Calling all roofing opinions-I have a small area of flat roof (to be
modified bitumin) with a dropped ceiling below with insulation laid
above the ceiling. I think the insulation in the walls goes to the
underside of the roof. Is it better to drill air holes in my fascia
board to allow air to circulate and reduce moisture or (since I am
about to add a new layer of roof)is it better to lay insulation boards
down and then roofing and skip the ventilation holes? The space below
this small roof is a bathroom and the ceiling drywall is moisture
resistant drywall plus we have an exhaust fan when we remember to use
it.... Also, we have had roof leaks and I am afraid mold may have
started growing-ventilation holes may help that?????
any suggestions would be appreciated.
Your second plan is the best. Insulation panels on the roof, then a new
roof over that. Don't put fascia vents in, this will not be good.
If you are worried about trapped moisture, take out the drop ceiling
tiles and run a dehumidifier and a fan for a day or so.
Fascia ventilation is not good because....water may blow in through the
holes? Why do you think it is not good in this case? I would like to
get above the ceiling and see if there is mold, but the ceiling is
drywall and would involve some demo to the newly renovated space
(double ouch). Any thoughts on how to dry out the space? The area
above the ceiling of the bathroom actually is open to the space above
the ceiling in the rest of the house and given that this is a 100 plus
year old house there is natural ventilation of sorts already going on.
If I were to add ventilation holes I would have to somehow close this
opening up. I don't really get the whole ventilation of roof
thing....Just rambling now... Thanks for your thoughts.
Well, I am confused now. In your first post you said you had
a drop ceiling. (I had to reread your original post). Then
you said that you had a drywall ceiling. Which is it?
If you have a drywall ceiling, then you could put in some
soffit vents preferably, or if no soffit, then a few fascia vents.
If you have a drop ceiling, then it would not be good to put
in vents as drop ceilings are notorious about leaking air
which would increase your heating/cooling costs. If it is a
drop ceiling, it is better to remove the drop ceiling tiles
and air it out that way, then replace the ceiling tiles.
Sorry. The roof is flat roof. The roof beams do not have insulation
between them. The moisture resistant drywall is dropped say 2 feet
below. There is fiberglass insulation laid above the framing for the
I've done a bit of reading. If I want to have a non vented roof
assembly and I lay insulation on the roof, I think the underside of the
roof deck would still be cold and may condense. But now, I do have the
batt insulation above the ceiling..... I could (assuming I can squeeze
the body into this space) remove the insulation from above the ceiling
and install it between the roof beams, making it a somewhat
"conditioned space". The cavity is in a leaky old building so I'm not
sure what that means. The worse case is in cold weather when the air
in the cavity is moist and warm and may condense on building materials
correct? help. none of this makes sense to me....
thank you thank you thank you Robert. Any more advise?
Robert Allison wrote:
Take a look at the Building Science Corporation web site.
This is researched information on issues like yours.
I would agree witn Mr. Allison.
His comments about treating the potentially dead air space is critical.
Wow. Lot's of great info. Now I am more educated, more scared, and
unfortunately more confused. The literature deals more with sloped
roofs and never assumes that the building is not well sealed. Not sure
where that puts my situation. If I am insulated around the envelope
and the cavity or above ceiling space is cold, other than loosing heat,
is that bad as far as condensation goes?
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.