Patio Cover header board with aluminim

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Old 02-05-14, 01:58 PM
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Patio Cover header board with aluminim

Hi All:

I am new to the forum and I have a question. I am planning to add an aluminum patio cover over our back deck. The structure will be free standing to get the height I need on the front edge after the slope. The nature of the cover I am looking at is it has an aluminum channel that gets mounted to a header board in the rear that the cover then get set into. I would normally choose PT wood for the support posts and the header board, but I understand modern PT wood is very copper heavy and will react with and corrode aluminum. So PT seems to be out as a choice for the header board and possibly even the posts. What type of wood would be recommended for this use. I am figuring I will paint it anyway to match the white powder coat on the patio cover.

Thank you in advance for your advice.
 
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Old 02-05-14, 03:30 PM
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Got a web site so we can see what your talking about?
I'm guessing you really mean a ledger board not a header. A header is what's over a window or door in most cases.
 
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Old 02-05-14, 06:31 PM
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Yes, I probably do mean a ledger board.

Here is the Mfr link. It may not quite show the attachment, but it is basically an aluminum channel that mounts to your house, or in my case to a ledger board, that the aluminum runners thewn set into.

Feria 4 White - Palram Applications
 
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Old 02-06-14, 03:01 AM
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Why not mount the aluminum ledger directly on the house? Skip the wooden ledger board, prone to rotting and maintenance issues, and bolt the aluminum to structural elements of the house framing. Get the permission of the manufacturer, including beefing up their standard aluminum channel if necessary.

I noticed the stuff comes all the way from Israel. No American manufacturers or distributors?
 
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Old 02-06-14, 04:17 AM
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I could bolt it directly to the house, but it would be substantially lower than the MFR recommends and throw the pitch way off. The back of my house has 2 x 4 rafter tails extending out from the roof. The patio cover I am looking at is 20' L x 13' W and I know there is no way the rafter tails could support the snow load or wind load of that patio cover.
If I attached a ledger board to the house below the level of the rafter tails it would put the ledger board height at about 7' 6". The patio cover is recommending about a 3:12 pitch with the recommended back height at just over 9' and the front height just over 6'. I think they recommend the steeper pitch because the roofing medium is open polycarbonate cells and they can collect condensate inside the cells. The steep pitch helps ensure the cells drain any moisture out that they accumulate. I live in Seattle, so there be moisture here. Even if I went with a 2:12 pitch I'd still end up with the front end of the patio roof just over 5' in height which is not very head friendly.
So I decided the best way to approach it would be to build a free standing support with 4 x 6 posts and dual 2 x 8 joists spanning the top of the 4 x 6 posts to a height of 9' above the deck in the rear. Then attach the aluminum channel to the 2 x 8's. My question in this post relates to the preferred PT lumber being corrosive to the aluminum rear channel.
I had not noticed the country of origin, but this was the best economical solution for an attractive, yet mostly plug and play solution at about $3000. I linked the MFR page, but there are several USA distributors. GE does make a very similar panel called thermoclear panels, but they are sold in individual panels which you then must fabricate into your structure, vrs the Palram Feria solution which is already designed out in pre-formed sizes for patio roof covers.
 
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Old 02-06-14, 08:21 PM
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What you're saying doesn't make sense. Going with a less-steep pitch (2-in-12) vs. a steeper one (3-in-12) shouldn't decrease the outboard headroom. It will increase it, by a difference of 13" for a 13' run. This means instead of a front height of just over 6' that you mentioned, you'll have about 7'-2" of headroom, going with the shallower pitch.
 
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Old 02-06-14, 08:50 PM
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Yes, I would have more headroom using the Mfr recommended rear height of 9' and a 2:12 pitch.
What I was saying was going from the Mrf recommended 3:13 pitch to a 2:12 pitch would still not net me enough head room in the front if I mounted a header to the house beneath the rafter tails at a height of 7' 6". That is why I am saying I need to build the free standing support in the back at 9'.

So again, what would be the recommended lumber type for the 2 x 8's that I would be mounting the aluminum channel to??
 
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Old 02-06-14, 09:24 PM
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I thought you said it would be "free standing". (i.e. not attached to your house) Covers like this are available with aluminum poles, aluminum beams, etc. There is no reason for anything to be wood. Sounds like maybe you need to look at a different company if they can't provide you with everything you need to build it freestanding.
 
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Old 02-07-14, 12:17 AM
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It will be free standing. I was explaining to Bridgeman45 why I could not mount the ledger to the house (which was his first suggestion).
It does not appear the company I am looking at has aluminum boards to mount to. The cover is made to fit the most common applications in whichj the homeowner has room to install a ledger board or mount directly to the house.

I agree an aluminum 2 x8 would be awesome, but I'm not sure where to get one. Assuming I will use wood, I wonder if perhaps someone could answer if there is a good type of wood I could use for my 2 x 8 that is not pressure treated that would do OK in the weather.
 
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Old 02-07-14, 01:58 AM
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Somewhere in Washington (Seattle, perhaps?), there must be a metal supply place that can provide an aluminum channel or other shape to meet your needs. Just tell them the uniform load it has to carry, and the necessary span length. And then sit down when they tell you how much it will cost.

If you insist on using wood, cedar might be your best bet. It weathers well, but can be subject to warping when exposed to alternate wet-dry scenarios. And it also won't be inexpensive, either, for the size you'll probably need.
 
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Old 02-07-14, 07:04 AM
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The nature of the cover I am looking at is it has an aluminum channel that gets mounted to a header board in the rear that the cover then get set into.
okay... so what do you propose that the header board gets mounted to? posts?

This company does not seem to offer a free standing patio cover... only free standing carports. A free standing patio cover needs to be engineered to resist swaying... so that the posts always remain plumb. When a cover is attached to a building, that automatically stiffens the cover. When it is free standing, it needs to be engineered to resist those forces.

Patio covers that are designed to be free standing do not get mounted to ANYTHING at the rear. The roof panels set across the beams that run from column to column, and they cantilever off both sides. They need to be designed to withstand uplift for your wind loads. They usually will have a gutter that surrounds the entire roof perimeter, capping the ends of all the roof panels.

If you try and do this on the cheap and become your own engineer for something that was not designed to be freestanding, you will probably be the proud owner of a very expensive kite if you ever have a high wind situation.

They also only seem to be rated for a snow load of 35lbs/sq ft, and that is when it's attached to a wall (not freestanding) What is the snow load in your area?
 

Last edited by XSleeper; 02-07-14 at 07:52 AM.
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Old 02-07-14, 01:43 PM
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XSleeper, Thank you for the thoughtful and informative post. My snowload depending on the source I use to look it up is between 20 and 25 psf. We occaisonally get wind storms that can get to about 50 mph. In the rear I was planning on using (4) 4 x 6 posts notched 4" deep across the top to allow (2) 2 x 8's to set on into the notch and be bolted into the back of the post with steel ties on the front. The posts would go down to 4 x 6 strong ties set into a concrete pillar and footer. I also planned to brace each post to the 2 x 8's to improve lateral stability.

I was also planning to leave approximately a 6-8" open gap in the back of the patio cover as the back would be higher than the level of the top of the house roof. I think this would allow wind to escape out of the back of the roof rather than exert it's full force upward when it reaches the house.

It seems to me that a cover designed to withstand wind and snow loads when mounted to a ledger board with no way for wind to escape except to put upward pressure of the cover should be equally able to withstand those loads when mounted to a well designed free standing structure. The main difference would seem to be the reduced lateral support.
 
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