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-   -   notching beams on pergola (http://www.diychatroom.com/f19/notching-beams-pergola-147945/)

SeanB 06-22-2012 09:51 PM

notching beams on pergola
 
I am getting ready to to put up the pergola over part of my deck project. I really like the look you get with notching the beams so they interlock, but worry about weakening the beams. I have seen notching a 10" beam about 3" and the upper about the same but there is still a height increase with the upper beam. What do you guys think of notching? In the YouTube video below they notch out held the beams, is that really ok?

I am going to have a ceiling fan in the center , which doesn't weigh slot, but want to be sure this thing doesn't collapse.

http://www.youtube.com/watch?v=0SyGxVP5HXk

Bonzai 06-22-2012 10:50 PM

A picture of some sort would make like so much easier in terms of giving constructive input. However unless you plan to do something weird or build the biggest pergola ever, notch away ... a typical pergola is not supporting any load above so as long as it supports itself that's all you need.

SeanB 06-22-2012 11:03 PM

Quote:

Originally Posted by Bonzai (Post 949377)
A picture of some sort would make like so much easier in terms of giving constructive input. However unless you plan to do something weird or build the biggest pergola ever, notch away ... a typical pergola is not supporting any load above so as long as it supports itself that's all you need.

look at the video. they notch half the boards.

Bonzai 06-22-2012 11:23 PM

I meant a picture of what you plan to build. Also they're big boards & not supporting any load above so not really a problem from a structure perspective. Also each cross member fills the notch of the beam it crosses so actually it can't flex ... this is totally different from someone notching a joist that supports the floor of a house as that would be a potentially serious issue.

tony.g 06-23-2012 02:59 PM

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Notching a beam is not normally a problem when done at or near the end of the beam. This is because the bending stress in the beam is at its lowest near the ends.
However, if you notch near the middle, the bending stress there is greatest, and this would be a problem; you would effectively be reducing the beam depth to the amount of timber you have left.

SeanB 06-25-2012 12:42 PM

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Thanks guys. Bonzai, I knew what you meant and sorry about the lack of details. I have just been so focused on the deck I got rushed and did not want to take the time to draw anything. My bad.

So here is the concept drawing of the deck we (my wife as I can't draw) did and I painted on the pergola as we have it planed (for the most part). Its not a full rectangle which poses its own design problems. My wife would really like it to follow the shape of the lower edge of the Octagon but I just don't know how to do that without having an extra post or 4 support beams instead of 2. I have done a rectangle pergola before and it was really no problem, but with this one we have the odd shape and due to height issues I have to keep that in mind.


So, here are my restrictions on height. At the house we have an eave on one corner of the house coming down in the way. So keeping an inch or so off the eave means my max height is 9'4".

The picture of the pergola I am trying to build is the second one. This is kinda how we want to do it, notice the 3 levels. I won't be boxing the columns or anything. By measuring it looks like the 2nd and 3rd levels take up 11 inches, add to that the 2x10 girders and that is 21" off the top, meaning headroom we would have 7'7". What I want to do it maximize that that height number. I want to put a ceiling fan in the middle as well as just not feel crowded by a low beam. So if I can notching half the height that will raise my min headroom past 8'.

With the deck I know beefy, strong stuff, braces, and good BUT they are hidden. I can't hide stuff on a pergola so I need some help on knowing what is good and bad practice. Thoughts?

Bonzai 06-25-2012 06:39 PM

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Here's a couple of ideas (simplified somewhat obviously) to give you something other than a basic rectangular box pergola. In both cases the rafters of the pergola would be attached to a ledger so as to avoid having to have 2 posts right at the house.

Edit: of course if you wanted to have the '3rd level' running perpendicular to the rafters then of course you could do so ... you may need additional posts mid way though depending on what that span is.

SeanB 06-25-2012 08:07 PM

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That actually how I started of my thinking. But, due to shape of the house and that I really didn't want to rip off more siding and mount a new ledger I just am putting post in. I already poured concrete footers for the posts as well. Here is the house side.

I also remembered that the inside ceiling is actually as high as the soffit you see, so there is no ledger there for me to mount to. Which seems really odd to me, but hey, what ever. lol

SeanB 06-25-2012 08:11 PM

oh, spans...that would be helpful to supply!

13' long
10' long
8.5' wide


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