Timber Screw Usage Chart Fastener typeWood-to-wood fasteningLag bolt replacementDecks and ledgersMarine/coastalSDWS, Oversize washer ✓✓SDWH, Hex washer ✓✓SDWH, Hex washer HDG ✓✓✓✓SDWH, SS Hex washer ✓✓✓