Flat Roofing Issues and Problems – What to Look Out For

A well designed, maintained and waterproofed flat roof should not cause problems or leak, but how would you know that your flat roof is not watertight or that a problem is just around the corner? There are a number of tell-tail signs to look out for and spotting them early can save time and money:

Roof Deck – Surface

  • Debris accumulation and vegetation growth
  • Warped, sprung or broken wooden boards (wooden deck)
  • Cracks, blistering and wear spots
  • Movement in the roof underweight

Roof Deck – Underside (Wood)

  • Rot
  • Warped boards

Roof Deck – Underside (Concrete / Gypsum)

  • Cracks and stains
  • Spots of rust from reinforced rods
  • Chips or splinters

Roof Deck – Underside (Metal)

  • Rust spots

Roof Lights & Detailing

  • Cracks and chips
  • Leakages around the joints
  • Internal moisture and condensation
  • Build-up of moss and lichen


  • Unintentional damage
  • Puncturing and water ingress
  • Poor maintenance


  • Ponding / standing water (in cold weather ice accumulation)
  • Incorrect or lack of falls
  • Blocked drains and gutters

Flashing, Coping & Jointing

  • Damaged or fragile roof lights
  • General / thermal movement
  • Loose, torn or missing
  • Improper installation and bonding
  • Visible rust indicating a lack of coating
  • Cracks, gaps or damage to the joints


  • Saturated roofing build-up
  • Dampness or mould on the ceiling, walls or within a cavity

Exterior & Interior Walls

  • Settlement cracks
  • Stained, displaced flashing or drainage facilities
  • A white / salt coating or surfacing
  • Damp or stained walls and ceilings (usually brown in colour)
  • Chipped or discoloured paint


  • If the school was built before 2000
  • There are several areas throughout the roofing structure where asbestos can potentially be found

IKO’s Long Term Solution
Remember a flat roof which has been designed and installed in accordance with the relevant British Standards and an IKO long-term solution can be trouble-free, providing it is properly maintained and checked at routine and regular intervals, with a note made of any items requiring attention. Key detail areas to check include flashings, upstands, penetrations, edge trims and drainage channels. Maintaining these checks will extend the life expectancy of the roof.

IKO also consider the longevity and lifetime value of an existing, updated or new roof, partnering with a school to make sure any future upgrades or developments such as solar or photovoltaic (PV) possibilities, increased insulation benefits, accessibility or additional drainage can be achieved and conform to building regulations.

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