Step 1
Select the correct species of hemlock lumber. Western hemlock makes a better building material than Eastern hemlock due to its smoother grain and greater longevity. Western hemlock, unlike Eastern hemlock, doesn't contain resin, and this makes it easier for the wood to take paint or stain.
Step 2
Buy only treated hemlock. Left exposed to the elements, untreated hemlock will degrade rapidly and your deck will fall apart within a few seasons. Once treated, the dense hemlock wood will resist rot and insects. Over time, the wood hardens, which increases its strength and longevity.
Step 3
Purchase only dried hemlock or have the lumber dried by a professional. Hemlock has a large shrinkage when it dries. If you build your deck with wet wood (also known as green wood), you will be left with large gaps in the deck once the wood dries. Drying the wood also increases its strength and reduces the weight of wood, making it easier to carry.
Step 4
Cut your hemlock with a power saw or handsaw. The power saw will make a smoother cut than the handsaw. Because hemlock is soft, cutting the wood has little dulling effect on your blades. If you use Eastern hemlock, clean the blade between cuts to clear away the resin residue.
Step 5
Use screws with your hemlock rather than nails. The wood doesn't retain nails well. Screws make a better choice for any building project because the threads help hold everything together better than nails do. Hemlock accepts and grips screws well. Drill a guide hole slightly smaller than the diameter of your screw before inserting the screw. This helps keep the wood from splitting as you place the screws.
Step 6
Sand your deck floor once it's completed. Sanding makes the surface of the deck smoother and improves the appearance of the wood. After sanding, sweep the deck clean. At this point, you can stain or paint the deck if you want.