Pergola Foundation concrete vs., bracet?
Hello,
I was looking to build a 12′ x 14′ pergola, and I have a question with the post foundation. Here are my options:
– dig a hole about 4′ down (to get below the frost line) and pour concrete around the post and allow to cure
– dig hole down 4′, but instead of cementing the post, just pour the cement and use a bracket to attach the post to the cement.
I would prefer to use the backet system since it would be easier and also it would prevent against rot (I am using regular P/T lumber)
Here is some background info which may be useful:
– I live in an area where there is 4 seasons (around Detroit, MI)
– I am going to use P/T lumber for the entire project
– I am using 6″ x 6″ posts (4 of them) for the structure. The remaining structure will be 2″ x 10″‘s, with 2″ x 8″‘s crossing over top (16″ on centre), and then finally 2″ x 2″‘s to tie in the top crossing over the 2″x8″‘s.
My thoughts are that the bracket should work fine since the top of the structure will be tied all in together with the 2 x 8’s crossing the 2×10’s and finally the 2 x 2’s on top keeping everyting together and in line.
My major concern is will the bracket (I am going to use the one recommended in the recent article re: deck foundation instructions) is will it be strong enough. With such a large pergola, I want to make sure I have a sound founation, and I am worried the brackets will make the pergola “sway”. However, the weight of the lumber, etc., should prevent that from happening.
Any help / recommendations on the matter would be greatly appreciated! FYI – a local deck-building company recommended cementing the posts right into the concrete vs. using brackets).
Thanks! Look forward to hearing your responses
Replies
This is the way I almost always set pergola posts.
http://woodsshop.com/FootingDetails.htm
Thanks for the reply!
One question - the copper band you are using I am assuming is used on redwood or cedar. I am planning on using pressure-treated wood (since the previous two are very expensive in my area), so the copper band will likely not work. Do you have any suggestions on what I should use in between the post and the concrete to prevent rot from occuring.
The copper will do the same job on PT as it does on any other wood. Copper is what the new PT is treated with. The trick is, as that copper band oxodizes, copper solution runs down the post and saturates the area where rot will occur.The next important issue is to keep that area dry by sloping the concrete away. Looks pretty nice too ;-)
Last question I promise. I tried to find these copper bands at local stores (Home Depot, etc.), but they didn't know what I was talking about and I couldn't find any of them. Do you know where I can find these copper bands?
I just have my local sheet metal shop cut them up for me, 3" wide and 23" long (for 6x6 posts), then tack them in place with copper nails of course.Here's a shot of a jig we use as we're bending it around. Helps keep it level as you bend it around so that the lap lines up in the back. As you bend around the radiused corners, use a little hardwood block (and hammer) to form it around so that it fits tight.Oh, and, we lightly sand the copper with 150 grit to clean/shine it up, and wear gloves so you don't get fingerprints everywhere!
Thanks again! I really appreciate it!
I should've also said that it's a two person operaton, as one pulls it around, the other taps and forms the corners tight.you go getum now, and post alot of pics for us!
Will do, but you'll have to give me a couple of weeks as I am quite busy, but I promise to post pics once I am done
One more question - do you think I can get away with only 4 posts for a 12' x 14' (interior dimensions) pergola? I was thinking of just using 4, and then re-inforcing the rafters by making a "corner brace" out of extra 6 x 6 stock. Is this necessary? Should I have 6 posts? The only weight this will be bearing besides the lumber itself it possibly a vine of some kind. Again your help is appreciated.