porch/sunroom needs support

Old 07-09-08, 08:15 PM
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Question porch/sunroom needs support

Ok all. Need some help on this one. Pic'd below is the "3 season porch" (or whatever you want to call it). It is even with the main floor of the home; about 4 1/2 ft off the ground, and is roughly 12x14 ft in size. Currently there are only 3 4x4s holding this baby up.



We knew when we bought the house last summer this would be an area that needs work. Turns out over winter the drywall got some cracks in it. Which tells me it was shifting over the freeze/thaw (we live in SE MN). I have already removed the 12x12 deck that was attached to it which I think was contributing to the problems. The deck joists were fastened into the porch (not the house) which was not properly supported either and then add the snow load on top of that -- not a good situation. As you can see in the picture, previous owners added an additional steel jobber you commonly see in the basement so quite obviously there was sagging happening before.

STRUCTURALLY, this is my "plan" to fix it. Tell me where I'm goin' wrong here. Come back 18" from the edge of the porch and drop at least 3 (maybe 4) treated 4x6s sandwiched between 2 treated 2x10s to run the entire 14' length underneath the floor joists (which are also 2x10s, 12" O.C.) making sure it is level. Would need about five feet footing to get down to/below the frost line. WOULD IT BE BETTER TO SET THE 4xs IN CONCRETE OR ANCHOR THEM TO CONCRETE? HOW "BIG" SHOULD THE FOOTING BE? IS THIS ADEQUATE SUPPORT?

Once I have this sured up, I will add the deck back on, this time tying into the house instead of the "porch", beef up the insulation underneath the porch, and so on.
Old 07-10-08, 02:07 PM
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You should definitely beef up the vertical support, as the 4x4's are woefully undersized. I would opt for 6x6 vertical support, and if you want, a beam across the width, even better. Be sure to bolt this thing to your house using 6' x 1/2" carriage bolts and washers. Footings will be dictated in size and depth by your local inspection department, so get really friendly with them, and heed their sage advice.

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