Can My House Take a Second Story?

The short answer

Many single-story houses can take a second story, often with some reinforcement. Whether yours can, and how much reinforcement it needs, depends on four things: the structure, the zoning, the layout and the budget. A second story that needs extensive foundation work may still be possible, but another option might serve you better. See build up versus build out.

1. The foundation

The existing footings carry the weight of the house into the soil. Adding a floor adds weight. The engineer looks at footing width and depth, the condition of foundation walls, and whether there are signs of settlement. Where footings are too small, options include enlarging them in places, adding new footings under new posts, or supporting the new floor on a separate structure. Each has cost and disruption. See addition foundations.

2. The walls and framing

Walls in a single-story house were sized to carry a roof. Adding a floor changes the loads on studs, headers over windows and doors, and the connections to the foundation. The existing ceiling joists are rarely strong enough to become a floor, so most second stories add a new floor structure. The engineer also identifies where loads can come down through the house and where new posts or beams are needed.

3. Earthquake and wind bracing

A taller house has more force acting on it in an earthquake or strong wind. Along the Wasatch Front, this is a major part of second-story design. Bountiful's published design criteria, for example, list seismic design category D2 and a 140 mph design wind speed. Meeting those usually means new shear walls, hold-down hardware and stronger connections from roof to foundation, which can affect interior walls and finishes on the main floor.

4. Height limits and zoning

Zoning limits how tall a house can be. Bountiful's single-family zones allow up to 35 feet measured at average grade, and foothill lots may have additional ridgeline rules. Other cities and zones differ. Height limits rarely block a typical second story, but they can affect roof pitch and ceiling heights, especially on sloped lots. HOA rules and covenants may be stricter. See HOA approval.

5. Room for a stair

A second story needs a code-compliant staircase, which takes real floor area on both levels. If there is no place for it without losing a room you need, the project changes. Options include sacrificing a small bedroom, reworking an entry, or a small addition to hold the stair.

6. Systems and utilities

Bathrooms upstairs need drain and vent routes down through the house. The heating and cooling system may need a new zone or unit. The electrical service may need upgrading. None of these usually block a second story, but they shape cost and design.

A homeowner's pre-check

Before calling an engineer, you can gather useful information:

• Year built and any original plans or permits
• Foundation type: basement, crawlspace or slab
• Visible cracks in foundation walls, sticking doors or sagging lines
• Past additions or remodels, and whether they were permitted
• Your zone from the city map, and any HOA
• Where a stair could go on the main floor

What happens next

With that information, a feasibility visit and an engineer's first look can tell you whether a second story is realistic, roughly what reinforcement is involved, and how it compares with building out. Then design can start with confidence. See second story additions, second story cost and does an addition need an engineer?

Second story feasibility questions