Plumbing for Home Additions and ADUs in Severna Park, MD

New Bathroom Addition — Ground Floor or Second Floor

Adding a bathroom to a Severna Park home requires planning the drain, supply, and vent connections from the design stage — the location of the bathroom relative to the existing drain stack determines whether drain routing is straightforward or complex.

Ground floor addition: Drain lines can often be run under the floor to the existing stack or through the crawlspace. Access is generally good. Anne Arundel County permit required.

Second floor addition: Drain lines must be routed through interior walls to reach the stack. In an existing home, this typically means opening finished walls or ceilings below — a factor in the total project cost that needs to be understood before committing to a floor plan.

Key decisions at the rough-in stage:

• Toilet drain location (the most constrained by slope requirements)
• Shower drain type and floor preparation
• Vent connection — wet vent configuration or dedicated vent to exterior
• Supply line routing from the nearest supply branch

We assess these before any walls open and give you accurate cost figures at the design stage — not after the carpenter has committed to a layout.

Basement Conversion to Living Space or ADU

Converting a Severna Park basement to living space almost always involves a bathroom addition — and in a basement where drains sit below the main sewer line, an ejector pump system is required.

The ejector system in a basement bathroom: The ejector basin is sized and positioned to collect gravity flow from all fixtures in the basement — toilet, sink, shower — before pumping the sewage up to the main drain system above. Basin location determines everything about the drain routing; positioning the basin incorrectly means breaking concrete twice. We plan the ejector system before any concrete is cut.

For ADU conversions: A self-contained ADU in a Severna Park basement needs separate supply shutoffs accessible to the unit, independent water metering if Anne Arundel County’s ADU ordinance requires it (confirm current requirements), and sufficient supply capacity if the main home’s supply lines are already marginal.

For Severna Park’s polybutylene era homes: If the home was built between 1978 and 1995 — covering most of the Cypress Creek and Benfield Road corridor — a basement conversion project is the ideal time to assess the full supply system and repipe at the same time as the rough-in is open.

In-Law Suite Plumbing

An in-law suite in a Severna Park home — whether a ground floor bedroom suite with a bathroom or a converted attached garage — typically involves a new bathroom rough-in and potentially a kitchenette wet bar connection. The plumbing considerations are:

Separate shutoff access: If the in-law suite is intended for long-term occupation, individual shutoff valves for the suite’s fixtures that are accessible without entering the main home are a practical addition.

Hot water demand: If the in-law suite is a significant distance from the water heater — typical in a ground floor suite at the opposite end of the home from the utility room — a recirculating hot water system or a point-of-use mini water heater reduces the wait time for hot water at the suite’s fixtures.

Vent routing: New bathroom fixtures in a one-story suite addition often require a roof penetration for the vent stack. Anne Arundel County permit covers the vent routing as part of the bathroom rough-in approval.