I’m designing a pergola for a client .to be attached to the house on 1 side.
Its 8′ high, 2 10″ round tapered fiberglass columns, either 4×10 cedar beam or 2 gapped 2x10s supporting 2×8 cedar joists,supporting 2×2 ipe.
pergola is approx 12’x12′, to be built on an “inside corner” of the house
the joists and ipe will be 16″ on center.
questions: Ive seen in another post someone used a 4×4 in the center of these columns.Is this necessary? I suppose it s for solid attachment rather than bearing?
what do you think of the proportions of this? the elements almost look too skimpy when i draw it.
should i be concerned with lateral bracing?
Im tempted to prebuild the top assembly on the ground , lift it into place and bolt to house so i can attach the joists to the plate from behind .am I crazy?
Thanks much ,mike
Replies
well whadya think?
Are you asking about a 4x4 in the center of the manufactured column? If it is a structurally rated column ... why?
Yeah, you're crazy to pre-build it, unless you have a crane to lift it into place.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Personally, I think the 2x2s being on 16" centers would, visually, be too far apart - just an opinion. Look around in the photo album (or whatever it is called) here at BT. Several people have posted good pergola pictures including Mike Smith (I think his showed construction techniques), Piffin, and ProDeck.
Also search for the word "pergola". I think that would be the most direct route.
Personally, I think you should definitely put a 4x4 inside your factory made column. The 4x4 will not only give you something to attach your top structure to, but, it will also give you something to anchor into the ground. While the factory column is plenty strong to support the weight, it won't give you much lateral stability. Matt
Thanks for your reply. the purlins and joists would be @ 16" , making a square grid. It seems to me that most pics ive seen show this.What would be your suggestion?
thanks
bump
Bump??? I asked a question ... how about an answer.Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Yes, im refering to a 4x4 in the middle of something like a permacast column. Its structural but Im concerned about fastening the pergola beam through the polystyrene cap. That dosent seem sufficient on the face of it. Also, you know the bases and caps just get glued together.
Whats this BUMP about?
rez does it a lot. You bump the thread back up to the top by adding a new post to the thread. The closer it is to the top, the more likely someone will see it and respond. But you probably already knew that...
I never met a tool I didn't like!
This pergola design sounds fairly straight forward. I think it is a good idea to have a 4x4 in pressure treated or naturally rot resistant wood (locust, white oak) It will give you solid wood to bolt to with paired 2x10s or mortise and tenon into a 4x10.
The placing of the pergola on an inside corner makes lateral bracing unnecesary if two sides are bolted to the house. Why are you only bolting one side?
The element seem fine in porportion. It's easier to build the pergola in place one piece at a time. Stringing things and keeping things straight seems easier if the members are attached where thay will ultimately be.
Tip: Stain and finish or paint all of the pieces first on the ground. Its much easier to touch up the finish in those tight spaces than try to get it even and run-free.
Thanks for the confirmation on the 4x4.The design has changed to a free standing pergola with 4 columns and 2 beams. The column spacing describes a 8' square and the framing is 12' square. The joists will overhang the beam by 18" or so and will not be attached to the house unless I contrive to bolt a long L shaped bracket to the house to screw down into the joist ends {with the og} or the purlins.Do you think the 2x2 ipe purlins will provide enough lateral bracing? What do you think of the column width ? When I draw it it looks a little skimpy.
thanks
I posted this pergola awhile ago. I used fiberglass columns, no post inside. These were from Chattsworth, the columns looked like any other but the cap and base were cast, not two piece plastic. Once the deck part was built, I stood the columns, built a beam on top and framed the joists. I used 2x8 PT for the joists. Instead of using a strap on top to form the grid, I chose to frame it with 2x8 to make a flush grid. I didn't want the PT to twist and warp and this seemed like a more stable alternative. It also gave the top grid some presence. I made a copper flashing for the top of the capital and put a piece of PT on the deck that fit the inside of the base. The capital and base are secured to the framing.
A square grid pattern up in the air is not all that stable laterally. The tight fit of the railings helped strengthen the structure. I would use some diagonal bracing if the pergola had no railings. If you are in a corner, attached to two walls, I think you will be fine without diagonals. The decorative tails on mine are just ends that are screwed to a rim joist. This was easy to do on the band saw and gave consistent results. I think I kept the ledger away from the wall while fastening the joists from behind. Then slid it in place. The grid was made to be evenly spaced for the size of the run but it was pretty close to 24" OC.
http://forums.taunton.com/tp-breaktime/messages?msg=50461.102
Beat it to fit / Paint it to match
Thanks hammer, I think I saw your post before. Were you playing with photo shop? I think maybe you attached the wrong message in your last post,
How did you attach the joists from behind? Attach the 2 end one first and use a temporary support?
thanks, mike
My memory is getting worse every day. I remember not wanting fasteners to show so I likely supported the ledger away from the wall enough for my gun to get in. I don't like to attach ledgers directly to the wall. I use 1/2" lags, hit studs and place heavy PVC electrical conduit connectors as spacers. The spacers can be cut on an angle to match the siding bevel. I stick a dowel inside and cut on my miter saw. I've been trying to play with iPhoto all afternoon. I can't get my iMac to download the pictures I just took on a trip to Winterthur. Too bad, the folks at Knots would probably love to see the highboys and secretaries I shot.I do remember that the column bases were not uniform. I had to make at least two different size infill pieces. I still have the bandsaw jig I made for cutting the rails to fit the columns.Under the gallery, I clicked on the header. This opened more gallery photos, I scrolled down to my post. I then copied and pasted the address bar to you. Guess that didn't work. The title of my post was 'kitchen and pergola'. I've done a couple of other pergolas that were of similar construction but never took pictures.Sorry if you're on dial up, I've tried to resize to 50kb but it isn't working.
Beat it to fit / Paint it to match
Yep seen it .Looks great are those 8 or10" columns?
12"Beat it to fit / Paint it to match
Mike,
I have built similar structures that used inserted acrylic panels making it like a roof that had to bear a snow load. It had the same span between columns and has never required a centre support. I had to use three timbers instead of two but your's will not have any load beyond the 2x2s' My acrylic version is still shedding rain, snow and dispersing light after 15 years on client's house.
Eddy
Since you are using structural columns, I would anchor each to a concrete footing using an embedded j-bolt, connnector nut and a length of all-thread through the core. Run the all-thread right through your beam ends and then tighten down the nut over a 3" square washer, cutting off the excess rod above the nut.
Complete the rest of your pergola. Notching the cross-members over the beams will improve the stability of the structure and using hurricane ties (such as HGAM10's) on both sides of each end of the cross-members will improve it even more. These L-shaped ties will be practically invisible on the top of the main beams. You could go cheaper with standard hurricane clips (H2.5's) but these hang down over the sides of the beam and would need to be disguised as they detract from a clean look.
If you can reach the house from one, or better, two corners high on the pergola, a small diameter rod with flanges for screws on each end would further stabilize the structure and be mostly invisible, too.