Bathroom Additions That Fix the Morning Line

When the house needs another bathroom

A three- or four-bedroom house with one full bathroom was common when many Davis County neighborhoods were built. Families grew, and so did the line outside the bathroom door. Guests, teenagers, a home office or a relative moving in all add pressure. A bathroom addition is often the smallest project that makes the biggest difference to how the house works day to day.

Types of bathroom additions

• A small addition or bump-out that holds a new bathroom next to bedrooms or a hallway
• A bathroom as part of a larger addition, such as a primary suite or in-law suite
• A half bath near the family room or entry, with a toilet and sink
• A bathroom paired with a mudroom at the back door. See mudroom additions

Plumbing decides the location

Water supply lines can go almost anywhere. Drains cannot. Waste lines need a continuous downhill slope to the building sewer, and every fixture needs venting. That makes the location of the existing sewer line, the depth of the foundation and the direction of slope the first things to check.

• Near existing plumbingUsually the simplest: short drain run, easy vent connection.
• Far from the sewerA longer trenched line under the addition, planned with the foundation.
• Below the sewerA basement-level bathroom may need an ejector pump if gravity cannot do the work.
• On a slabDrains are placed before the concrete, so fixture locations must be final early.

Ventilation and moisture

Bathrooms produce a lot of moisture. A properly sized exhaust fan ducted to the outside, not into the attic, protects framing, insulation and finishes. Shower waterproofing is just as important: tile is not waterproof on its own, and the membrane or backer system underneath is what keeps water out of the walls. These are the parts of a bathroom that last or fail over time.

Layout and accessibility

Even a small bathroom benefits from careful layout: door swing, toilet clearance, where the vanity light falls, and where towels hang. If the bathroom might serve an older relative or support aging in place, a curbless shower, a wider door, blocking for grab bars and a comfortable-height toilet are worth building in now.

Permits and inspections

Adding a bathroom involves plumbing, electrical and ventilation work that is inspected before walls are closed. On an addition, it falls under the main building permit review. Our permits guide explains how that works.

What shapes the cost

Bathrooms are among the most expensive rooms per square foot to build. The main drivers are plumbing distance and depth, the shower design and waterproofing, tile and fixture selections, ventilation, and whether water heating needs an upgrade. The home addition cost guide explains how we build a budget.

We add bathrooms for homes in Bountiful and throughout Davis County.

Bathroom addition questions