Sunroom Information

Can A Patio Room Be Impact?

(Commentary by flb}

Building codes require 8" CMU walls or well connected wood studs for a reason. If they allowed the use of Styrofoam and a thin sheet of aluminum, driving down I-95 you would see what looked like a 3rd world country. More than just impact, there are countless other code violations to building a 'house' with elite parts. If you could do it, everyone would and the housing industry would crumble.

Would you feel safe in a styrofoam and thin aluminum skin room in Hurricane Andrew? We'd all be in jail if someone got hurt after telling them it was designed to meet an Andrew. I won't seal it, and I don't recommend anyone pursue false truths to homeowners that an Elite room is safe in an category 5 storm, it just doesn't exist. Find a safer source of income, this one will get someone killed someday, and us in a lot of trouble.

More on Impact - 2004 FBC Section 1609.1.4

Note #4 that "Openings in sunrooms, balconies, or enclosed porches constructed under existing roofs or decks are not required to be protected provided the spaces are separated from the building interior by a wall and all openings in the separating wall are protected in accordance with Section 1609.1.4 above. Such spaces shall be permitted to be designed as either partially enclosed or enclosed structures."

For purposes of journaling code issues, the below was prepared to help the 2003 IBC (FBC similar) define habitable space and proper use of building deflections.

The building department in NY didn't go for it and required the L/240 anyway, but that was an isolated case.

First, Section R301.6 is for areas of habitable space only. By definition in chapter 2 (page 14): HABITABLE SPACE: A space in a building for living, sleeping, eating, or cooking. Bathrooms, toilet rooms, closets, halls, storage or utility spaces and similar areas are not considered habitable spaces. Patio rooms affixed to the outside of an existing structure are not habitable spaces unless the envelope of the structure is compromises.

By definition of chapter 3 itself, "Building Planning", see p 10 of definitions of building: BUILDING: Building shall mean one and two family dwelling or portion thereof... intended to be used for human HABITATION, living, sleeping, cooking... Meaning the L/240 requirement is only for the house in which you live. So this book isn't even for a patio enclosure, and the Building Code of the State of New York actually governs.

With that said, chapter 20 of the Building Code references aluminum design which points to chapter 16 of that code which has been the governing chapter all along. If you look at table 1604.3, which is pretty much the governing table nationwide, for non plastered ceilings and not supporting a ceiling (our condition), the deflection is L/180.

For greenhouses it's L/120 which some argue we could use. Further reading allows L/60 for structural roofing made of formed metal sheets, and L/150 for secondary roof structural members supporting formed metal roofing.

Last, we must also design against ponding. With that all said, the safe deflection in this case to satisfy all code criteria is L/180. I hope you find this information to be helpful. Please contact this office if any additional information is needed.

Use of H*H/3 for Pressures

Comment on what your opinion is on what design method to use in calculating pressures acting on primary columns in a glass enclosed aluminum enclosure:

One argument supports using H*H/3 for component and cladding, one supports MWFRS. Component and cladding brings out end zone difficulties, while references like table 2002.4 of the FBC indicate the use of MWFRS is appropriate. Clients are obviously begging for us to change to MWFRS, but we have historically used components and cladding, but with simultaneous loading, that conservative estimate is no longer acceptable so we are hoping to switch to MWFRS

Here are my (FLB) thoughts on the determination of design pressures for columns in a glass room. The importance factor is a significant determinant and I think that most people heretofore have used .77, treating the glass room as if it were a screen room. In the development of the AAF manual I discussed this issue with Joe Belcher and Dr. Reinhold and we all felt that .77 was not appropriate for a glass enclosure. They are, after all, room additions.

We  (Engineering Express) used 1.0. I think one is obliged to use component and cladding loads. In the typical aluminum framed glass enclosure, the column, or at least some portion of it, is exposed directly to the wind, unlike a lumber stud in a house, where the stud is covered by sheathing. SSTD 10-99 Appendix B Design Load Assumptions, lists "wood stud walls in flexure" (based upon an effective wind area of 32 sqft) in its Components and Cladding design elements. I readily concede that this makes the design more complex. The issues of the end zone and edge strip are clearly involved.

FBC 1606.2.3 specifies the formula for the edge strip, which I think usually calculates to 3 ft for the typical glass room, and therefore, the end zone should be 6 ft (I have found that most people think this dimension is 3 ft). FBC 2406.1 requires L/175 for the deflection limit.

We used L/180 in the AAF manual. I believe that the effective wind area for the column will be the column span times the spacing, which will generally exceed the product of the span X span/3, and will therefore produce a lower C&C design pressure.

This is another case where the industry engineers should compare code interpretations and calculations. It's one thing for a group to get together and agree in principle to a methodology; it is another to get the same numerical results. Getting agreement on the concept is an obvious first step. This subject would seem to be a good topic for discussion at one of our conferences. David Miller 4-4-05

Minimum Headroom Clearance

This post is copied from a public post from Joe Belcher:

I find no headroom provisions in the FBCR (§4101).

For commercial pools the FBCB addresses bridges and overhead obstructions and calls for a minimum height of 8 feet. (§424.1.3.2) Overhead wiring is prohibited within an area extending a distance of 10 feet horizontally from the inside edge of the pool walls, diving structures, observation stands, towers or platforms. (§424.1.4.2.4) The code also calls for a vertical clearance above the pool deck of 7 feet. (§424.1.3.1.8)

The National Electrical Code states:

680.8 Overhead Conductor Clearances. (A) Power. With respect to service drop conductors and open overhead wiring, swimming pool and similar installations shall comply with the minimum clearances given in Table 680.8 and illustrated in Figure 680.8. FPN: Open overhead wiring as used in this article typically refers to conductor(s) not in an enclosed raceway.

Thank you,

Joe Belcher

Joseph D. Belcher, CBO JDB Code Services, Inc. 41 Oak Village Boulevard Homosassa, Florida 34446 352-382-3873 352-382-4716 Fax jdbcodeservices@tampabay.rr.com