[Greenbuilding] Insulation fasteners

[John Straube]

I used three gutter spikes per 9' long 2x3.  The method was chosen partly because it used less labor, and partly because it used less material cost than our more standard approach of using a screw every 16-24" vertically.
Hitting the stud is dead easy.  The stud is completely visible in this approach, as the nail is attached before the foam is.  Not a single nail missed a stud.
Screwing blind through strapping and 4" of foam is not very easy and requires more care.  Crews that do this regularily (BSC works with some companies in Massachusetts who do pretty much nothing but exterior foam retrofits like this) dont report any problems, but then they often have the option of screwing to solid board sheathing (eg, no studs need to be hit).

John  

On 12-11-19 9:46 AM, Kat wrote:
> That's the detail that showed up in FHB, no?  When I looked at that detail I thought, "surely that would be terribly expensive, labor-wise."
>
> Kat
>>
>> PS. Because of my choice to experiment on my own retrofit, we installed gutter spikes through the long direction of pre-drilled 2x3's, and held the 2x3 off the wall 2" to allow spray foam to cover the existing wall and embed the 2x3. The nail in this application was needed only for initial installation: the ccSPF does all the work after.
>
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-- 
Prof. John Straube, Ph.D., P.Eng.
Faculty of Engineering
Dept of Civil Engineering / School of Architecture

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