Category Archives: Construction

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

What R-Value Is Good Enough?

I plan on retiring at my lake home in Northern Minnesota. The first step in my retirement preparations is building a large garage on my retirement property that will allow me to work on my various projects – I have not mentioned it before, but I love doing auto body work. I am currently building a garage similar to that shown in Figure 1. Because northern Minnesota is quite cold in the winter, I needed to insulate and heat this structure. This post will review some observations that I made as to the value of insulation and of using modern ventilation systems with heat recovery capability. Continue reading

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Effective R Value of Common Wall Construction Methods

Because the winters are hard in this part of the country, I have become interested in the insulation value of different types of wall construction. My contractor has his preferred approach, and I am curious as to how it compares with other framing methods.

In this post, I will put together a simple model for computing the R-value of different types of wall construction. This analysis will provide me a quantitative basis for understanding which methods are the most economically sound. Continue reading

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Shimming and Trimming Stairs to Equalize the Risers

In this post, I will show how to generalize my previous stair solution to handle these three cases. I also present some illustrations of what is involved in adjusting the stairs. The general solution used a Mathcad program to compute both the final riser height and the thickness of the shims or trim cuts required for each step. In general, you may need a combination of shims and trim cuts to resolve a riser height problem caused by changes in flooring height. Continue reading

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Lateral Force Rating for Various Nails

I am an amateur carpenter, and I work hard to ensure that I always comply with the applicable building codes. The various codes include requirements for a properly nailed joint (examples). Since I like to understand where these requirements come from, I have been the reading some sections of the National Design Specification for Wood Construction (NDS) that address fastening. During my reading, I saw many interesting formulas associated with determining the NDS design ratings for nail withdrawal (covered here) and lateral force resistance – the subject of this post. Continue reading

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Layout Formula for a Balustrade

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

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

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

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

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

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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