How to inspect roof flashing (2026)
Quick Answer
To inspect roof flashing, start from the ground and inside the loft or top-floor ceiling area, looking for signs of leaks around chimneys, walls, vents, skylights and valleys. If conditions are safe and you can inspect from a stable ladder or accessible eaves, check for loose sections, lifted edges, corrosion, cracked sealant and damaged surrounding roofing. Stop and call a qualified roofer if you see active leaking, major movement, rust-through, damaged masonry joints, or if access would put you at risk.
Safety first
- Do not climb onto a roof that is wet, icy, steep, fragile, mossy or affected by high winds.
- Use ground-level inspection first; only use a ladder if you know how to set it up safely on firm, level ground.
- Maintain three points of contact on a ladder and do not overreach.
- Keep clear of overhead power lines when moving or using ladders.
- Wear non-slip footwear and gloves, and avoid loose clothing that can snag.
- Do not disturb flashing, lift tiles, or start repairs during an inspection if you are not trained.
- If you suspect structural weakness, rotten roof edges or unstable chimney masonry, stop immediately and keep away.
When to call a professional: Stop and consult a qualified roofer immediately if you find active leaks, loose or missing flashing, rust-through or holes, repeated damp after rain, cracked chimney mortar where counter-flashing is set, damaged valleys, signs of rot, or any issue that requires stepping onto the roof or disturbing roof materials. Also use a professional if the roof is steep, high, fragile, inaccessible, or if you are unsure whether the fault is flashing or a broader roofing problem.
Overview
Roof flashing is the thin metal or formed material that directs water away from joints and penetrations in a roof, such as chimneys, abutment walls, roof windows, vents and valleys. It often fails before the main roof covering because it sits at movement points and exposed edges where wind, heat and water are concentrated. A good inspection is mostly about spotting early warning signs rather than trying to fix them on the spot. For routine care, inspect flashing from ground level and indoors at least twice a year, ideally after winter and after periods of severe weather. Also check after storms with high wind, hail or heavy rain. On the roof itself, only inspect areas you can reach safely from a secure access point; many problems can be identified from binoculars, a torch in the loft, and a view from a ladder without stepping onto the roof. What you are looking for is simple: gaps where water can enter, signs the flashing has come loose, and deterioration in the flashing or the material it is fixed into. Catching these issues early matters because small flashing faults can lead to hidden timber decay, insulation damage, mould, ceiling staining and more expensive structural repairs.
Who this is for
Homeowners and property managers carrying out basic roof maintenance checks who want to identify obvious flashing problems safely before arranging repairs.
What you’ll need
- binoculars
- torch
- stable ladder if needed for a closer view from the eaves
- camera or phone for photos
- notepad or inspection checklist
- basic PPE such as non-slip footwear and gloves
Before you start
Check the weather first and do not inspect during rain, high winds, ice, or when the roof is wet. Identify a safe viewing method before you begin: ground-level inspection first, then indoor loft inspection, then ladder-only if you can maintain safe access. If the roof is steep, fragile, high, or has no safe access point, do not climb up; arrange a professional inspection instead.
Step-by-step
- 1
Start with an indoor leak check
Inside the loft, attic or top-floor rooms, look around chimneys, roof windows, vents and wall junctions for damp patches, staining, mould, peeling paint, wet insulation or daylight showing where it should not. Use a torch and take photos of anything suspicious.
Why: Flashing is designed to keep water out at roof joints. Interior signs often appear before damage is obvious outside, especially where leaks travel behind finishes.
- 2
Scan the roof from ground level
Use binoculars to inspect all visible flashing locations: chimney bases, step flashing along side walls, valley flashing, vent pipe flashings, skylight edges and dormers. Look for pieces that appear lifted, bent, missing, corroded, poorly seated, or separated from the wall or roof covering.
Why: Ground-level viewing is the safest way to spot obvious defects without exposing yourself to fall risk.
- 3
Check for warning signs around the flashing
Note any cracked or missing mortar at chimney flashings, sealant that has split or pulled away, stains below the flashing line, debris build-up in valleys, and roofing materials around the flashing that are broken, slipped or worn. Also look for plant growth or persistent damp marks.
Why: Flashing often fails where adjacent materials fail. Debris and damaged roof coverings can divert water under otherwise sound flashing.
- 4
Inspect closer from a ladder only if safe
If you can safely do so, set a ladder on firm level ground and inspect from the eaves or another secure position without overreaching. Look at exposed flashing edges for cracks, punctures, rust, pinholes, open laps, failed fasteners, and loose counter-flashing where it enters brickwork or render joints.
Why: A closer visual check helps distinguish between cosmetic ageing and defects that can admit water, but only if you can keep three points of contact and avoid stepping onto the roof.
- 5
Assess drainage paths
Check that valleys, gutter edges near flashing, and lower roof junctions are free from leaves, moss and silt. If safe from the ground or ladder, remove loose debris by hand only where it is easily reachable; do not scrape, pry or disturb the flashing.
Why: Blocked drainage can force water sideways or backwards under flashing, causing leaks even when the metal itself is intact.
- 6
Record condition and monitor changes
Photograph each flashing area and note what you found, including date, location and whether the issue appears minor, worsening or urgent. Recheck minor concerns during the next routine inspection or sooner after heavy rain.
Why: Photos make it easier to compare movement, corrosion or gaps over time and help a roofer assess the problem accurately if repairs are needed.
Why this works
Flashing works by overlapping materials so water is shed out onto the roof covering instead of getting into joints. Inspection works when you focus on places where that overlap has been lost through movement, corrosion, cracking, failed sealant, blocked drainage or damaged adjoining materials.
Common mistakes to avoid
- Walking on the roof when a ground or ladder inspection would be safer
- Relying on sealant alone as proof the flashing is sound
- Ignoring small ceiling stains near chimneys or roof windows
- Clearing debris aggressively and bending or dislodging flashing
- Checking only the metal and not the surrounding tiles, slates, masonry or roof membrane
Troubleshooting
Brown ceiling stain near a chimney or wall junction
Check indoors and from outside for loose flashing, cracked mortar joints, slipped nearby roofing and signs of water tracking. Arrange a roofer if the stain is growing, fresh after rain, or the source is not obvious.
Flashing looks rusty but not holed
Photograph it and monitor closely; surface corrosion may still need professional assessment, especially on older metal. If there is flaking, perforation or staining below, stop and book a roofer.
Sealant around flashing is cracked
Treat this as a warning sign rather than a DIY sealing job. Sealant failure may indicate movement or poor previous repair, so have the flashing and the substrate checked properly.
Debris keeps collecting in a valley
Clear reachable loose debris safely and check again after the next bad weather. Repeated build-up can hide flashing faults or indicate drainage issues that a roofer should assess.
Compare your options
Ground and indoor inspection
Best for: Routine twice-yearly checks and post-storm checks
Pros: Safest option, no roof access needed, good for spotting obvious leak signs
Cons: May miss small defects or hidden movement
Ladder-level visual inspection
Best for: Getting a closer look at accessible low-level flashing
Pros: Better detail without standing on the roof
Cons: Still carries fall risk and is unsuitable in poor conditions or for awkward roofs
Professional roof inspection
Best for: High roofs, steep roofs, persistent leaks, uncertain findings
Pros: Safer, more thorough, can diagnose flashing and surrounding roof details together
Cons: Costs more than a DIY check and may not be immediately available after storms
| Option | Best for | Pros | Cons |
|---|---|---|---|
| Ground and indoor inspection | Routine twice-yearly checks and post-storm checks | Safest option, no roof access needed, good for spotting obvious leak signs | May miss small defects or hidden movement |
| Ladder-level visual inspection | Getting a closer look at accessible low-level flashing | Better detail without standing on the roof | Still carries fall risk and is unsuitable in poor conditions or for awkward roofs |
| Professional roof inspection | High roofs, steep roofs, persistent leaks, uncertain findings | Safer, more thorough, can diagnose flashing and surrounding roof details together | Costs more than a DIY check and may not be immediately available after storms |
Alternatives
- Use a qualified roofer for an annual inspection if the roof is difficult to access or you are not comfortable using ladders
- Use photos taken from safe ground positions to monitor known flashing areas over time
Pro tips
- Inspect after severe weather as well as on your regular schedule
- Compare suspected problem areas with similar details elsewhere on the roof
- Take wide and close photos so you can show both the defect and its exact location
- If a leak appears indoors, note which weather conditions seem to trigger it
Legal & regulatory notes
Any repair work may need to meet local building rules, listed-building requirements, lease conditions or insurer requirements, especially around roof coverings, chimneys and weatherproofing details. If the property is shared, tenanted or part of a managed block, check who is responsible before arranging work.
What this guide does not cover: This guide covers visual inspection and routine care only. It does not provide step-by-step repair instructions, material-specific installation details, structural assessment, chimney repointing methods, internal mould remediation, or local code compliance advice.
Cost considerations
Routine inspection is usually low-cost if done from the ground or as part of planned property maintenance, but delayed action can turn a small flashing defect into much larger costs through water damage to timbers, insulation, ceilings and decoration. Professional access costs can also rise if problems are left until emergency call-out is needed.
Prefer to hire a professional?
If this job is beyond a confident DIY — or the work needs to be done by a licensed professional — you can find a verified roofer through Trade Directory (tradedirectory.co.nz), New Zealand's directory of real, verified trade businesses. Compare local tradespeople, read their details and request quotes before you commit.
Find a roofer on Trade DirectoryFrequently asked questions
How often should I inspect roof flashing?+
A practical routine is twice a year, plus after severe weather such as strong winds, hail or prolonged heavy rain.
Can I inspect flashing without going onto the roof?+
Yes. Many useful checks can be done from inside the loft or top floor, from the ground with binoculars, and from a safe ladder position at the eaves.
What are the main warning signs of flashing failure?+
Look for interior damp marks, staining near chimneys or roof windows, lifted or loose metal, cracked sealant, corroded sections, missing pieces, broken mortar where counter-flashing enters masonry, and debris causing water build-up.
Should I reseal cracked flashing myself?+
Not as a first response. Cracked sealant can be a symptom of movement, poor installation or deeper failure, so inspection by a qualified roofer is usually the safer next step.
Is rust always a reason to replace flashing?+
Not always, but rust should never be ignored. Light surface corrosion may be manageable, while flaking, perforation or staining below the area suggests the flashing needs professional assessment and likely repair or replacement.
Sources & references
Guidance on this page is traced to documented sources. Last checked 24 September 2026.
- Health and Safety Executive (UK) – Working at height · government
Supports the need to avoid unnecessary roof access, use safer means of inspection where possible, and treat falls from height as a serious risk.
Basic flashing inspection principles change slowly, but local safety rules and repair standards can vary by location and building type.