Parallel - Building Stairs Math

The picture below provides you with a perfect example of two parallel lines that run in the same direction. In the construction business, roof rafters, floor joist, stair stringers and even some walls run parallel to each other.

Parallel house framing components like roof rafters and floor joist, usually make it easier to install insulation, plywood, wallboard and siding.


Parallel Building Tips

One of the most important things that any framing carpenter needs to understand is the importance of parallel building parts. If I'm building a roof and my roof rafters aren't parallel to each other, it's can create problems when I start to lay the plywood down, for the roof sheeting.

For Example: The plywood used by most carpenters to sheath a roof is usually 4 foot wide and 8 foot long. If I have all of my roof rafters laid out correctly on the bottom, but they're not laid out correctly as I work my way towards the top of the roof ridge, I'm going to have problems installing my plywood.

Building components that aren't parallel or laid out correctly, are going to eventually lead to more waste. It's going to take longer to install the plywood and you're usually going to end up with more cuts and wasted plywood.

Even though it might take you a little longer to frame the roof correctly and make sure that all of the rafters are parallel to each other, you will eventually make it up on the next step, when you start to install your roof plywood.


Stairs / Stair Glossary

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