Sun Terrace over sloping roof extension

[Stevex]

I am constructing a wooden framed sun terrace at the rear of my property. The terrace will be located above an existing extension with a sloping tiled roof. The property is terraced and on either side the ajoining properties form the left and right walls of the existing extension. ie, the area for the sun terrace is between the two walls above my extension and runs from the original back wall of my property to the edge of the sloping tiled roof extension. I do not want the sun terrace to be in contact with the extension sloping roof.
The plan is to fix two verticals in a secure base either side of the extension, fixing them to my extension wall. A horizontal would join the two verticals together. Another horizontal running along the length of the original rear wall would be secured in place. These 4 pieces would then form the base of a cantilever type to provide further front to back supports as necessary finally with decking on top.
What are the best fixings for the rear horizontal to the original wall?
Can anyone offer any additional guidance to the project? Thanks Steve
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[thedoctor]

Hi Steve, depending on the soundness of the walls in question we would suggest using chemical anchor fixings. These are suitable for any surface providing it has integrity and is not damaged. You can find out more about chemical fixings in the projects section. It would also be a good idea to contact the building control office of your local council as you are providing a loading over an existing dwelling and the load you impose on the structure needs to be checked against the timbers you intend to use. See our project on floor joist spans.