P2603.4(1)
PIPE PROTECTION
Commentary Figure P2603.4(2)
Commentary Figure P2603.4(2)
BUILDING DRAIN PENETRATION OF BLOCK FOUNDATION WALL
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