Yep, a properly sized pilot hole is the key. As far as I know splitting of rafters has not been a problem for me; it's not always possible to get inside to see. When the lag tightens down and doesn't spin out, I assume it's good.
Maybe we have better quality building supplies in Indiana. A lot of the Amish buildings that I install on are built with native lumber. It is generally MUCH stronger than the knotty Home Depot variety, and a 2x4 really is 2x4.
The benefits of a pilot hole are duly noted and accepted.
I have the luxury of working in a market where I don't need to worry about inspectors finding fault with things just to justify their existence. God knows we do have that kind in Indiana too.
5 modules that I know of perished in our recent high winds:
3 are missing and presumed dead because the barn roof they were on is also missing.
1 was beaten to death because the customer screwed it down with screws intended to be used on steel roofing, and did not even hit a rafter.
1 well, may have been my fault. One lag pulled out and allowed the panel to bow and break. It's location shouldn't have been a problem as far as wind is concerned. We apparently have lots of mini-twisters.
Two or three trees in the middle of a woods were twisted together with the rest barely touched.
We live and learn. My eyes have been opened to a few new things. Thanks.
-------- Original Message --------
Subject: Re: [RE-wrenches] L feet no flashing in shingle roof
From: benn kilburn <[email protected]>
Date: Mon, July 02, 2012 9:19 pm
To: RE-wrenches <[email protected]>
Mark,You wrote, "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."Drilling a properly sized and depth pilot hole will…-reduce the possibility of the rafter splitting,-reduce further opening an existing split and-reduce the chance of splitting a rafter when lagging directly into solid knot that will surely split without a pilot hole...and if the whole roof is built with the same 'cheap stuff from home depot' then wouldn't you want to reduce the chance of every penetration/rafter splitting and compromising the integrity of the installation?A properly sized pilot bit will not reduce the pullout or shear strength of a lag bolt. There are charts for reference for different types of wood.Anyone who works with wood and where splitting, structural or aesthetics are a concern (carpenter, cabinet maker, framer…rooftop PV installer) should know that wood splitting is significantly reduced when a pilot hole is used. It is a 'best practice' method.I don't sweat over using just L-feet, because when I do I'm confidant that I'm using an approved sealant and enough of it to make each hole I drill in the roof leak-free, but I will not deny that a flashed roof penetration is a superior and first choice method.Cheers,BennDayStar Renewable Energy Inc.780-906-7807Certified Construction Electrician Solar Photovoltaic Systems CertifiedCertificate # 0007SHAVE A SUNNY DAYOn 02/07/12 4:40 PM, "[email protected]" <[email protected]> wrote:_______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.orgMy 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 <[email protected]>
Date: Mon, July 02, 2012 10:29 am
To: [email protected]
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, [email protected] 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 <[email protected]
> <mailto:[email protected]>>
> Date: Fri, June 29, 2012 3:09 pm
> To: RE-wrenches <[email protected]
> <mailto:[email protected]>>
>
> 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:* [email protected]
>>> <mailto:[email protected]>
>>> [mailto:[email protected]] *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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