how to support this post to remove saddle

[havabeer69]

Hi everyone,

I'm looking to replace a deck and concrete slab below. but I have a problem, there is a post that needs to remain while the new slab is poured as its holding up a corner of the roof.


this is how the deck was (please ignore all my kids crap). I'm going to replace the deck and at the same time I wanted the old slab removed and a new slab poured. this slab (in blue) is to wrap around the rest of the house.

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I've since removed the deck, I've also added some temporary bracing to the existing pole just to stop any bow or flex as its no longer being supported horizontally by the deck bearers. its 90 x 90 post approx. 6m long supporting 3 trusses above. the roof is only colour bond not tiles.

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my original hope was that the saddle was poured in its own footing while the first floor etc was built and then later on the 100mm slab was poured around them. This would mean we could cut up the slab leaving the saddle, post and footing as is, do the rest of the excavation work around the bracing and just pour the new slab. I could then come back later, support the post properly off the new concrete, cut the saddle and replace the lot with something most substantial.

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I've started to try and dig down but I can't really seem to find the footing so I might be back to square one.

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So does anyone have and suggestions for supporting the post so I can either cut it or at the very least come back later and just die grind out the saddle and do a 30mm patch in the concrete where the hole was? My only real thought is so just beef up the current angled bracing from a 90x35 to a much beefier LVL beam for the downward load just a bit concerned about it twisting or rolling.

[r3nov8or]

My first thought is that if there's no decent footing for the stirrup, and over the years there's no cracking in the slab, that it's either a very well made/super high strength slab, or it's not actually holding up much. I imagine you've been in the roof and there is no chance of any large or steel members provdiing the cantilever for the roof? And the stirrup definitely doesn't go through the slab to a deeper footing?

Anyway, your idea of a bigger diagonal member from the house to outside the slab area to take the weight seems like a good one, and to help stiffen it you could either do a horizonal beam across from the house like the front of a new deck, or another diagonal from the post midpoint to the boundary on the right.

As a precaution, only take away the stirrup and the bottom of the post, just enough to concrete under it, so if an emergency happens you are working with it at ground level.

[ErrolFlynn]

Consider a couple of acrow props positioned off the concrete you’re going to remove. Locate them out of the way and use them to support the roof. Possibly with a beam of some kind placed between them.

I did something similar when I had to replace a rotting decking post. In my case, one prop supported the upper deck and a second prop supported the roof adjacent to where the old post was located. I bought some SHS to form an extension to one of the props so that it would reach the roof. Plates were welded to the extension so that it could be bolted to the prop. In my case, the props rested on concrete and were bolted to the deck (and roof), for safety. Not sure how it would work placing them on the lawn. You may need to make a decent base for them.

All a bit awkward now that you’ve removed the deck. If you want to do something similar seems like some scaffolding or a cherry picker may be required.

[havabeer69]

My first thought is that if there's no decent footing for the stirrup, and over the years there's no cracking in the slab, that it's either a very well made/super high strength slab, or it's not actually holding up much. I imagine you've been in the roof and there is no chance of any large or steel members provdiing the cantilever for the roof? And the stirrup definitely doesn't go through the slab to a deeper footing?

Anyway, your idea of a bigger diagonal member from the house to outside the slab area to take the weight seems like a good one, and to help stiffen it you could either do a horizonal beam across from the house like the front of a new deck, or another diagonal from the post midpoint to the boundary on the right.

As a precaution, only take away the stirrup and the bottom of the post, just enough to concrete under it, so if an emergency happens you are working with it at ground level.

no not that lucky up in the roof. there's just a ledger board that is resting/nailed on the house frame and the other end on post. on that board is the 3 trusses for the old deck roof


I'll keep digging and see if I can't find whats under the slab (if anything) the house was built in 1997, so its old but not THAT old.

[ErrolFlynn]

Another idea: Given that side of the house has a gable end I wonder if there’s anything solid in the roof for a prop to hook onto.

You might check in the roof. If you can support the same truss/structure that the existing post is supporting, with a prop at the side, where I’ve indicated with the arrow, you might be able to remove the concrete safely.

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[jack620]

Consider also with a tin roof that the post is not only holding the roof up, it's also holding it DOWN in high winds. Acrows will support the weight, but they won't provide any tie-down. I'd be surprised if the stirrup wasn't embedded in a footing for that reason. I can't see how you would build the house without the stirrup pre-positioned in a footing.

[ErrolFlynn]

Consider also with a tin roof that the post is not only holding the roof up, it's also holding it DOWN in high winds. Acrows will support the weight, but they won't provide any tie-down. I'd be surprised if the stirrup wasn't embedded in a footing for that reason. I can't see how you would build the house without the stirrup pre-positioned in a footing.

Excellent points, Jack.

Though, I'm no longer surprised by what people will do if they can get away with it. I was doing some work on a deck. New posts went in. And I gave them decent footing, but as part of the clean up, I removed the old.

I cut the stirrup. I'm chipping away at what I thought was the footing (it was raised above the concrete footpath by about 50 mm). Then I spotted a strange depression. I get the stirrup out to show a hole in the footpath directly underneath the stirrup. See how the hole is square. It's reasonable to assume a post used to be in there. It had rotted and was replaced. So, rather than cutting the concrete and digging a hole to secure it properly, the stirrup was set resting on the footpath (over the hole) and a glob of concrete was dumped on top.

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[havabeer69]

Yep, up lift is also a big one, and while no great storms are predicted in the next couple of weeks Murphy's law states that a tropical cyclone will rip through.


Ive done some more excavation and found the saddle does have a footing deeper then the slab. So my be able to go back to my orginal plan of cutting up original slab
Break away slab around saddle leaving most of the footing
Leave bracing
Pour new slab around exisiting saddle.
Let everything cure
Install new deck
Attach post to new deck
Cut off saddle
Die grind out left over saddle as much as possible
Patch with concrete
Paint and hope no one notices it

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I think my last ditch effort will be to take the roof sheet off inside the house, cut off and reinstall a new beam and support it out side in a screw down stirrup till the concrete is done

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[ErrolFlynn]

You might be able to bolt the horizontal piece to this (remaining bit of a joist) rather than extend it inside the house:

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[r3nov8or]

Good to hear there was a footing further underground

[havabeer69]

Did some re-jigging today.

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We ended up adding another 190mm going upwards basically forming a triangle braced against the house. With some backing against the post so its all locked together.

Also moved the side bracing to one of the old beams.

Seemed very solid so we cut the beam at the base and it didnt even try and pinch the blade on the recipro or close the gap left by it, so i dont think theres much "down force" so assuming the triangle will also help with the up force of any wind.

Rather then tempting fate have screwed it back together till we need it out of the way.

[r3nov8or]

Triangles are the best