I am going to build an 8x8 porch roof with two 4x4 posts as the support, with single 2x8 beams for the front and sides.

Would it be a good idea to notch the 4x4 posts at the top to support the two intersecting 2x8s?

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  • It is unclear what you mean by "intersecting 2x8s" Please provide a very detailed description of your plan. A sketch might be helpful. Typically 4x4 posts support a beam and the joists sit on top of the beam. – Alaska Man Nov 21 '18 at 1:35
  • Maybe the picture will help. – Scott McCartney Nov 21 '18 at 2:47
  • What size porch? – Kris Nov 21 '18 at 13:16
  • The porch size is an 8ft x 8ft. I’m for using on the roof of the porch. Not going to start the deck. – Scott McCartney Nov 21 '18 at 13:44
  • My thought would be it wouldn't change the load-bearing capacity of the beams, but being able to secure the beams into the side of the posts in that way would provide additional rigidity. – Phaelax z Aug 21 '19 at 15:33

I understand you drawing. It is not using single point projection, as many of us learnd in drafting. It is OK! IMHO (in my humble opinion) I would not use a 4x4 to sit a front & side rail 2x8 on top of, with no notch (not great) or a notch (worse). If this is for a porch, correct? You are going from a burried concrete pier, or a precast concrete pier, going up 1-3 feet? I would use no less than a 6x6 or 8x8 with no notch. Go to the top of the 2x8's and use at least 3 - 5/8" diameter bolts. No counter sinking either, but use carriage bolts. They have the button top, with a square shank, then the bol. Get bolts 1" longer than you need, only drill to the bolt size. That will require a spade bit with an extension. Using a 3/8 to 1/2" chuck drill. Notching a 4x4 only gives you 2x4 + 2x2 to hang your joists on. With a 2x2 vertical support. I'm a MORE is never wrong, kind of builder. I've been at for 50 years.

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  • Would I be able to run carriage bolts through the 4x4 and be able to support the the gables? This will be for the top of the 4x4 at 8 feet? If that makes sense. – Scott McCartney Nov 21 '18 at 13:42
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    More is often wrong when it comes to absurd waste. 4x4 is plenty big, and no, you can't hang on carriage bolts alone, at least in my area. You need substantial direct bearing. – isherwood Nov 21 '18 at 20:02
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    To clarify, we're talking about a roof here. If the same posts are intended to carry the deck itself, I'd agree that they're probably too small. That's not the question, though. – isherwood Nov 21 '18 at 20:09

Your plan seems fine. 4x4s are plenty stout for a porch of that size, barring any extraordinary roof arrangement.

Whether you notch the post is up to you. If you have the tools and skill to do so, it makes for a nice way to anchor the beams. If not, use some sort of builder's hardware, or dowels, or simply screws set in at an angle, to keep the beams in position. If you're in an earthquake zone you'll want to follow locally applicable ordinances.

Either way is fine, as long as the posts can't be knocked out of position with any impact to be reasonably expected.

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