Sunday, November 13, 2016

The Garage Attic Retracting Stairway



We just finished building our garage. Probably the most interesting feature is the attic stairway.
Most people with attics have used those weak and narrow pull down folding or telescoping stairways. They are narrow and steep and not very strong. I wanted to be able to easily use the attic storage area so I wanted a really good stairway.

It is important to understand that attics need to be designed properly to support the weight. From the beginning of the garage design this stairway has been planned for. I discussed it with the truss engineer and we made sure to design for the truss spacing, the weight and the point loads. Additionally, the whole system has been designed to account for the various loads and weights on all of the components.

I did lots of drawing to design and build the stairway and components but this one sketch illustrates the basic function:


And here is a video of the stairway in action!


Details
The counterweight:
 



The pivot:


The cane bolt:
 




The pulley system:


The stair to cable attachment:


My thanks to Jorge Tafoya of Tafoya Construction in San Diego for his help with this project. I couldn't have done it without him:

2 comments:

  1. Very nice! How did you calculate the counter-weight amount? Looks like maybe 8" square tube, capped at one end, with maybe lead bars or something?

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  2. You are correct, the counter weight is a 8" x 8" x 9" steel tube with a bottom welded on it. I weighed the ladder before installing it and knew I'd need to support about half the weight in the up position when it is horizontal. I used a stack of 6" x 6" steel plates for weight and just kept adding them into the bucket until it worked as I desired. I no longer remember the exact total, but I think the total counterweight is about 100 pounds.

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