Split or cracked timber weatherboards

Causes

Boards have been double nailed, preventing movement 

Boards are single-fixed but nailed through the lap preventing movement 

The timber has become too dry 

Splitting occurred during installation

An insufficient gap was left between rusticated or rebated weatherboards during installation 

Listed under: Exterior, finishes, timber and wood-based, paint, timber, cladding, walls, moisture, leaks, wall cladding, painted timber weatherboards

Cause

Boards have been double nailed, preventing movement 

Repair

  • if splitting allows water entry into the wall cavity, replace the boards
  • if there is no water entry, the boards can remain. Scrape or sand back paint; prime; fill joints with putty or exterior grade flexible (polyester) filler; paint with at least two coats of semi-gloss or high gloss acrylic paint. Caution: old layers of paint may contain lead. Lead can be a health hazard if fumes, dust or paint fragments are swallowed or breathed in. For more information see Health and safety: lead-based paint
  • before replacing boards, check that wall underlay (building paper) and framing behind weatherboards are sound
  • where it is suspected that the building may be leaking and there is a risk of damage behind the cladding, engage an experienced building surveyor to report on the building 

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Cause

Boards are single-fixed but nailed through the lap preventing movement 

Repair

  • if splitting allows water entry into the wall cavity, replace the boards
  • if there is no water entry, the boards can remain. Scrape or sand back paint; prime; fill joints with putty or exterior grade flexible (polyester) filler; paint with at least two coats of semi-gloss or high gloss acrylic paint. Caution: old layers of paint may contain lead. Lead can be a health hazard if fumes, dust or paint fragments are swallowed or breathed in. For more information see Health and safety: lead-based paint
  • before replacing boards, check that wall underlay (building paper) and framing behind weatherboards are sound
  • where it is suspected that the building may be leaking and there is a risk of damage behind the cladding, engage an experienced building surveyor to report on the building 

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Cause

The timber has become too dry 

Repair

  • if splitting allows water entry into the wall cavity, replace the boards
  • if there is no water entry, the boards can remain. Scrape or sand back paint; prime; fill joints with putty or exterior grade flexible (polyester) filler; paint with at least two coats of semi-gloss or high gloss acrylic paint.  Caution: old layers of paint may contain lead. Lead can be a health hazard if fumes, dust or paint fragments are swallowed or breathed in. For more information see Health and safety: lead-based paint
  • before replacing boards, check that wall underlay (building paper) and framing behind weatherboards are sound
  • where it is suspected that the building may be leaking and there is a risk of damage behind the cladding, engage an experienced building surveyor to report on the building

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Cause

Splitting occurred during installation

Repair

  • if splitting allows water entry into the wall cavity, replace the boards
  • if there is no water entry, the boards can remain. Scrape or sand back paint; prime; fill joints with putty or exterior grade flexible (polyester) filler; paint with at least two coats of semi-gloss or high gloss acrylic paint. Caution: old layers of paint may contain lead. Lead can be a health hazard if fumes, dust or paint fragments are swallowed or breathed in. For more information see Health and safety: lead-based paint
  • before replacing boards, check that wall underlay (building paper) and framing behind weatherboards are sound
  • where it is suspected that the building may be leaking and there is a risk of damage behind the cladding, engage an experienced building surveyor to report on the building 

Back to top

Cause

An insufficient gap was left between rusticated or rebated weatherboards during installation 

Repair

  • if splitting allows water entry into the wall cavity, replace the boards
  • if there is no water entry, the boards can remain. Scrape or sand back paint; prime; fill joints with putty or exterior grade flexible (polyester) filler; paint with at least two coats of semi-gloss or high gloss acrylic paint. Caution: old layers of paint may contain lead. Lead can be a health hazard if fumes, dust or paint fragments are swallowed or breathed in. For more information see Health and safety: lead-based paint
  • before replacing boards, check that wall underlay (building paper) and framing behind weatherboards are sound
  • where it is suspected that the building may be leaking and there is a risk of damage behind the cladding, engage an experienced building surveyor to report on the building

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