Repair stilt home post.

Discussion in 'Framing and Foundation' started by Zook, Jan 6, 2014.

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  1. Jan 6, 2014 #1

    Zook

    Zook

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    Hello! I hope that I can get some feed back on the way I am looking to repair an 8x8 post that supports the house.

    This is a home that sits on cedar posts about 8' above the ground. One post has a lot of rot on the top and I am going to have to replace it. This is made more difficult because the house is located on an island so everything will need to be done with hand tools.

    I am thinking about going about 2' underground and cutting the current post off. I will then notch the new post and what is left of the old post and then bolt them together. I will then pour concrete around them up to ground level.

    Any suggestions are welcome.

    Thanks
     
  2. Jan 6, 2014 #2

    nealtw

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    Welcome to the site, Just a few questions. Do you have a plan for holding the house up while you work on it? Depending on where you are you will need the bottom of the concrete to be below frost depth, do you know what that depth is for the area?
    Is the old post set in concrete? Are the old posts treated wood? If it is rotted at the top, has rot got to the beams that are sitting on it.
     
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  3. Jan 6, 2014 #3

    Zook

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    The post is cedar and the beams on it also need to be replaced. I will be jacking up the house and supporting it with several 4x4's on each side while I make the repair. The house is located in Florida so I don't have a freeze problem.

    The old post is not in concrete.
     
  4. Jan 6, 2014 #4

    nealtw

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    I beleive some parts of Florida do have min. depth. Likely not mor than 2 ft but I would want to remove all the old post below ground level as the condition while be questionable at best and the surronding fill has been dug up before and a few inches of gravel on top of undesturbed soil would be best to set new post on, I would go with treated post rated for in ground use. Jacking the house can make it unstable so angle braces between other posts is a good idea and add angle braces to your temp supports as soon as you get the height you need
     
  5. Jan 7, 2014 #5

    Zook

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    Thanks Neal for your response. I wanted to replace the entire post because I thought it would be easier but now I don't think so. The house was built in 1982 so most of it is in decent shape. The post is in excellent shape other than the rotten top. I have checked down to 5' below the ground and the post still continues down.

    Since I can not get anything to the house to dig it out I am concerned about trying to dig by hand what I am guessing would be an 8 - 12' deep hole. I also believe that by 5' down I am going to be into water.

    So any other suggestions?

    Thanks
     
  6. Jan 7, 2014 #6

    nealtw

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    Then I would go below ground level of the joint. Leave it up where you can inspect it over time. They have put this deep so that it holds the house up straight so I would think the lower the joint the weaker the post. I would put the loint as close to top as you can and still bolt on some steel straps. Galvinized steel and bolts maybe 18- 24 inches from the top.
    That's just me, an engineer may not agree.
     
  7. Jan 8, 2014 #7

    GBR

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  8. Jan 8, 2014 #8

    nealtw

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    Gary; There are reasons why a lap joint may not be the best
    House on island implys possible high winds, moisture fungus and more. Florida, evan more!
    These posts were planted deep for a reason, anything that weakens one weakens the whole house, they also have to take a bend factor. Any cut you put in the wood will weaken it the best you could get is to have a radius cut on the 90 degree cut of the lap joint. Then you have to figure the length of the lap joint to regain the bend factor strength and with direction you put the lap. Any bending stress will put pressure on the above and below the joint.
    Unless they were really pick when they bought these posts, we can assume there is heart wood in the center, heart wood is much more susseptable to fungus evan with a perfect joint moisture will have another entry point.
    The bearing of the post itself now has 64 square inches, with a lap joint you get 2 x 32 inches maybe, only if you made perfect cuts more likely somewhere in between.
    With some damage in the future that we could expect with both. A butt joint will requir inches to be removed while a lap joint will require ft to be removed.
    I will argue for a butt joint with 4 x3' steel straps and 3/4 bolts, 2 above and 2 below.
     
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  9. Jan 8, 2014 #9

    GBR

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    I've seen many joints like this in old buildings, never any as you describe, must be a local thing; "Fig. 220.—Lapped Scarf Joint with Bolts for Heavy Timber. is an example of a lapped scarf joint which is secured with nuts and bolts. It effectively resists compressional stress in vertical posts and it may, if required, be strengthened by the addition of wrought iron fish plates. It is quite a serviceable joint for all general purposes, such as shed or garage building where fairly heavy timbers are used." From; http://sawdustmaking.com/woodjoints/scarf.htm

    Ask A SE. to be safe. And with cedar, cover the top to prevent end grain moisture. Check for a water source, unless environment.... Changing out the top 3' in a 16' post will not get much "bend factor" but it is your forum, I digress.

    Gary
     
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  10. Jan 8, 2014 #10

    nealtw

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    Your link shows joints for beams and joists the sample 219 has straps around it to protect against stress that would split the beam on the cut line. I can't find anything on joining posts and an engineer would be a good idea.
     
  11. Jan 8, 2014 #11

    Zook

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    Thank you guys for your input!

    Now that I have a few different ideas I will talk to a SE and I will go from there.

    Thanks
     
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  12. Jan 8, 2014 #12

    bud16415

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    The posts are actually pilings and most likely driven to refusal. The correct course of action is to get with a pro on this. Along the coasts there are many companies set up to do just this and they build docks with similar methods in the water. Many are done from water crafts even. They make these repairs from rot and insect damage all the time and many times at the water line. The experts will know the best repair method they sometimes surround the damaged area with a metal boot and inject a stronger than original substance in to make a repair.

    Ask around in your area that does docks and see if you can’t get a lead. I personally don’t see this as a DIY project. Local code will most likely also come into play. Stuff we never much see up north.
     
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  13. Jan 12, 2014 #13

    GBR

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    Have someone read my Post #9 to you..... while you are looking at that page, link.

    gary
     
  14. Jan 14, 2014 #14

    nealtw

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    I have since found samples in timber framing of post repairs like you suggested but they are always inside a barn or such. I would still voice my concerns to an engineer that suggested it, but he would be the guy that garrentees it, I think we agree on that much.
     
  15. Jan 16, 2014 #15

    GBR

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    "It is quite a serviceable joint for all general purposes, such as shed or garage building where fairly heavy timbers are used.""------------ from post #9. All about liability- use an SE or local AHJ.

    Gary
     
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  16. Mar 7, 2014 #16

    Zook

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    Ok, here was the recommendation from my SE. Cut the post past the rotten wood and then use a Simpson BC8 connector to attach a new top. This works since the top is connected to beams. He said that the lap joint would be fine but that this is an easier fix.
     
  17. Mar 7, 2014 #17

    nealtw

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    Thanks for the update, have you done the work yet?
     

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