low slope roof

What do you think the slope of this lower roof is?

The builder says its within the range where 2 layers of 15 lb felt can be used under the shingles.


My Android roof pitch app says Too Low :wink:

It may be OK

See this mfg. recommendation for installation on low pitch roofs.


Make sure they dump the upper gutter on the lower roof (like they do around here) and see what happens!

Wonderful job security! :slight_smile:

From here less than 4/12

What does manufacturer of shingles he’s using say?

                                                         **                                                                                                                          [15lb or 30lb felt ?](http://lrhomesolutions.com/roofing/Ice_and_water/main.htm)**
                                                                                                                      In order to achieve                  fire-resistant ratings (Class A or C), an underlayment                                                              must be used                                                              regardless of the                                                              type of shingle                                                              being installed. 

A minimum of 2 layers of felt or 60lbs of base (2 layers of 30lb) is required for roofs with slopes less than 4/12. In such cases, the application must meet the requirements for low slope roofs.

Alternatives for 2 layers would be 1 layer ice and water shield.

In most cases it’s not only the additional felt, but it’s also in the modification of the shingle exposure. Reducing the shingle exposure can result in a so-called “triple coverage”.

I’ve done this on several projects and have never had an issue. Many manufacturers explain this process in their training manuals.

But again, I’m in the land of not having to deal with “ice dams”.

2006 IRC code
R905.2.2 Slope
Asphalt shingles shall be used only on roof slopes of 2 units vertical in 12
units horizontal (2:12) or greater. For roof slopes from 2 units vertical in 12
units horizontal (2:12) up to 4 units vertical in 12 units horizontal (4:12), double
underlayment application is required in accordance with Section R905.2.7
Look up 2009. May have changed.
International Residential Code (IRC) 2006 | Section R905

The simplest solution would be to install a standing-seam metal roof over it. Many (not all) metal roofs are fine at a 1:12 pitch pitch or even less. Snap-Loc 24 can be installed at a nearly-level 1/4:12 pitch!

Less than 3 in 12
Low slope materials required…
If he can convince a Municipal Building Inspector to accept
(Which it appears to be)
what is the question?

Another issue: It appears the builder ran out of StraightFlash (the correct product to flash the top and sides of the windows when using a house wrap)…and switched to mere Tyvek seam tape to flash 3 of the windows. This is incorrect.

Optimally the sills would be done with FlexWrap, but a roll is really expensive (I bought a roll today:roll:)… so don’t ever expect to find it on a spec home.

You can check with Tradition Roofing & Exteriors. Who are in roofing & exteriors for more than 15 years providing quality work and excellent customer service.


If this is NC then check the NCRC and go from there because that is all the builder has to conform too…that and the manufacturer which will ultimately state to adhere to local and state codes.

Hard to say for sure. I’d put it in the report, make the buyer aware of the requirements and put the burden on the builder to prove it is greater than 2 in 12.


In Canada you can use 2 layers of 15lb non perforated felt and asphalt shingles on a 2/12 roof pitch.

Nice observation oh great one.:wink:

I basically reported this during a predrywall inspection as irregardless of actual measured slope or code, this will leak over time if proper low slope methods are not installed. The buyer and I convinced the builder to do what I rcommended and they did!

Sometimes the code angle will hurt your client since the builder can refuse to do something if it actually meets code. Many roofs like this will meet code and leak.
I guess I just have the right way of communicating because I get lots of things done for my clients.

Nice Bruce.
Very eloquent and respectful of all parties involved.
I will copy it and paste it to my notes.
I have not done a full 4 point phase. I am trying.