March and April are the right months to assess what Tonbridge's winter has done to your roof. The freeze-thaw cycles of December and January will have widened any cracks present in autumn. The sustained heavy rainfall of February will have found any weakness in flat roofs and flashings. Addressing what you find in spring — before summer growth accelerates moss and before next autumn — keeps the maintenance cost manageable.
The Spring Check — What to Look for and Where
Pitched Roof — From the Ground
- Ridge line — look along the ridge from the garden. Any tiles shifted, mortar gaps opened up, or white powder on the roof surface below the ridge indicates winter freeze-thaw damage. A clean ridge line in April means the mortar held through winter.
- Slipped tiles — particularly relevant on 1960s-80s Cage Green and Trench Wood properties where nail sickness is progressive. Any tiles lower than their neighbours that were not there in autumn means the nail sickness has advanced.
- Verge mortar — look at the gable ends. Gaps in the mortar line that weren't there in autumn indicate freeze-thaw expansion over winter.
- Valley line — check the valley for lifted or cracked lead, cracked valley tiles or areas where the valley surface appears proud of the surrounding tile.
Chimney Stacks
- Check for white efflorescence (salt staining) on the chimney face — this indicates water has been moving through the stack all winter
- Look for open mortar joints in the stack brickwork that were not visible in autumn
- Check the flaunching (mortar cap) around chimney pots — frost expansion can crack flaunching that was borderline in autumn
- Look for any lifted lead at the base of the chimney stack
Gutters and Downpipes
- After the final spring leaf fall, clear gutters of winter debris before summer
- Check all gutter joints for leaks — run a hose through and watch for drips at unions and stop ends
- Check downpipes are clear — a downpipe blocked with winter debris will cause overflow at the first summer storm
- Inspect fascia boards at any point where you know or suspect the gutter has been overflowing
Flat Roofs
- Check the entire membrane surface for blistering, cracking or splits that weren't present before winter
- Confirm outlets are clear and the roof drains freely
- Check all upstand junctions for any signs of lifting or de-bonding — winter thermal movement can open small defects at these points
- Look for any soft or spongy areas that might indicate water has reached the deck (relevant on older felt systems)
Spring survey appointments now available — most issues found in spring are minor. Call 0173 224 1138
📞 0173 224 1138Inspection frequency: BS 6229:2018 (Flat roofs with continuously supported flexible waterproof coverings) recommends that flat roofs are inspected at minimum twice per year — once in spring and once in autumn — with additional inspection after any severe weather event. The standard notes that blocked drainage is the leading cause of premature membrane failure. Source: BS 6229:2018, Clause 10.2
What to Do With What You Find
| Finding | Priority | Best Time to Fix |
|---|---|---|
| Slipped tiles — isolated (1–3) | Low–Medium | Spring/summer |
| Widespread nail sickness advance | High | Spring — before summer growth |
| Cracked ridge mortar | Medium | Before autumn — mortar works best in dry weather |
| Lifted chimney flashing | High | Spring — before summer heat opens it further |
| Gutter overflowing at joint | Medium | Anytime — simple repair |
| Fascia rot discovered | High | Spring/summer — dry conditions needed |
| Flat roof blister/crack | High | Spring — before summer heat expansion |
| Chimney efflorescence | Medium | Survey now, repair before next winter |
Why Spring is the Best Time for Moss Treatment
Spring is the most effective time to apply biocide moss treatment to Tonbridge roofs. Moss is actively growing in spring — the biocide translocates through the living plant most effectively when the plant is active. Treatment applied to dormant moss in December has lower efficacy. Spring treatment followed by a return clearance visit in May or June, after die-back is complete, leaves the tile surface clean and treated going into summer — when UV and drying winds do additional work. This is particularly relevant for lower Tonbridge properties near Haysden Country Park and the Medway corridor where moss growth is above average due to the valley microclimate.
The Spring Checklist — Summary
- ☐ Ridge line — check from ground for displacement or mortar gaps
- ☐ Slipped tiles — scan all slopes from garden
- ☐ Verge mortar — inspect both gable ends
- ☐ Valley — check line for cracks or lifting
- ☐ Chimney flashings — look for lifted lead or efflorescence
- ☐ Chimney pots and flaunching — inspect for cracks
- ☐ Gutters — clear debris, flush and check joints
- ☐ Downpipes — confirm clear flow
- ☐ Fascia boards — check at any known overflow points
- ☐ Flat roof membrane — full surface check
- ☐ Flat roof outlets — confirm drainage
- ☐ Loft space — quick torchlight check of felt and rafters
- ☐ Moss — consider spring treatment on affected roofs