Possible causes
- Long-term water damage to rafters, battens or decking
- Heavier replacement coverings than the structure was built for
- Removed or altered roof timbers
- Rotten flat roof decking
Warning signs
- A visible dip along the ridge or across a slope
- Soft or spongy areas on a flat roof
- Cracks in ceilings below
Typical solutions
- Investigation of the timbers and covering
- Replacing decking or battens
- Referral to a structural engineer where needed