A Continuous Load-Path Strap-and-Anchor Roof Tie-Down Assembly for Low-Cost Housing: A Computed Uplift Budget and Its Limit Wind Speed

SIMULATED, NOT MEASURED. This paper specifies a continuous load-path hurricane roof tie-down assembly for low-cost housing - galvanised steel straps over each rafter, screwed to the rafter and wall framing, continued by M12 threaded rods grouted 350 mm into grout-filled masonry cells - and computes its uplift budget for a 9.0 m x 6.0 m single-storey house with a 77.4 m2 sloped roof. The governing link is anchor pull-out by grout-to-masonry bond in weak masonry: 6.60 kN characteristic and 3.67 kN design per unit. With zoned detailing (0.9 m spacing in the field, 0.6 m at the edges, doubled at 0.6 m at the corners), the assembly reaches its design limit at a wind speed of 41.3 m/s (149 km/h), set by the edge zone, against 30.1 m/s for uniform 0.9 m spacing. Whole-roof net uplift rises from 41.9 kN at 30 m/s to 90.4 kN at 40 m/s and 229.1 kN at 60 m/s. Thirty units cost USD 264.00 per house. The limit falls to 29.5 m/s in very weak masonry at 250 mm embedment and rises to 57.0 m/s in medium masonry at 450 mm embedment. No assembly was built or load-tested; performance is computed under stated assumptions and is not a safety certification. All numbers are outputs of the deposited computation script.