On Feb 21, 2:37*pm, "Chomper" wrote:
wrote in message

...





I'm getting a new roof which of course has lead into
the age old discussion of how best to vent it. *I've
got 2 contractors saying ridge only is best, the other
insisting that power fans are superior. *Personally, I
can see advantages and disadvantages to both. *I'm
interested in other experiences and opinions.

So, here's the deal. The roof consists of 3 seperate
sections. *One of those is a cathedral ceiling, so using
a ridge vent there is a given. *The other two sections which
are the area of interest a

Section 1 - Currently has a gable vent in one end and
a power fan near the other end.

Section 2 - Currently has a gable vent in each end, with
a power fan blowing air out behind one of those gables. *This
section is over the 2nd floor bedrooms where keeping it cool is
very important.

All sections have continous soffit venting, about 2" wide.
All 3 roofers say that is sufficient and doesn't need to be
improved.

Two of the roofers say to go with ridge vent on both of
these roofs, get rid of the existing power fan.

One roofer insists that I should stay with using fans on
the two roofs as it is now. *His argument is that a power
fan moves a lot more air than a ridge vent system can.
Climate is NJ.

Thoughts?

I would assume, being in NJ, you do have cold (freezing) weather.

Here's some thoughts before you decide.

- If you decide on ridge vent (which I would suggest), you do not want the
existing gable vents to act like the intakes even though you have soffit.
I have seen where ridge vent was installed leaving the existing gable
vents. *During rain storms in hot weather, the natural flow of air actually
pulled in the elements of water through the gable vents.

From the research I did today, it seems most credible
sources agree with this.




- Power vents are the absolute worst solution to use, where freezing
climates occur. *They don't work in the winter. A structure must be able to
exhaust any hot air of the building envelope, which rises through the
ceiling insulation in the winter. *I believe I may have told the story in
this forum of actually observing water dripping through ceilings in the
winter, because the only type of ventilation installed was power vents.

Currently both roof sections that have fans also have
a gable vent, plus the soffits. So, you have two openings
up top for the air to exit. No moisture issues.




If you do go with ridge vents, you must close off the gable end vents. You
must make sure the soffit vents are cut through and unobstructed by
insulation. In most cases, baffles are used in the initial 4 ft from top
plate of the wall. This helps provide a continuous unobstructed ( think
insulation) passage from the soffit intakes.

When I bought the house 18 years ago, that was one
thing I caught and corrected. There were no baffles and
the insulation was blocking the soffits. I installed baffles.





I guess you must decide what is the most economical, but it won't
necessarily will be the best functional system. By this I mean if you must
close off the gables, without ruining the appearance of the structure,

No problem with that. All that needs to be done is close
it off from inside the attack.




and
making sure you have clear intake passage from the soffits, makes enough
sense for the money involved in doing it right. *Otherwise, you may want to
use another method of choice.

If it were me, I'd have to give some serious thought on just using the
existing gable vents _without_ power vents (which block the vent in the
winter), and putting ridge vent on the cathedral room. I would also give
some serious thought to additional insulation where you can add it. *Attic
blankets are pretty economical.- Hide quoted text -

- Show quoted text -

Given all that I've learned researching it so far, I'm
hjeading in the direction of going with the ridge vents.
Next thing is there are all kinds of product, from rigid
plastic ones that come in 4 ft sections, to ones that
come in rolls. Oddly, the price is almost the same.
I'm guessing that the roofers like the roll material
because it's probably easier to install. However the
rigid ones have more airflow, like 20 sq in per foot
versus maybe 14 for the other stuff. And with the
roll type, I think it would be easier to not install correctly,
ie mash it down, etc so you could wind up with even
less venting. So, if I go ridge vent, I'm going to spec
which one.

Thanks for the help. And if you have any more tips,
I'd be happy to hear them.