I got a little busy to keep the updates current but here is where I’m at. Last week was a good one for progress! The form worked out great for the brick work and I’m pretty happy with how the vault turned out. These things are very irregular and setting them was more like coursed, squared off stone than bricks. Having never done brickwork like this I’ll say it was a pretty cool to build with them. But man am I slow at it! The vault took me 2 days..they weren’t 8 hr days but still. If this was a dry stone vault I could have done it in 6 hours or so…big time difference. But I don’t have the stone and I wanted to use these so…..
Starting out, the base course is set on a thick bed of mortar and checked for level. I used Type N mixed with the sand I got out of the ground here at the house. I kept the bed mortar away from the front edge of the brick so I could point it up nice after I drop the arch form.
You need to use mortar with soft brick like this because of the pressure from the weight above. One thing I don’t want is a strong mortar ( a common problem in modern masonry ) because it would damage the brick over time. I had really wanted to use lime but I couldn’t find any locally so I went with type N mortar which has a relatively low PSI [ 750psi ] compared to other types. Plus, I mixed it a little on the lean side… like 3.5:1 which worked out well. No matter what mortar was used, it will do little to hold everything together if I don’t build the drystone base correctly…it will serve as a buttress to keep the sides from bowing out causing the arch to collapse and make me crawl into a corner to find my happy place.
Now that my base is down we can start our coursing. Mason jumped in to have a turn parging the back of the brick.
After every course, I would parge ( Mason too) the brick and fill the joints.
Every course was checked to maintain level. The last thing I want is an uneven distribution of weight on the vault.
The key bricks.
All cut and dry fit, waiting for the granite keystones.
Next post is carving the granite, mortaring in the keys, dropping the form. See ya tomorrow!
Side point – this is post 50!
-Explain the dry fit keystones. they will stay that way?
-wow, you could of done faster in drystone!
Matt Sevigny says
No, the keys are mortared in, I always dry fit to check how they fit. It is something I do with all my mortared stonework too. I build this way because then the structure is built in consideration of the way forces work against and with it. Like I’ve said, I don’t treat mortar like glue.
Yeah, I could go much faster going with drystone for the arch. I guess that will be the next base I build. Except then it will be a ribbed cross vault so that won’t be as simple as this one…but it will still be dry!
Mellissa Sevigny says
Congrats on 50 posts Hon! And the arch is looking great – can’t wait until the oven is finished and we’re actually making pizzas in it!
Matt Sevigny says
Yeah me too!