Category Archives: Construction

I regularly encounter interesting math, particularly geometry, in my woodworking and remodeling projects.

Layout Formula for a Balustrade

Posted on 16-July-2016 by mathscinotes

I am about to begin some construction on my cabin in northern Minnesota, and the design of the stairs has been on my mind. I consider well-designed stairs to be both beautiful and functional. A major factor in making a stairway beautiful is its balustrade – a railing with supporting spindles (aka balusters). The balustrade for a stairs is often referred to as a banister. Continue reading →

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Withdrawal Force Rating for Various Nails

Posted on 11-July-2016 by mathscinotes

I have been reading some specifications on fastener requirements in carpentry. To ensure that I understand what I am reading, I decided to see if I could duplicate the design values for nailed connections. In this post, I will duplicate a table (Figure 1) for the withdrawal force ratings of various nails when used in a toe-nailed connection. In general, I try to avoid nails with a withdrawal load, but it is an allowed connection and it was easy to duplicate the results in a National Design Specification (NDS) document. I will be performing a similar computation for the lateral load rating in a later post. My Mathcad source and a PDF are stored here. Continue reading →

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Stud Length Requirements

Posted on 9-May-2016 by mathscinotes

I usually use 92 5/8" studs when I am building standard 8' tall walls – they sit sit in piles at my nearby lumber yards next to piles of 8' long studs. I recently saw (example) that there are three pre-cut sizes available:

92-5/8" : used for 8' ceiling heights
104-5/8" : used for 9' ceiling heights
116-5/8": used for 10' ceiling heights

In this post, I thought I would take a look at these pre-cut sizes to (1) learn why these values are used, and (2) to decide if any of them would be appropriate for my building activities. Continue reading →

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Interior Non-Load Bearing Wall Construction Methods

Posted on 6-May-2016 by mathscinotes

I am an hobbyist carpenter who is about to do some wall building. I was reading a forum discussion on the best way to build a non-load bearing, interior wall as part of a remodeling situation. The forum conversation was very thoughtful, but no real conclusions were reached. This makes sense because each forum contributor was making assumptions about the construction conditions – the construction conditions dictate which method would be "best." Continue reading →

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Shoot Boards for Handheld and Table Saws

Posted on 31-December-2015 by mathscinotes

I live in a small home, and I have to do my woodworking in the garage. Since I have two cars that "live" in the garage, I do not have sufficient room for a full-size table saw (Figure 1).

The biggest challenges I face have to do with cutting large sheets of plywood (4' x 8'). Without the space for a table saw, I had to begin looking for alternative approaches that I could setup and teardown in my garage. Continue reading →

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Stairway Rise Angles

Posted on 21-December-2015 by mathscinotes

Quote of the Day History is a tool used by politicians to justify their intentions. — Ted Koppel I was reading this month's Journal of Light Construction (JLC) when I saw an article on building safe stairways per the International … Continue reading →

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Incorrectly Computed Discount Followed By Markup

Posted on 20-December-2015 by mathscinotes

A few years ago, I hired a tile installer to tile a bathroom I was remodeling. He was a talkative guy, and he casually mentioned that he had chosen not to make any money on his material – he would make his money on labor alone. He said that most of the tile shops he works with give him a 15% discount on material, which he passes on to his customers. Other contractors markup their material charge by 15% to bring the cost back to retail price – this statement bothered me because the markup should be larger than the discount. The math did not seem right to me at the time, but I did not raise any questions because I wanted my bathroom done. I did not think much about this math error at the time until I saw an article in the Journal of Light Construction (JLC) telling contractors that this is a math error that is costing them money. As I read the article, I realized that this is exactly the same error I heard my tile contractor make. Continue reading →

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Not The Way To Take A Chimney Down

Posted on 13-December-2015 by mathscinotes

I have worked on construction sites and farms, and the lack of imagination that people show with respect to safety never ceases to amaze me. This video shows what happens when someone does not think about what could happen. Continue reading →

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A Little Sandpaper Kirigami

Posted on 11-December-2015 by mathscinotes

I started using this sandpaper folding technique years ago, but I just ran across this video that does a nice job of illustrating the technique. Continue reading →

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How I Orient My Electrical Outlets

Posted on 16-November-2015 by mathscinotes

For years, I have mounted most my electrical outlets upside down (see Figure 1). Recently, I have started to see more folks orienting their outlets this way. I see that Finehomebuilding Magazine and the Journal of Light Construction (JLC Field Guide) recommend this approach as well. However, it is not required by the National Electrical Code. Continue reading →

Posted in Construction | 2 Comments