When searching for a new home, buyers evaluate many attributes like location, size, style and condition. One key consideration is the height and number of stories or levels within the home’s vertical footprint. But what exactly constitutes a “story” and what determines the total height from foundation to rooftop? Let’s take a deep dive into the nuanced structural formula of residential story heights.
Defining a Story Per Building Codes
To understand house stories, we must first define what comprises a story based on building codes. According to the International Residential Code (IRC) that regulates home construction in most areas, a story is technically defined as:
“That portion of a building included between the upper surface of a floor and the upper surface of the floor or roof next above.”
This building code description equates a story to a livable level that has a solid floor surface below and a ceiling surface above. The habitable space in between must meet minimum height requirements, which IRC sets at 7 feet for the first floor and 7 feet 3 inches for upper floors. Some local codes have minor variations.
So, in simple terms, a full story per code is a section of the home enclosed top and bottom that achieves legal ceiling height standards for habitation. The number of stories then depends on how many stacked levels meet IRC height allowances.
Differentiating Room Height vs. Story Height
Note there is a distinction between room ceiling height – the required vertical distance between finished floor and finished ceiling per IRC – and total exterior story height, which adds in the thickness of the floors and roof structure.
For example, consider this room and story height breakdown:
- Bedroom ceiling height: 8 feet
- Floor truss depth: 1 foot
- Roof rafters: 1 foot
While the interior room height is 8 feet, the total exterior story height is 10 feet when you account for the sandwiching floor and roof assemblies. This difference between minimum legal room clearance and overall height of each story is a critical concept.
Now that we’ve defined a story based on building code standards, what are typical heights for single story versus two story homes? Well, the answer involves several influencing factors.
Impact of Foundation and Basement on Height
The foundation system and presence of a basement can greatly impact total house height. Consider these examples:
- Slab on Grade: With a basic concrete slab foundation poured at ground level, the first-floor elevation is minimally above grade just a foot or two.
- Crawlspace: A shallow crawlspace foundation may add 2-3 feet of height below the first floor, elevating it slightly off the ground.
- Basement: A standard 8-foot interior height finished basement adds approximately 9 feet of overall foundation height when you include the concrete walls and floor.
- Walkout Basement: A walkout or lookout daylight basement has the concrete foundation wall exposed on one side, which adds perceived height. The exposed foundation wall on the walkout side may be 9-10 feet tall from ground to the first-floor level.
As you can see, foundation and basement options alone can create a height variance of 8-10 feet or more before even counting the visible above ground stories of the home!
Typical Height Ranges for Single and Two Story Homes
Given the significant impact of basements and foundations, what are typical total height ranges for single story versus two story homes?
Single Story Home Height
- Slab on Grade: With a slab foundation, single story home heights are often in the range of 13-15 feet total from ground to roof peak.
- Crawlspace: A shallow crawlspace adds 1-2 feet, so typical single story home height is often 15-17 feet.
- Basement: With a walkout or daylight basement with approximately 8 feet of interior clearance, total single story home height is commonly in the 20–22-foot range.
Two Story Home Height
- Slab Foundation: Having a slab, two story home height often ranges from 22-25 feet total.
- Crawlspace: A crawlspace typically adds 1-2 feet, so two-story home height often ranges 25-28 feet.
- Basement: By adding a full 8-foot height basement, two story homes are commonly 28-32 feet tall from bottom to top.
As shown in these examples, while the IRC sets minimum interior room height requirements, several other structural factors cause the total exterior height of both single- and two-story homes to have wide variance.
How Walls, Floors and Roof Framing Influence Height
To understand what makes up the differences between minimum legal room clearance and total exterior story height, let’s look at how structural elements like walls, floors and roof framing add height:
- Foundation Walls: Concrete foundation walls connect the footing below to the first-floor framing above, commonly adding 1-2 feet.
- Floor Joists: Standard 2×10 floor joists add approximately 1 foot of height per floor. Manufactured floor trusses may add 1.5-2 feet.
- Roof Rafters: Standard roof rafter framing adds roughly 1 foot from the top floor ceiling to the roof ridge.
Given the typical thicknesses of these framing components, you can see how IRC mandated room heights of 7-7.5 feet for livable stories translate to total exterior house heights that commonly exceed 13+ feet for even single-story homes.
For a conceptual two-story home over a crawlspace for example, let’s assume the first-floor ceiling height is 9 feet and the second-floor ceiling is 12 feet. Add 1 foot of crawlspace clearance, 1 foot of floor joists, 2 feet for the thicker second floor trusses, and 1 foot of roof rafters. This totals approximately 27 feet of overall house height.
This exercise demonstrates how required interior room clearances and the depths of framing like floors and roof relate to complete exterior house heights.
Impact of Minimum Room Height on Overall Height
Now let’s examine a scenario where room heights are designed right at IRC minimums to understand the impact on total height.
If a single-story home was built with 7-foot first floor ceiling clearances and 2×8 floor joists, the total exterior height would end up around 13 feet if constructed on a slab foundation.
For a two-story home with 7-foot first floor ceiling height, 7.5-foot second floor ceiling height per code, and thinner 2×6 trusses, the total exterior height works out to approximately 22 feet with a crawlspace.
Comparing these outputs to the previous examples with 9-foot main floor and 12-foot second floor ceilings illustrates how every inch of designed interior room height gets exponentially multiplied into overall exterior house height. Carefully targeting code minimum interior clearances does meaningfully reduce the total vertical envelope.
Influences on Achievable Room Height
Besides desired design heights, achievable interior room clearances are also impacted by factors like ceiling style and depth of HVAC ductwork. Here are some common elements that can alter usable ceiling height:
- Tray ceilings: Tray or coffered ceilings reduce headroom versus simple flat drywall ceilings.
- Dropped ceilings: Lower dropped ceilings are sometimes installed to cover HVAC ductwork running through the truss space.
- Ductwork bulkheads: The edges of vertical ducts eating into headroom are often boxed in with bulkheads.
- Lighting fixtures: Ceiling mount lights, fans and chandeliers consume space that lowers ceiling height.
- Energy heel trusses: These engineered designs provide more insulation room but less interior headroom.
- Structural beams: Required load-bearing beams may drop below the ceiling plane.
These types of items intrude into the vertical room envelope, reducing livable ceiling height. Careful coordination is required so that factors like ductwork routes and lighting plans don’t diminish clearance below legal limits or desired aesthetic heights.
Is Adjusting Story Height Possible?
Can builders easily modify planned story heights by adjusting factors like room clearance, truss depths, and roof pitch? Yes, to some degree if the building plans and codes permit flexibility.
For instance, switching floor and roof framing from standard trusses to shorter dimensional lumber joists could potentially reduce each story height by 6 inches or more. Going from a hip roof design to a shallower sloped shed style can lower the peak height several feet. Omitting ductwork running through truss spaces avoids dropped ceilings trading height for mechanical space.
However, available flexibility is limited by structural and building code requirements. For example:
- Legal egress window and room height minimums cannot be violated just for the sake of gaining a lower exterior height.
- Engineered trusses have load, span, and cutting angle limitations that may restrict height adjustments.
- Widening floor joists from 2×10 to 2×12 to reduce height gains strength but loses valuable inches.
- Roof pitch and style impact drainage and attic space, not just height.
While some modifications are possible, the structural integrity, usage, and code compliance impact must be thoroughly evaluated by architects, truss engineers, and builders. Significant height changes often require re-engineering foundation sizes, bearing points, joist layouts, spans, truss configurations and roof loads to ensure safety and conformance to building standards.
Maximizing Height Within Zoning Code Allowances
When designing new home plans, how can designers and builders maximize overall height to take full advantage of IRC allowances and zoning limitations?
A common baseline is designing for standard 8-foot ceiling height on the first floor and 9 feet on additional upper floors. This allows space to make minor adjustments while remaining within code.
Additionally, local zoning setback regulations provide a maximum building envelope specific to each lot. Carefully positioning the new home on the lot to take advantage of this full height allowance is wise planning.
For example, codes may prohibit total heights over 35 feet. But moving the building footprint 20 feet away from rear setback could allow for a 33-foot design height plus an extra 2 feet to accommodate roof overhangs.
Experienced home designers and builders will collaboratively work to optimize interior room and total exterior heights within governing codes and zoning constraints to maximize living space.
Terminology Describing Story Heights in Listings
Now that we’ve covered what comprises room, floor and overall house heights, let’s clarify some common terminology used when describing stories or levels in real estate listings or builder plans:
- Single Story Home: This typically refers to a ranch style home with one level of living space, potentially over a basement or crawlspace.
- Two Story Home: As defined earlier, a two-story home has two full stacked levels of living space typically over a first-floor foyer.
- Three Story Home: Three story homes add a third fully enclosed upper level over a two-story layout, typically over a walkout basement.
- Multi-Level Home: Indicates more than three levels of living space stacked vertically. Could be a tri-level split, staggered split level, or additional full stories.
- 1.5 Story Home: Describes a home with a main first floor, finished upper level tucked under angled roof framing, and optionally a basement.
- Raised Ranch: A ranch style home with a taller first floor on top of an exposed basement or walkout lower level.
- Cape Cod: A single story home with usable living space finished under the roof framing, accessed by stairs to a second level loft.
As you can see, real estate descriptive terms refer more to the usable living space than precise interior or overall exterior heights. Function takes priority over form in naming conventions.
Ideal Story Height Based on Needs and Design
Choosing the ideal number of interior stories as well as defining room and total house heights should be based on factors like:
- Location: Blend with the scale of surrounding homes. Corner lots often permit greater heights.
- Lifestyle Needs: Ranch style single level living is preferred for aging in place. Younger families often gravitate toward two story designs.
- Budget: Adding height adds costs for roofing, siding, foundation, and truss work.
- Intended Use: Entertaining spaces like great rooms warrant increased height versus utilitarian rooms.
- Ceiling Styles: Tray ceilings reduce headroom but add visual interest. Flat planes feel most expansive.
- Foundation Options: Daylight basements appear to add a story when the wall is exposed on one side.
- HVAC Considerations: Dropped ceilings and duct soffits can cramp rooms but conceal systems.
- Natural Lighting: More space under roof peaks improves light from skylights and upper windows.
- Starting the design process by defining both desired aesthetic heights and practical minimum clearances will help determine the appropriate vertical dimensions and number of stories. Build floor plans from the interior space needs outwards.
Demystifying House Story Heights
Understanding how IRC mandated minimum room heights, standard construction assemblies, and foundation configurations combine to create overall exterior house height helps demystify the common terminology of ranch height versus two story homes. Hidden framing dimensions explain why the total heights end up substantially taller than interior living spaces in many new homes.
This allows buyers, designers and builders to make informed decisions when planning ideal ceiling heights, truss configurations, foundation options and number of stories. With realistic expectations of how room functions, construction methods and codes define total house height, you can confidently shop or design a home tailored to your family’s needs.
The complex matrix of code minimums, material spans, site variability, and user needs requires expertise to solve. Seek out experienced architectural designers, truss engineering consultants, and home builders well-versed in harmonizing the elements to craft comfortable, functional living spaces within the three-dimensional envelope from footer to rooftop.
Last Updated on 9 months by admin
