Florida No Sheathing and Custom Polycarbonate windows

[CyberPine]

Hello I have 3 questions about Florida Building code and if something like this would meet code. Asking about allowed, not advised or best practices.

We have a small minimum dwelling size (750sqf) on a residential 1/4 acre lot .

We want to build a small, simple open concept house, owner-builder.

Assuming a 40x20 dwelling with 4" walls and 12" flat sloped roof. Assuming mineral wool R15 in walls and R30 in roof.

We want to side it with standing seam metal, but we want frame (metal, wood or some combination) and cross brace so that sheathing is not required.

1. Given the above possible to frame strong enough to not have to sheath it?
2. Given 20x40 living open concept no posts in the middle, no interior walls, okay if only two 80" doors open?
3. Can our non-opening windows be custom 16"wide x 36" long 1/8 thick polycarbonate (lexan) ?

Thank You.

 

[e hilton]

You mention 750 sf … is that a maximum size allowed by code? Your proposed 20x40 exceeds that.

 

[Paul Sweet]

It's possible to use let-in bracing for the walls, although it might be difficult to get adequate let-in bracing for Florida wind loads. Steel portal frames might be necessary.

You would have use a structural roof panel to avoid roof sheathing. Your picture shows an architectural roof panel which has to be installed over sheathing.

It will be a LOT easier to install sheathing than go through all the engineering and gymnastics necessary to avoid it.

 

[jar546]

Here are some thoughts.

• Your building as described sounds like it may be Category II.
• If you are in Flagler County, your wind zone is 130mph for most areas
• I don't know what exposure category you are in and that is a major factor.
• Since your wind zone exceeds 115mph you only have two options for wood framing:
  • The AWC WFCM manual (this is outside the scope of the FBC Residential, so hire an engineer)
  • ASCE 7 (get an engineer)
• The entire section 602 for wall framing is RESERVED in the FBC because of the wind zone.
• No one here can actually answer your questions appropriately. You need an architect or engineer.
• Nothing you want to do is prescriptive or can be prescriptive due to the wind zone. I am in a 170+mph wind zone and it is very restrictive.

 

[e hilton]

• The entire section 602 for wall framing is RESERVED in the FBC because of the wind zone.

What does that mean?

 

[jar546]

What does that mean?

It means it is empty.

R602.3Design and construction.​

Exterior walls of woodframe construction shall be designed in accordance with Section R301.2.1.1 or ANSI AWC NDS.
Table R602.3(1) Fastening Schedule.
Reserved.
Figure R602.3(1) Typical Wall, Floor and Roof Framing.
Reserved.
Table R602.3(2) Alternate Attachments to Table R602.3(1).
Reserved.
Figure R602.3(2) Framing Details.
Reserved.
Table R602.3(3) Requirements for Wood Structural Panel Wall Sheathing Used to Resist Wind Pressures.
Reserved.
Table R602.3(4) Allowable Spans for Particleboard Wall Sheathing.
Reserved.

 

[Joe.B]

Meaning they need an architect or engineer, correct? In other words, no prescriptive building allowed, all engineered design?

 

[jar546]

Meaning they need an architect or engineer, correct? In other words, no prescriptive building allowed, all engineered design?

Yes, of course. The wind zones dictate that.