# Forum Home Renovation Structural Renovation  attach frames to slab

## craig 75

prefab frames have arrived ,,90/35, but no information on attaching to slab before i phone the company i thought i would get opinons ,iassume normal ,,loxens ,dyna bolts or ramset guns, what do diffirent people prefer  
thanks in advance craig :Smilie:

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## les88

I would use dyna bolts
les

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## Metung

From my understanding of the framing code (and I regularly have trouble understanding it), it depends on what type of bracing, if any, the wall has. 
The minimum seems to be one 75mm masonary nail at not more than 1200mm centers for no or type A bracing. 
M10 bolt or other 13 kN capacity connection at each end intermediately at  max.1200 mm centers for type B bracing. 
The plans should specify the type of bracing for each wall. 
It seems to me that you couldn't go wrong with 10 mm dynabolts at 1200mm centres on all external walls and any internally braced walls and 75 mm masonary nails at 1200 mm centers on internal partition walls.

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## Barry_White

This may be overkill but knowing what I know now I would be at 1800 centres I would be fixing chemical anchors through the bottom plate attaching a length of threaded rod to it with a threaded rod joiner to go up through the top plate with a large washer and a nut on the threaded rod on top of the top plate.

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## DvdHntr

Not that anyone pays any attention but a dynabolt only 45mm from the edge a concrete slab is not sufficient. It needs to be a chemical anchor to avoid shear cone failure. But everyone uses dynabolts and gets away with it.

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## silentC

NSW Framing manual says tie down at max. 3000mm centres for trusses spanning 1200mm and 1800mm centres for spans greater than 1200mm but less than 16000mm. 
The actual tie-down depends on the required design strength, which is a factor of the wind rating in your area and the type of construction. 
For slab, it pretty much requires bent bolts embedded in the slab. However it's only an extract, so there could be other details in the standards or the building code that it doesn't cover. 
As it's too late for that, I'd go along with the chemical anchors. We used both at our place. Embedded bolts mostly but chemset anchors wherever the bolts were in the way or we thought we needed more tie down in a particular spot where we hadn't put a bolt. 
Bazza's suggestion is worth considering. 
Is there no tie-down detail in your engineering drawings?

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## monkeyrelish

Forget dynabolts use the concrete screw bolts as they can be used closer to the slab edge than a dyna without cracking/spalling and if you ever need to, they can be removed easily and even reused unlike a dynabolt. 
Nominal fixings of bottom plate to slab (i.e. nails) are ok however you must have dyna/screw bolts at each end of any braced wall section. 
See if you can get/borrow a copy of AS1684.2 - non-cyclonic (Residential timber framing manual) it isn't that hard to follow and will give you all the info you need. The fixings are dependant on what wind clasification/region you are in. 
Another thing to think about if using chem-set is that you have to be very sure that the holes are cleaned out, this is very important otherwise you won't get the full bond required.

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## Ivan in Oz

> Forget dynabolts use the concrete screw bolts 
Nah!!!!!!!!! 
Forget both! 
Go Chemical Anchors,
they're for me.

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## Gaza

ramset the frames in place then get young bloke or wife to go around putting screw bolts in. 
screw bolts kill chmeical anchors in this application i do like chemical anchors but not for this job.

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## silentC

> screw bolts kill chmeical anchors in this application

  How so?

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## Gaza

1. you can drill hole and 100% tighten screw bolt in one go, chemical anchor you have to come back after it has gone off and tighten. 
2, for 100x10mm screw bolts box of 100 around 60 dollars, to use chemset you have to buy large gun (little size containers run out to quick) buy the chemset and extra nozzlez plus the buy anchor of some type or cut threaded rod up and using nuts and washers. 
3. you dont need to clean / blow out concrete dust from hole 
4. it sees to be quicker using screw bolts plus you cn tigthen them up with cordess fitted with socket and adaptor 
both methods work fine and are a massive improvmnet on dyna bolts

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## silentC

Fair enough, just curious, I thought you might have been suggesting that the screw bolts were stronger. Yeah probably quicker but you have to get the hole size right. Hadn't seen those screw bolts before when we built our place. One of the guys came home with some and we used them here and there but wasn't sure about them.

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## Gaza

i dont know the numbers but both chemset and screw bolts and stronger than dyna bolts. 
you also use frame anchors (big plastic plug with large screw) these are also stronger than dyna bolts and easyer to use. 
i just like screw bolts.

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## Barry_White

> i dont know the numbers but both chemset and screw bolts and stronger than dyna bolts. 
> you also use frame anchors (big plastic plug with large screw) these are also stronger than dyna bolts and easyer to use. 
> i just like screw bolts.

  From an old Ramset Rep 
A Dynabolt and a Screwanka at the same diameter and the same embedment depth the Dynabolt is slightly stronger in tensile strength to the Screwanka. 
A 10mm chemical anchor at a 90mm embedment depth has twice the tensile strength of both of the above.

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## sports fan

builders use concrete nails or dynabolts (1200cts) as this is the most effecient method of fixing the bottom plate, and nothing wrong with it either i am yet to see the walls of a house ripped off a slab.. if you think its worth the extra money and time to chemset the plates down even better

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## Metung

One other small point, I presume you will have tie downs - metal straps that go under/over the bottom and top plate and up/down either side of a stud. Seems they are normally located on studs either side of any external frame opening, namely doors and windows and external corners. I regret not having rebated the stud on the internal side because there is generally a small bump in the plaster where the ties occur. Nobody else probably notices but I certainly do.

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## silentC

There's two different things being talked about here: one is fixing the bottom plate to the slab, and the nominal fixing for that is a concrete nail every 1200mm. The other is tie-down and that needs to be an anchor such as a bolt embedded in the slab or similar.  
The tie-down is continuous through the wall frame to the trusses and it is spaced at 3000mm centres for trusses spanning 1200mm and 1800mm centres for spans greater than 1200mm but less than 16000mm (as per the framing manual). It can be separate fixings, like a bolt for slab to bottom plate, GI strap for bottom plate to stud, GI strap for stud to top plate and framing anchor for top plate to truss, or you can have a bolt/rod all the way up from the footing to the top plate as per Bazza's suggestion. 
Dynabolts are sure to be OK for fixing the wall frame down (probably overkill) but possibly not for tie down. You're probably going to need more than concrete nails on internal bracing walls. 
My engineering detail included tie-down instructions. Strap-braced walls need GI strap or something at the top and bottom plate connections too. Not sure about ply bracing units, since they fix to the top and bottom plate as well.

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## Metung

Silent, there was only one thing being talked about till I opened my big trap and tried to offer a little bit of extra advice.   :Cry:    I don't dispute what you say, except for the missing 0's in some of your spans, but it has made me wonder whether Craig is aware that there is more to putting the frame up than just fixing the bottom plate to the slab. If so, then he might like to explore this further.

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## silentC

My first post was about tie down. Seemed people were just talking about fixing the bottom plate (which to be fair is the question that was asked) but obviously you need to do more than just whack in a concrete nail every 1200mm.   

> the missing 0's in some of your spans

  Shouldn't be any, just copied that straight from the framing manual which is on my desk in front of me. Which ones did I miss?   

> there is more to putting the frame up than just fixing the bottom plate to the slab

  Yeah I just wanted to make that clear.

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