Repiping in Lakewood, CA

Lakewood amended its building code rather than adopting the state's unchanged code, and one amendment addresses foundations on soils containing sulfates. It is a city provision, most recently touched when the city moved onto the 2025 code cycle, and it has consequences for pipe.

Read it as a chain, because that is how it works. When soils contain sulfates, the Building Official may require special provisions in the foundation design and may call for a special investigation and report. Concrete floor slabs are cast on a moisture barrier membrane of at least 10 mils, at least 4 inches thick, and reinforced. And for residential buildings, where an approved method of construction is not provided, foundations and floor slabs must be of Type V cement, with under-slab pipes, conduit, and ducts non-metallic.

Every one of those conditions matters. This is not a city-wide ban on copper under a slab, and anyone who tells it to you has read one sentence of it. It is a rule that bites where sulfate soils are present and where no engineered alternative has been approved. An engineered alternative, based on a geotechnical recommendation and signed off by the Building Official, is expressly available.

What it changes about a job is the order of the questions. On a slab house here, the material under the concrete is no longer an installer's preference between copper and a plastic system. It becomes a question with a code answer that depends on your soil and on what has been submitted, and it has to be settled before a route is chosen and long before a slab is opened. The ten-mil barrier and the four-inch reinforced slab matter too, because a penetration through a slab has to be detailed to work with both.

This is also why two Lakewood repipe quotes can differ for reasons belonging to neither company. One may have assumed an overhead route and never met the question. The other may have priced a through-slab run on a material the Building Official would want justified. Ask each one which assumption it made.

A whole-house repipe has three broad routes and the choice is usually made in the first hour. Overhead through the attic and down inside walls is the common answer on a single story with accessible framing above: it leaves the new system reachable for as long as it lasts, it puts the work in the ceiling and the wall, and it sidesteps the slab question entirely. Around the outside and back in low is the answer where the attic is unusable, or the house has been added to sideways, and it trades some appearance for a great deal of access.

Under the slab is the third, which carries the local condition. It is sometimes genuinely the right route, particularly on a house where the fixture groups sit far apart, and an overhead run would mean opening most of the ceilings. If it is chosen in Lakewood, the material question stops being a preference. The code chain above governs it, the soil is the trigger, and what has been submitted and approved decides whether the fallback applies.

The reason to make this decision deliberately is that it is close to permanent. A repipe happens very rarely, and the route chosen today will be inherited by whoever works on this house decades from now. An overhead system stays reachable. A run under a slab is reachable too, through concrete. That difference deserves an hour of thought, and it usually gets ten minutes.