Home Construction Basics: Understanding How Houses Are Built

Learn essential home construction fundamentals for Seattle buyers: foundations, framing, materials, Pacific Northwest considerations, and how to spot quality issues during tours.

Tags:construction, home-inspection, property-evaluation, seattle, pacific-northwest
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You're touring a home. The agent says "post-and-beam construction." You nod, but have no idea what that means. You see cracks in the foundation. Are they normal or serious? The roof looks old. How old is too old?

Understanding basic home construction helps you make smarter decisions when buying. You'll spot potential issues during tours, ask better questions, understand inspection reports, and know what maintenance your home needs. You don't need to be a contractor, but knowing the basics protects your investment.

Table of Contents

Why Understanding Construction Matters

Make Better Buying Decisions

Spot issues during tours:

  • Foundation cracks: Normal settling or structural problem?
  • Roof condition: 5 years left or 15?
  • Moisture damage: Surface issue or systemic problem?

Ask better questions:

  • "What type of foundation does this have?"
  • "When was the roof last replaced?"
  • "Is this original siding or replacement?"

Understand inspection reports:

  • Inspector mentions "balloon framing" – what does that mean?
  • "Inadequate crawl space ventilation" – why does it matter?
  • "Galvanized plumbing" – is that bad?

Budget for Maintenance

Different materials = different lifespans:

  • Composition roof: 20–25 years
  • Metal roof: 40–70 years
  • Wood siding: 20–40 years
  • Fiber cement siding: 50+ years

Plan for replacements:

  • Know when major systems need replacement
  • Budget accordingly
  • Avoid surprises

Understand Your Home

How it works:

  • Where is the main water shut-off?
  • How does the heating system work?
  • Why is there moisture in the crawl space?

What maintenance it needs:

  • Crawl space homes: Check for moisture
  • Flat roofs: More maintenance than pitched
  • Wood siding: Needs painting every 5–7 years

Foundation Types

Crawl Space (Most Common in Seattle)

What it is:

  • Raised foundation
  • 18–48 inches of space under house
  • Access through small door
  • House sits on foundation walls

Why common in Seattle:

  • Sloped lots (common in Seattle)
  • Moisture management (keeps wood off ground)
  • Access to plumbing and utilities
  • Seismic performance (flexible)

Components:

  • Concrete foundation walls (perimeter)
  • Concrete footings (below frost line)
  • Floor joists (support floor)
  • Subfloor (plywood on joists)
  • Vapor barrier (plastic on ground)
  • Vents (for air circulation)

Pros:

  • Access to plumbing and utilities
  • Easier to repair
  • Better for sloped lots
  • Good seismic performance

Cons:

  • Moisture issues (common in Seattle)
  • Pest access (rodents, insects)
  • Cold floors (if not insulated)
  • Requires maintenance (check for moisture)

Seattle-specific:

  • Most common foundation type
  • Moisture management critical (rainy climate)
  • Check for standing water, mold, rot
  • Vapor barrier and ventilation essential

Slab-on-Grade (Less Common in Seattle)

What it is:

  • Concrete slab poured directly on ground
  • No crawl space or basement
  • House sits on slab

Components:

  • Concrete slab (4–6 inches thick)
  • Gravel base (drainage)
  • Vapor barrier (under slab)
  • Insulation (around perimeter)
  • Rebar or wire mesh (reinforcement)

Pros:

  • Lower cost
  • No moisture issues (no crawl space)
  • No pest access
  • Warm floors (thermal mass)

Cons:

  • No access to plumbing (in slab)
  • Difficult to repair plumbing
  • Cracks can be serious
  • Not suitable for sloped lots

Seattle-specific:

  • Rare in Seattle (sloped lots, moisture)
  • More common in newer developments
  • More common in eastern Washington

Full Basement (Uncommon in Seattle)

What it is:

  • Full-height space under house
  • 8+ feet tall
  • Can be finished or unfinished

Components:

  • Concrete foundation walls (full height)
  • Concrete floor slab
  • Floor joists above
  • Stairs for access

Pros:

  • Additional living space
  • Storage
  • Access to utilities
  • Can be finished

Cons:

  • Expensive to build
  • Moisture issues (common in Seattle)
  • Flooding risk
  • Requires waterproofing

Seattle-specific:

  • Uncommon (expensive, moisture issues)
  • More common in older homes (pre-1950)
  • Daylight basements common on sloped lots

Pier and Beam (Older Homes)

What it is:

  • House sits on concrete piers
  • Beams span between piers
  • Floor joists on beams
  • Similar to crawl space but piers instead of walls

Components:

  • Concrete piers (every 6–8 feet)
  • Beams (span between piers)
  • Floor joists (on beams)
  • Subfloor

Pros:

  • Good for sloped lots
  • Flexible (seismic)
  • Easy to level (adjust piers)

Cons:

  • Less stable than continuous foundation
  • Moisture issues
  • Pest access
  • Settling (piers can sink)

Seattle-specific:

  • Common in older homes (pre-1950)
  • Often needs releveling
  • Check for settling, rot

Framing Types

Platform Framing (Most Common)

What it is:

  • Modern standard construction
  • Each floor is a platform
  • Walls built on platform
  • Next floor built on top

How it works:

  • Foundation → First floor platform → First floor walls → Second floor platform → Second floor walls → Roof

Components:

  • Studs (vertical 2x4 or 2x6, 16" or 24" apart)
  • Plates (horizontal top and bottom)
  • Headers (over windows and doors)
  • Sheathing (plywood or OSB)

Pros:

  • Strong and stable
  • Fire-resistant (fire stops at each floor)
  • Easy to build
  • Standard in modern construction

Cons:

  • More lumber than balloon framing
  • Slightly more expensive

Seattle-specific:

  • Standard in homes built after 1950
  • Required by modern building codes

Balloon Framing (Older Homes)

What it is:

  • Older construction method (pre-1950)
  • Studs run from foundation to roof (continuous)
  • Floors hang on studs

How it works:

  • Long studs (20–30 feet) run full height
  • Floor joists attached to studs
  • No fire stops between floors

Pros:

  • Less lumber
  • Faster to build (historically)
  • Strong vertical support

Cons:

  • Fire hazard (no fire stops, fire spreads quickly)
  • Difficult to insulate
  • Settling issues
  • Not used in modern construction

Seattle-specific:

  • Common in homes built before 1950
  • If you buy one, add fire stops
  • Check for settling

Post-and-Beam (Specialty)

What it is:

  • Large posts (vertical) and beams (horizontal)
  • Fewer, larger members
  • Open interior spaces

How it works:

  • Large posts (6x6, 8x8) support beams
  • Beams support roof and floors
  • Walls are non-structural (can be moved)

Pros:

  • Open floor plans
  • Exposed beams (aesthetic)
  • Flexible interior layout
  • Strong

Cons:

  • Expensive
  • Requires skilled labor
  • Fewer contractors familiar with it

Seattle-specific:

  • Common in mid-century modern homes
  • Popular in contemporary custom homes
  • Expensive to modify

Exterior Materials

Siding Types

1. Wood siding (Cedar, common in Seattle):

  • Lifespan: 20–40 years
  • Maintenance: Paint/stain every 5–7 years
  • Pros: Beautiful, natural, traditional
  • Cons: High maintenance, rot, insects
  • Cost: $8–$12 per sq ft installed (2024)

2. Fiber cement (Hardie Board):

  • Lifespan: 50+ years
  • Maintenance: Paint every 10–15 years
  • Pros: Durable, low maintenance, fire-resistant
  • Cons: Heavy, expensive
  • Cost: $10–$14 per sq ft installed (2024)

3. Vinyl:

  • Lifespan: 20–40 years
  • Maintenance: Wash occasionally
  • Pros: Low maintenance, affordable
  • Cons: Can crack, fades, looks cheap
  • Cost: $4–$8 per sq ft installed (2024)

4. Brick:

  • Lifespan: 100+ years
  • Maintenance: Minimal (repoint mortar every 25–30 years)
  • Pros: Durable, low maintenance, fire-resistant
  • Cons: Expensive, heavy
  • Cost: $15–$30 per sq ft installed (2024)

5. Stucco:

  • Lifespan: 50–80 years
  • Maintenance: Repaint every 5–10 years
  • Pros: Durable, fire-resistant
  • Cons: Cracks, moisture issues (in Seattle)
  • Cost: $6–$9 per sq ft installed (2024)

Seattle-specific:

  • Cedar siding very common (traditional)
  • Fiber cement increasingly popular (low maintenance)
  • Stucco less common (moisture issues)
  • Check for moisture damage behind siding

Roofing Types

1. Composition shingles (Most common):

  • Lifespan: 20–25 years (Seattle climate)
  • Maintenance: Inspect annually, remove moss
  • Pros: Affordable, easy to install
  • Cons: Shorter lifespan, moss growth (Seattle)
  • Cost: $5–$8 per sq ft installed (2024)

2. Metal:

  • Lifespan: 40–70 years
  • Maintenance: Minimal
  • Pros: Durable, fire-resistant, no moss
  • Cons: Expensive, noisy (rain)
  • Cost: $10–$16 per sq ft installed (2024)

3. Cedar shake:

  • Lifespan: 20–30 years
  • Maintenance: Treat for moss, inspect regularly
  • Pros: Beautiful, traditional
  • Cons: High maintenance, fire risk, expensive
  • Cost: $12–$20 per sq ft installed (2024)

4. Tile (Clay or concrete):

  • Lifespan: 50–100 years
  • Maintenance: Minimal
  • Pros: Durable, fire-resistant, beautiful
  • Cons: Very expensive, very heavy
  • Cost: $15–$30 per sq ft installed (2024)

5. Flat/low-slope (Tar and gravel, TPO, EPDM):

  • Lifespan: 15–30 years (depends on material)
  • Maintenance: Inspect regularly, clear drains
  • Pros: Modern aesthetic, usable space
  • Cons: More maintenance, drainage issues
  • Cost: $8–$15 per sq ft installed (2024)

Seattle-specific:

  • Composition shingles most common
  • Moss growth is major issue (remove annually)
  • Metal roofs increasingly popular (no moss)
  • Flat roofs require more maintenance (drainage)

Interior Systems

Plumbing

Pipe materials:

1. Copper (1950s–present):

  • Lifespan: 50–70 years
  • Pros: Durable, reliable
  • Cons: Expensive, can corrode
  • Status: Good, standard

2. PEX (1990s–present):

  • Lifespan: 50+ years (estimated)
  • Pros: Flexible, easy to install, freeze-resistant
  • Cons: Relatively new (long-term unknown)
  • Status: Good, increasingly common

3. Galvanized steel (pre-1960):

  • Lifespan: 40–50 years
  • Pros: Strong
  • Cons: Corrodes, low water pressure, rust
  • Status: Bad, needs replacement

4. Polybutylene (1970s–1990s):

  • Lifespan: 10–15 years (failed early)
  • Pros: None
  • Cons: Brittle, leaks, class action lawsuit
  • Status: Very bad, replace immediately

5. Cast iron (pre-1975, drain pipes):

  • Lifespan: 50–75 years
  • Pros: Durable, quiet
  • Cons: Corrodes, cracks, heavy
  • Status: Okay if not corroded, monitor

Seattle-specific:

  • Many older homes have galvanized pipes (replace)
  • Sewer lines often clay or cast iron (scope before buying)
  • Tree roots invade sewer lines (common issue)

Electrical

Wiring types:

1. Copper (1960s–present):

  • Lifespan: 100+ years
  • Pros: Safe, reliable, standard
  • Cons: Expensive
  • Status: Good

2. Aluminum (1960s–1970s):

  • Lifespan: 100+ years (if properly connected)
  • Pros: Cheaper than copper
  • Cons: Fire hazard (if improperly connected), oxidizes
  • Status: Okay if properly maintained, monitor

3. Knob-and-tube (pre-1950):

  • Lifespan: 100+ years (but outdated)
  • Pros: None (outdated)
  • Cons: No ground, fire hazard, not insurable
  • Status: Bad, needs replacement

Electrical panels:

1. Modern breaker panel:

  • Standard in homes built after 1960
  • Safe, reliable
  • 100–200 amp service typical

2. Fuse box:

  • Common in homes built before 1960
  • Outdated, undersized
  • Should be upgraded

3. Federal Pacific or Zinsco panels:

  • Known fire hazards
  • Should be replaced immediately

Seattle-specific:

  • Many older homes have undersized panels (60–100 amp)
  • Upgrade to 200 amp for modern needs
  • Knob-and-tube common in pre-1950 homes (replace)

HVAC

Heating types in Seattle:

1. Forced air furnace (Most common):

  • Natural gas or electric
  • Ductwork throughout house
  • Lifespan: 15–20 years
  • Can add AC easily

2. Heat pump:

  • Heating and cooling
  • More efficient than furnace
  • Lifespan: 15–20 years
  • Increasingly popular

3. Baseboard electric:

  • Individual room control
  • No ductwork
  • Lifespan: 20+ years
  • Expensive to operate

4. Radiant floor:

  • Hydronic (water) or electric
  • Very comfortable
  • Lifespan: 30+ years
  • Expensive to install

5. Boiler (Older homes):

  • Radiators or baseboard
  • Natural gas or oil
  • Lifespan: 20–30 years
  • Less common now

Seattle-specific:

  • AC not standard (mild summers)
  • But increasingly desired (heat waves)
  • Heat pumps increasingly popular (heating + cooling)
  • Many homes have no AC (add window units or mini-splits)

Pacific Northwest Construction Considerations

Moisture Management

Seattle's biggest challenge:

  • 150+ rainy days per year
  • High humidity
  • Moisture causes: rot, mold, pests

Critical construction features:

1. Proper drainage:

  • Gutters and downspouts
  • Downspouts drain 5+ feet from foundation
  • Graded lot (slopes away from house)

2. Vapor barriers:

  • In crawl space (plastic on ground)
  • Behind siding (building paper or house wrap)
  • Prevents moisture intrusion

3. Ventilation:

  • Crawl space vents
  • Attic vents
  • Bathroom exhaust fans (vented outside)
  • Prevents moisture buildup

4. Flashing:

  • Around windows and doors
  • At roof penetrations
  • Prevents water intrusion

5. Overhangs:

  • Roof overhangs (12–24 inches)
  • Protects siding from rain
  • Common in Seattle homes

Red flags:

  • No gutters or downspouts
  • Downspouts drain next to foundation
  • No crawl space vapor barrier
  • Inadequate ventilation
  • Missing or damaged flashing

Seismic Considerations

Seattle is in earthquake zone:

  • Cascadia Subduction Zone
  • Seattle Fault
  • Homes should be earthquake-resistant

Seismic retrofitting (for older homes):

1. Bolt to foundation:

  • Anchor sill plate to foundation
  • Prevents house from sliding off foundation
  • Cost: $3,000–$7,000 (2024)

2. Cripple wall bracing:

  • Strengthen short walls in crawl space
  • Prevents collapse
  • Cost: $3,000–$7,000 (2024)

3. Soft story bracing:

  • Strengthen garage or large openings
  • Prevents collapse
  • Cost: $5,000–$15,000 (2024)

When needed:

  • Homes built before 1990 (pre-seismic codes)
  • Especially pre-1950 homes
  • Check with structural engineer

Seattle programs:

  • City of Seattle offers grants for seismic retrofits
  • Up to $7,500 for low-income homeowners
  • Check seattle.gov/emergency-management

Slope and Drainage

Seattle has hills:

  • Many homes on sloped lots
  • Drainage is critical
  • Retaining walls common

Construction considerations:

1. Daylight basements:

  • Basement on downhill side
  • Windows and doors
  • Additional living space

2. Retaining walls:

  • Hold back soil
  • Prevent erosion
  • Need proper drainage behind wall

3. Drainage systems:

  • French drains
  • Catch basins
  • Prevent water from flowing toward house

Red flags:

  • Cracks in retaining walls
  • Leaning retaining walls
  • Water flowing toward house
  • Erosion

How to Assess Construction Quality

During Home Tours

Foundation:

  • Walk around perimeter
  • Look for cracks (hairline okay, wide cracks bad)
  • Check for settling (doors/windows stick)
  • Look for moisture (stains, efflorescence)
  • Check crawl space (if accessible)

Framing:

  • Check for level floors (marble test)
  • Look for sagging (ceiling, floors)
  • Check for cracks (walls, ceilings)
  • Look for additions (match original construction?)

Roof:

  • Look from street (sagging, missing shingles)
  • Check age (ask seller)
  • Look for moss (common in Seattle)
  • Check gutters (full of debris?)

Siding:

  • Look for damage (cracks, rot, missing pieces)
  • Check for moisture (stains, mold)
  • Look for paint condition (peeling, fading)
  • Check caulking (around windows, doors)

Windows and doors:

  • Open and close (stick or smooth?)
  • Check for drafts (feel around edges)
  • Look for condensation (between panes)
  • Check condition (rot, damage)

Interior:

  • Check for water stains (ceilings, walls)
  • Look for cracks (walls, ceilings)
  • Check floors (level, squeaky, damaged)
  • Test faucets (water pressure, leaks)
  • Flush toilets (work properly?)
  • Test lights and outlets (work?)

Red Flags

Foundation:

  • Wide cracks (>1/4 inch)
  • Horizontal cracks
  • Stair-step cracks in brick
  • Bowing walls
  • Doors and windows stick

Framing:

  • Sagging floors or ceilings
  • Sloping floors (marble rolls)
  • Large cracks in walls or ceilings
  • Doors don't close properly

Roof:

  • Sagging
  • Missing shingles
  • Curling shingles
  • Heavy moss growth
  • Age 20+ years

Moisture:

  • Water stains
  • Mold or mildew smell
  • Rot (soft wood)
  • Efflorescence (white powder on concrete)
  • Standing water in crawl space

Electrical:

  • Knob-and-tube wiring
  • Aluminum wiring (if not properly maintained)
  • Federal Pacific or Zinsco panels
  • Fuse box (outdated)

Plumbing:

  • Galvanized pipes
  • Polybutylene pipes
  • Low water pressure
  • Rust in water

Construction and Home Age

New Construction (0–5 years)

Pros:

  • Modern materials and methods
  • Energy efficient
  • Up to code
  • Warranty (typically 1–2 years)
  • No deferred maintenance

Cons:

  • Higher price
  • Smaller lots (typically)
  • Less character
  • Settling issues (first few years)

What to check:

  • Builder reputation
  • Warranty coverage
  • Quality of finishes
  • Lot drainage

Modern (5–30 years)

Pros:

  • Modern amenities
  • Good condition (if maintained)
  • Energy efficient (relatively)
  • Up to code (mostly)

Cons:

  • May need updates (kitchens, baths)
  • Systems approaching end of life (15–20 years)

What to check:

  • Maintenance records
  • Age of major systems (roof, HVAC, water heater)
  • Updates and improvements
  • Deferred maintenance

Mid-Century (30–75 years, 1950–1990)

Pros:

  • Established neighborhoods
  • Larger lots (typically)
  • Character and charm
  • Solid construction (if maintained)

Cons:

  • Needs updates
  • Systems at or past end of life
  • May not be energy efficient
  • May need seismic retrofit

What to check:

  • Foundation condition
  • Electrical (aluminum wiring, undersized panel)
  • Plumbing (galvanized pipes)
  • Roof age
  • Seismic retrofit status

Historic (75+ years, pre-1950)

Pros:

  • Character and charm
  • Established neighborhoods
  • Larger lots
  • Quality materials (old-growth lumber)

Cons:

  • Needs significant updates
  • Systems outdated
  • Not energy efficient
  • Needs seismic retrofit
  • May have knob-and-tube wiring

What to check:

  • Foundation (pier and beam, settling)
  • Electrical (knob-and-tube)
  • Plumbing (galvanized, cast iron)
  • Framing (balloon framing)
  • Seismic retrofit status
  • Historic designation (limits changes)

Summary

Understanding basic construction helps you make informed buying decisions and spot issues during tours. Seattle homes typically have crawl space foundations where moisture management is critical. Platform framing is standard in modern homes, while balloon framing appears in pre-1950 homes.

Common siding includes cedar (high maintenance), fiber cement (low maintenance), and vinyl (affordable). Composition shingles last 20–25 years, while metal roofs last 40–70 years. For plumbing, copper and PEX are good, but galvanized and polybutylene need replacement. Copper electrical wiring is good, aluminum is okay if maintained, and knob-and-tube is bad.

Pacific Northwest challenges include moisture management, seismic retrofitting, and slope drainage. Red flags include wide foundation cracks, sagging, water stains, and outdated systems. Older homes (pre-1990) may need seismic retrofitting costing $3,000–$15,000.

Next Steps

During home tours:

  1. Identify construction types
  2. Check for red flags (foundation cracks, water stains, sagging, outdated systems)
  3. Ask questions about roof age, plumbing type, and seismic retrofits

After finding a home:

  1. Review inspection report carefully
  2. Budget for updates based on home age and condition
  3. Understand your home's construction needs
  4. Maintain properly based on construction type

Additional Resources

Learn more:

  • This Old House: thisoldhouse.com
  • Family Handyman: familyhandyman.com
  • Fine Homebuilding: finehomebuilding.com

Seattle-specific:

  • Seattle DCI (permits, codes): seattle.gov/sdci
  • King County (building codes): kingcounty.gov/depts/local-services/permits
  • Seismic retrofitting: seattle.gov/emergency-management/hazards/earthquakes

Find contractors:

  • Verify licenses: lni.wa.gov
  • Check reviews: Angi, Thumbtack, NextDoor

Disclaimer: This article provides general information about home construction for educational purposes. Construction standards, building codes, and best practices vary by location and change over time. Always consult with licensed professionals including home inspectors, structural engineers, and contractors for specific advice about any property you're considering. Cost estimates are approximate and based on 2024 Seattle-area averages – actual costs vary significantly based on project scope, materials, and contractor.

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