Building Spec

Overview

Before generating any building, floor plan, or spatial design, always look for a project-specific specification file. This skill defines the workflow for finding, parsing, and applying custom dimension constraints so that every generated element matches client requirements. When no spec file exists, fall back to defaults from the architectural-dimensions skill.

Instructions

Step 1: Find the Spec File

Search the project root (and parent directories) for any of these filenames:

• BUILDING_SPEC.md
• DIMENSIONS.md
• building-spec.md
• dimensions.md

If found, load it and treat it as ground truth for all dimensions. To search the project and its parent directories from a shell:

find ~/projects/riverside-house ~/projects -maxdepth 1 \( -iname 'BUILDING_SPEC.md' -o -iname 'DIMENSIONS.md' -o -iname 'building-spec.md' -o -iname 'dimensions.md' \) 2>/dev/null

Step 2: Parse the Spec

Extract structured parameters from the spec file:

• Units: metric (meters) or imperial (feet/inches)
• Floor heights: ground, upper, basement ceiling heights
• Wall thicknesses: external, load-bearing, partition
• Door dimensions: main entrance, internal, bathroom (width x height)
• Window dimensions: sill height, standard size, room-specific overrides
• Room requirements: minimum area and width per room type
• Special requirements: accessibility, max height, setbacks, parking

Step 3: Apply During Generation

When generating building geometry:

1. Use spec values as absolute constraints for all dimensions
2. Fill any gaps with defaults (ceiling 2.7 m, exterior wall 0.25 m, partition 0.10 m, door 0.9 m x 2.1 m)
3. Every room must meet the spec minimum area and width
4. All doors and windows must use spec-defined sizes

Step 4: Validate Against Spec

After generation, check every element:

• Ceiling heights match spec per level type (ground vs upper)
• Wall thicknesses match spec (exterior vs partition)
• Door widths meet spec minimums
• Room areas meet spec minimums per room type
• Any violations must be reported or auto-corrected before output

Standard BUILDING_SPEC.md Template

Projects should create this file in the root directory:

# Building Dimensions Specification

## Project Information
- **Project name:** [Your Project Name]
- **Standard:** Metric (meters) | Imperial (feet/inches)
- **Building type:** Residential | Commercial | Mixed-use

## Floor Heights
- Ground floor: 2.7m
- Upper floors: 2.7m
- Basement: 2.4m

## Wall Thicknesses
- External walls: 0.25m
- Internal load-bearing: 0.20m
- Internal partitions: 0.10m

## Doors
- Main entrance: 1.0m wide x 2.1m tall
- Standard internal: 0.9m x 2.1m
- Bathroom: 0.8m x 2.1m

## Windows
- Standard sill height: 0.9m from floor
- Standard window: 1.2m wide x 1.2m tall

## Room Requirements
| Room | Min Area | Min Width |
|------|----------|-----------|
| Bedroom | 10m2 | 2.7m |
| Master bedroom | 16m2 | 3.2m |
| Kitchen | 8m2 | 2.4m |
| Bathroom | 4m2 | 1.5m |
| Living room | 20m2 | 3.5m |
| Corridor | -- | 1.0m |

Default Fallback Values

When no spec file is found, use these defaults. They are project conventions chosen by this skill, not code minimums. Local building code always governs. For US residential work, the 2021 IRC (section R305.1) requires a ceiling height of at least 7 ft (2134 mm) in habitable space and hallways, and 6 ft 8 in (2032 mm) in bathrooms, toilet rooms and laundry rooms. Section R304 requires habitable rooms other than kitchens to have at least 70 sq ft (6.5 m2) of floor area and no horizontal dimension under 7 ft (2134 mm). No default may fall below these. Confirm the edition and any local amendments with the ibc-building-codes and architectural-dimensions skills before relying on a value.

Examples

Example 1: Generate a Building from a Custom Spec

A project has BUILDING_SPEC.md with ground floor height 3.5 m (retail), upper floors 2.7 m, external walls 0.30 m, and minimum bedroom area 12 m2.

1. Find spec: BUILDING_SPEC.md exists in project root
2. Parse: ground=3.5 m, upper=2.7 m, ext_wall=0.30 m, bedroom_min=12 m2
3. Generate: ground floor level with 3.5 m ceiling, 0.30 m exterior walls, all bedrooms >= 12 m2
4. Validate: check each element against spec values
5. Result: all rooms meet custom minimums, ground floor has retail-height ceiling

Example 2: Validate an Existing Model Against Spec

A model has a bedroom at 9 m2 and 2.5 m wide, but the spec requires at least 10 m2 and 2.7 m width:

1. Load spec: bedroom min area = 10 m2, min width = 2.7 m
2. Scan model rooms: bedroom R-bed2 is 2.5 m x 3.6 m, area 9.0 m2, width 2.5 m
3. Violation detected:

ERROR  Bedroom 2 (R-bed2): area 9.0 m2 < spec minimum 10 m2
ERROR  Bedroom 2 (R-bed2): width 2.5 m < spec minimum 2.7 m
ERROR  2 violation(s), 0 warnings

4. Auto-fix: widen the room from 2.5 m to 2.8 m, keeping depth 3.6 m, so the area becomes 10.08 m2 (2.8 x 3.6)
5. Re-validate: the area (10.08 m2) now passes the 10 m2 minimum, and the new 2.8 m width passes the 2.7 m minimum width

Example 3: No Spec File Found

No BUILDING_SPEC.md or DIMENSIONS.md in the project:

1. Search project root and parent directories -- not found
2. Fall back to default values (2.7 m ceiling, 0.25 m ext wall, 0.10 m partition)
3. Generate using defaults from the architectural-dimensions skill
4. Validate against standard minimums

Guidelines

• Always search for a spec file before generating any architectural elements
• Spec values override all defaults -- treat the spec as ground truth
• If a spec value is missing for a particular element, use the default fallback
• Report all spec violations as errors, not warnings
• Pair this skill with architectural-dimensions for comprehensive validation
• When creating a new project, generate the BUILDING_SPEC.md template for the client to fill in
• Keep spec files in the project root for easy discovery