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Creating Support for roof while repairing joists under wall.

Creating Support for roof while repairing joists under wall.

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  #1  
Old 12-16-14, 11:57 AM
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Creating Support for roof while repairing joists under wall.

I'm not sure if this is the correct location for this question, but here it goes. I've got a house from the teens or twenties and the front porch, which runs from one side of the house to the other, is closed in entirely. The roof covers the entire house and porch. I've got to replace the rotten floor joist on the front exterior wall. This is the wall that has been added to the porch. Looking in the crawl space, the porch subfloor is attached to the main beams of the house, but not part of the main structure.... in other words it's only attached with nails. I feel the porch can be lifted without interfering with the structure of the house.. only lifting the room. Of course, it will and could effect the entire roof. My plan is to dig out from under the house for cement piers and install a 30 foot cedar beam (4x8) under the wall. Then lift with jacks. My main concern is supporting the roof / wall while digging out from underneath it. My thoughts are to support the eave of the house with boards... probably 2x4s screwed together or 2x6, starting with a 2x 6 along the underside of eave and possibly a 2x6 on the ground with the supports between the two. I'm wondering if this will support the roof so that the work can be done below. In a couple of places there is no joist any longer... one corner of the house needs to come up approximately 5" and the other corner approximately 1" or 2". Also, what are the chances of the roof decking buckling? I hope this is clear to whom ever will read it and give me their opinion / advice. Thanks so much.
 
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  #2  
Old 12-16-14, 12:32 PM
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If I understand correctly it sounds like your roof support idea will work. I generally use 4x4 to the ground but 2x4's or 2x6 nailed or screwed together can do the same thing. If it's enough support depends on how many temporary posts you install. More of them and they can be smaller and fewer will need to be heavier and possibly require some type of beam across the top to support the roof rafters.

If it's just a roof and you work relatively fast and don't let the project drag out for months you can get by with surprisingly little support. Really though you have to look at what you've got as houses of that age can be constructed any number of ways. There were no building codes so how well it was built depended on the builder.

Will the roof deck buckle? Probably not. It's a flat surface so it can accommodate a fair bit of twisting without buckling.
 
  #3  
Old 12-16-14, 07:28 PM
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Hey Pilot... Thanks so much for taking the time to respond. I've literally sat and studied it over and over, always feeling like I needed to support the wall itself. The more I read and the more I studied it, I realized supporting the roof might work as well. Therefore, holding up the wall while I worked underneath. After studying the roof from the attic, it appears all the roof joist extend out to the eave. This is what gave me the idea of holding it at those points.

For a 27 foot span across the front of the building, do you think four cement piers underneath would be sufficient? Also, what are your thoughts on using the 4 x 8 cedar beam across the front? Would one long beam raise the building appropriately? Also, your thoughts on how many jacks I might need? I'm not looking for a life long fix. I'm just looking to raise the porch area and possibly get another 15-20 years out of it. Thanks again for taking the time to respond, it's greatly appreciated.
 
  #4  
Old 12-17-14, 04:51 AM
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Around here pressure treated lumber is required for anything that touches masonry. Cedar is not permitted as a replacement for treated.

Your four cement piers. Are they temporary to support the roof during the repairs or are they your new footings for your porch, walls and roof?

As for what wood to span a distance you can find span tables online. Cedar is not used around here structurally so I have no idea how it would rate for a beam.
 
  #5  
Old 12-17-14, 08:08 AM
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Thanks again Pilot for taking the time to respond. The cement piers I'm speaking of would be permanent ones.... also planned to jack up beam from them. I probably should use treated 2x8s for my beam instead of the cedar. Thanks again for your replies. Richard
 
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