Actually it's not a dormer. A ridge perpendicular to the main body ridge.
Anybody got a pointer to a web doc that shows the proper way to apply felt?
Here's a sky view of it: http://tinypic.com/view.php?pic=4oz8zg7
In my area, the ice and sheid in the valleys isn't to code. Metal is
needed, and I would recommend that it be galvanized. If the dormer
roof slope is above 4 inches per foot than skip the ice and shield
altogether. This stuff is mainly useful along the rakes, eves, and on
low slope roofs, and in my opinion whether you follow the package
instructions to glue it down to the deck or over the paper is up to
you. I can't see any reason why it would make any difference after
the shingles are nailed down. For the felt, layer from the bottom up,
as would shingles, but otherwise paper down anyway you want, making
sure that drainage will flow over and off, and not into the roof
deck. Vertical rolls are OK, especially along the valley before the
metal goes down. Use two layers of 15lb or 30lb, and then nail the
metal valleys over the paper. Leave the bottom ends of the metal
valleys without nails so that you can put the asphalt shingle or wood
shake under before nailing it down. This will allow the drainage off
the metal valley to drain onto the roof. Don't nail any closer than
two inches from the center of the valley, rather nail the metal down
along the edges. Later, you can nail through the valley (still at
least 2" away from center though) to hold the shingles down. A little
neopreme along the underside of the valley edge of the asphalt shingle
will help ensure moisture doesn't get up under the shingles, but it's
not strickly required by the shingle manufacturers.
Do you live in a snow area? The purpose of the ice and water shield
is to seal the nail holes. This is required by code where I live. .
Ice dams in valleys result in standing water in the valley. Two
layers of felt and metal flashing alone will not seal the nails. We
too use flashing in the valleys (later covered by shingles, since most
people around here use a woven valley), but the OP was asking about
how to run felt, not how to shingle a valley.
On more thing, put either ridge vent along both ridges, or a
galvanized steel roof vent high on the side of the dormer that's
hidden from the ground view, close to the junction with main ridge, to
ventilate the attic space. You may want more than one of these in the
roof. These can be cut in with sawsall after the paper is nailed
down. The thermostatically controlled heavy duty electric ones are
nice, but for many homes the passive rain protected vent will work
Dude, you really are a bozo.
For one, it's not if someone wants more than one vent, there is a formula
to figure out proper ventilation.
Another thing, those thermostatically controlled vents don't work in the
Before attempting to give out information on passive venting, please look
up exactly what it is. At least you will have a clue next time. Hint: It's
not just venting you install on the roof.
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