[Greenbuilding] Insulation fasteners

[John Straube]

The increase of heat flow through fasteners in wood fame walls has been studied a bit, not enough. One of the reasons to aim for smaller screws is material efficiency, another is cost, and a final one is heat flow. 1000 screws is very feasible for a slightly modest home. This is a good estimate.
Three-D heat flow modeling at NREL showed that fasteners (drywall screws, siding nails, furring strip screws) had an impact of about R1-R1.5 for typical types of scenarios.
It might be noted that the R-value of 4" of XPS increases by more than R1 as the temperature drops from room temperature of freezing.

On 12-11-15 9:57 AM, Alan Abrams wrote:
> John (Straub)--
>
> what is your take on the conductivity of the fastener?  it may sound trivial, but at 1 fastener per 2 sq ft (plus more at corners and openings, etc) there could easily be a thousand fasteners in a modest house.
>
> look at it this way--the x section of 1000 - quarter inch screws is 49 sq in.  Carbon steel has roughly 2 1/2 times the thermal conductivity of stainless steel...what's that in Btus/year?
>
> -AA
>
>
> _______________________________________________
> Greenbuilding mailing list
> to Send a Message to the list, use the email address
> Greenbuilding at bioenergylists.org
>
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org
>

-- 
Prof. John Straube, Ph.D., P.Eng.
Faculty of Engineering
Dept of Civil Engineering / School of Architecture

www.buildingscience.com