Garage Cavity Wall Threshold Detail

[Wendelspanswick]

Doing the footings for my new workshop, the block work comes up 2 courses and this is used as the screeding level for the poured concrete floor. I am trying to get my head around what to do at the threshold for the garage doorway, its a cavity wall with a 100mm gap.
The floor is compacted base level, 25mm sand, DPM, 50mm Celotex, polythene and then 150mm reinforced concrete.
I want the concrete floor to finish flush with the external face of the external leaf.
Anyone have a link to a good image showing the sectional view?

 

[roofman]

Doing the footings for my new workshop, the block work comes up 2 courses and this is used as the screeding level for the poured concrete floor. I am trying to get my head around what to do at the threshold for the garage doorway, its a cavity wall with a 100mm gap.
The floor is compacted base level, 25mm sand, DPM, 50mm Celotex, polythene and then 150mm reinforced concrete.
I want the concrete floor to finish flush with the external face of the external leaf.
Anyone have a link to a good image showing the sectional view?

Cant you take a corse of block out at the door front and shutter the front so in effect your concrete slab will come to the outside edge.

 

[Wendelspanswick]

Cant you take a corse of block out at the door front and shutter the front so in effect your concrete slab will come to the outside edge.

Just wondering what to do with the DPM.

 

[roofman]

Just wondering what to do with the DPM.

cut and turn it up at the inside edges and put visqeen over the cavity to give yourself a barrier.

 

[Gritineye]

As said knock out a couple of courses and carry concrete through, don't run the Celotex through but allow the concrete to drop in front of it to cover the edge if it.

Use a stout timber shutter across the front wall and a then fix a straight length of 6"x2" across the opening behind the point where the inside of the door will be, cut a 1:1/2" rebate each end where it sits on the wall to form a step below the finished floor surface , this will stop water blowing inside under the door.

Make this former strong by screw fixing struts off the front shutter and weight it down at the ends, to stop it floating.
Don't try to get a good finish under the struts at first. wait till after the concrete has 'gone off' solidified but not set too hard carefully unscrew the struts, and gently float the surface smooth. Lift off the 6x2 the next day and clean off any rough bits.

Also a good idea to use so 1" celotex vertically around the entire slab to stop cold bridging into the floor.

I always do garages doorways this way, hope this all makes sense to you...