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A friend used trim head screws for ALL of the 2x4 framing (including the outer walls) of his 2400 sq. ft. house. The house uses 8x8s to carry the load; none of the 2x4 framing is load bearing. The inspector did not see a problem with it (but maybe she didn't even see the screws).

Edit- the picture below shows a similar (post and beam) style of building. The original building was a wood/furniture shop (not commercial); it was erected about 20 years ago (±5 years). The old exterior walls were removed (I don't know anything about them); the new walls are 2x4 construction with trim head screws, including the exterior walls. The friend is a maintenance guy... not an engineer.

Is it built to code? Would it be correct to assume that (at least) the outer walls are in danger of windy conditions and earthquakes?

enter image description here

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    Where is the home that 2x4 exterior walls meet code? Questions about legality must necessarily mention jurisdiction. – isherwood Apr 5 '16 at 19:10
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    In my experience, screws of this type are very hard (to retain integrity while driven) and therefore somewhat brittle. They're much more likely to crack under shear stress or from repeated bending than wire nails. Subscribing. – isherwood Apr 5 '16 at 19:14
  • @isherwood I would be suprised to find where it meets any building code. But he's in Virginia. I told him that screws were brittle, and he agreed, but said it was easier than nailing and cheaper than a nail gun (and compressor). – Ben Welborn Apr 5 '16 at 19:22
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    If he was trying to avoid costs, why not just use Elmer's paper glue? Those nails cost a lot more than simple glue. ;-) – wallyk Apr 5 '16 at 19:25
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    They're not structural screws and therefore do not meet the requirements as replacement for 16d nails. 16d nails will bend when house framing is subjected to earthquake, non-structural screws can snap off, causing join failures. This however sounds like it's a post and beam construction house. – Fiasco Labs Apr 5 '16 at 20:55
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According to Table R602.3(1) of the International residential code (IRC), you have to use two 16d (3 1/2" x 0.135") fasteners to end nail the top or sole plate to a stud. If the studs were toe nailed to the sole plate, then either three 8d (2 1/2" x 0.133") or two 16d (3 1/2" x 0.135") fasteners would be required.

International Residential Code 2012

Chapter 6 Wall Construction

Section R602 Wood Wall Framing

R602.3 Design and construction. Exterior walls of wood-frame construction shall be designed and constructed in accordance with the provisions of this chapter and Figures R602.3(1) and R602.3(2) or in accordance with AF&PA’s NDS. Components of exterior walls shall be fastened in accordance with Tables R602.3(1) through R602.3(4)...

Table R602.3(1)

If by some chance these screws are equivalent to 16d nails, then they should be acceptable. However, I doubt they're equivalent, and therefore should not be used.

There's no specific fastener schedule for interior nonbearing walls, while interior load-bearing walls are required to be framed the same as exterior walls.

R602.4 Interior load-bearing walls. Interior load-bearing walls shall be constructed, framed and fireblocked as specified for exterior walls.

R602.5 Interior nonbearing walls. Interior nonbearing walls shall be permitted to be constructed with 2 inch by 3 inch (51 mm by 76 mm) studs spaced 24 inches (610 mm) on center or, when not part of a braced wall line, 2 inch by 4 inch (51 mm by 102 mm) flat studs spaced at 16 inches (406 mm) on center. Interior nonbearing walls shall be capped with at least a single top plate. Interior nonbearing walls shall be fireblocked in accordance with Section R602.8.

  • Hmmm... end nail the top or sole plate to a stud. I'll ask him next time I see him... but obviously I couldn't verify it without pulling the wall down to see it, but I'm gonna say that I saw some toe-screwing. – Ben Welborn Apr 5 '16 at 20:00
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    Consider the screw thread. Does it have good bite into both pieces being attached? – Harper Apr 5 '16 at 20:32
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    I would not be so quick to leap to this conclusion. If the exterior walls are not load bearing and there are 8x8 posts used for the structure it's not clear to me that section R602 is even applicable. This is clearly not a "regular" wood-framed house... maybe it's heavy timber construction, maybe something else. Also it is certainly possible for a screw to be designed to have the same shear strength as a nail. Did the builder just pull something off the shelf at Home Depot or was it spec'd by the engineer? We don't know. – Hank Apr 5 '16 at 20:52
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    @BenWelborn: OK well if this is a commercial structure than residential building codes do not apply, you would want to look at the IBC. But the fact remains that you have not really established whether this is a "wood framed structure" or just a building that has some wood in the exterior wall. – Hank Apr 5 '16 at 21:11
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    @Tester101: R301.1.2 says: "The requirements of this code are based on platform and balloon-frame construction for light-frame buildings. [...] Other framing systems must have equivalent detailing to ensure force transfer, continuity and compatible deformations." The specific design criteria are given in the rest of R301 that an engineer may use to design the structure. – Hank Apr 5 '16 at 22:02
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You have a complicated question here and the best (and most legally-correct) answer will probably come from talking to your local building inspector. Preferably before a lot of work has already been done...

First, the question of which building code is even applicable is not clear to me. The International Residential Code ("IRC") only applies for 1- and 2-family homes, but this sounds like maybe it is a commercial structure in which case the International Building Code ("IBC") would apply. The exact version and any local amendments (which can be significant, by the way) would depend on your specific location.

The IRC does provide some pre-computed nailing patterns for wood-framed that Tester101 has quoted, but those only apply to light-framed platform or balloon-framed structures (see R301.1.2). It sounds like this structure is probably not that, since you have heavy timber columns. It could be post-and-beam or some other construction technique. In which case the structure needs to be designed by an engineer. (Or maybe the heavy timber is just decorative?)

Finally, screws can be used for structural purposes but they must be designed as such. If you are straying outside the prescriptions of the building code you need to have an engineer do the design first.

  • I didn't talk to the building inspector. The only time I have seen the house was last Sunday. I would not frame a house (inside or out) with screws! This was never a commercial building. It is a 2400 sq. ft. (two story) single family home now (or it will be, very soon). Yes, it is a post and beam house. 8x8s are the only structural support. All of the 2x4 walls were added about a week ago... converting an old post and beam wood shop (originally built about 15-25 years ago- I would guess) into a home. The new 2x4 walls support nothing but themselves and some windows. – Ben Welborn Apr 6 '16 at 12:24
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Just found this.

The SDWS Framing screw is designed and load-rated for replacing 16d, 10d and 8d nails in framing applications. The SDWS Framing screw is 0.160" in diameter and superior to nails in holding power and pull-out resistance. It is code listed under IAPMO UES ER-192 and meets 2012 and 2015 IRC® and IBC® code requirements for several common wood framing applications.

https://www.strongtie.com/strongdrive_exteriorwoodscrews/sdws-q_screw/p/strong-drive-sdws-framing-screw

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