Key Change to Ice Barrier Requirements in the 2024 IRC: What You Need to Know

[bill1952]

I would expect the ICC to have the correct latest version on their website.

CHAPTER 9 ROOF ASSEMBLIES - 2024 INTERNATIONAL RESIDENTIAL CODE (IRC)

ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.

codes.iccsafe.org

But perhaps that is asking too much. : - )

Cheers, Wayne

I'll have to look again because I didn't find it earlier today. Thank you.

 

[Sifu]

I have requested an opinion from ICC about this. I'll update if I find out more.

 

[Sifu]

This is the message I sent:

Question Details: IRC 905.1.2 has a requirement for ice barrier protection on roofs with a slope of 8/12 or greater to run from the lowest edge of the roof along the roof slope 36" wide. This appears to have been introduced in the 2015 IRC, but the code change proposal for this section I found does not include this provision (RB435-13 from the "Complete Revision History to the 2015 I-Codes", 1st printing, published September 2014) , and I cannot find RB435-13 in any of the code change monographs on the ICC website, nor any other change to this section. Because of this I can find no clarification for it and no reason statement, and it is not covered by any of the supplemental information such as code commentaries. This would not appear to be editorial in nature as it is a new requirement for ice barrier protection in additional locations. Why was this added, and is there a code change proposal for it with a reason statement? If there is no change proposal how was it added to this section?

 

[steveray]

I have requested an opinion from ICC about this. I'll update if I find out more.

Inquiring minds want to know....

 

[SCBO1]

If the 36-inch requirement has been removed did the new code change revert back to 24-inches, is that a summary of the change?

 

[steveray]

If the 36-inch requirement has been removed did the new code change revert back to 24-inches, is that a summary of the change?

Since before 1997 it has been 24" in...just often misunderstood...

 

[Sifu]

If the 36-inch requirement has been removed did the new code change revert back to 24-inches, is that a summary of the change?

Can't find any confirmation it has been removed, but the 36" requirement, as written, is not tied to a heated wall line like the 24" rule, it is just 36"....The more I look at this code, the more unsure I am of what it requires and why.

 

[steveray]

I believe the intent was to give a break to steep slopes and only requiring 36" up from the eaves on those roofs regardless of wall line....They don't form at the wall line, they form at the eave...

 

[SCBO1]

Is there an issue with the installation of an I&WS product on a steep roof for it to be removed from code? Is it hard to install the steeper the roof?

Sifu, the 4/12 open porch pic you provided, seems a bit overkill, is that really the intent of the I&WS, I haven't ran into that issue yet but wonder if I would get pushback on that from a contractor. I guess there's really no other way that can be installed on the open porch. I just started enforcing the I&WS, it was exempted from code for several code cycles.

 

[Sifu]

Is there an issue with the installation of an I&WS product on a steep roof for it to be removed from code? Is it hard to install the steeper the roof?

Sifu, the 4/12 open porch pic you provided, seems a bit overkill, is that really the intent of the I&WS, I haven't ran into that issue yet but wonder if I would get pushback on that from a contractor. I guess there's really no other way that can be installed on the open porch. I just started enforcing the I&WS, it was exempted from code for several code cycles.

Well! Since I went down this rabbit hole I am now questioning everything I thought I knew. But, for the porch roof, that is how it has been enforced everywhere I have been. The reason is that the melting water from the warm roof (not defined, not entirely settled IMHO) hits the cold roof at the porch and and freezes, potentially backing up under the shingles causing damage. Does it need to go all the way to the roof edge? Maybe not, but the code says "from the lowest edges of all roof surfaces" so that is what has been required.

OK, so I may be making some progress, even without the help from ICC. An editorial change was made in the 2024 IRC, it no longer says "also". So if we take them as separate conditions then I think Steveray may have the answer. No requirement to go inside the wall line for a 24" (horizontal?) distance, just 3' from the eave edge "measured up the slope of the roof". Period. Still think it is really bad language, but maybe we see the intent. A steep slope might require 2 strips of barrier to get in a 24" (horizontal) distance, where a 3' "measured up the slope" would not. Gosh this was too much work. But I would still like to see the actual code change and reason statement.

Does that make sense?

 

[Sifu]

Per codes.iccsafe.org, the word "also" is in the 2021 IRC but not in the 2024 IRC. Going back to the OP, that, along with the addition of a paragraph break, is the only change in R905.1.2 between the 2021 and 2024 IRCs. A change for clarity, not a change in meaning, so not "key."

Cheers, Wayne

If I only would have paid better attention to this post! I actually think it was key, at least it made it clear for me that I may have been looking at it all wrong. Time to go fall on my sword.

 

[wwhitney]

If I only would have paid better attention to this post!

I still think that there's no language in R905.1.2 making the 36" requirement on 8/12 or steeper roofs and alternative to the primary 24" requirement. It reads to me as in addition to the primary 24" requirement. No opinion on what the intention was, just on the text. No words like "instead" or "exception".

Cheers, Wayne

 

[Sifu]

Certainly agree the language and intent are poorly articulated. The '24 removed "also", which could be read to be a partial replacement for the first part.

So if < 8/12 provide the barrier to a point 24" inside the exterior wall line, if 8/12 or greater then disregard the wall line and provide it to a point 36" measured up the slope from the lowest edge of the eave. Since the first part doesn't say "measured up the slope" I guess we assume it means measured horizontally. If my revised understanding is correct, a 2' horizontal overhang at the eave on a 12/12 roof would have no ice barrier inside the exterior wall line. Doesn't seem editorial to me so I am still baffled by the lack of a code change for adding this language in the first place.

I finally found something.....RB262-22 was a proposed change striking the entire section. I have not found any resulting code change, but my ambition to keep looking has waned for the week. So maybe they disapproved it and it was abandoned, or it was not voted for, and they then made the editorial change. So the OP stating that it was removed may have been for a proposal that just never made it.

 

[bill1952]

The word "also" may have been a careless code writing but removing it is not editorial, because it changes the requirement big time.

 

[Sifu]

What is clear is I was interpreting and enforcing this wrong. Whether my error was justified or not is irrelevant to the folks that had to deal with. Now I just gotta go back and try and find the poor guys who are still scratching their heads over it. I got in touch with one Friday afternoon and explained it. He was very grateful, hopefully that is what I find with the rest of them.

 

[jar546]

What is clear is I was interpreting and enforcing this wrong. Whether my error was justified or not is irrelevant to the folks that had to deal with. Now I just gotta go back and try and find the poor guys who are still scratching their heads over it. I got in touch with one Friday afternoon and explained it. He was very grateful, hopefully that is what I find with the rest of them.

What do you think you were doing wrong? Under what code cycle were you enforcing?

 

[Sifu]

2018 IRC. Long excuse...Since there was an "also" I couldn't figure out how both the requirements were to be applied, so I was thinking about this as two separate and distinct requirements. The first, for all roofs since no slope limits are provided, and the 2nd for 8/12 roofs and higher, but since the first requirement covered all roofs, I considered how and where the 2nd requirement could be applied. In other words, if on a 8/12 roof, ice barrier was applied to a point 2' inside the wall line, and "also" 3' from the lowest edge "up the slope" my mind said why/could both apply to the same condition. So I attempted to critically think out why and where this requirement came from. I could find no commentary, and no reason statement to help me, so I thought that the requirement was to prevent ice dam damage when a conditioned room was adjacent to the slope of the roof, like a bonus room or attic room in a 1 1/2 story house, and that it had to run "up the slope", 3' from the outer edge. I could never quite reconcile this, although in trying the only possible reason would be that the ice dam that would build up on the rake could cause it to be stressed and damage the roof edge, but it never really came up until this situation (pictures of roofs). I imagined the reason for the 8/12 trigger was that the sun would heat the roofs unevenly (that occurs quite commonly where I am). Many times I see roofs in my area where the sun hits one side and melts it completely, but on the other side a clear line can be seen where the attic room heat warms the roof enough to cause melting, but then at the knee wall line there is far less melting. The snow and ice builds up from the eave to the point where the roof is heated by the space below. Since I have seen this my mind just jumped to that being the reason for this code. I now realize it was not, and removing the "also" and the reason statement behind the proposal to remove the entire sentence made me see that.

To be frank, I think the code should specify the first part by slope, and the 2nd part by slope. Since the first part doesn't specify any particular slope it can be read as ALL roofs, and then only on the 2nd part does it introduce a slope trigger.

Still very curious about how this got into the code in the first place (2015). It does not seem to be editorial. If it was incorporated in the normal way I wonder if the language would be the same. But just because I can't find the proposal or reason statement, doesn't mean it doesn't exist.

 

[wwhitney]

2018 IRC.

Still not clear on what your previous interpretation was, and what your current interpretation is. The only way I see to misinterpret the text are (a) infer from "also" that two layers are required, one for the first requirement and one for the second requirement and (b) infer that the second requirement is in lieu of the first requirement, rather than in addition to the first requirement.

If you like the two requirements could be combined as "extend from the lowest edges of all roof surfaces to a point not less than 24 inches (610 mm) inside the exterior wall line of the building, or in the case of roofs sloped 8/12 or greater, not less than 36 inches (914 mm) measured along the roof slope from the eave edge of the building, whichever is greater."

As per the geometry in my first post in this thread (post #9), depending on the roof overhang and slope, the second requirement sometimes extends farther than 24" inside the exterior wall line of the building.

Cheers, Wayne

 

[bnymbill]

Catching up late on this thread but looking for clarification:

When installing ice and water shield, do you install roofing felt down to the edge of the roof over top of the ice and water shield? For my application, code requires 2' of ice and water shield past the inside wall of the house. So, including the roof overhang and 2x6 exterior wall, I'd need 3.5' of ice and water shield.

Would I install felt overlapping the edge of the top layer of ice and water shield (shingle style) or start the felt at the edge of the roof and install it over top of the ice and water shield?

I didn't see code specify this detail and couldn't find it in Certainteed's manual, so figured I'd see what others are referencing.