How to Center feed Emphase IQ7+ from a soladeck?

[foo1bar]

I'd probably agree that most reasonably constructed roofs are strong enough to support an array. I'd also think that most roofs are OK with respect to most external loadings such as wind with the caveat that most applications need checking for imposed loadings, usually per ASCE 7-16 or other recognized standard.

FWIW- my city they have an "expedited" permit for solar - and if it's that every 4' there's a attachment point they don't need detailed roof calcs.

I don't know how common that is with other AHJs, but made it easier for me.

[J.P.M.]

FWIW- my city they have an "expedited" permit for solar - and if it's that every 4' there's a attachment point they don't need detailed roof calcs.

I don't know how common that is with other AHJs, but made it easier for me.

Thank you.

I'd take an educated guess that the structurally weakest, least uniformly secure point in a rooftop array and also the most uncertain point is the lagging.

On the expedited process, in San Diego county, and I'd suggest probably most other CA AHJ's, that process requires rooftop systems to conform with sec. 1609 of the CA building code to an 85 MPH wind speed. Those requirements generally follow ASCE 7 requirements with respect to wind loadings.

I suspect the reality is enforcement is probably lax to non existent with respect to wind loading and designing to them with respect to roof top residential PV, but that's different from not requiring detailed calculations.

[ChrisBarrett]

Just heard back from the inspector, they would like a structural analysis done Slightly annoying, just in that if I had known up front I would've had it completed a couple weeks ago and included it with the rest of the documentation.

[Ampster]

I have had luck using the engineering diagrams from the racking company. You have to provide the data regarding roof rafters, spacing and the sheeting material and thickness.The ones I have used are Unirac and Ironridge.
They are stamped by an engineer but it is not a wet stamp only a photo copy. That did not matter in my case. Good luck.

[ChrisBarrett]

yeah i'm getting a whole workup - might as well. Just want to get on with the installation

[ChrisBarrett]

Quick update. I got the engineering stamp and the permit from the city. I pulled through the MC 10/2 cable from basement to attic yesterday and I need to start doing the layout of all the mounts. That'll be the worst part of the install for sure.

I do have an install question: with the Ironridge Flashfoot 2 is sealant required (like an upside down U shape) underneath the flashing? I have seen a couple videos where people do that, but it's not included in the installation instructions.

[Mike90250]

as long as sealant goop allows trapped water to drain downhill and not pool at the mount, it should not hurt. (only apply in an upside down U shape, so it wont collect water)

[ChrisBarrett]

I'd like to not install it at all if not required Just fill the pilot hole, and then put the flashing over. Just wanted to make sure that was reasonable.

Because how would an upside down U help anyway? The water wouldn't be coming from that direction if your flashing is under 2 courses of shingles....

[Mike90250]

....The water wouldn't be coming from that direction if your flashing is under 2 courses of shingles....

That's disproven in real life, water always finds a way !

[ChrisBarrett]

Ha! Well, I think I'll just follow the manufacturers instructions in this case.

[Ampster]

That's disproven in real life, water always finds a way !

What is proven is that water always finds a way to flow downhill unless driven by wind. Thatch roofs have proven that for hundreds of years.

[J.P.M.]

What is proven is that water always finds a way to flow downhill unless driven by wind. Thatch roofs have proven that for hundreds of years.

Well, I get some valid grief around here for drifting off topic some, but besides having nothing to do with the thread topic that I can see or think up, that's simply an incorrect and also a misleading statement, so I'll follow you into the weeds and see if we can correct the error.

Other phenomena besides wind that you may not know about that will cause a liquid to flow against a gravity field (or as you write "downhill") are, among other things, capillary action and turgor pressure as related to osmatic processes, not to mention adhesion and the effects of surface tension. Not putting words in Mike's mouth or doing his thinking for him, but those things and others are what help water "find a way".

One other thing you may not have considered is condensation of water vapor in elevated but moisture sheltered places. Think frost heaving or lifting of roof material at imperfect seams caused by condensate puddles that freeze on not quite flat, mostly horizontal roofs.

Although wind can defeat gravity, in a general sense, if the applied wind force is greater than > the gravity force on a droplet or spray, when it comes to thatched roofs, a well designed thatched roof will win out at the point where the force of the wing is reduced as it penetrates the roof.

Thatched roofs function by acting as a big wick that operates using surface tension and gravity by sloping the roof against the horizontal. Moisture/precip. will partially penetrate and flow toward the perimeter of the structure or maybe to a cistern, etc., with the droplets that form on/inside the roof material becoming heavy enough so that gravity overcomes the wicking and adhesion of water to the roof material.

Unless strong enough to have enough momentum to penetrate the entire depth of the roof, wind has little or nothing to do with how a thatched roof works to help keep what's under it dry.

[ChrisBarrett]

lol that is quite the tangent.

[Ampster]

lol that is quite the tangent.

Yes it is. I haven't bothered to read it. But I suspect it resembles

My apologies to you if my post triggered that tangent. I was trying to support your assumption to follow the manufacturers directions with regard to your installation of the Ironridge Flashfoot 2. Maybe i went to far in trying to clarify the comment from @Mike90250 , ".... water always finds a way."

[ChrisBarrett]

I actually called Ironridge, and they said they have a tech brief that notes that the flashing passed all tests with no sealant at all. So... I'm just putting sealant in the hole and I'll check the attic on the first big rain and see if there are any leaks.