I'm wondering if we should have ventilation in our ceiling cavity. Right now there's just the small gap where the roof iron meets the soffit / eaves. Main reason is it's dusty and smelly and when we open the access hatch we sneeze for a while - sometimes and hour, sometimes two days.

 

We have an iron roof on an 50+ year old house with building paper under it, there's heaps of space up there. In the summer it can get up to 50 degrees. It doesn't smell great, there's the smell of the old wood, decades of dust, multiple types of insulation, rat poison, borer poison, who knows what else. When the ceiling access hatch is open for more than a couple of minutes (which happens every few weeks) allergies are upset. We've never noticed any moisture up there at all.

 

In the ceiling space we have:

 

  • Storage (all kinds of random things - clothes, Christmas tree, old books, etc, mostly in sealed plastic boxes)
  • Alarm system central unit
  • Ducted heat pump
  • Ventilation system (air comes from outside, through a filter, then pushed inside, no air from the ceiling space comes into the house)
  • Bathroom fan
  • Electrical wires

I've read that venting the ceiling can reduce house temperatures in summer, even if there's good insulation above the ceiling.

 

 

 

If we decide it's worth doing, then my reading (good summary here) suggests a few main options:

 

  • Soffit inlet vents, with or without outlet vents at the ridgeline ( I guess this means getting a roofer to install vents or getting something like these dome vents)
  • Mechanical ventilation
  • A combination like a dome vent that has a solar fan in it

With mechanical I guess you'd want a central exhaust, as if you just put an extractor fan in the eaves it would mostly remove air from that area.

 

Any thoughts? Are the enough benefits or it it just a waste of money?