Short answer
Wind can carry embers to gaps at the roof edge and into exposed vents. Embers can also ignite debris in gutters or beneath a deck. For a rebuild, review these areas together while the roof, exterior walls and garden are still being designed.
Look closely at the roof edge
Ask your architect to show a drawing cut through the roof, eave and wall. Use it to locate any open tile ends, the attic air intake and places where leaves can collect. CAL FIRE recommends closing ember entry points and considering listed flame- and ember-resistant vents. Have the designer confirm the required ventilation and the vent product with the local building official.
Follow the wall into the yard
A deck, gate and fence often arrive from different trades, yet all three can touch the house. Draw each connection on the same exterior plan. At a timber fence, ask about a noncombustible section next to the wall. For a deck, review access underneath so leaves can be cleared and furniture cushions or firewood can be stored elsewhere.
Record the details you will maintain
Before ordering finishes, ask the team to list the proposed vent model, roof-edge detail, deck material and fence connection. At handover, request the installed product information and photos of the concealed details. Have the builder point out where debris is likely to settle and how those locations can be reached for cleaning. A household can act on that record long after the drawings are filed away.