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beam, post size and connection for semi-covered deck
I am building a deck with a pergola cover, and would like some advice on size of post, and connection of beam to post. The attached picture shows the basic layout.
I plan to put a support beam underneath through the middle (easy), so the effective joist span is only 6'. The front header/beam is my main issue. I'm thinking of "splitting" the front beam, meaning run the two 2x's on each side of the post, but notch the post to get the support of wood-on-wood. If I notch in 1", I get most of the beam supported, but retain 3.5" of post if I use 6x6. ( I assume anyone will suggest 6x6 for this project)
Another issue is supporting the top. I plant to make the top lightweight, maybe 2x4's 36"OC supported by a bigger rim all the way around, then run screen on the top to filter most of the sun. Do I need to attach it to the house up top, or would posts at all the corners do?
Any suggestions to links or books concerning covered decks would be much appreciated.
I'm wondering if 6x6 posts is overkill.
Any thoughts on using 4x4 instead, including a clever way to support the header/beam?
If I only notched in 1/2", that would leave 2" of post, but is that enough?
I'd stick with the 6 X 6. You'll need all the wood you can get when you start notching.
I have a couple of concerns about you design. Notching the post for you miter corners is going to be difficult. You words say you are going to double the front beam. You drawing shows a single front beam and a double center beam. Single front beam should be more than adequate and a double does not enhance appearance. Same thing for center beam. Front elevation appears to have post and miter at center beam. Top view has miter joint half way between front post and center post. With joist on 36' centers screen will probably sag considerably. Do you have any snow load? Any snow or ice will probably destroy screen.
Its hard to see in the full photo but note the 2x4 perpendicular to the 2 x 8 joist to provide sun screening. 8x8 post.
I tried to draw a sketch and attach it but needed to edit the file size or something. Your sketch is good, but instead of notching the 6x6 post for the headers, I would use a 2x4 nailed to the post as a trimmer. That makes a 1" x 1 1/2" reveal at every corner. The post is now 5 1/2 x 8 1/2 giving an effect of mass. Most importantly, the reason I have done this on many patio covers is that the 5 1/2' void between the headers is an ideal place to conceal a roll up shade. I generally drill the headers and use 2 - 1/2 x 9" bolts. I let the post stick above the header 3-6" and chamfer the top. The bolts keep the 2x headers from ever twisting. The bolts would even carry the load, but using the trimmer, it's easier to hold the header in place while drilling. If you use a post base. Just set the post and add the 2x4 after.
Harold, thanks for the input. my apolgies for the misleading drawing, thanks for pointing out my mistakes
the 2x4's is a good idea; I was planning to take the screen down for the winter to let the snow through
good catch on the mitered corner; I was thinking of doing it like your version, with the post at the miter; the pic I showed is wrong. I was planning to have the center beam underneath, but if I only need a single 2x center beam, I could still run the post up just like the front. Perhaps I could set the post just off the corner so I do not have to do a complex notch?
regarding the front beam, you say a single 2x is sufficient? That is good news. It seems most of the info I have found on the web says two 2x's is required.
I think I get the idea with the header; it sandwiches the post, but is supported by cleat.
I think I misused my terms; my main concern is the beam for the deck, which is more critical for me at the moment. I'm doing the deck first, but build it so I can add pergola soon after.
OK on the deck. We used to use a 2x6 floor joist @ 16" spacing over 4x6 girders 8' on center with pier post 8' apart. This carried floor load of a house. Back when they built everything on sub-floor rather than slabs. Why not use the same method at the front of the deck as I described for the patio roof, sandwiching the post with 2 - 2x8 headers ? you can add strength by usind a solid block between them at midpoint of the posts if you want. 2- 2x members are stronger than a single 4x beam because of the variance of the grains. This is overkill, but you said something about snow. For the center beam under the floor, I think a 4x8 supported as your sketch shows would be plenty. Again, good luck with it.
As an afterthought, If you do use 6x6 posts at the front, you could splice them right at the deck line. Leave the lower post 1 1/2 " below the top of the 2x8 header. The header would hold the base of the upper post in place using screws or nails.
applying house subfloor construction to deck sounds very much like what I am finding for the strongest deck construction.
Regarding the front of the deck, if I understand correctly, you suggest sandwiching the post with 2x, then supporting the 2x with cleats, is this correct? I thought about doing something along those lines, but running the clean all the way to the concrete, effectively making the 6x6 into 9x9 below the deck.
I'm trying to run a continuous post from the ground through the deck to the cover, thinking it would be much stronger that way with a minimal amount of wood.
after reviewing the responses and info on the Web, I have concluded that I am out of my league a bit with the angled deck, and am going back to making a rectangle with square corners.
I realize one could use a cantilever to do the angle, but having done a small cantilever on the other side of the house, it does not look right. It hangs out over a slope, and I think posts on the corners would look better.
I like the look of the angle, but unless I am convinced of a clever way to make the 45's, its beyond me at the moment.
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