G1nzo, hi.
You have not stated how old the property is? or, if the property has been owned by you for some time?
Reason for the question is that if you have uncovered this void filled with debris? could lead to the thought that what is the cavity below the new patio door filled with?
Where is all this going? if the cavity and the area between the patio door, and more especially between the wall below the patio door and the first joist in the floor is blocked then ground water can and will get through the cavity wall, and if blocked the cavity then march on and into the inner surface of the external wall, from there the potentially ingressing ground water will percolate across the blocked up Chanel and if you lay the new Laminate on to what could be a potentially shall we call it "Damp / potentially Wet" fill in the Cavity then the life expectancy of the Laminate is shall we say limited, not only but also? how stable will the Chanel fill be??
If possible, can you get a close up of the Chanel? the present posted digital image is difficult to zoom in to, a closer up photo would possibly assist?
Have a thought about, remove all the debris from the Chanel, depending on what you uncover? the inner surface of the external wall may need to be made as proof as you can against the ingress of ground water, Bituthene may assist??
Depending on what you find when the Chanel is cleared then that will dictate what needs to be done from there?
A close up series of images may? assist?
Ken
