When you're installing a deck, use existing structures where possible to install a ledger. I generally use minimum 10g 100mm Ramset anchors with 400mm spacing (the more the merrier).
Make sure you leave spacing between the timber and the structure so moisture (rain) is able to drain through rather than pooling on top of the timber frame and gradually degrading it and/or affecting the structure itself (water stains, cracking render) - also leave a small gap between the deck and the structure for the same reason but be sure not to leave the frame visible. Easiest way to do this is with some stainless steel washers (2-3 is normally fine (depending on size)).
Make sure you position the anchors so they don't interfere with 400mm spaced joists.
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