Framing vs Cutting: the pros and cons of two approaches to Windows and Doors
Thursday, December 8, 2022 8:27 PM
This was the main motivation for trying another set of domes: by avoiding the framing process, it would provide significant time and material savings. After building 7 window frames that were later trashed ( 2 x 4s and 3/4" plywood - all imported wood from hundreds or thousands of miles away), we wanted a better use of resources. Also, when interrupting the flow of bagging a circle, each frame (for instance, a window) means a new start of a bag, a new stop at the next frame, a new series of barbed wire, etc. All this takes time that a sigle long bag length would avoid. Thus, cutting doors and windows would be much faster (or so I thought)
Here are the forms from 2008:
I was convinced that a ‘cutting’ method for all windows and doors (except the door required for a diameter line run) would enable a quick build and then cut out the doors and windows on Day 2. Well, alas, this is not feasible when building bigger domes with a springline and manual mixers. Maybe it would be with a qualified crew and a cement truck with a good conveyor belt to deliver masterial quickly to bags that were handled expertly. But that’s a tall order to go from 'springline’ to close in a day.
Placing Frames: from 2008, below is a ‘moon window’ frame - heavy, hard to lift, and used concrete to fill - and imported wood to brace it.
Here is using trash (old tires) to achieve same result in 2022:
The end result is that the cutting did work, but not as we envisioned it. I had brought 18” masonry sawzall (reticulating saw) blades with me to ‘cut’ the material after bagging and tamping, In fact, my tests showed that about 36 hrs after ‘curing’ (ie, tamping a row in place) would be the ideal time to ‘cut’ the window. Alas, the sawzall blade did work, but not nearly as well as an old-fashioned techique my borther-in-law, Dave Martin, devised: a ‘chain saw’ using two people and a length of chain. Check it out here on this video - it was like a knife through butter.
If I was going to use this cutting technique again, I would add 10% to the width estimate for my doors and windows, as it’s MUCH easier to fill in with plaster an ‘over cut’ but you need a chisel to open up a space to allow for a good door andor window frame after curing. We did a lot of chiseling to get the windows and doors to proper shape.
In the end, I’d suggest that the cutting technique is environmentally better than framing, at least in a wood-scarce place like Baja. The material that we ‘cut out’ fromn the bags, we pushed into the domes and this became the 3’ flooring sub-surface we needed. So, we avoided extra resources and wasted nothing. Which my ideas were aligned with.
But we spent more time getting the door and window framing space 'just right’, knocking out the spaces was not eqasy (see this video for how we did this physical act) and so I think the balance of the analysis is that I’d buy wood next tine and get perfect frames built for my doors and windows.