Continuing 'Roof turbines, are they a good idea"...

I have an old and small two story house that gets very hot upstairs. I just checked the
roof vent situation and discovered there were no soffits, and the two vents, one on
either end of the house just under the ridge, are 7 inches high and 12 inches wide. I
measured the air temp difference and outside the vent it was 72 degrees and 4 inches
inside the vent 86 degrees. This was on the cool end of the house, probably a larger
difference on the other end. I also saw there was no insulation above the ceiling. The
max distance from the ceiling to the ridge is about 2 feet. The ceiling area square
footage is about 500 sq ft.

I had no sense of any convection or air movement out of these two vents, could they be
just too small to do anything?

Given the situation, and the fact that the area where the soffits would be is covered
with asbestos siding so not something I can easily cut holes in, what should I do?
Enlarge the small roof vents, add a roof turbine, something else?


John

jbclem wrote:
Continuing 'Roof turbines, are they a good idea"...

I have an old and small two story house that gets very hot upstairs.
I just checked the roof vent situation and discovered there were no
soffits, and the two vents, one on either end of the house just under
the ridge, are 7 inches high and 12 inches wide. I measured the air
temp difference and outside the vent it was 72 degrees and 4 inches
inside the vent 86 degrees. This was on the cool end of the house,
probably a larger difference on the other end. I also saw there was
no insulation above the ceiling. The max distance from the ceiling
to the ridge is about 2 feet. The ceiling area square footage is
about 500 sq ft.

I had no sense of any convection or air movement out of these two
vents, could they be just too small to do anything?

Given the situation, and the fact that the area where the soffits
would be is covered with asbestos siding so not something I can
easily cut holes in, what should I do? Enlarge the small roof vents,
add a roof turbine, something else?

Whatever air that goes out has to come in somewhere. With no soffits....

Can you put a fan at one of the existing vents?

jbclem wrote:
Continuing 'Roof turbines, are they a good idea"...

I have an old and small two story house that gets very hot upstairs.
I just checked the roof vent situation and discovered there were no
soffits, and the two vents, one on either end of the house just under
the ridge, are 7 inches high and 12 inches wide. I measured the air
temp difference and outside the vent it was 72 degrees and 4 inches
inside the vent 86 degrees. This was on the cool end of the house,
probably a larger difference on the other end. I also saw there was
no insulation above the ceiling.

*** Lack of insulation should be #1 on your list! ***

The max distance from the ceiling
to the ridge is about 2 feet. The ceiling area square footage is
about 500 sq ft.

I had no sense of any convection or air movement out of these two
vents, could they be just too small to do anything?

To have convection you need to have high and low level vents. You only
have high. Adding turbines will not change that. It will add some vent
area, which is good and if the wind is blowing they may help (of course with
wind the vents you have will work better.


Given the situation, and the fact that the area where the soffits
would be is covered with asbestos siding so not something I can
easily cut holes in, what should I do? Enlarge the small roof vents,
add a roof turbine, something else?

I suggest checking with the pros and let them take a look at your home
and see if they can see a good way of providing low (soffit) vents. An
experienced professional often has a few tricks up their sleeve that allows
them to get the job done.



John

--
Joseph Meehan

Dia duit

I suggest you first read about venting in the Building Science
Corporation web site.
A number of architects have noted the usefulness of the information on
this site.
There are a number of issues that influence or are connected with attic
heat.
Climate, vapor barriers, air leakage from the house, & insulation come
to mind.
TB

Add Ceiling Insulation First.

If you still feel the need to ventilate the attic, install 2 gable end
fans, one blowing in, the other blowing out. This will reduce the
chance that you will be sucking air conditioned air out of the house
with the fans.

Stretch