How do I clean a timber frame pavilion or pergola?

Regular cleaning is the simplest and least expensive thing you can do to maintain the appearance and longevity of your timber frame structure. Here’s the correct approach:

Annual cleaning process:

1. Remove loose debris – sweep leaves, needles, and debris from the roof deck and surfaces with a soft broom
2. Mix cleaning solution – dilute a deck cleaner or wood brightener in water according to product instructions; alternatively, a diluted dish soap solution works well for light cleaning
3. Apply and scrub – apply generously with a soft brush or mop; work with the grain of the wood on all surfaces; pay attention to horizontal surfaces where dirt accumulates
4. Rinse thoroughly – use a garden hose; avoid pressure washing at high PSI as it can raise the wood grain and damage the surface
5. Allow to fully dry – wait 48–72 hours before applying any stain or sealant; applying a finish to damp wood traps moisture inside and can cause blistering

Special situations:

• Mold or mildew – if black or green discoloration appears, use a purpose-made wood mold cleaner (oxygen bleach-based products work well on Douglas Fir without damaging the wood)
• Bird droppings – clean promptly; acidic droppings can etch into stain finishes if left to bake in the sun
• Climbing plant residue – cut back plants before cleaning to allow access to all timber surfaces

Avoid:

• Pressure washing at high settings — can raise wood grain and strip protective finish
• Chlorine bleach — weakens wood fibers over time; use oxygen bleach alternatives instead