Roof space – flexible ducting is crushed/folded

Flexible ducting (extracts or ventilation system) in roof space is crushed/folded

Causes

Poor initial installation

Ducting has been shifted or crushed when work was carried out in the roof space

Cause

Poor initial installation

Repair

  • if existing ducting is basically sound and damage is minor, straighten out runs to give a clear flow

  • where crushed or damaged ducting restricts airflow or allows air to escape into the roofspace, replace it

  • check that the design and specification of the ducting is appropriate to the situation

  • larger ducting gives better airflow performance. (Long runs of relatively small-diameter flexible ducting connecting extraction fans to the outside also increase the potential of moisture condensing)

  • internal surfaces of ducting should be as smooth as possible to minimise air flow resistance

  • have the minimum number of bends possible

  • where bends are unavoidable, have them as large diameter as possible

  • have no tight bends as these can cause significant air flow resistance

  • ducting that passes through a cold air space should be insulated to reduce the risk of condensation forming in the duct

  • check that all the connections are properly made

Cause

Ducting has been shifted or crushed when work was carried out in the roof space

Repair

  • if existing ducting is basically sound and damage is minor, straighten out runs to give a clear flow

  • where crushed or damaged ducting restricts airflow or allows air to escape into the roofspace, replace it

  • have the minimum number of bends possible

  • where bends are unavoidable, have them as large diameter as possible

  • have no tight bends as these can cause significant air flow resistance

  • ducting that passes through a cold air space should be insulated to reduce the risk of condensation forming in the duct

  • check that all the connections are sound