Pergola support

[Bope]

I am putting in a patio out the back of the house and I want to put a pergola over it to give some sun protection. One side of the pergola I will attach to the house. The other side will need posts. The pergola will be about 11'x19'. The posts will come at the edge of the patio. My question is the footing for the posts. Would I need footings below frost line? Thinking of aesthetics should I put a footer just outside the patio and have the patio pavers come up to the inside face of the posts? Have the footer under the patio or coming up through the pavers so it surrounds the post?

The pergola will be along the 19' length of the house sticking out 11'. Can I span the 19' between two posts or would I need a third post?

[Splinter Puller]

I always like the post to be surrounded by the pavers (on three sides at least).  It's harder to construct but looks more correct.

If you don't have a frost depth footing you run the risk of the post heaving.  On a deck it's  very noticable... on a purgola, maybe not so much.  Code usually requires a frost depth foundation on any structure physically attached to a dwelling.

That said... I think you could just bury the post to below frost depth and get the same result.  There is not much weight on a pergola nor wind uplift unlike a solid roof.

Another key will be proper diagonal braces at the freestanding posts to keep the pergola from racking.

[FIB 1]

I built a pergola off of plans published in a Sunset publication.  It was an elevated deck consisting of seven internal rectangles in the shape of an "L".  I did not attach it to the house because of the movement of the pergola structure from wind gusts.  The project was in Illinois, so I had frost issues to address.  Columns were 4X4 amended with 2X4 stock.  Beams were 2X10 stock.  All buried or ground contact structural material was pressure treated.  All above grade material was Cedar.  2X10 beams were doubled on the perimeter and tied together at 4 foot intervals by 4X4 stock.  One center beam was doubled 2X10 stock.  I can't send you a picture, as I no longer own the house.  The interior of the pergola was comprised of rectangles and had 50% shading.  Flat material in the interior rectangles was 5/4X6 pressure treated decking material ripped to 50% (3") and spaced 3" apart.  The flat shading material was mounted on 2X2 PT stock and rested on 1X4 cedar ledger boards which also functioned as trim on the interior.  In alternate years the shading rectangles are (or were) removed, scraped and re-stained, as was the exterior.  Most recently, last year, the flat shade rectangles received two coats of a filler deck stain, lightest density.  The perimeter received the same color, but not the thicker formula.  No permit was required because it had no stairs, no electricity and nobody walked on it.  It has withstood 11 northern Illinois winters with scant deterioration.

[Alan S]

FIB 1:

That sounds good, but how did you support it?  How deep were the 4x4 posts and what were they anchored into?  What do you mean by "Columns were 4X4 amended with 2X4 stock"?  Does that mean you reinforced each 4x4 with a 2x4 along it?

[jbiddle]

I'll take a slightly contrarian view.  I built my pergola around a brick paver patio, but kept all of the posts outside of the patio area.  I didn't want the posts to reduce the effective space of the patio.  I'm in Michigan with 42" frost requirements.  I poured four 18" diameter tubes of concrete 48" deep because the minimum delivery for concrete was 1 yard and that worked out perfectly.  A yard of concrete delivered was something around $220.  I set Simpson strong ties into the wet concrete and bolted a post attachment to the strong ties.  That way I don't have any wood buried underground (I also added a conduit run from about 2' down through the top of the concrete for electrical).  I used a transit (a water level would also work) to measure the height difference at each post and used that measurement to cut the posts to height before install.  Mine is also free standing.  Contrary to some, my pergola is extremely heavy.  I have 16 posts, 8 beams, 16 rafters, and 36 slats...all made from ipe'.  I told my son to strap himself to the pergola during tornados.  

[FIB 1]

1.  It is a free-standing structure.  There is no need to attach a deck or pergola to an abutting structure for stability, but it is simpler than building the structure free-standing.  There is a little extra work because you need to dig a few extra post holes and long 4X4 stock is pricey.  All columns are beyond the perimeter of the patio. 

2.  2X4 stock was added to each column to provide some visual relief and provide a base for the 2X10 beams

[R Clark]

I built a pergola last summer.  Sized about 14' X 22' and about 10' tall.

It's very close to the house, but not attached.  I don't like hanging stuff like that on the house.

The 6" X 6" corner posts are sunk 48" deep and anchored by packed 3/4" gravel.  The posts were put in place in fall 2014.  Structure is rock solid to this point.

[Bope]

Thanks for the replies. I am now leaning to doing 8" sono tube and having it stick up about 2.5' above the patio. Then I can have pavers built up around the tube to match the pillars the wife wants at the ends of the bench that will be around the fire pit.