[RE-wrenches] L feet no flashing in shingle roof

Tue Jul 3 10:46:21 PDT 2012

Chris

Bronze Star Construction Lags are what I use.  I usually use the 5/16" and
1/4" with the most thread I can into the truss without popping out the
other side.  I have dropped to #7 with more penetrations if the truss
warranted it.

http://www.screw-products.com/star-drive-construction-lag-screws.htm

Here is their strength tests for 5/16", very comparable to lags.  I tend to
be pretty conservative and use a 2x - 2.5x strength tests safety factor
with almost all my fasteners, especially blind attachment to trusses.  Full
test results are available.

http://www.screw-products.com/specs.htm

I have had luck with Cannon gasket for butyl or EDPM washers, use .75 dia
outer with dia of fastener inner about .25" thick. About $.15 each for
1000, about half that for 2500.  Can order direct online.  Buytl to me
works better since it flows well when tightened.

http://www.cannongasket.com/

I believe there are several manufacturers making these types of screws now,
so there may be other sources.

Hope that helps!

Bill

On Tue, Jul 3, 2012 at 6:43 AM, Chris Mason <cometenergysystems at gmail.com>wrote:

> Bill,
> Can you provide a link to the product you are using - I found a lot of
> screws on that site but none called "structural".
>
> Thanks
>
> Chris
>
> On Mon, Jul 2, 2012 at 7:08 PM, Bill Hoffer <sunengser at gmail.com> wrote:
>
>> Mark
>>
>> Lags for me are old hat after using the newer structural screws.  I get
>> them local from www.screw-products.com although I know there are more
>> companies out there that make them for the Structural Insulation Panel
>> industry.  Thinner than lags with comparable strength, they drive easy with
>> no predrilling, and are less likely to blow out a truss.  Come in many
>> different lengths and use a special star head with a built in washer.  I
>> use thick butyl tape on the foot and a small rubber washer on the screw
>> head , together they work great!  If you want a little more security a dab
>> of the appropriate sealer in the foot slot before finally tightening it
>> down works too.  Only way to go on corrugated metal roofs where there is no
>> real option for flashing.
>>
>> Bill
>>
>>
>> On Mon, Jul 2, 2012 at 3:40 PM, <mark at hurshtown.com> wrote:
>>
>>> My 18V Milwaukee cordless hammer drill has no trouble driving a 5/16"
>>> lag into anything I've ever encountered.
>>> If you put the lag anywhere near the middle of the rafter it won't
>>> split.  If it splits, it must be some cheap stuff from Home Depot.
>>> Only an engineer with no practical experience would insist on a pilot
>>> hole and the resulting reduction in holding strength.  I'm assuming the IBC
>>> consists of a bunch of bureaucrats that value control over common sense.
>>> In this instance flashing offers no benefit, and may even be
>>> counter-productive if incorrectly installed and it causes rain to collect
>>> under it.  My experience is in northern Indiana where it does rain and the
>>> wind does blow.  (Record 91 mph winds last Thursday.)  Less severe weather
>>> than Michigan, but close.
>>> I use the best silicone caulk Menards has to offer.  I've never worried
>>> about compatibility.  It definitely won't dry up and crack away like the
>>> black roof cement some swear by and insist on.  15+ year old silicone caulk
>>> is yellowed a bit but that's the only change.
>>> If the silicone and shingle aren't getting along, I've never heard them
>>> complain.
>>>
>>> Mark
>>> (Disclaimer: Portions of the preceding are the opinions of the author.)
>>>
>>>  -------- Original Message --------
>>> Subject: Re: [RE-wrenches] L feet no flashing in shingle roof
>>> From: Dave Click <daveclick at fsec.ucf.edu>
>>> Date: Mon, July 02, 2012 10:29 am
>>> To: re-wrenches at lists.re-wrenches.org
>>>
>>> I always thought that installing lag screws was tough enough with pilot
>>> holes- I should hit the gym. I'm not a structural PE, but I think that
>>> not drilling pilot holes violates the American Wood Council's National
>>> Design Specs and therefore violates the IBC too. I would imagine that
>>> you'd be much more likely to split your trusses. IBC also requires
>>> flashings be used but at least around here inspectors never ask for it
>>> (which makes sense- as you all know, Florida never sees wind or rain,
>>> and definitely not at the same time). What silicone do you use that's
>>> compatible with asphalt shingles?
>>>
>>> DKC
>>>
>>> On 2012/7/1 21:13, mark at hurshtown.com wrote:
>>> > In my 20 year experience of lagging down L feet on shingle roofs in
>>> > Indiana with a good dollop of silicone caulk under the foot, I've never
>>> > had an issue. No pre-drilling, just drive the lag home. Drilling a hole
>>> > first is not necessary, and reduces holding strength. No reason to make
>>> > a science project out of it and increase cost and labor.
>>> >
>>> > Mark
>>> >
>>> > -------- Original Message --------
>>> > Subject: Re: [RE-wrenches] L feet no flashing in shingle roof
>>> > From: Drake <drake.chamberlin at redwoodalliance.org
>>> > <mailto:drake.chamberlin at redwoodalliance.org<drake.chamberlin at redwoodalliance.org>
>>> >>
>>> > Date: Fri, June 29, 2012 3:09 pm
>>> > To: RE-wrenches <re-wrenches at lists.re-wrenches.org
>>> > <mailto:re-wrenches at lists.re-wrenches.org<re-wrenches at lists.re-wrenches.org>
>>> >>
>>> >
>>> > Hi Jay,
>>> >
>>> > There is no room for flashings. The L feet will go very close to the
>>> > skylights and the flashing would hit the edge of them. Plus there is
>>> > an existing array that was done by another installer that is done
>>> > with L feet only. The new array would be higher.
>>> >
>>> >
>>> >> And given that we have really good off the shelf approved flashed
>>> >> feet, why would you use anything else?
>>> >>
>>> >> My 2 cents,
>>> >>
>>> >> Jay
>>> >>
>>> >> peltz power
>>> >>
>>> >>
>>> >> On Jun 29, 2012, at 5:16 AM, Glenn Burt wrote:
>>> >>
>>> >>> We have used a variety of sealants over the years, and determined
>>> >>> simple Henry roofing cement is the best product for use on comp
>>> >>> roofing.
>>> >>>
>>> >>> We also used to bend our own L-foot flashing, which we cut from
>>> >>> standard Al coil stock (before all the manufactured options were
>>> >>> available). This might be a good option for you in this case.
>>> >>>
>>> >>>
>>> >>>
>>> >>> Glenn
>>> >>>
>>> >>> *From:* re-wrenches-bounces at lists.re-wrenches.org
>>> >>> <mailto:re-wrenches-bounces at lists.re-wrenches.org<re-wrenches-bounces at lists.re-wrenches.org>
>>> >
>>> >>> [mailto:re-wrenches-bounces at lists.re-wrenches.org<re-wrenches-bounces at lists.re-wrenches.org>]
>>> *On Behalf Of
>>> >>> *Drake
>>> >>> *Sent:* Thursday, June 28, 2012 6:40 PM
>>> >>> *To:* RE-wrenches
>>> >>> *Subject:* [RE-wrenches] L feet no flashing in shingle roof
>>>
>>> >>>
>>> >>> I'm quoting a job that has an existing array with L feet bolted
>>> >>> down to a shingle roof with no flashings. I want to match the
>>> >>> height of the existing array. Also some modules are being worked
>>> >>> in around skylights where it is unlikely that room would be
>>> >>> available for flashings to center over rafters.
>>> >>>
>>> >>> I've always used flashings. Would it be completely crazy to
>>> >>> follow suit of the existing array and bolt L feet straight to the
>>> >>> shingle roof with good roof sealant? If so, how would you seal it?
>>> > Drake Chamberlin
>>> > ATHENS ELECTRIC LLC
>>> > OH License 44810
>>> > CO license 3773
>>> > NABCEP Certified PV
>>> >
>>> ------------------------------------------------------------------------
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>>
>>
>> --
>> Bill Hoffer PE
>> NABCEP Certified Solar PV Installer™
>> Sunergy Engineering Services PLLC
>> 2504 Columbia Ave NW
>> East Wenatchee WA 98802-3941
>> SunEngSer at gmail.com Cell:(509)679-6165
>>
>>
>>
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>> List sponsored by Home Power magazine
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>
>
> --
> Chris Mason
> President, Comet Systems Ltd
> www.cometenergysystems.com
>  Cell: 264.235.5670
> Skype: netconcepts
>
>
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-- 
Bill Hoffer PE
NABCEP Certified Solar PV Installer™
Sunergy Engineering Services PLLC
2504 Columbia Ave NW
East Wenatchee WA 98802-3941
SunEngSer at gmail.com Cell:(509)679-6165
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