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how to build a pergola?

I have a 14x14 slab of cement that is 3 to 4 inches deep. I would like to use 4x4 for posts not in the ground there will be a metal base. or use 6x6 for corner post. i will be building a pergola with 1x2 or 2x2 rafters.+++++++++++++ thanks to everyone with pics and options safety ones too. soo how about 6 4x4x8 with 2x10x12 rafters??

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rickharris5 years ago
This is pretty much what I have in the yard
pergala.jpg1-DSCF0499.JPG
sanchez05 (author)  rickharris5 years ago
what is the span of the rafters and the total area covered? it looks like a 10x10 maybe a 12x12
About 9 feet - 3 meters square - the uprights are 4 x 4 inch ad the rafters only 4 x 2.
sanchez05 (author)  rickharris5 years ago
thanks did you install angle bracing at a 45 degress?
No the cross members between the uprights fit into a slot in the top of the upright - the other cross joists are on top and screwed to the members beneath.

The posts ar5e set in concrete below the level of the patio.
jrh0655 years ago
You can use 2x6's or 2x8's for posts by arranging them as the picture shows. It allows you to make a square post without any cuts and using cheap lumber. If you want to of course.

When I made mine I built four of these posts, and then stood two of them up spaced them out the distance I liked(8 feet for me, more for you) I then nailed a rafter from post to post on each side to hold them together, and repeated that with the other posts.

From there I arranged the two post pairs so they were square, and ran rafters across the four rafters attached to the post.
post.jpg
sanchez05 (author)  jrh0655 years ago
I've never heard of this method before is there a picture of the actual post, what about strength is it the same as a so call 4x4 or 6x6?
Here's a picture of the whole thing. It's missing a rafter or two because i decided I wanted more of them after getting started. Rafter's are 2x6's and the legs were made of 2x8's though I should have used 2x6's for those as well because the legs turned out a little large.

The area under the rafter's is 10'x10'.

I've been trying to stain it the last few weeks, but it always rains when I have the time.
IMG_20120429_161005.jpg
sanchez05 (author)  jrh0655 years ago
is there anything inside the pillards especially at the top were the rafters meet with the pillards?
No, the hollow post are left open at the top, and the rafters are screwed into the post.
It is quite strong. I'll try to get a picture up soon.
Re-design5 years ago
You need to find a proven plan and follow that.

If your posts are not anchored in the ground you have to have good bracing at the top or it will fold up like a card house in a hight wind. 2x2s are not adequate to span 14 feet. That would take at least 2 x 6 with no decking and even then they are going to sag in a short time.  Ask your building inspector what works well in the area.

I design buildings for a living.
What do you mean by decking?
Plywood over the rafters. That's what holds up roofing.
Vyger5 years ago
Well, to start with here are a few pictures of some designs.  Once you find one that you think is interesting or that you like look up the plans in more detail. For example here are some.
canucksgirl5 years ago
You definitely need metal post supports to anchor them to the cement slab, and enough posts to support the load of the rafters. You may want to check with building codes in your area... The goal is to ensure that the structure is strong enough to withstand any storms/wind, and not be a risk to injuring anyone or causing damage to other structures (in which case you could be sued and find your Insurance null and void), so its important to look into.

As far as plans, there are many to be found online, but here's a good one from Lowe's website.