Vaults for a Primary school.

Through a query about bricks, I mentioned our roofs to an architectural firm in Dar.  That lead to me speaking at a workshop of theirs and then this job for Dickson.  It is a private primary school roof .

Classroom is 3 vaults.  One is clay brick and others are cement paving blocks.  Hallway outside the classroom has vaulted roofs and groined vault in the middle.  This job is leading to more jobs.

Catalan vaulted roof/ceiling

This was a project done last year and  I thought I had made a post about it, but looks like I did not.

After several small span  Catalan  roofs  we decided to roof this room using our new skills.  This method is referred to by many names:  Catalan, timbrel, cohesive tile.  I will use Catalan.

(Note the modern scaffolding!)

First we built end walls to draw the catenary shape  templates, run strings to control the shape, and "glue" the tiles.
  I bought handmade  floor tiles for the first course for aesthetic reasons.

 Butter two sides of a tile with gypsum plaster.

Tap into place and hold 1-10 seconds.


And then move on to the next one.  It is a bit tricky as the first one has to be "set" so better to build in two places or use gypsum that is almost set.

  A video is found here


Building on each side .

Conduit pipe for ceiling light.

From above 3/4 done with first course of tiles.  Sometimes extra gypsum plaster applied to help hold until an arch is completed.  gypsum gives no strength to the vault, it is just to hold until an arch is finished.

About to close the first layer.  We were excited about how good it looks.

 After finishing the first course.   We had disagreement on whether to do the other 2 laminate layers as we went along or finish one course at a time. 

It did bring and issue .

Before I talk about the hole.  This shows the 2nd and third courses with different bonds, first at 45* then at right angle to original bond.  After 24 hours you can stand on the 3 layers.  Mortar is cement - lime - sand  1-1-6.

Mason Dickson preferred to finish first course then sit on the end wall and lay 50cm of other courses, next day sit on the first 50 cm and lay another 50cm.  Worked okay until someone put something heavy on current days work and it collapsed!

As it dried out efflorescence occurred on the beautiful tiles but i figured it would dry and fall off like our bricks.  It is a year and still ugly like this.  I just tried washing it off and that looks like it will work.

we filled in level and then put heavy plastic and then 5cm concrete sloped into a drain pipe.

On a small Catalan vault we roofed with tiles to see how well that would waterproof the roof.

Pointed Vaults and Pointed Arches

I just had a Renaissance moment, a real eureka moment.

My friend Matt and others will say "jeez, he is only realizing that now?"

I am not a trained professional engineer or builder, but I have some experience. All my arches and vaults are semicircular or catenary curves. Vaults I build without centring, and but arches over openings with centring, as i need a wall to "glue" the bricks. Like the first arch below.

So here it is

IF I USE POINTED ARCHES (middle type) IT WILL MEAN THE LAST BRICKS WILL BE MORE VERTICAL INSTEAD OF HORIZONTAL!

Pointed arches are like the second arch above and this one below.

Duh.

I see it all the time in pictures but it just dawned on me now that it will make some vaults easier, as the curve stays more vertical, hence less gravity pulling it down before the arch is closed! Jeez Matt why didnt you yell at me? Your latest WTO has pointed in it!

I see some issues as they will require greater height in arches over doors.

So my groined vaulted rooms will look like this maybe.



Which means I should be able to go horizontal course much higher

"The main advantage of the pointed arch was that it concentrated the thrust of the vault on a narrow vertical line that could be supported by the flying buttresses, a major feature of Islamic architecture and also European Gothic architecture. The pointed arch enables the reduction of the lateral thrust on foundations. It enabled architects to lighten the walls and buttresses which had to be massive to support earlier semicircular arches(endnote 2). Additionally, it resolved the difficulty of achieving level crowns in the arches of the vault allowing the vault to become suitable for any ground plan." The Arch that never sleeps (Publication) by: FSTC Limited


I mean look how steep that is!

Is this the new look on my buildings?

Winery Vaults in Progress

Our crew went a month ago to Langarini SE of Arusha to put up some brick vaults. Above are the vaults outside the walls. Since they will be loaded they are segments of circles.

And the vault finished inside one room. span is 3.5 meters. We didn't do the walls or the columns and beams. This is to be the office and retail store for Infinity Winery owned by Erik Zweig.

Two parallel vaults and then arches extending 1 m past the walls on big beams.





Back of the building.


The corners will be corbelled off both sides.

Our man Dixion finishing one end.





Inside one room with the wine master.

Another room

Looks good after pointing.

On top. the space between will be filled with lava gravel and then a slab.

Festo pointing



the 'eaves" from the top


Me admiring the building. Dixon uses level on top to keep the courses true to shape.





Some pictures during the process










closing the final bit in middle with bricks the other way. I like the light coming through.

Pointing:













We see this happen sometimes. a seperation to the vault courses later in the day. We now clean off the bricks any dust, as they are put up dry. Not a problem structurally later, but is visible to someone like me later.