Deck balusters/posts, balustrades and barriers – insecure when pressure is applied

Cause

Rotten timber

Repair

  • replace all rotten or damaged timber. If using Pinus radiata, it should be treated to minimum H3.2, otherwise use a timber that is naturally durable. For framing, use timber grade of at least SG8 (wet in service). Infill members may be SG6 (wet in service)

  • select metal fixings with at least the same durability requirements as the timber they connect. (NZS 3604:2011 Timber-framed buildings has the details in section 4.4). Steel fixings in ‘sheltered’ locations – open to airborne salts but not rain washed – must typically be galvanised as a minimum. Those in ‘exposed’ locations – open to airborne salts and rain – require Type 304 or 316 (for marine exposure) stainless steel

  • details for deck barriers can be found in this Build magazine article and in this MBIE publication

Cause

Fixings have pulled out or corroded

Repair

  • replace all missing or corroded fixings. Check that the timber around the fixing is sound – if timber is damaged by fixing corrosion, replace the timber (see details above)

  • select metal fixings with at least the same durability requirements as the timber they connect. (NZS 3604:2011 Timber-framed buildings has the details in section 4.4). Steel fixings in ‘sheltered’ locations – open to airborne salts but not rain washed – must typically be galvanised as a minimum. Those in ‘exposed’ locations – open to airborne salts and rain – require Type 304 or 316 (for marine exposure) stainless steel

  • details for deck barriers can be found in this Build magazine article

Cause

The barrier structure is inadequate (undersized framing or framing support too far apart)

Repair

  • add new framing members to strengthen the existing structure (replace damaged timber as necessary to ensure a safe and secure barrier)

  • barrier details can be found in the MBIE guidance document Guidance on Barrier Design

  • some details for deck barriers can be found in this Build magazine article

  • if using Pinus radiata, ensure it is treated to minimum H3.2 – otherwise use a timber that is naturally durable. For framing, use timber grade of at least SG8 (wet in service). Infill members may be SG6 (wet in service)

  • select metal fixings with at least the same durability requirements as the timber they connect. (NZS 3604:2011 Timber-framed buildings has the details in section 4.4). Steel fixings in ‘sheltered’ locations – open to airborne salts but not rain washed – must typically be galvanised as a minimum. Those in ‘exposed’ locations – open to airborne salts and rain – require Type 304 or 316 (for marine exposure) stainless steel

Cause

Deck baluster/balustrade/post fixings are loose

Repair

  • check and retighten all bolt fixings to the balustrade or posts – fixings can become loose as a result of timber shrinkage (or they were not particularly tight in the first place)

  • where access is available, check and tighten as necessary all other bolts on the deck structure at the same time

Cause

The baluster/balustrade/post fixings to the deck are inadequate

Repair

  • the posts should be fixed with M12 bolts and 50 x 50 mm washers with at least two bolts per baluster or post
  • select metal fixings with at least the same durability requirements as the timber they connect. (NZS 3604:2011 Timber-framed buildings has the details in section 4.4)

Cause

Deck barrier does not meet with current Building Code requirements

Repair

  • for barriers in sound condition there is no statutory requirement to upgrade to current requirements if it was installed before 1992. Where a barrier is replaced it is recommended that the new barrier comply with current requirements. Check with your local building consent authority for consent requirements. A barrier constructed post 1992 that has not met Building Code durability or structural requirements will require a building consent for the replacement 
  • details for compliant deck barriers can be found in this Build magazine article and this MBIE publication