Spotting DIY Work Issues Reference

Why this matters

Many homes show evidence of previous DIY work - by the current owner or a former one. Some is fine; some is dangerous; some is a ticking time bomb. The tech who recognizes amateur work + flags concerns helps customers avoid disasters. The communication matters: customer often did the work + may be defensive. This is the field card.

What "DIY work" means

Spectrum of competence:

• Skilled enthusiast: did it well, sometimes better than pro
• Average homeowner: did it OK; followed YouTube; mostly safe
• Inexperienced: did it wrong; safety implications
• Reckless: dangerous workmanship; immediate hazard

Most DIY falls in middle. Watch for the dangerous end.

Plumbing DIY signs

Common DIY mistakes:

• No P-trap under sink (sewer gas entry)
• S-trap instead of P-trap (siphons; not allowed)
• Saddle valve on water line (for ice maker, humidifier; leak-prone)
• Push-on (SharkBite) under wall / concealed (intended for accessible repair only)
• Improper venting (wet vent OR no vent)
• Galvanized fittings on copper OR copper on galvanized without dielectric union (corrosion)
• PVC for water supply (only for drain/vent + cold water in some applications)
• PEX without proper fittings OR exposed to UV (degrades)
• Vent termination into attic (moisture in attic; code violation)
• Drain line without proper slope (1/4" per foot minimum)
• Wax ring stacked (3 wax rings = installation that should have used flange extender)
• Backflow risk (anti-siphon devices missing on outdoor faucets, irrigation)

Electrical DIY signs

Common dangerous DIY:

• Aluminum wiring with regular outlets / switches (not CO/ALR rated; fire risk)
• Backwire / backstab connections on outlets (less reliable than screw terminals)
• Wire nuts undersized OR over-stuffed (loose connections; heat; fire)
• Tape over wire nuts (not necessary; sometimes covers bad connection)
• Bare wire ends in junction boxes
• Multiple wires under one screw (when not allowed)
• Open junction box OR no cover (live wires accessible)
• Junction box buried in wall without access (code violation)
• Romex run exposed (not allowed; must be in conduit OR concealed)
• Romex inside outdoor location without UV-rated jacket
• Improper grounding (ground floating; bonding issues)
• DIY service entrance (homeowner work on utility-side connections)
• Bootleg ground (neutral connected to ground at outlet = false 3-prong)
• Overloaded circuits (15A breaker with 12 outlets + appliances)
• Doubled-up wires under one breaker (when not designed for it)
• Aluminum + copper twisted together in wire nut

HVAC DIY signs

Common DIY mistakes:

• Ductwork sealed with regular duct tape (fails; should be foil tape OR mastic)
• Refrigerant line damaged / kinked
• Outdoor unit sitting in puddle (concrete pad missing OR sinking)
• Filter never changed (or wrong size, OR improperly installed)
• Thermostat wiring crossed OR not labeled
• Combustion air missing for furnace
• Vent pipe not properly sloped OR terminated
• Mini-split DIY install (refrigerant lines need proper evacuation; DIY often skipped)
• Ducts disconnected in attic (cooling attic, not house)
• DIY return air cuts (no balance; pressure issues)

Roofing DIY signs

Common issues:

• Tar over shingles (band-aid; doesn't address underlying problem)
• Missing flashing at chimney / vent / valley
• Caulk used instead of proper sealing
• Damaged ridge cap
• Shingles installed wrong direction OR with wrong overlap
• Roof penetrations without proper flashing (satellite, solar mount, etc.)
• Vent stack flashing failed + patched with tar

Drywall + carpentry DIY signs

• Drywall joints not taped + mudded properly (visible seams)
• Patches that bulge OR show through paint
• Floor squeaks from missed fasteners
• Door installed plumb without level frame
• Cabinets hung in drywall (no stud anchor)
• Deck attached to house with screws / nails (not lag bolts + ledger flashing)

Painting DIY signs

• Paint over wallpaper (didn't strip first)
• Visible roller marks / brush strokes in finish coat
• Drips at edges
• Bleed-through (stains coming through finish coat)
• Improper sheen for the area (high gloss in bedroom)
• Paint over moldy surface (without addressing source)

Gas DIY (RARE; usually professional)

If you see DIY gas work:

• IMMEDIATE concern
• Often unlicensed work
• Customer + neighbors at risk
• Notify customer + utility may need to be involved

Signs:

• Flex line where rigid required
• Unbonded gas piping
• Improper appliance connector
• Soap-bubble leak test gone wrong (leak still present)
• DIY conversion from natural gas to propane (improper jet sizing)

Insulation DIY signs

• Insulation against can lights (non-IC rated; fire risk)
• Compressed insulation (less R-value than rated)
• Vapor barrier on wrong side for climate
• Knee wall insulation missing
• Insulation in attic without baffles at eaves (blocks soffit ventilation)
• Spray foam against non-rated cans / wires

Communicating with customer

Customer often DID the work themselves. They're defensive. Approach:

Don't say:

• "Who did this work?" (judging tone)
• "This is wrong"
• "You shouldn't have done this"
• "This is the worst I've seen"

Do say:

• "I noticed [specific observation]"
• "This could cause [specific issue] over time"
• "Current code requires for this; this may be older / different"
• "Here's what I'd recommend to address it"

Be factual; explain why it matters; let customer decide on response.

Documenting

Photo each significant issue:

• Show clearly
• Annotate (arrows, notes)
• Date

Document in service record:

• Item observed
• Risk level
• Recommendation
• Customer notification (did + said what)

If customer chooses NOT to address: document customer's decision. Protects you legally.

When to refuse to work alongside DIY

Some situations:

• Active safety hazard (gas leak, exposed energized wiring): refuse until corrected
• Code violation that affects your work scope
• DIY work that compromises your installation
• Insurance / warranty implications

Don't add to a problem; address the underlying issue OR refer.

Risk categorization

High risk (immediate hazard):

• Gas leaks
• Energized exposed wires
• Major structural defect
• Active water leak with mold concern
• CO source

Medium risk (developing problem):

• Code violations not actively dangerous
• Inadequate ground / bonding
• Slow leak

Low risk (cosmetic / minor):

• Visible amateur workmanship that works
• Patches that look bad but don't fail
• Older code work that's been grandfathered

References

• NEC (National Electrical Code) - code requirements
• IPC (International Plumbing Code)
• IMC (International Mechanical Code)
• Local permit requirements (varies by jurisdiction)
• Manuall internal: Install Quality Red Flags, Code Violations Identification