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

Chris Mason cometenergysystems at gmail.com
Tue Jul 3 18:06:40 PDT 2012


Thanks for the information, I really like these fasteners.
Bronze not stainless? We normally use stainless for everything. Given our
coastal location, we want to avoid corrosion.


On Tue, Jul 3, 2012 at 1:46 PM, Bill Hoffer <sunengser at gmail.com> wrote:

> 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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>>
>>
>> --
>> 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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-- 
Chris Mason
President, Comet Systems Ltd
www.cometenergysystems.com
Cell: 264.235.5670
Skype: netconcepts
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