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Maintenance · Paint & sealants

Painting and sealants on a dormer

Paint and sealant work is the boring, decisive maintenance category. Done on schedule, a dormer stays watertight for decades. Skipped twice in a row, repair costs jump by an order of magnitude.
5 min leestijd·Onafhankelijke informatie

Short answer

Repaint exposed timber every 5–7 years; check every sealant joint annually and replace any that show splitting or pull-away. The total cost of staying on schedule is a fraction of the cost of one rot repair.

Paint cycles by material

  • Painted softwood: recoat every 5–7 years; full sand-back every 15–20.
  • Western Red Cedar (stained): recoat every 8–12 years.
  • Accoya (factory-coated): recoat every 10–15 years.
  • PVC cladding: no paint; wash twice a year with mild detergent.

Sealants — what goes where

  • Frame-to-cladding: neutral-cure MS-polymer, paintable, 8–12 mm joint width.
  • Glass-to-frame: neutral-cure silicone; never overpaint.
  • Lead-to-wall: lead sealant or butyl mastic — never standard silicone.
  • EPDM-to-upstand: manufacturer-specified bonding adhesive, not silicone.

Maintenance schedule

  • Annually: visual check, clear gutters, look for sealant cracks.
  • Every 3–4 years: top up any failed sealant joints.
  • Every 5–7 years (softwood): light sand and recoat.
  • Every 15–20 years: full sand-back, prime, repaint; inspect lead apron for fatigue.

DIY or pro

Annual cleaning and minor sealant top-ups are reasonable DIY tasks if you can safely reach the dormer. Full repaints, lead repairs and anything on a steep roof slope belong with a professional — falls from roofs are the most common serious accident in DIY building maintenance.

FAQ

FAQ

Veelgestelde vragen

01How often should a timber dormer be repainted?
Painted softwood every 5–7 years, factory-coated Accoya every 10–15 years. South- and west-facing elevations shorten those intervals.
02Which sealant should be used around dormer windows?
A neutral-cure, paintable polymer sealant (MS-polymer or similar). Silicone is fine on glass-to-frame joints but should not be used where it will be painted over.
03Why do sealant joints fail?
Three reasons in this order: wrong sealant for the substrate, joint too narrow to absorb movement, and skipped primer on absorbent surfaces. All three are installer errors, not product failures.
Conclusie
Paint and sealant maintenance is predictable and cheap on schedule, expensive and disruptive off it. Put the cycles in your calendar the day the dormer is installed.