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05-31-2011, 09:33 AM   #1
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## load bearing for flat roof

Hi there,
Can anyone help me out with some calculations for how many 4 x 4 wooden posts I'll need to safely carry the weight of the flat roof over our Florida room?

As the attached picture shows, we currently have a very unsightly wall across our Florida room that seems to have been added on after the house was built. We'd like to open ip up again to create a covered patio that makes more sense of the area.

I'm trying to figure out how many posts I should put in place to adequately bear the weight of the flat roof once I take out the wall. Excluding the ends, I thought three should be enough.

I've torn away some of the dry wall on the inside, and there's a beam, about 3 1/2" by 6", in place running across the 22' length of the room. I assume that the ends are set on top of the brick structure of the house, though I'll know for sure when i tear all the drywall away. The roof, by the way, is made up of 2" x 6" beams running out from the house - I know that the ends coming from the house's structure are set on top of the walls, because I saw them when i was replacing some drywall inside the house.

Lastly, can I assume that the concrete floor in the room must have adequate footings along the edge where the wall was put in place, assuming that there must be some load bearing aspect to the structure? I'll drill with a concrete bit to be sure, and put in adequate footings for the post mounts if necessary.

PS - Excuse the mess in the picture. The are has become my dumping ground while I complete work inside the house!
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05-31-2011, 05:24 PM   #2
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I don't understand what you want to do. You want to enclose the room with the windows and doors with a flat roof? So, you want to remove the current roof that is pitched a create a flat roof there?
Or,
You want to put a flat roof in front of the wall with the door and two windows? Would it go over the pool at all? If not, this looks like it would be about a 4' flat roof that extends the width of the picture?

 05-31-2011, 05:29 PM #3 Framing Contractor   Join Date: Feb 2009 Location: NE Ohio Posts: 1,207 Rewards Points: 112 I think he just wants to remove that wall, and install 3 or 4 posts instead. Open porch versus closed.

 05-31-2011, 09:20 PM #4 Member   Join Date: Mar 2010 Posts: 137 Rewards Points: 101 As the last guy said, all I want to do is remove the wall you can see in the picture and replace it with enough posts to adequately hold up the flat roof - I simply need to know how many I should put in place.
 05-31-2011, 09:26 PM #5 Framing Contractor   Join Date: Feb 2009 Location: NE Ohio Posts: 1,207 Rewards Points: 112 The first thing you need to do is verify that there is a footer under that wall. After that, if you post enough info, someone may do the calcs for u.
 06-01-2011, 03:24 AM #6 Member   Join Date: Dec 2008 Location: Fairbanks, AK Posts: 1,893 Rewards Points: 1,092 I think you may be oversimplifying this. What kind of beam are you using over the posts and under the roof? Maybe I missed that. There is a strong chance you are either going to have a ton of posts, or lose a lot of head room for the beam. You now have "posts" every 16" or so, so unless you want 4x4's 16" OC, you'll need a beam. You likely have a footer there already, as that is a load bearing wall, so that should not be an issue. How are you going to stop water from creeping back up the present roof when it suddenly goes flat? That will take some figuring. Maybe you already have all this figgered out????
 06-01-2011, 08:21 AM #7 Member   Join Date: Mar 2007 Location: Long Island, NY Posts: 11,188 Rewards Points: 5,336 You can't answer the question with the stated information. The current load bearing beam is doubtfully one continuous beam, so you would need to replace that or put supports under all the butt joints. If the entire wall was removed and there were no vertical framing members, you might need to increase the size of the beam to compensate for the loss of structure, or add more 4x4 posts. Ron
 06-01-2011, 08:44 PM #8 Member   Join Date: Mar 2010 Posts: 137 Rewards Points: 101 Okay, just to backtrack to some points I made in the first post. 1) I'm pretty certain that room in question was open to start with, and that it was enclosed later. 2) As mentioned, there is a beam already in place running the length of the roof above the wall I want to remove - the wall was built underneath it. That's one of the reasons I stated that I thought it was open to start with. A normal wall would have been built up to the roof - not have a beam added to it. The beam is 3.5" x 6" (it may be 8", I can't be sure till I take a peak through the ceiling.) My best guess is that the beam originally had posts supporting it, and that they were taken out and replaced by the wall. Now I want to reverse the process. 3) I mentioned earlier that I believe a footer would have to be in place to support the wall, but that I would check and correct if necessary when placing the posts. 4) As for changing the pitch of a flat roof, I have no idea what you mean. It's obviously not dead flat, otherwise our Florida rains would drown us out during the summer. It's subtle, but the roof does angle down towards the pool deck. We just had a roofer lay a new surface on it recently as a matter of fact. 5) I don't have an issue having to reinforce the existing support beam, though I don't think it should be necessary. I intend to put a one foot lip, or section, under the roof along where the wall used to be, for the purposes of putting a curtain rail in place. That one foot section, though cosmetic, should be more than enough to allow for further reinforcing to be placed inside if necessary.
06-02-2011, 02:36 AM   #9
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OK. Much clearer now.

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