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Wall bracing for sunroom

M

MeasureTwice

Registered User
Joined
Apr 22, 2021
Messages
8
Location
Michigan
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.
 
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
 
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:
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.
 
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
Click to expand...
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.
 
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:
R301.2.1.1.1 Sunrooms. Sunrooms shall comply
with AAMA/NPEA/NSA 2100. For the purpose of
. . .
Click to expand...
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?
 
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.
 
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.
 
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.
Click to expand...
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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Reactions: SDS
steveray said:
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...
Click to expand...
Hello, you are right, they don't. they sell the DIY kit if they are not in their area of work, and mail everything to you, or they do the whole job.
 
MeasureTwice said:
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.
Click to expand...
Hello, there, I am having a similar problem like you are having, and just researched about pre engineered sunroom kit, they just sell the DIY kit if they are not working in your area, or do the job with their materials. I have a patio cover, insulated, and a slab, those have permits, and I bought the windows, but now the city ask me for structural calculations. I presented the floor plan with the elevation, but my designer has to hire an engineer to do the calculations, (more money), but there is no engineer willing to stamp a plan if the patio cover and slab are already there. It is very complicated and my city (Fontana) does not have any idea of sunrooms. My designer told me to present the plans as patio enclosure,
 
MeasureTwice said:
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.
Click to expand...
EXACTLY!!!! that was my point, the City of Fontana (planning and building and safety) has no idea but they keep asking for structural calculations. My designer wants to present as a patio enclosure , but the sheer walls have to be 4 feet at each corner, and my patio cover (already permitted because is part of the property), is 14' x 10'. I might be pretty bad at math but that would leave me a 2' space for a window, not to mention the long walls, the door alone is 3 feet.
I contacted sunroom dealers and installers but of course , they want to get the job, and I already have all the windows. And even if I pay to an engineer to do the structural calculations, they would not do it because I already have the roof and the slab.
 
Engineers do exist that will evaluate existing structures and help with add-ons. It will take some hunting, but you will be able to find one.

The wall bracing requirements are very important, especially if you are in a seismic area. The portal frames as described by SDS can get your walls much smaller than 4' at each corner and meet the bracing requirements of the IRC.
 
Beniah Naylor said:
Engineers do exist that will evaluate existing structures and help with add-ons. It will take some hunting, but you will be able to find one.

The wall bracing requirements are very important, especially if you are in a seismic area. The portal frames as described by SDS can get your walls much smaller than 4' at each corner and meet the bracing requirements of the IRC.
Click to expand...
Thanks for your response, I am really frustrated, as I already consulter 5 engineers, and no luck, if they would come to see what I have, it would be easier for them to figure out, it is a patio cover of course it has portal beams, and the slab can easily be seen by digging a little since I have dirt at the end of the patio slab.
The sunroom is full of glass, therefore it does not have the room for the bracing requirements.
I am a home owner, and my designer who es the ones I have always used for all my projects, apparently does not have any idea because he was never asked to design a sunroom, and his engineer would not help.
 
Mr. Inspector 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:
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.
Click to expand...
Hello, pardon my ignorance but I do not see the difference, therefore here goes my question. In what category falls a patio cover that I am trying to enclosure to a sunroom with more of 60 percent windows with screen, intended to use as a gym, with a wall a/c , 2 doors connected to the den's room?
 
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