Learning Center tool
Home systems: what costs the most.
Every home is a stack of systems with different price tags and different clocks. Pick a home type, tap a numbered system, and see its replacement-cost tier, typical lifespan, what the inspector will look for — and what to have up to spec before you list. No dollar figures, on purpose: costs vary too widely to print honestly.
Interactive cutaway
Pick a home type, then tap a numbered system.
Modern house — system 1 of 8
Roof & gutters
- Replacement cost
- Among the most expensive systems in the house to replace — usually the largest single exterior line item a buyer or seller faces.
- Typical lifespan
- A composition shingle roof typically lasts 20–30 years; metal and membrane roofs commonly run longer. Typical ranges only — varies with maintenance, ventilation, and climate.
- What the inspector looks for
- The general inspector reads the roof from the surface down: shingle or membrane condition, flashing at every penetration, gutter slope and downspout discharge, and moss — the Seattle constant. Anything ambiguous escalates to a licensed roofer, who can say repair-versus-replace with a number behind it.
- Have it up to spec when you list
- Have the moss treated, gutters cleaned, and flashing intact before photos. If the roof was replaced, have the permit and the installer's paperwork ready — a documented roof age answers the buyer's biggest exterior question before it's asked.
The modern house, system by system
Eight systems carry most of a land home's replacement risk. Here's each one — cost tier, typical lifespan, what the inspector looks for, and what to have up to spec before you list.
What does a roof cost to replace, and how long does one last?
Among the most expensive systems in the house to replace — usually the largest single exterior line item a buyer or seller faces. A composition shingle roof typically lasts 20–30 years; metal and membrane roofs commonly run longer. Typical ranges only — varies with maintenance, ventilation, and climate.
What the inspector looks for: The general inspector reads the roof from the surface down: shingle or membrane condition, flashing at every penetration, gutter slope and downspout discharge, and moss — the Seattle constant. Anything ambiguous escalates to a licensed roofer, who can say repair-versus-replace with a number behind it.
Have it up to spec when you list: Have the moss treated, gutters cleaned, and flashing intact before photos. If the roof was replaced, have the permit and the installer's paperwork ready — a documented roof age answers the buyer's biggest exterior question before it's asked.
Exterior section of the inspection checklist · What a licensed roofer sees · Vendor partners
How long do a furnace and heat pump last, and what do they cost to replace?
A top-tier mechanical expense — replacing a furnace or heat pump is one of the costlier single-equipment jobs in the house, and ductwork adds to it. A gas furnace typically runs 15–20 years; a heat pump 10–15; ducts far longer if sealed and intact. Typical ranges only — varies with maintenance and run hours.
What the inspector looks for: The inspector runs the system in its normal modes, checks the filter, visible ducts, and venting, and reads the data plate for age. Cracked heat exchangers, refrigerant health, and end-of-life calls belong to a licensed HVAC professional.
Have it up to spec when you list: Have the system serviced and the receipt in hand, put in a clean filter, and clear access to the equipment. A serviced HVAC with records reads as a maintained house — the inverse reads as deferred everything.
HVAC section of the inspection checklist · What an HVAC pro checks · Vendor partners
What does electrical work cost, and when does a panel need replacing?
A panel upgrade sits mid-tier; whole-house rewiring is one of the most invasive and expensive projects a house can need — which is why old wiring moves negotiations. Modern copper wiring outlasts the owner; panels typically serve 25–40 years, and certain legacy brands and knob-and-tube or aluminum branch wiring get flagged regardless of age. Typical ranges only.
What the inspector looks for: The inspector opens the panel cover, looks for double-taps, scorching, and legacy wiring, and tests GFCI and AFCI protection where today's standards expect it. Anything inside the panel beyond looking is a licensed electrician's job — bids, not adjectives, win credits.
Have it up to spec when you list: Label the panel, make it reachable, and fix the cheap misses — dead outlets, missing GFCIs at kitchens, baths, and exterior. Permits for any electrical work you've had done belong in your records folder.
Electrical section of the inspection checklist · When an electrician needs to look · Vendor partners
What do plumbing and sewer problems cost to fix?
Supply repairs are usually modest; a failed side sewer is one of the most expensive surprises in Seattle's older housing stock — which is why the sewer scope exists. Copper supply lines commonly serve 50+ years, PEX decades, galvanized steel is end-of-life on sight; clay and concrete sewer laterals in older neighborhoods are exactly what the camera checks. Typical ranges only.
What the inspector looks for: The inspector runs fixtures, checks water pressure, looks under every sink, and finds the main shut-off. On older homes the escalation is a dedicated sewer scope — inexpensive against what it can find.
Have it up to spec when you list: Fix drips and slow drains before listing, know where your shut-off is, and if you've had the sewer scoped or repaired, produce the report. A clean scope in the listing folder removes a buyer's scariest unknown.
Plumbing section of the inspection checklist · Why buyers order a sewer scope · Vendor partners
How long does a water heater last?
One of the more affordable major replacements — but a leaking tank damages everything under and around it, so age still matters. A tank water heater typically lasts 8–12 years; tankless units commonly longer with maintenance. Typical ranges only — hard water and no maintenance shorten both.
What the inspector looks for: Age from the data plate, rust at the fittings, a functioning temperature-and-pressure-relief (TPR) valve with a proper discharge line, and — in Washington — seismic strapping. Gas units get their venting checked.
Have it up to spec when you list: Strap it to code, verify the TPR discharge line, and clear the space around it. If it's past its typical life, expect the buyer to price a replacement in — deciding that before listing beats negotiating it after.
Plumbing section of the inspection checklist · Vendor partners
What does window replacement cost, and when is it worth it?
Whole-house window replacement is a top-tier project — per-opening costs multiply fast, which is why failed seals get negotiated rather than ignored. Quality vinyl and fiberglass windows typically serve 20–30 years; insulated glass seals often fail sooner — fogging between panes is the tell. Typical ranges only.
What the inspector looks for: The inspector operates a sample of windows, looks for fogged glass, rot at sills and trim, and checks the envelope story: siding condition, caulking, and where water is being told to go.
Have it up to spec when you list: Replace fogged panes where practical, repaint failing trim, and re-caulk gaps. The envelope is the first thing a buyer touches on a tour — small envelope maintenance reads as whole-house care.
Exterior section of the inspection checklist · Vendor partners
How serious are foundation and drainage problems?
The widest range in the house: minor crack sealing is cheap, structural underpinning is among the most expensive work a home can ever need. Drainage fixes are usually the affordable prevention. A sound poured foundation lasts the life of the house; what ages is the water management around it — grading, downspouts, and footing drains. Typical patterns only.
What the inspector looks for: Cracks and their width, moisture staining in the crawl space or basement, posts and beams, and whether grade slopes away from the walls. Real movement escalates to a structural engineer — one report replaces everyone's guessing.
Have it up to spec when you list: Clean the crawl-space access, extend downspouts away from the foundation, and disclose any past work with its engineering paperwork. Documented repairs with permits are a strength, not a confession.
Foundation section of the inspection checklist · When to escalate to a specialist
Do appliances matter in an inspection?
The lowest tier on this diagram individually — but a kitchen's worth of dated appliances adds up, and buyers mentally price the bundle. Ranges and refrigerators typically run 10–15 years, dishwashers and disposals less, washers and dryers in between. Typical ranges only — varies with brand and use.
What the inspector looks for: The inspector runs what conveys: a heat cycle on the range and dryer, a dishwasher cycle, disposal, and the anti-tip bracket behind the range. What conveys is a contract question — read the offer, not the assumption.
Have it up to spec when you list: Decide what conveys and say so in the listing, run everything before photos, and leave the manuals in a drawer. A dead appliance discovered at inspection is a small credit — and a large tone-setter.
Appliance section of the inspection checklist · Vendor partners
The floating home, system by system
On the water the list changes: the float replaces the foundation as the single largest line item, moorage becomes the defining cost, and power, water, and sewage all arrive differently. Many floating homes heat with mini-splits rather than furnaces — the details below say so where it matters.
What does float or flotation work cost on a floating home?
The floating home's single largest line item — re-flotation or major float repair is the marine equivalent of replacing a foundation, and it moves sale prices accordingly. Old-growth log floats have served for many decades and can keep serving with added flotation; sealed concrete floats are the modern standard and typically outlast ownership. Condition, not age alone, is the question — which is why the dive report exists.
What the inspector looks for: This is specialist territory from the start: a marine surveyor and a dive inspection evaluate the logs or concrete, added flotation, freeboard, and how level the home sits. No land-based inspector evaluates what's underwater.
Have it up to spec when you list: Have a recent dive report ready — it is the floating-home seller's single most persuasive document. Know your float type, any added flotation, and when work was last done, with paperwork.
Floating section of the inspection checklist · Dive report, defined · Float, defined
How much does moorage cost, and what should I check at the dock?
Not a replacement item but the defining ongoing cost of floating-home life — moorage terms often move value more than the structure itself does. Moorage is an arrangement, not equipment: owned, co-op, or leased, each with different security and monthly obligations. Dock hardware — cleats, lines, ramps, pilings — is inspected for condition rather than lifespan.
What the inspector looks for: The surveyor looks at mooring lines and cleats, the ramp and its connections, and how the home is secured; your broker reads the moorage documents — the lease term, dues, rules, and transferability — with the same care.
Have it up to spec when you list: Assemble the moorage paperwork before listing: the lease or co-op documents, current dues, and any dock rules. On the water, the paperwork IS the curb appeal.
Moorage, defined · Floating section of the inspection checklist · The moorage guide on the specialty page
What's different about electrical systems on the water?
Mid-tier — pedestal and connection work is manageable, but corroded or non-marine wiring on the water is a safety finding that stops deals until fixed. Marine-rated connections and pedestals serve for decades with maintenance; corrosion is the clock that actually runs. Houseboats add battery banks and bilge-pump circuits that want regular attention.
What the inspector looks for: The specialist checks the shore-power connection, ground-fault protection, marine-rated wiring, and — on floating-on-water residence houseboats — the battery and bilge-pump systems. Electricity next to water gets zero benefit of the doubt.
Have it up to spec when you list: Have the shore-power connection and pedestal area clean and accessible, GFCI protection working, and any electrical work documented. A tidy power pedestal is the dock version of a labeled panel.
Shore power, defined · Floating section of the inspection checklist · When an electrician needs to look
How does sewage work on a floating home or houseboat?
Modest equipment, meaningful logistics: floating homes connect to city sewer through community systems; houseboats carry blackwater tanks that need regular pump-out service. Sewer flex connections and community pumps are maintained items rather than lifetime installs; marine toilets and holding tanks want servicing on a schedule, not on failure.
What the inspector looks for: The surveyor traces how waste actually leaves: the flex connection and community pump for floating homes, tank condition and pump-out arrangements for houseboats. Smell and slow drains are data, not quirks.
Have it up to spec when you list: Have pump-out records (houseboats) or the community-system arrangement (floating homes) documented and current. Buyers new to the water always ask — a written answer beats a shrug.
Pump-out, defined · Floating section of the inspection checklist · Utilities on the specialty page
What about the roof and envelope on a floating home?
Same tier as on land — a top exterior expense — with a marine twist: everything on the water weathers faster, and weight matters on a float. Typical roofing ranges apply — 20–30 years for composition shingles, longer for metal and membrane — but marine exposure works the short end of every range. Varies with maintenance and material.
What the inspector looks for: Surface, flashing, and drainage as on land, plus the water questions: where runoff goes, how much weight any rooftop deck adds, and how the envelope handles constant humidity.
Have it up to spec when you list: Moss off, gutters clear, and any roof-deck additions documented — added weight up high is a stability question on a float, and permits answer it.
Exterior section of the inspection checklist · What a licensed roofer sees
How are floating homes heated?
Usually lighter than a land house: many floating homes heat with ductless mini-splits or electric heat rather than a ducted furnace — smaller equipment, smaller replacement bills, but still a real line item. Mini-split heat pumps typically serve 10–15 years; electric baseboard and panel heaters longer. Typical ranges only — salt air and run hours vary the math.
What the inspector looks for: The inspector runs each head unit in heating mode, checks the outdoor unit's mounting and condensate path, and reads age from the data plate. Refrigerant questions go to an HVAC professional, same as on land.
Have it up to spec when you list: Service the units, clean the filters, and have the model and install paperwork ready. On a small home, one working heat source per zone is the whole story — make it demonstrably true.
HVAC section of the inspection checklist · What an HVAC pro checks
How does fresh water reach a floating home?
Generally modest — flexible supply connections and compact plumbing runs — but freeze protection and connection condition are the items that bite when ignored. Supply flex lines and quick-disconnects are replace-on-condition items; interior plumbing follows the same material rules as land homes. Houseboats add winter considerations — hoses and tanks that must not freeze.
What the inspector looks for: The surveyor checks the supply connection at the dock, traces lines for wear where the home moves against them, and runs fixtures. Winterization habits show — and get asked about.
Have it up to spec when you list: Know your shut-off at the dock, replace tired flex lines before listing, and be ready to explain the winter routine to a land-raised buyer. It's a selling point when it's organized.
Plumbing section of the inspection checklist · Floating section of the inspection checklist
What about the water heater on the water?
Same affordable tier as on land — with the same caveat sharpened: a leaking tank on a floating home is leaking into your float, not just your floor. Tank units typically last 8–12 years; compact and tankless units are common on the water where space is tight. Typical ranges only.
What the inspector looks for: Age, rust, the TPR valve and discharge line, seismic strapping, and — the floating extra — where a leak would drain. A pan and a clear path matter more afloat.
Have it up to spec when you list: Strap it, verify the TPR line, and if it's near the end of its typical range, decide replace-versus-credit before the buyer decides for you.
Plumbing section of the inspection checklist · Vendor partners
Why no dollar figures? Because they'd be wrong somewhere. Replacement costs vary widely with the home, the material, the access, and the month — the honest way to price a repair is local bids from licensed contractors, and the honest way to weigh a system is the tier and lifespan above. When a real number matters to a real negotiation, get local bids — and we'll help you read them.
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