Question on cavity under patio doors

H

hayabusa

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Folks
Can you please help me on the following:
When installing patio and french doors, are you suppose to maintain the cavity under them or should it be filled. I have been informed that this should remain as a cavity,. If this is the case how do you support the base of the door. I have one patio door 10 feet wide so this certainly requires support from underneath. Are the cavities narrowed slightly and use the edge of the bocks to support the base of the door.
Any help on this would be greatly appreciated.
 
The outside of the frame should be tight to the inside of the outer wall with the dpc coming onto frame, ie: frame sits in cavity,the cavity is not filled, the frame is supported with brackets onto the inner wall all around, top sides and bottom, your insulation will fill the void left and cement/plaster on inside will close gap onto frame, same will happen on outside onto dpc and frame.
 
Thanks for the reply bskinti.
I have these installed as per you details. however i need to support the base of the door. So in order to do this i will have to fill the cavity under the door in order to support it. would this be correct.
 
Hi,
I had this issue 2-3 years ago, at the time one of the tradesmen recommended that I knocked away the front leaf of the cavity, then make a frame & pour a mass concrete step - with DPC & insulation lapped up in front of the inner leaf of the cavity - obviously you can lower the level of the step if there is to be a slab to be laid on top. This worked out well in my case - to be honest I can't remember why the guy recommended to do it this way but he was adamant it was superior to leaving the cavity under the door.
 
DACMAN said:
Hi,
I had this issue 2-3 years ago, at the time one of the tradesmen recommended that I knocked away the front leaf of the cavity, then make a frame & pour a mass concrete step - with DPC & insulation lapped up in front of the inner leaf of the cavity - obviously you can lower the level of the step if there is to be a slab to be laid on top. This worked out well in my case - to be honest I can't remember why the guy recommended to do it this way but he was adamant it was superior to leaving the cavity under the door.
Click to expand...

What you did is pour an insitu door threshold.
In my early days on the sites a pre cast concrete threshold would always be laid surrounded by a damp proof membrane
 
Dacman is correct, knock out the outside block and build your step out from there
 
hayabusa,

The detail for a standard house is that you would normally have 3 courses (675mm) high on top of your foundation.The blocks are laid on edge with the cavity maintaned between them.The outside leaf only goes up 2 courses and the inside leaf goes up 3.The cavity should be filled with concrete up to the level of the outside leaf to stop the inside leaf moving when the sub-floor is being filled.The dpm laps over the inside leaf out to the external face of the outside leaf.
bskinti is correct your door will sit tight against the inside face of the outside leaf.
If I were you I would fill the cavity with a fairly dry sand and cement mix (about 3:1) and pack it down will with say a hammer.There is only a need to make sure that the outside leaf across the door is 1 course (225mm) below finished floor level.
As Sydthebeat said continue out the dpm to the outside leaf.Your vertical edge insulation should already be in place on the internal face of the inside leaf the depth of the finished floor screed.
 
All

Thanks for your reply on this matter. I will continue with this work over the weekend.

Regards
 
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