# Forum Home Renovation Concreting  dynabolting new concrete.

## nww1969

Anyone have any idea how long I should leave newly laid concrete before dynabolting.
The concreting  is a home job to the strength recommendations on the bag so will not
have the strength like bought stuff from the truck.

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## Bloss

Will be at >90% of its strength after a week - so that's the minimum I'd use. If the dynabolts/ ankascrews are near an edge (should be no closer than 50mm anyway) then take extra care - break the edge off and you an't fix it.

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## nww1969

> Will be at >90% of its strength after a week - so that's the minimum I'd use. If the dynabolts/ ankascrews are near an edge (should be no closer than 50mm anyway) then take extra care - break the edge off and you an't fix it.

  
Thanks Bloss. 
That's interesting info to know     "Will be at >90% of its strength after a week" 
Thanks again.

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## woodhunt

I'd also be thinking of using very long bolts that expand at the base or below the slab so a majority of force is bolting the frame to the slab, not pushing sideways as a dynabolt would. 
I keep thinking of some type of hook bolt that would bring a bit of the applied base force inward from the edge, but unless there was a spring loaded wall anchor type, you'd have to access under the slab to insert the bolt. 
I'm in the position of building my frame on a 100m reo slab and you've just made me think very carefully about how I bolt it down....

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## Master Splinter

Or you could use epoxy anchors.  No cracking pressure on the concrete during installation, and they'll hold as well as mechanical anchors.

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## NigeC

chemset and all thread (all thread is threaded bar and comes in 1 metre lengths) cut to what ever length you like. I think 100mm long all threads should be fine for home job. 
Cut the bottom end of the all thread on a 45 degree angle. fill the hole up with chemset, push the all thread in ( chemset should come out of the hole). twist the all thread about 10 degrees and let set over night. the all thread sticking out of the ground should be enough for a washer and nut plus about 3 threads sticking out over the top.
1 week for concrete to set sounds about right too.

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## Bloss

Yep the chemset types are a good choice if near edges especially. If the concrete is ;green' then the drilling can be the problem and you can get a breakaway, but the use of holes too small or some clumsy handling can cause a crack or breakaway when using a fixing.  :2thumbsup:

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## nww1969

ok some interesting replies here. 
Now all Im doing is putting up a 3x2.5 colourbond shed  and think maybe small dynabolts may be overkill. 
Epoxy anchors sounds interesting , will this attach to new concrete and does Bunnings supply this.    
Any suggestions appreciated.

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## woodhunt

Didn't consider chem as I just expect something to go wrong with the edge (especially with store bought/home mixed concrete), and knowing my luck any uplift is going to be accompanied by just as much if not more force sideways. 
If an annoying gust of wind is going to take my shed out of the backyard, I would at least like it to take the slab with it so I have less work installing the larger shed.

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## Bloss

> ok some interesting replies here. 
> Now all Im doing is putting up a 3x2.5 colourbond shed  and think maybe small dynabolts may be overkill. 
> Epoxy anchors sounds interesting , will this attach to new concrete and does Bunnings supply this.    
> Any suggestions appreciated.

  Relatively small diameter ankascrews work fine - 6mm. I know of two 3m x3m garden sheds in a high wind area that have stayed in place for more than 15 years and they are held down on slabs by construction adhesive alone! Not recommending, just saying . . .  :Smilie:

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