13 November 2009

ACK! THE ROOF: TO VENT OR NOT?

Reader beware...
Nuances of this roof:

  • Rafters (2"x6" ripped to 6" "exactly") are running parallel to the width (not length as is standard)
  • I'm planning on using two pieces of 2 5/8" rigid foam between the rafters, (potentially) leaving about 3/4" space for venting (holes in rafters and blocking could allow for venting from side to side of the house, OR from eave through rafters up to ridge)
  • There is 2"x6" diagonal blocking (not 6" exactly) with an 18 gauge metal strap nailed into it
  • I'm stubborn about not wanting to use plywood for sheer strength
  • the vapor barrier on the roof (bitchathane/ ice & storm most likely... .... ....) needs a consistent uniform surface to lay upon; Therefore, if I do vent at the top, I imagine I'll need to sandwich a few layers of corrugated plastic (same stuff ridge vents are made from)
  • It is possible to vent the longer side (seen with the diagonal in place) but not the loft side (which will have a hatch roof that pops up)
  • There will be small windows at the loft level to open for ventilation

IF NO VENTING
PROS: I just want to put the roof on, enough already

CONS: worried about mold developing in ceiling

IF YES VENTING
PROS: the roof is vented! longevity
CONS: pain in the neck, less space in loft's head room

BOTTOM LINE:
I have to make a decision. The rain is coming.


2 comments:

  1. BUILDER ONE SAYS:
    Don't vent it. You just need to make sure there are NO air gaps in the installation, period. That will avoid condensation problems.

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  2. BUILDER TWO SAYS:
    If you can create any air space in the roof, I think it'd be worthwhile. Otherwise, you run a higher risk of getting moisture on the inside ceiling. I had this happen on an old yaght that I owned. Every morning, I'd have to wipe down the inside roof with a towel. Not a big deal as long as you have a good coat of paint on the ceiling, and don't mind wiping things down. That could be a pain in the neck if you think you'll be moving to a colder climate. When i first got into the yaght, the ceiling paint was stained and peeling from past condensation problems. It was pretty hard on the ceiling wood.

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