Roof Renovation: Steps & QA
- Pre-works (design, safety, protection)
- Survey & engineering
- Measured survey, photos, moisture mapping, check rafters/trusses, ridge, wall-plates.
- Structural engineer confirms loads (existing vs new tile/metal/slate), pitch, and if a reinforced ring beam (RC “bond beam”) is required for lateral tie and uplift resistance.
- Method, permits & H&S
- Scaffolding with guardrails + fall arrest, debris netting, covered entries.
- Temporary weather plan (shrink-wrap or tarps + pumps). Book crane/hoist if needed.
- Material strategy
- Choose build-up: Warm roof (insulation above deck), Cold roof (between/below rafters + ventilation), or Hybrid.
- Choose covering: concrete/clay tile, metal standing seam, metal tile/stone-coated steel, slate, etc.
- Fixings/wind zone schedule; ventilation and drainage layout; gutter/downpipe spec.
- Strip-out & structural base
- Selective demolition
- Remove existing covering, battens/lathe, membrane, gutters; keep temporary protection active.
- Salvage reusable tiles/slate if planned.
- Structure assessment & repairs
- Replace decayed rafters, ridge/valley boards; tighten connections; install hurricane ties/straps.
- Check wall-plates; treat/replace where needed.
- Ring beam (if required)
- Formwork, rebar, cast reinforced concrete bond beam at wall top; anchor wall-plate with bolts/straps after cure.
- Verify levels to avoid uneven eaves lines.
- Geometry & plane
- Straighten rafters with packers/sistering; set consistent pitch and valleys/hips line. Laser check for flatness/plane.
- Deck, membranes, insulation & ventilation
- Sheathing/deck
- Fix OSB/ply or boards to spec; maintain expansion gaps; nail pattern per code.
- Air & vapor control
- Cold roofs: VCL/airtight layer on warm side; maintain ventilation paths (eaves + ridge/vents).
- Warm roofs: continuous insulation above deck; sealed VCL below deck; no ventilated void over insulation unless system requires.
- Insulation
- Warm: PIR/EPS/XPS boards staggered, taped; upstand insulation at parapets/dormers.
- Cold: mineral wool/cellulose between rafters; add over/under-rafter layer in hybrids to cut thermal bridges.
- Underlay / waterproof layer
- Breathable roofing membrane (pitched) laid with correct laps; or full adhered underlayment where required (ice/water shield zones).
- Ventilation hardware
- Eaves ventilators, ridge vents, tile/slate vents as required to meet airflow targets; maintain clear 50–65 mm paths in cold roofs.
- Battening/rails & coverings
- Battens/rails
- Set out to gauge/pitch for chosen covering; stainless or galvanized fixings; counter-battens over membranes in warm roofs for drainage.
- For standing seam: fix clips at prescribed centers; allow thermal movement.
- Flashings & junctions
- Chimney/apron/valley flashings, dormer abutments, wall upstands, skylight kits; all prebent and installed before final covering.
- Drip edges and verge details to system drawings.
- Covering install
- Tiles/slate: lay to bond pattern, headlap to pitch, storm clips/straps in high-wind areas.
- Metal standing seam/panels: set starter, seam progression, expansion joints, compliant cut-edge treatment where relevant.
- Metal tile/stone-coated steel: follow batten spacing and interlocks; screw schedule per zone.
- Rainwater system
- Fix gutters, downpipes, leaf guards; confirm falls and outlets; connect to drains.
- Openings, services & finishes
- Skylights & penetrations
- Install certified kits (underlay collars, insulation frames), pipe boots, solar mounts with dedicated flashings.
- Edge protections & accessories
- Snow guards (if applicable), bird stops, verge/eaves closers, ridge tapes.
- Lightning protection (where required)
- Air terminals, down conductors, bonds to metal elements; test continuity.
- Commissioning, QA & handover
- Quality checks (hold points)
- Structure: fixings/straps, straightness of ridges/valleys.
- Warm roof: continuous insulation + taped seams; no membrane punctures.
- Ventilation: clear eaves paths, ridge vents open; verify free areas.
- Covering: fixings per schedule, no high spots/lippage, aligned courses.
- Water test (controlled hose at flashings/valleys).
- Thermal imaging (optional) to spot major air leaks.
- Clean-down & protection
- Remove debris/metal swarf; magnet sweep for screws; clean gutters.
- Documentation & warranties
- As-built photos (layers/flashings), product data sheets, wind uplift compliance, maintenance guide, color/finish codes, warranty cards.
Key choices & their implications
- Concrete/Clay Tile vs Metal Standing Seam
- Weight: Tile/slate is heavy → structure + ring beam often critical; metal is light → easier on structure.
- Pitch: Metal can work on lower pitches; tiles/slate need higher minimum pitch.
- Noise/heat: Metal needs acoustic underlay; high-reflectance coatings reduce solar gain.
- Maintenance: Tile/slate: crack/replacement of pieces; metal: inspect coatings/fasteners.
- Warm vs Cold Roof
- Warm: better condensation control, fewer thermal bridges; +20–45% upfront vs cold, but −5–15% lifecycle issues.
- Cold: cheaper now, requires reliable cross-ventilation to avoid condensation.
Typical timelines (one villa, simple geometry; weather-dependent)
- Design/permits/engineering: 1–3 weeks (parallel to procurement)
- Strip-out & temp protection: 1–3 days
- Structure repairs + ring beam (if needed): 3–7 days (plus curing)
- Deck/membrane/insulation/ventilation: 2–5 days
- Battens/flashings/covering: 4–10 days
- Gutters/openings/accessories: 1–3 days
- QA, clean, handover: 0.5–1 day
% Cost guide (percentages only; baseline = re-roof with new covering on sound structure, no insulation change = 0%)
(Ranges vary by size, height, access, geometry, wind zone.)
- Add ring beam + structural repairs: +10–35%
- Warm roof (insulation above deck) vs cold: +20–45%
- Switch to metal standing seam vs concrete tile: +30–80% (material/skill)
- Switch to clay tile vs concrete tile: +20–50%
- Complex flashings (dormers/chimneys/valleys): +10–25%
- Skylights/roof windows (each installed): +5–10% of roof scope
- Lightning protection system: +5–12%
- Premium gutters/downpipes (aluminium/copper): +5–15%
Lifecycle upkeep over ~15–20 yrs (cleaning, minor repairs)
- Warm roof + metal standing seam: −10–20% vs baseline
- Concrete/clay tile (quality install): 0–10% vs baseline
- Slate (quality): −5–15% vs baseline
Risks & how to avoid them
- Condensation & mould (cold roofs): missing/blocked ventilation. → Ensure clear eaves-to-ridge path; keep insulation off underlay; use baffles.
- Wind uplift/fixings failure: under-specified clips/screws. → Follow zone fixing schedules; site pull-out tests where needed.
- Leak paths at junctions: weak flashing details. → Use full system flashings; stage a hose test before demobilizing.
- Thermal bridging (warm roof edges): uninsulated upstands/eaves. → Wrap insulation over edges; use insulated upstands.
- Galvanic corrosion (metals): mixing dissimilar metals. → Match materials; isolate fasteners; treat cut edges.
- Uneven eaves/ridge lines: poor geometry control. → Laser lines; packers/sistering before battening.
Value impact (rent & sale)
- New roof with warm build-up + premium covering: curb appeal ↑, survey red flags ↓ → listing impact +4–9%, days-to-sell/let −10–25% (market dependent).
- Skylights/clean details: photos ↑, perceived quality ↑.
Quick checklist (print-ready)
- ☐ Engineer sign-off (loads, ring beam need, fixings schedule)
- ☐ Scaffolds, fall arrest, weather plan in place
- ☐ Structure repaired; wall-plate anchored; ties/straps installed
- ☐ Deck fixed; VCL/airtight layer continuous; insulation installed as per warm/cold strategy
- ☐ Underlay lapped; ventilation clear (eaves/ridge/vents)
- ☐ Flashings fitted (chimney, valleys, abutments, skylights)
- ☐ Battens/rails set to gauge; fixings per wind zone
- ☐ Covering installed true to lines; gutters/downpipes sloped and fixed
- ☐ Hose test passed; site cleaned; warranties + maintenance guide delivered
Pro tips (hot climates incl. Dubai)
- Prefer light/reflective finishes or high-SRI coatings on metal to reduce attic heat.
- Ensure continuous airtight layer to keep sand/dust out; specify insect/bird guards.
- Oversize eaves ventilation and use ridge vents; plan for easy filter/mesh cleaning.
- Choose corrosion-resistant fasteners/coatings (marine grade near the coast).
