# Wall bracing for sunroom



## MeasureTwice (Apr 22, 2021)

I am designing and plan on building a 12 x 13 sunroom addition. I have seen several examples of sunrooms that are almost entirely glass and I don’t understand how these can be code compliant given the IRC rules for wall bracing. Is there some kind of exception for sunrooms or small additions that allows these to be built with reduced or even without wall bracing requirements?

Thank you in advance.


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## SDS (Apr 22, 2021)

one word...portal frames.

I just did some preliminary design work on a sun room a couple weeks ago...it would've required a welded steel frame...no way it would've qualified for prescriptive bracing...but prescriptive portal frames would be the way to go if one had to be done prescriptively I think


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## Rick18071 (Apr 23, 2021)

The 2015 IRC has the following special requirements for sunrooms. Here is a link to get the sunroom book that you are required to design by: 


			https://www.nationalsunroom.org/AAMA-NPEA-NSA-2100-12.pdf
		


R301.2.1.1.1 Sunrooms. Sunrooms shall comply
with AAMA/NPEA/NSA 2100. For the purpose of
applying the criteria of AAMA/NPEA/NSA 2100
based on the intended use, sunrooms shall be identified
as one of the following categories by the permit
applicant, design professional or the property owner
or owner’s agent in the construction documents.
Component and cladding pressures shall be used for
the design of elements that do not qualify as main
windforce-resisting systems. Main windforce-resisting
system pressures shall be used for the design of
elements assigned to provide support and stability
for the overall sunroom.
Category I: A thermally isolated sunroom with
walls that are open or enclosed with insect
screening or 0.5 mm (20 mil) maximum thickness
plastic film. The space is nonhabitable and
unconditioned.
Category II: A thermally isolated sunroom with
enclosed walls. The openings are enclosed with
translucent or transparent plastic or glass. The
space is nonhabitable and unconditioned.
Category III: A thermally isolated sunroom with
enclosed walls. The openings are enclosed with
translucent or transparent plastic or glass. The
sunroom fenestration complies with additional
requirements for air infiltration resistance and
water penetration resistance. The space is nonhabitable
and unconditioned.
Category IV: A thermally isolated sunroom with
enclosed walls. The sunroom is designed to be
heated or cooled by a separate temperature control
or system and is thermally isolated from the
primary structure. The sunroom fenestration
complies with additional requirements for water
penetration resistance, air infiltration resistance
and thermal performance. The space is nonhabitable
and conditioned.
Category V: A sunroom with enclosed walls.
The sunroom is designed to be heated or cooled
and is open to the main structure. The sunroom
fenestration complies with additional requirements
for water penetration resistance, air infiltration
resistance and thermal performance. The
space is habitable and conditioned.
R301.2.1.2 Protection of openings. Exterior glazing in
buildings located in windborne debris regions shall be
protected from windborne debris. Glazed opening protection
for windborne debris shall meet the requirements
of the Large Missile Test of ASTM E 1996 and ASTM
E 1886 as modified in Section 301.2.1.2.1. Garage door
glazed opening protection for windborne debris shall
meet the requirements of an approved impact-resisting
standard or ANSI/DASMA 115.
Exception: Wood structural panels with a thickness
of not less than 7/16 inch (11 mm) and a span of not
more than 8 feet (2438 mm) shall be permitted for
opening protection. Panels shall be precut and
attached to the framing surrounding the opening
containing the product with the glazed opening. Panels
shall be predrilled as required for the anchorage
method and shall be secured with the attachment
hardware provided. Attachments shall be designed
to resist the component and cladding loads determined
in accordance with either Table R301.2(2) or
ASCE 7, with the permanent corrosion-resistant
attachment hardware provided and anchors permanently
installed on the building. Attachment in
accordance with Table R301.2.1.2 is permitted for
buildings with a mean roof height of 45 feet (13, 728
mm) or less where the ultimate design wind speed,
Vult, is 180 mph (290 kph) or less.


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## MeasureTwice (Apr 26, 2021)

SDS said:


> one word...portal frames.
> 
> I just did some preliminary design work on a sun room a couple weeks ago...it would've required a welded steel frame...no way it would've qualified for prescriptive bracing...but prescriptive portal frames would be the way to go if one had to be done prescriptively I think


Thank you. Portal frames looks like the way to go if I am required to use the same wall bracing codes as specified in the IRC.


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## MeasureTwice (Apr 26, 2021)

Rick18071 said:


> The 2015 IRC has the following special requirements for sunrooms. Here is a link to get the sunroom book that you are required to design by:
> 
> 
> https://www.nationalsunroom.org/AAMA-NPEA-NSA-2100-12.pdf
> ...


Thank you. I download and read the AAMA-NPEA-NSA-2100-12 document. It doesn't say anything about bracing requirements. Does that mean they don't apply to sunrooms?


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## Rick18071 (Apr 26, 2021)

1.5.2 Matters Not Addressed
Any requirements essential to the safety of sunrooms that are not specifically addressed in these specifications or applicable codes and standards adopted in the jurisdiction shall be determined by the building official. The building official shall determine the provisions for permitting approvals, professional services, occupancy, violations and appeals as well as other requirements not expressly included herein. Procedures for these activities shall be set by local code adoption, ordinance or at the discretion of the building official.

6.2 LOADS ON SUNROOM STRUCTURES
6.2.1 Wind Loads
Basic wind speed in miles per hour (mph) or kilometer per hour (kph) shall be determined by the local or regional building official. Sunrooms including exposed structures, components, cladding and roof covering shall be designed to resist the wind loads established in accordance with Section R301 of the IRC, or Chapter 16 of the IBC, whichever is applicable, or local wind load criteria as determined by the local building official. Wind pressures for the design of Category I sunrooms shall be determined in accordance with Table AH107.4(1) of the IRC or local wind pressures criteria as determined by the local building official.
Component and Cladding (C&C) pressures shall be used for the design of elements that do not qualify as Main Wind Force Resisting Systems (MWFRS). Examples of components and cladding for vertical wind pressures include roof panels, purlins and connections attaching a roof element to supports. Examples of components and cladding for horizontal wind pressures include enclosure wall panels, mullions, doors, windows and their connections. MWFRS pressures shall be used or the design of elements assigned to provide support and stability for the overall sunroom. Examples for the MWFRS for vertical wind pressures include columns, headers, structural fascias, ledgers and concrete footings. Examples of MWFRS for horizontal wind pressures include the roof as a horizontal diaphragm, shear walls, wall bracing and anchorage to foundations.
6.2.5 Seismic Loads
Sunroom structures shall comply with the requirements of ASCE/SEI 7 for the design of earthquake forces. Site specific design parameters shall be defined by ASCE/SEI 7.
Where rational justification of the Response Modification Factor (R) cannot be determined through rational analysis, R may conservatively be set to 1.4 for the purpose of determining the applied seismic forces.
The seismic Importance Factor shall be set to 1.0.
6.2.6 Load Combinations
Load Combinations shall be determined in accordance with Chapter 2 of ASCE/SEI 7 and shall be used for determination of the “design” pressure which shall be applied to the structural elements of the Sunroom.
6.3 STRUCTURAL PERFORMANCE CRITERIA FOR SUNROOM ROOF ASSEMBLIES
6.3.1 Allowable Load
The allowable transverse load capacity of the sunroom roof assembly shall be the lesser of the load at the maximum allowable deflection or the ultimate transverse load divided by a Factor of Safety of 2.0 for bending caused by load combinations which include Roof Live Loads, Wind Loads or Earthquake Loads, 2.5 for bending caused by all other load combinations and 3.0 for Shear caused by all load combinations. The ultimate transverse load capacity of the sunroom roof assembly shall be determined by testing in accordance with ASTM E72 or other approved criteria.
6.3.2 Maximum Deflection
For aluminum structural members or panels used in roofs or walls of sunroom additions or patio covers, not supporting edge of glass or sandwich panels, the total load deflection shall not exceed L/60. For continuous aluminum structural members supporting edge of glass, the total load deflection shall not exceed the lesser of 19 mm (3/4 in) or L/175 for each glass lite, or L/60 for the entire length of the member, whichever is more stringent. For sandwich panels used in roofs or walls of sunroom additions or patio covers, the total load deflection shall not exceed L/120.
8.1 SCOPE
General requirements for sunrooms shall include minimums as established by this specification. Local building and fire code agencies have the authority to adopt differing requirements. Where conflict exists between this standard and the requirements of the local authority having jurisdiction, those of the authority having jurisdiction shall prevail.


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## SDS (Apr 27, 2021)

If classified or designated as a "SUNROOM" in the permitted plans, then it must be an engineered design...with stamped plans...in other words a 'SUNROOM" cannot be done prescriptively, under any circumstances.

That is not to say that one cannot build a 12x13' addition, using portal frames, and install as much glass as desired in the wall areas between the portal frames. However, where you run into prescriptive issues is in the roof....and that is also where you would be deviating from the true definition of a 'SUNROOM", prescriptively.

The OP's specific question was regarding wall bracing, although the SUNROOM designation is the important factor here, which is what I think Rick is pointing out. I was only addressing the wall bracing question.


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## MeasureTwice (Apr 27, 2021)

SDS said:


> If classified or designated as a "SUNROOM" in the permitted plans, then it must be an engineered design...with stamped plans...in other words a 'SUNROOM" cannot be done prescriptively, under any circumstances.
> 
> That is not to say that one cannot build a 12x13' addition, using portal frames, and install as much glass as desired in the wall areas between the portal frames. However, where you run into prescriptive issues is in the roof....and that is also where you would be deviating from the true definition of a 'SUNROOM", prescriptively.
> 
> The OP's specific question was regarding wall bracing, although the SUNROOM designation is the important factor here, which is what I think Rick is pointing out. I was only addressing the wall bracing question.


Thank you. I see that in my original question I didn't specify that I am planning a conventional (plywood, shingles) roof. It's the amount of glass in the walls that I was asking about.  Sorry for the ambiguity. 

I was able to play around with the APAs wall bracing calculator to get an idea of what I can do prescriptively. I was also going to explore the idea of getting a pre-engineered sunroom kit. These seem to use metal bracing with a lot of glass inbetween.


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## steveray (Apr 27, 2021)

Just bear in mind that they may give you building plans but usually not the foundation or as we see them, on a deck...Then you still end up at another engineer...


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## ADAguy (Apr 27, 2021)

Good advice from all.


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