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Defect library

Insulation & damp defects in new builds

Damp and insulation problems show up as condensation, staining or mould, often in corners and around window reveals. Some of the causes, such as a bridged damp-proof course or high ground against a wall, can only be seen from outside.

Updated 19 October 2026

SiteSnag’s library has 10 entries under insulation & damp. They’re listed below with the most serious first. Each one gives the wording an inspector would put in a report and the trade that would fix it, and 6 carry a reference to the standard or guidance they relate to. The references help you look up the relevant section and aren’t a statement that a particular home does or doesn’t comply.

All 10 entries

  1. Rising damp signs

    Major

    Tide marks or salts at low level suggest rising damp. Investigate DPC.

    Trade
    Builder
    Reference
    Approved Document C

  2. DPC bridged

    Major

    Damp-proof course bridged by ground, paving or render. Lower levels or cut back.

    Trade
    Builder
    Reference
    Approved Document C

  3. Penetrating damp

    Major

    Damp staining from external defect. Trace source and repair.

    Trade
    Builder
    Reference
    Approved Document C

  4. Cavity wall insulation concerns

    Major

    Signs of damp or failed cavity wall insulation. Specialist inspection.

    Trade
    Specialist
    Reference
    None listed

  5. Loft insulation missing / disturbed

    Moderate

    Loft insulation incomplete or disturbed. Lay to full depth.

    Trade
    Builder
    Reference
    Approved Document L

  6. Condensation at reveals / cold bridging

    Moderate

    Condensation or mould at window reveals indicating cold bridging. Investigate and rectify.

    Trade
    Builder
    Reference
    Approved Document L

  7. Black mould on walls / ceilings

    Moderate

    Mould on wall or ceiling, usually from condensation. Treat and improve ventilation.

    Trade
    Builder
    Reference
    None listed

  8. Damp from defective gutter / downpipe

    Moderate

    Damp patch below a leaking gutter or downpipe. Repair rainwater goods and dry out.

    Trade
    Roofer
    Reference
    None listed

  9. Ground level too high against wall

    Moderate

    External ground or paving within 150 mm of DPC. Lower levels.

    Trade
    Groundworker
    Reference
    NHBC Standards 6.1

  10. Condensation on windows

    Minor

    Heavy condensation forming on glazing. Improve ventilation and heating.

    Trade
    Builder
    Reference
    None listed

Using these in a report

In the SiteSnag app, starting to type a defect title in the camera brings up these entries. Picking one fills in the description, severity, trade and reference, and you can edit the wording or add your own defects to the library. Every snag then goes into the branded PDF report with its photos and a numbered pin on the floor plan.

For a room-by-room walk-round, use the new build snagging checklist, or go back to all defect categories.

Other categories

Previous: Ventilation (6). Next: Roofing (18).