Please take a look at the elevation below. Should the entire porch have
IWS? Should I flash the siding to roof with IWS? Thanks.

http://mropartner.com/frontelevation.htm

On May 20, 11:34 am, "Bgreer5050" wrote:
Please take a look at the elevation below. Should the entire porch have
IWS? Should I flash the siding to roof with IWS? Thanks.

http://mropartner.com/frontelevation.htm

IMO, ice and water in this location is unnecessary. I would flash the
siding with coil stock/step flashings. Ice and water doesn't really
work because none of it can be exposed. If you expect extreme wind
driven rain, you might consider it as an insurance layer under your
flashing (lapped up under your building paper). I would use ice and
water on eaves in valleys in climates with snow, and under asphalt
shingles applied to a pitch less than 3/12.

What size stock flashing would you recommend?


"marson" wrote in message
oups.com...
On May 20, 11:34 am, "Bgreer5050" wrote:
Please take a look at the elevation below. Should the entire porch have
IWS? Should I flash the siding to roof with IWS? Thanks.

http://mropartner.com/frontelevation.htm

IMO, ice and water in this location is unnecessary. I would flash the
siding with coil stock/step flashings. Ice and water doesn't really
work because none of it can be exposed. If you expect extreme wind
driven rain, you might consider it as an insurance layer under your
flashing (lapped up under your building paper). I would use ice and
water on eaves in valleys in climates with snow, and under asphalt
shingles applied to a pitch less than 3/12.

On May 20, 12:34�pm, "Bgreer5050" wrote:
Please take a look at the elevation below. *Should the entire porch have
IWS? *Should I flash the siding to roof with IWS? *Thanks.

http://mropartner.com/frontelevation.htm

yes because the extra cost will be low

The IBC states the following:

1507.8.3 Underlayment.
Underlayment shall comply with ASTM D 226, Type I or ASTM D 4869. In
areas where there has been a history of ice forming along the eaves
causing a backup of water, an ice barrier that consists of at least
two layers of underlayment cemented together or of a self-adhering
polymer-modified bitumen sheet shall be used in lieu of normal
underlayment and extend from the eave's edge to a point at least 24
inches (610 mm) inside the exterior wall line of the building.

Yes, ice and water shield (or equivalent) should be used if there is a
history of freezing temperatures and it should extend BEYOND the
exterior wall to OVER the interior of the structure 24" min. This is
also the standard used by most shingle manufacturers and warranties
may be voided if not installed.

JMHO

Terry

On May 20, 5:02 pm, "
wrote:
The IBC states the following:

1507.8.3 Underlayment.
Underlayment shall comply with ASTM D 226, Type I or ASTM D 4869. In
areas where there has been a history of ice forming along the eaves
causing a backup of water, an ice barrier that consists of at least
two layers of underlayment cemented together or of a self-adhering
polymer-modified bitumen sheet shall be used in lieu of normal
underlayment and extend from the eave's edge to a point at least 24
inches (610 mm) inside the exterior wall line of the building.

Yes, ice and water shield (or equivalent) should be used if there is a
history of freezing temperatures and it should extend BEYOND the
exterior wall to OVER the interior of the structure 24" min. This is
also the standard used by most shingle manufacturers and warranties
may be voided if not installed.

JMHO

Terry

Sorry wrong reference... IBC 1507.2.8.2 Ice dam membrane... verbatim

wrote

1507.8.3 Underlayment.
Underlayment shall comply with ASTM D 226, Type I or ASTM D 4869. In
areas where there has been a history of ice forming along the eaves
causing a backup of water, an ice barrier that consists of at least
two layers of underlayment cemented together or of a self-adhering
polymer-modified bitumen sheet shall be used in lieu of normal
underlayment and extend from the eave's edge to a point at least 24
inches (610 mm) inside the exterior wall line of the building.

Yes, ice and water shield (or equivalent) should be used if there is a
history of freezing temperatures and it should extend BEYOND the
exterior wall to OVER the interior of the structure 24" min. This is
also the standard used by most shingle manufacturers and warranties
may be voided if not installed.

JMHO

Terry

Sorry wrong reference... IBC 1507.2.8.2 Ice dam membrane... verbatim

Well inspector, you should have noticed, this is an _unheated_ area in
question.

So much for being an inspector.

Every notice the heating effect of the sun on a cold winter day? Melts the
snow, runs down to the gutter and re-freezes night. It can be a very real
cause of ice damming; not just heat loss from the structure.

I also would not hesitate to use IWS underlayment. Cost is low and excellent
insurance. (I used it 100% on my roof.) It's not a code requirement in this
particular area, but it's good common sense to add extra insurance at little
extra cost. (I'm also an inspector / plan reviewer as well.)

Well inspector, you should have noticed, this is an _unheated_ area in
question.

So much for being an inspector.

On May 20, 5:02 pm, "
wrote:
The IBC states the following:

1507.8.3 Underlayment.
Underlayment shall comply with ASTM D 226, Type I or ASTM D 4869. In
areas where there has been a history of ice forming along the eaves
causing a backup of water, an ice barrier that consists of at least
two layers of underlayment cemented together or of a self-adhering
polymer-modified bitumen sheet shall be used in lieu of normal
underlayment and extend from the eave's edge to a point at least 24
inches (610 mm) inside the exterior wall line of the building.

Yes, ice and water shield (or equivalent) should be used if there is a
history of freezing temperatures and it should extend BEYOND the
exterior wall to OVER the interior of the structure 24" min. This is
also the standard used by most shingle manufacturers and warranties
may be voided if not installed.

JMHO

Terry

Sorry, wrong reference... See

IBC 1507.2.8.2 Ice dam membrane.

In areas where there has been a history of ice forming along the eaves
causing a backup of water, a membrane that consists of at least two
layers of underlayment cemented together or of a self-adhering polymer
modified bitumen sheet shall be used in lieu of normal underlayment
and extend from the eave's edge to a point at least 24 inches (610 mm)
inside the exterior wall line of the building.

On May 20, 6:19 pm, "
wrote:
On May 20, 5:02 pm, "



wrote:
The IBC states the following:

1507.8.3 Underlayment.
Underlayment shall comply with ASTM D 226, Type I or ASTM D 4869. In
areas where there has been a history of ice forming along the eaves
causing a backup of water, an ice barrier that consists of at least
two layers of underlayment cemented together or of a self-adhering
polymer-modified bitumen sheet shall be used in lieu of normal
underlayment and extend from the eave's edge to a point at least 24
inches (610 mm) inside the exterior wall line of the building.

Yes, ice and water shield (or equivalent) should be used if there is a
history of freezing temperatures and it should extend BEYOND the
exterior wall to OVER the interior of the structure 24" min. This is
also the standard used by most shingle manufacturers and warranties
may be voided if not installed.

JMHO

Terry

Sorry, wrong reference... See

IBC 1507.2.8.2 Ice dam membrane.

In areas where there has been a history of ice forming along the eaves
causing a backup of water, a membrane that consists of at least two
layers of underlayment cemented together or of a self-adhering polymer
modified bitumen sheet shall be used in lieu of normal underlayment
and extend from the eave's edge to a point at least 24 inches (610 mm)
inside the exterior wall line of the building.

Ice dams occur because heat from the interior of a building melts
snow, and the resulting water runs onto the eave, where it freezes,
since the eave is no longer heated from the interior of the building.
The resulting ice dam causes water to back up under the shingles, and
preventing the resultant leaks is the function of the ice and water
shield, and this is why codes require it. So I guess the question is,
will ice dams form on your unheated porch? I've never seen it happen,
even in climates that get a lot of snow (300+ inches).

Thanks to all for your input.


"marson" wrote in message
oups.com...
On May 20, 6:19 pm, "
wrote:
On May 20, 5:02 pm, "



wrote:
The IBC states the following:

1507.8.3 Underlayment.
Underlayment shall comply with ASTM D 226, Type I or ASTM D 4869. In
areas where there has been a history of ice forming along the eaves
causing a backup of water, an ice barrier that consists of at least
two layers of underlayment cemented together or of a self-adhering
polymer-modified bitumen sheet shall be used in lieu of normal
underlayment and extend from the eave's edge to a point at least 24
inches (610 mm) inside the exterior wall line of the building.

Yes, ice and water shield (or equivalent) should be used if there is a
history of freezing temperatures and it should extend BEYOND the
exterior wall to OVER the interior of the structure 24" min. This is
also the standard used by most shingle manufacturers and warranties
may be voided if not installed.

JMHO

Terry

Sorry, wrong reference... See

IBC 1507.2.8.2 Ice dam membrane.

In areas where there has been a history of ice forming along the eaves
causing a backup of water, a membrane that consists of at least two
layers of underlayment cemented together or of a self-adhering polymer
modified bitumen sheet shall be used in lieu of normal underlayment
and extend from the eave's edge to a point at least 24 inches (610 mm)
inside the exterior wall line of the building.

Ice dams occur because heat from the interior of a building melts
snow, and the resulting water runs onto the eave, where it freezes,
since the eave is no longer heated from the interior of the building.
The resulting ice dam causes water to back up under the shingles, and
preventing the resultant leaks is the function of the ice and water
shield, and this is why codes require it. So I guess the question is,
will ice dams form on your unheated porch? I've never seen it happen,
even in climates that get a lot of snow (300+ inches).

marson wrote:


Ice dams occur because heat from the interior of a building melts
snow, and the resulting water runs onto the eave, where it freezes,
since the eave is no longer heated from the interior of the building.
The resulting ice dam causes water to back up under the shingles, and
preventing the resultant leaks is the function of the ice and water
shield, and this is why codes require it. So I guess the question is,
will ice dams form on your unheated porch? I've never seen it happen,
even in climates that get a lot of snow (300+ inches).

Yes. It can happen. It's not always a function of heated/unheated
spaces. Often, the melting occurs due to sun/warm temperatures. For
instance, it's on an east exposure, it will warm on a sunny day, melt,
then as the sun moves west, it re-freezes. This causes an ice damn to
build over a period of several days.

People often want to blame faulty construction (not enough insulation,
etc), when it's simply a microclimate issue that the designer didn't
think about.

Yes. It can happen. It's not always a function of heated/unheated
spaces. Often, the melting occurs due to sun/warm temperatures. For
instance, it's on an east exposure, it will warm on a sunny day, melt,
then as the sun moves west, it re-freezes. This causes an ice damn to
build over a period of several days.

People often want to blame faulty construction (not enough insulation,
etc), when it's simply a microclimate issue that the designer didn't
think about.


This is true and is the reason for the code requirement.

There is no exception within the codes for roofs over unheated
porches, only for detached unheated structures.

I DIDNT WRITE THE CODE... i just enforce it within my jurisdiction.

Terry

On May 20, 11:34�am, "Bgreer5050" wrote:
Please take a look at the elevation below. *Should the entire porch have
IWS? *Should I flash the siding to roof with IWS? *Thanks.

http://mropartner.com/frontelevation.htm

Why not? I think the expense would be minimal. Even if the
ppotential for damage from ice-damming would be minimal, the possible
cost could be quite high. At worst, it would probably serve as
another layer against leaks.