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Fixing front porch and roof overhang

 
 
MEC
 
Reply Sat 7 Feb, 2009 11:11 am
My overhang is starting to sag on one side (due to concrete porch settling). I would like to take out the concrete porch and replace it with a wood deck. I need to know how to fix the overhang first though. Can I just prop it up as I jack-hammer the concrete away? Would this degrade any structural support? I would greatly appreciate any advice I could get! TY. Here are a couple of pics.
http://i355.photobucket.com/albums/r461/noznightowl/Home%20Repair/IMG_1182.jpg
http://i355.photobucket.com/albums/r461/noznightowl/Home%20Repair/IMG_1184.jpg
http://i355.photobucket.com/albums/r461/noznightowl/Home%20Repair/IMG_1183.jpg
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Type: Question • Score: 4 • Views: 17,890 • Replies: 25
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View best answer, chosen by MEC
Foxfyre
 
  1  
Reply Sat 7 Feb, 2009 11:30 am
Way out of my department MEC, but I'll bump this to keep it up until one of our construction experts can address it.
MEC
 
  1  
Reply Sat 7 Feb, 2009 12:25 pm
@Foxfyre,
TY Foxfyre!
0 Replies
 
parados
 
  1  
Reply Sat 7 Feb, 2009 12:59 pm
@MEC,
Can I just prop it up as I jack-hammer the concrete away? Yes, if done properly

Would this degrade any structural support? Not if done properly.

The problem isn't so much supporting it while you are working on it but putting in new supports that won't cause the same problem. Concrete footings are probably required. Local building codes are the first thing to check. Call a building inspector and explain what is happening and ask about codes for replacement.
jespah
 
  1  
Reply Sat 7 Feb, 2009 03:46 pm
@parados,
I wonder if there's anything settling underneath.
MEC
 
  1  
Reply Sun 8 Feb, 2009 08:45 am
@parados,
Yes, my thoughts exactly! So you think I can support both sides of the overhang while I remove the concrete porch (as well as constructing the wood deck) ? I think I will need something longer than a 12' 2x4. Maybe nail two together and use those on each side? Two supports for each side, coming out far enough so that I have plenty of room to work on removal and construction. Do you think two points on each side will be enough? Three maybe?
Thanks parados! I will call the building inspector tomorrow and see what kind of codes I need to adhere too.
MEC
 
  1  
Reply Sun 8 Feb, 2009 08:49 am
@jespah,
Yes jespah, something is settling underneath causing the overhang to sag. Is there something I can install there that has an adjustment to compensate for, if and when it continues to happen? Ya know like they do in basements with those adjustable supports.
jespah
 
  1  
Reply Sun 8 Feb, 2009 09:19 am
@MEC,
I'm totally out of my depth but I wonder if you need to do some sort of serious excavation. Where you live, is it sandy? Clay-ey? High water table? Hmm.
parados
  Selected Answer
 
  2  
Reply Sun 8 Feb, 2009 10:43 am
@MEC,
You are asking for engineering advice that could well be taken out of context by your or others reading this later. That makes it difficult to answer.

The present supports are considered enough to hold the overhang. Replacing them with something similar on a temporary basis will probably work.

There are presently 3 columns holding up the roof that look like 4x4s. Based on the pictures, you are in a region where snow load is considered. Assuming there is a beam that goes from column to column or at least a trussed rafter, you can probably remove the middle column for a short period of time without failure if you put no extra load on the roof. You might get some sag over the length and that could possibly stress the roof and cause problems. Without knowing the construction and the loads, I wouldn't suggest it.

Because you want a clear area under the overhang you need to replace the posts with a support that goes outside the porch area. The simplest way to do that is a beam that spans the porch with posts holding up each end. Simple to put up if you know what you are doing. Not so simple to calculate the required strength and sizes from photographs. Your beam has to be strong enough to hold the load and not sag or flex. The posts have to be securely anchored and strong enough to support the beam. Do any of it wrong and the roof could fall on you while jackhammering concrete risking injury and death.

A contractor might come in with a steel i-beam and screw jack supports for each end. This would allow them to raise the roof enough to remove the wooden columns. Removing the existing columns also needs to be considered in how you support the roof. Your temporary support has to allow for removal of the existing supports.

I would never use 2x4 for making a beam to hold anything up. When making a beam any 2x should probably be doubled up to make a 4x. Always use the strength of the wood wherever possible. Don't rely on nails or screws for vertical support unless you understand the technique. It's always better and safer to over engineer for strength.

Know what the weakest point is. That is what will fail if something does fail. It doesn't do any good to use 2 2x12's for a beam and then only use a couple of nails to attach them to the side of a 4x6 column.

A general rule for temporary supports is if you use similar materials and construction as the permanent support you will be strong enough. Just make sure it is all solidly tied in.
MEC
 
  1  
Reply Sun 8 Feb, 2009 07:29 pm
@jespah,
Thanks jespah,
Not sure whay lies beneath. I'm at 6600 ft. alt. Get alot of snow. This porch was constructed years ago and is covering a basement window. Will check with the local building inspector tomorrow to find out what all I need to do for solid support. I might not know what is under the porch until I get rid of all that concrete.
0 Replies
 
ossobuco
 
  1  
Reply Sun 8 Feb, 2009 07:56 pm
@parados,
Parados and MEC.

I try not to get into this stuff online.

That roof seems to me to be resting on toothpicks (4x's), perhaps on sand, with absolutely no effort to compensate for shear. Makes me grimace.

Please contact the city or county. They may have details for you to follow. That should save you some grief in the long run.
MEC
 
  1  
Reply Sun 8 Feb, 2009 08:02 pm
@parados,
Thanks parados!!!
This is exactly the kind of info I was hoping to find here. I understand and agree with the type of support you have just advised me of.
After reading this I believe I will purchase the material (4x6; 4x4 etc.) for my temporary support. Maybe leave the 4x6 beam(2-2x6 nailed together ok?) up for support permanently and attach my new colums to it, then do the wood deck around the colums. I'm not sure of what kind of beam is in place now. I was planing to keep the colums 4x4's.
How would I find out the equation of the load I need to bear that will instruct me on how big my beam should be? What would be overkill?
I don't know that I will be able to afford an I-beam or if I really need that kind of strength. I will call the building inspector in the morning and find out any and everything I can.
Your information is greatly appreciated parados!
Thank you again
MEC
 
  1  
Reply Sun 8 Feb, 2009 08:05 pm
@ossobuco,
Thanks ossobuco,
I was thinking of going bigger than a 4x4 but having a 12" pillar would look like crap. House isn't that kind of style.
Recomendations?
ossobuco
 
  1  
Reply Sun 8 Feb, 2009 08:07 pm
@ossobuco,
Reply to self, that "roof" also is lame, as parados mentioned, re a serious beam, as in, what??






ossobuco
 
  1  
Reply Sun 8 Feb, 2009 08:10 pm
@MEC,
Oh, stop it and talk to the city. (I know well about spans.)
ossobuco
 
  1  
Reply Sun 8 Feb, 2009 08:12 pm
@MEC,
You don't need an I beam, you need the right wood and bracing, assuming wood doesn't get gnawed in your area and given you have a secure foundation. Please look at city or county details. At least in LA, they pretty much work it out for you.
MEC
 
  1  
Reply Sun 8 Feb, 2009 08:13 pm
@ossobuco,
Will do ossobuco, first thing in the morning.
0 Replies
 
MEC
 
  1  
Reply Sun 8 Feb, 2009 08:14 pm
@ossobuco,
Great, I hope they work it out for me here too!
0 Replies
 
MEC
 
  1  
Reply Sun 8 Feb, 2009 08:18 pm
@ossobuco,
Speaking of roof. This is to be replaced this summer as well. Was planning on taking all the layers of shingles off, down to the ply-wood. Does it look to you that the ply-wood needs to be replaced?
0 Replies
 
ossobuco
 
  2  
Reply Sun 8 Feb, 2009 08:18 pm
@ossobuco,
My background is in designing overheads in earthquake country - Los Angeles.
I'm not interested in designing online -

but I would suggest looking at what Sunset magazine has to say. (We were sort of prominent there for x amount of years.. though retired now - but many knowledgeable folks had small or large articles at Sunset.)
 

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