Tugg you didn't actually ask any questions (!) but it does sound like you know what you are doing... We have a pergola that is approximately 16x30 and is made entirely of rough-hewn cedar (very hard, very very heavy stuff). The columns are about 6" in diameter and there are four of them, spaced 10' apart, and 14 feet from the house w/about a 2' overhang for 16 total extension away from the house. Not sure what a "lintel" is myself, but if it is that upper beam that is parallel to the house (at the top of the columns), that is (again rough-hewn) roughly a 3x10 or thereabouts, and the 16' rafters (which again overhang a couple of feet) are approximately the shape/size of a 2x8 though everything is an inch thicker than dimensional lumber. There are six of these, and over 30' that means they are spaced about 6' apart.

Across the top of the rafters, parallel to the house, are individual 6' cedar pieces (3-inchers) in an alternating configuration, which are screwed to the rafters and provide lateral support as well as shade and appearance of course. At the house is a header beam to which the rafters are secured by some very heavy steel L brackets w/lag bolts.

I tell you all this because we are on the top of a hill in the TX hill country and get some VERY serious winds from the north, which stresses our pergola laterally (the worst way it can be stressed) and our pergola has held-up exceedingly well for over 3 yrs now. This with no bracing at all at the columns (the posts are just set onto pieces of rebar I think that have been set into holes in the concrete below, and holes under the columns). Further, the house wall that the pergola is secured to is a very tall standalone wall (no internal perpendicular walls to support IT) and this wall has suffered no ill effects that we can tell e.g. no drywall cracking which we might otherwise have expected.

All this is said to advise: Bigger is better! It sounds like yours is a large structure and I suggest using the larger sizes you are contemplating. Have fun!

Redwood is a nice, long lasting material, but it isn't IMO environmentally friendly. Redwood is old growth forest materials, and due to decreasing amount available becoming prohibitively expensive. I would look at western red cedar or pressure treated or as an alternative some of the composite materials now available. (I like the looks of the composite posts that are available, plus they don't rot.)

As to the issue of support, no matter what materials you go with, your support beams will need to be sufficiently heavy enough to span the distances between posts, carry the beams over them, and whatever weight you will add in addition to that. Since your furthest distance is 14'8" I would use at least a 6x6 post set on a bracket attached to the concrete. Then your load bearing beams should be no smaller than 2x8 or 2x10. (This might be a bit of overkill, but you normally use at least a 2x10 set on 16" centers for a floor when you span up to 14 feet.) I would double these beams. (Place one on the outside and one on the inside of each post.) They need to be attached by carriage bolts ran through both beams and the post. If you want, or code requires it, use a galvanized bracket to provide additional support to the beams. Next you will want to run cross beams to provide side to side support for the posts and load bearing beams. Attach them to the load bearing beams using floor joist brackets and the proper fasteners at any center posts. On the ends I would also double these the same way that you did the load bearing beams, but overlap the posts and butt them into the load bearing beams using the appropriate screws through the outside beams and into the post, on the inside use the floor joist bracket. If you do not want the cavities between the beams visible from below you can place either a 1x6 or a 2x6 in there and fastened from the sides through the load bearing beams. This will also give you a chase that you can run electrical wiring through for lights or outlets. Now you can attach the top cross beams, for these you can use 2x4's or 2x6's set on edge and toenailed into the load bearing beams and a ledger plate you have set at the same height as the load bearing beam on the posts. I would also attach hurricane clips onto each cross beam. You can do this on both ends of each one, but if you at least do the ones on the load bearing beam you will be getting a great deal more wind resistance and seismic stability than you ever will without them. As to the ledger plate you need to remove the siding and attach it using lag screws, at least 4 inches long, into each stud. You will need to put a piece of aluminum flashing under the siding, and bend it to make a 90 degree angle onto the top of the ledger plate. You will need to caulk under the siding where it overlaps the flashing or use an appropriate means of securing the siding if it is vinyl.

The main thing I can tell you other than the above is to make sure everything goes up squared and level. The first thing I would do is measure out from the house at each end the distance to the outside of posts, then snap a chalk line on the concrete. Your drive pins should be at least 2 3/4" inside this line. This will be your outside reference line. Now check the retaining wall and patio for square. Either place a steel framing square onto the patio with one side on the chalk line and slide it against the retaining wall. If there is a gap at either end of your square, then you know that the retaining wall is out of square and you should not attach your post directly to that wall. Next check the retaining wall for level. Take a four foot spirit level and place one end (narrow end) onto the patio and place the level against the wall. If the bubble in the vial does not line up in the center the vial, the wall is out of level. Depending on which side of the center line the bubble is on, you will either be leaning in or out and will need to adjust your attachment to the wall to correct level. Now, take your level and turn it so that it is standing flat against the retaining wall, with one end lined up on the chalk line, and tilt it at the top until the bubble is in the center of the vial. Run a marker (pencil) along the side of the level to mark your level line for the front to back of the first post. Now go do the same thing on the other retaining wall.

Not as easy as you thought, huh? Things never are when you do it right, and we still aren't done with the lay out!

Measure up on the side of the house and remove the siding at a level equal to the height your load bearing beams will be on the posts, plus the additional height required to get up to the tops of your cross beams.

Now we need to attach your brackets to attach the retaining walls. Measure in 2 3/4" from the level line you made on the wall, measure down 6 to 8 inches from the top of the retaining wall and mark it. This point is where you will use a masonary bit of the appropriate size in a hammer drill to insert a drive pin at least 5 inches long and a 3/8 " in diameter. You will attach a standard U galvanized steel post bracket to this drive pin with a lock washer and nut. (This is if you are using a square post, for round or turned posts you will have to adapt or abandon doing any side attachments.) Now take the post and slide it into the U bracket. If there is no drive points in the concrete under where the bottom of the post sits, after you level it, then you will need to drill it and install a drive pin for the post bracket. It will need to be the correct distance from the wall and the chalk line, 2 3/4" in and away. Now attach the stand off post bracket to the drive pin, and put the post into place. Take two deck screws and run them into the post from opposite sides, closest to the wall. Now place your level against the post and slide the top in and out until the bubble is centered in the vial. Mark the post along the edge of the U bracket that you attached to the wall so you will not loose level when you set down the spirit level. Run deck screws into the post from opposite sides so that it is now secured to the wall. Go do the post on the opposite retaining wall using the same procedures. If the post needs to be shimmed between it and bottom bracket, do so using materials which will not deteriate. Finish attaching the bottom bracket to the post using as many deck screws as there are holes in the bracket.

I am sorry but I will have to come back later and finish these instructions. If you need more information I would suggest you look for books put out by Sunset on outdoor structures (Pergolas, Gazebos, Arbors). Most of thier publications are very informative and can give you good general design/construction instructions. Of course, check with your local code enforcement office. They can give you specific requirements for your area.

Lazerfan, I guess I did fail to actually "ask" a question but thanks for the information and encouragement, that was exactly what I needed and wanted! I definitely don't have wind to deal with where mine will be and hearing how yours is makes me confident that mine will be fine. I have to check the cost of the 6x6 (versus my other options) but they sound like the best choice for me.

Mokevinb, I definitely have a good solid ground setting for my pergola and have the right anchors (I am in the process now of calculating and sourcing all the bolts and misc fasteners.) and tools for the job. And am aware of the critical nature of the structure being square and level. Your info has me double checking everything (I know the rule: measure once cut twice.... oh wait.... ;-) But seriously I definitely didn't and don't expect this to be overly easy.

Thanks both for the advice and supportive words.

Tug

If I have 6x6 post and a 6x8 beam, what carriage bolt size do you recommend?