[Greenbuilding] Insulation fasteners
Tim Brown
tim34 at optonline.net
Sun Nov 18 18:27:59 CST 2012
Just an observation…..
Building with screws these days is hit and miss.
Quality of fasteners are atrocious or perhaps screws were never designed to be
installed with high torque/ high speed drills.
Over the years I have seen so many times where screws fail because of
the structural compromise that results from the actual driving of the screw with a drill.
Heads snap off and / or they strip.
Stripping is mostly due to improper used of screw gun me thinks. To fast , wrong orientation of drill and not enough pressure……
Cost of these things just keep going up.
Would it be possible to use hand hammed nails? Not a nail gun.
I think old school might be cheaper and more reliable if slow.
On Nov 18, 2012, at 7:14 PM, Eli Talking wrote:
> This issue is of interest to me.
>
> I installed 3/4”x3” osb furring strip over 3” iso boards over existing plywood siding. I had Z shaped metal flashing installed at the bottom that provided rodent protection and temporary support for the foam during assembly. The foam joints were sealed with acoustic caulk.
>
> I did have trouble with using 10 X 6 Drywall Screws / Fine / Phillips on the first part of the project which was installing 3”iso boards below a cathedral ceiling. Perhaps the problem was the fine threads that maybe are intended for sheet metal. However, we had difficulty getting them to penetrate the wood and maintain the Phillips head without stripping. Suggested by this list, I learned about the bugle head GKR fasteners. I absolutely love these fasteners. They always penetrate and very seldom strip. I would like to test some alternatives. However, since they have to be ordered in bulk, this is hard to do. Maybe the thicker thread sheetrock screw would work. However, John Straub, I am hearing you about the cost of the structural fasteners. Can you identify the screws you like?
>
> However, on the exterior, I was less conservative on the spacing, 4 per 8’ vertical. I analyze it like this. For the paneling mounted on furring strips to sag, they must rotate with fulcrum at plane where screw enters the wood below foam. In order to do this, they must compress the foam horizontally. Like a footing, the weight of the structure should be divided by area furring strip to determine if within compressive strength of foam which is specified by manufacturer.
>
> I am moving forward on a new project where I want all the insulation to be achieved with the exterior mounted eps foam. I found a source of eps that is as low a price as fiberglass/sf R. Therefore, I do not want to ues the framing as the thermal barrier. Since it is new construction, I can support most of the foam vertically be setting on the termite-rodent shield-flashing setting on the foundation. I am considering using a 2x3 for furring of the drain-dry plain to give real wood for mounting finishes. Perhaps this thicker furring strip will allow me to use fewer expensive structural fasteners. Because of the long screws this will require, I was looking at the possibility of accurately pre-drilling pilot holes with drill press in a shop such that if accurately located furring on house, the screw will maintain a perfect perpendicular axis and find the stud. I did have the issue this issue of finding the rafters on my ceiling mounted hand drilled installations. On exterior mounted insulation, I had original 3/4” plywood that gave plenty of grip where ever I drilled.
>
> Eli
>
>
>
>
> From: John Straube
> Sent: Thursday, November 15, 2012 9:36 AM
> To: John Salmen
> Cc: 'Green Building'
> Subject: Re: [Greenbuilding] Insulation fasteners
>
> John, much of what you say is not correct. This bothers me because I routinely hear these false claims made, and this incorrect information impedes progress in making good energy efficient buildings (something I know you care about).
> You can get long screws that are not "structural screws". I know, because we and many others installing thick layers of foam insulation and have been doing this for years. There must be a few dozen case studies alone on our website.
> Yes, long structural screws are what you find at Home Depot, but these expensive and problematic in a number of ways.
> It is quite possible to get #10 or #12 screws in lengths of 6" and up. #10 is typically only available to about 6" length, and then #12 to about 12 or 14" long, and then you are up to #14 / 1/4" dia for lengths up to 20" or so. We regularily find that a #12x6" can be cheaper than a #10x6" and thus use them, but #10 is what we have always tested in the lab because they are the smallest available and hence the most flexible with the lowest pullout loads. Their heads DO NOT torque off when used to attach foam. They are NOT intended for screwing through solid wood but through insulation, which is why they work perfectly well. Millions of 6" long or longer screws are installed every year through foam in the commercial low-slope roofing and EIFS industry (see for example Wind-lok for #10x6" long). This is the first stop if you are looking for long thin screws that have corrosion resistance, are easy to install and affordable. These products in these building niches all have a long track record of being installed by the thousands without problems of torquing off heads, driver slippage, bending, or whatever other excuses I have heard. They have been designed for embedding about 1 to 1.5" in wood after screwing through 4-12" of roof or EIFS insulation. What is not easy for individuals and small contractors is finding these screws because they are typically carried by larger supply houses and commercial sales outlets. If more people start super insulating their houses, I am pretty sure the fastener industry will respond by marketing their roof screws as wall screws and the problem will go away.
>
> The HeadLok screws are great for many structural applications, but I think these are used for attaching foam and furring only because they are available at retail outlets. There are quite nice, but are usually twice as expensive as the alternatives (40 cents each and up), and often three times the cost retail (eg we get supply house prices of 12 cents on a #10x6" and the contractor tells us that HeadLok or GRK cost $150 for a 250 pack).
>
> The screws are also NOT the most expensive part of the assembly. Not even close.
> If you purchase relatively heavy 6" long screws from, say, here
> http://www.bestmaterials.com/detail.aspx?ID=9221
> They cost maybe 20 cents each (these are #12-14 screws) Not the cheapest source but not bad. Often available for 15 cents. If you use one screw every 12" vertically and 24" horizontally (pretty conservative), that is 1 screw per 2 square feet or about 10 cents/square foot at 20 cents each. When labour is added, the screw might be 3 times as expensive (30 cents /square foot).
> 4" of polyiso will cost something in the order of $2 to $2.50 per square foot, making the screw less than 5% of the cost of materials for the exterior insulation (adding the cost of furring strips changes little). 4" of EPS will be about $1.50. With labour, the screw is still around 10% or less.
>
>
> Dr John Straube, P.Eng.
> www.BuildingScience.com
> On 12-11-14 11:10 PM, John Salmen wrote:
>> When you get into long screws they are structural screws - equivalent to a
>> 3/8" bolt (actually better). For sure they are overkill but that is where
>> eng. crosses practicality. When you increase length on anything the design
>> requirements for actually getting the screw into the material override the
>> design criteria for loading. The reason being that you cannot screw a long
>> softmetal screw into an assembly without torqueing off the head. - I don't
>> even think you can even find a #10 standard soft metal screw in long lengths
>> anymore - I remember putting an order in from one manuf. a decade ago and
>> half the screws were thrown away from having heads torqued off. 1/4" and
>> 3/8" lag bolts would also self destruct far too often in application to make
>> them practical for a load that an 1/8" of metal would carry. We are talking
>> about crews that have to install a lot of bolts/screws in a day and wasting
>> their time with defective material is an overriding consideration.
>>
>> Headlok screws that I mentioned will cost about .30 per for 6" and about .50
>> per for 8" and each screw will do what is supposed to do. They drive in
>> quickly and perfectly each time. They have a large wafer head equivalent to
>> a washer so one screw generally takes the place of at least 2 screws in
>> design.
>>
>> Fastening is the overriding cost in assemblies at this point and it is split
>> between the cost of the fastener and the time taken to fasten. That is why
>> most buildings are being put together with adhesives.
>>
>>
>>
>> -----Original Message-----
>> From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org]
>> On Behalf Of George J. Nesbitt
>> Sent: November-14-12 6:57 PM
>> To: jfstraube at gmail.com; Green Building
>> Subject: Re: [Greenbuilding] Insulation fasteners
>>
>> I'm about to screw through 4-1/2" of polyiso, I can only find 6" screws
>> affordably ($13/100ea), longer screws are $1ea. Sources & prices for 6"+
>> #10 screws?
>>
>> On 11/14/2012 7:53 AM, John Straube wrote:
>>> We have tested up to 8" of foam (EPS, XPS is stronger) with #10 screws and
>> furring strips. Works fine with siding ( safety factor of more than 10).
>>> 3/8" lags is crazy: never need it. The foam provides a lot of the
>> strength.
>>> Check our buildingscience.com website or my book for more detail on how
>> this works.
>>> Sent wirelessly from my BlackBerry device on the Bell network.
>>>
>>> -----Original Message-----
>>> From: Clarke Olsen mailto:colsen at fairpoint.net
>>> Sender: "Greenbuilding"
>>> mailto:greenbuilding-bounces at lists.bioenergylists.org
>>> Date: Wed, 14 Nov 2012 09:50:23
>>> To: Green Buildingmailto:greenbuilding at lists.bioenergylists.org
>>> Reply-To: Green Building mailto:greenbuilding at lists.bioenergylists.org
>>> Subject: Re: [Greenbuilding] Insulation fasteners
>>>
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>> --
>> George J. Nesbitt, Environmental Design / Build, Building Performance
>> Contractor HERS I Verifier & HERS II Rater, GreenPoint Rater new & existing
>> SF & MF, CABEC CEPE (Certified Energy Plans Examiner), Certified Passive
>> House Consultant, BPI Multifamily Analyst, www.houseisasystem.com, (510)
>> 655-8532 office, (510) 599-5708 mobile
>>
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>
>
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