Building the forms for the radial vaults

Posted on August 13, 2018 by Simon

Contents

The Video
The Chimney
The Gallery

In preparation for shooting the gunnite on the roof we needed to put up some forms that would keep the concrete from just falling thru. The radial vaults have simple curvature, so we could build the forms from boards pressed up against the steel arches. Making that happen took some compromises in the plan. As usual, challenges arose. Enjoy.

The Video

The Chimney

In the video I forgot to include any footage of the chimney going in. Basically, I built this form so the shotcrete would create a good base for my chimney on the vault. My one regret was that I didn’t think to close the top of the form in order to prevent the gunnite from going inside the chimney hole.

The Gallery

A picture is worth a thousand words and here a bunch of pictures

: We started with full panels and planned to but joint them and attach batons over the ends. But it definitely didn’t work. So I just sat and thought about it for a while.

: My first panel attempt. The vault is radial, so simple curvature and a panel should have fit smooth. But I forgot that the outer edge is inset 2 inches from the bar, which means I needed to notch the panel so it would work out.

: By the time we finished off the first vault, we had the plan mostly worked out.

: Just a pic of progress

: Sherri’s brother Steve showed up for a tour.

: The second layer tucked in easily. The hardboard fit above the previous hardboard and the wood baton fit under the previous hardboard so it could be screwed into the steel arch. Then additional lath screws would be added from the outside to attach the hardboard to the batons.

: Sherri working until past dark…

: Here you can see that the playroom vaults don’t have the end caps on yet. I can’t add the panels until after the end caps go on.

: Here you can see the insulated south wall. We plan to shoot the whole structure (roof and walls at once).

: Sherri put the lath vaults together. Here she is still adding the the rebar chairs and screen. The rebar chairs keep the rebar fully embedded in the concrete. The screen keeps the wet gunite from blowing thru the lath. It isn’t strong enough to actually hold the concrete, the lath does that.

: David at the end of the day…

: Our friends (Ryan and Aaron) came over to help for a few hours. We needed to put the end caps on the arches, so we started with that.

: A pigeon made a nest and we carefully worked around it.

: Michael hanging out with me while I was putting the forms up on the last standard sized vault.

: Sherri working hard

: Here is the pigeon after the vault forms are in place.

: Sherri working on the second lath vault.

: A standard end of the day pic.

: Just a close up pic on a standard vault.

: Pigeons make crappy nests. They are very sloppy and the eggs or chicks often fall out. This pigeon had 3 eggs initially. After the second one fell out, I decided to put some tape up to look after the last one. I double sided the tape so it wouldn’t be sticky against the birds.

: My father packing up the tools at the end of a long day.

: We usually recycle bill board vinyls to help with waterproofing. They always have an image, this one made me laugh.

: The smurf tube (ENT) electrical conduit will allow us to run wires up thru the vaults after the concrete is in place.

: This smaller vault had too tight of a radius for the hard board, so we went with lath. I was able to put hardboard on the sides.

: Inside of the dining room vaults.

: Here is an electrical box mounted on a lath vault. Why 4 tubes? Well, 2 are for the light and they go to 3 way switches on either side of the room. The other two are to run power from another switch to another light. We go thru the box because building code limits the number of turns in the pipe between two boxes.

: I wouldn’t have been able to add these boxes after vaults were on both sides, so I would add them between adding the vaults. So one vault, then the next electrical box, then the vault on the back side… After the concrete is in place, I can drill thru the box so wires can access both sides.