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More roof brick demolition

August 10, 2013

The Summer of Tar continues, with another brick wall (an old parapet) to dismantle. Rain has been on & off – which means ponding water, so I figured I should try to pump away as much as I could, since I’d be using some power tools. And just like all other brick walls on our roof, the tar removal is the biggest pain in the ass.

This wall is GOING DOWN.

This wall is GOING DOWN.

I’ve continued to improve my demo methods: for the previous wall demolition post, I explained how I graduated from chiseling through layers of roofing with the bulldog hammer tool, to cutting through them with a disc on an angle grinder. NOW, I’m going to try using my spare circular saw with some super cheap blades with as few teeth as possible. I figured I’d be trading $3 blades for a lot of saved time.

Believe it or not, it worked quite well.

A cheap circular saw blade works better...

A cheap circular saw blade works better…

The circular saw cuts much faster than the angle grinder.

The first 10-15’ of cutting went really fast. But then I could feel some sticking as the blade heated up. If I had the time, I could stop, let the blade cool, and then start cutting again. But in the summer heat it took a good 15 minutes to “cool down” to 95 degrees.

I won’t go into detail about removing tar & roofing from the brick wall, since I covered that last time. But I still had to peel it all off.

Hammer chisel gets behind the tar & roofing.

Hammer chisel gets behind the tar & roofing.

While peeling tar, I noticed the beige row of bricks near the bottom. They were different. Made of a lighter weight clay, and they were glazed. Hmmm… could these be the “raggle block” items I’ve seen written all over the old blueprints from 1928?

Here’s a clip from one of those old drawings:

1923 drawing showing "raggle block".

1923 drawing showing “raggle block”.

The “raggle blocks” were drawn at least a dozen times on our old blueprints; I asked other architects if they’d ever heard of them – nope. And there’s little info on the internet. I eventually figured out that they were intended to be a way to terminate the roofing, by tucking the roofing edge up into an angled continuous groove, which was then sealed or glued in place.

So I looked at the end of the last beige brick – and sure enough – this was the mysterious “raggle block”.

A "raggle block" exposed.

A “raggle block” exposed.

Moving on, I got the east side of the brick wall cleaned of the tar & roofing; then finished the entire west side in less than 30 minutes; my improved tools & techniques were definitely saving time.

I was surprised to see the remains of a small arched opening near the end of the wall.


It must be an old roof drain or scupper location, when BAB was smaller and this was the exterior wall. I didn’t notice it on the east side because the brick was a bit messier, but looking closer I could see it there too.

Before taking apart the wall, I wanted to take some time to try and remove that old concrete cant sitting out in the open. (This was leftover from the previous parapet demolition.) In the next picture, the green arrow is pointing to the concrete cant.

Green arrow: "cant"; yellow arrow: deep water hole.

Green arrow: “cant”; yellow arrow: deep water hole.

And then I remembered that deep hole that kept filling with water, which I made/discovered when I started the brick investigation, which I wrote about on July 5th. The yellow arrow above is pointing to that hole. Yup, still filled with black water.

While some might accuse me of being easily distracted, (which is sometimes true), this was more a case of wanting to be thorough. It would be foolish to just kept demolishing parts of BAB without fully understanding the overall impact.

So I cut away more roofing in that area to explore what’s going on down there. I cut a trough about 8” wide to the corner, and made a bigger hole in the corner. The material I scooped out was some kind of compressed filler. It was dark like dirt, but lighter weight, and it seemed to EXPAND as I dug into it. Check out the huge pile in the wheelbarrow – that all came out of the 8” wide strip.

Wheelbarrow full of junk from hole.

Wheelbarrow full of junk from hole.

So in that previous post, I assumed that this area was a “depressed slab” where a future stair would be installed when/if Southwestern Bell wanted to add a third floor to the building. (By making the slab thinner, it originally saved material cost, and made it easier to remove in the future.)

What I forgot back then was that I have an old construction photograph from 1923 when the building was doubled in length. (I got the photo from an AT&T archivist in Texas.)

Here’s a portion of that photo – I enlarged what was then the “back corner” of the roof, and traced a line showing how the concrete is thicker and then thinner where I’m currently working. (You may need to click on it a few times to zoom in.)


So that’s 100% confirmation what this depressed area is all about.

Back to the demolition…

The big spinning disc was still attached to the angle grinder so I used it to cut slots into the concrete cant.

Concrete is cut pretty easily with the right blade.

Concrete is cut pretty easily with the right blade.

A few good solid whacks with the sledgehammer and the pieces came loose.

Concrete cant loosened up.

Concrete cant loosened up.

And just out of curiosity, i removed the bricks that were filling in that little arched opening, in case there was something I could learn there.

Bricks removed from old arched opening.

Bricks removed from old arched opening.

But what I learned was that the bricks at the bottom of that “hole” were lower than the adjacent concrete deck (not so great), AND, they didn’t have much mortar between them, which meant that my removal of concrete cant from that area allowed water underneath the east side roof to now seep through the brick cracks into that depressed slab area.

Time to do something about that. Any water in that depressed area had no place to go (which is why it was smelly and dark) so I needed to give it a place to go. Like lancing a boil, (yuk), I’ll drill a hole right through the concrete roof and see if I can catch all the water with one of our tarps and a big barrel on the second floor.

Ready to drill a hole through the roof.

Ready to drill a hole through the roof.

After I felt the drill poke through, the water gushed in, and I got down to the second floor as fast as I could. The heavy force of the water changed the slopes of the tarp and the first few gallons of water missed the barrel, but I pulled the tarp and held it at the right angle to direct the water into the container. When the stream slowed down, I could leave it to drip on its own.

Tarp on second floor catching the dirty water.

Tarp on second floor catching the dirty water.

So here’s that depressed area again, with the first ever purposely-made hole in the roof.

Yellow arrow points to new hole.

Yellow arrow points to new hole.

Okay now back to demolition. Seriously this time.

I started at the corner of course. I was amazed at how many bricks I could remove from the lower end of the wall and let the upper portion cantilever out. (See next pic) You can also see the new pile of bricks I started at back of the next picture.

I was surprised by the amount of cantilever holding up.

I was surprised by the amount of cantilever holding up.

Then it was time to get serious and start demolishing stuff.

As I mentioned at the beginning of this post, I have continued to look for better methods of deconstruction. On the previous wall, I started taking bricks apart with a little hammer, then an air chisel, then the “bulldog”. Well, now it was down to using the sledgehammer and pure brute force. I originally avoided this method because I knew it would damage bricks, but I think we have plenty of “good” bricks saved up, so now it’s all about saving time.

Wish I had this guy to help...

Wish I had this guy to help…

I could take a dozen swings or so and break apart several feet of wall – crap went flying everywhere. I even saw a chunk fling over onto the neighbor’s roof. Then I’d stop and haul off the bricks to the new pile. If a brick broke free of mortar and was pretty clean, I’d save it on our “good brick” pile. (Compared to the FIRST time, when I was chipping tar off every single brick, you can see how much time I was saving now.)

Bricks smashed...

Bricks smashed… (just by me)

One benefit of the “smash a little, clean a little” method was that it gave my body a break from the smashing. Though picking up bricks isn’t exactly easy, it was much easier on me than the impacts of hitting a brick wall. Every once in a while, I’d hit the hammer face slightly off-square from the brick and I could feel the kickback up the handle. Hitting it square and flat felt really gooooood.

And another benefit was that I could take some time to see what I was destroying or removing. Like in the next photo – there were some odd steel pieces embedded in the concrete.

Uncovered some more steel underneath the brick wall.

Uncovered some more steel underneath the brick wall.

I dug a little closer and more carefully. Now it looked like there were TWO vertical pieces of steel about 8” apart. They had a slight curve which was puzzling.

Now TWO mystery pieces of steel.

Now TWO mystery pieces of steel.

Well this had me stumped. I measured their distance, just by stepping off paces, to the “corner” (what’s left of the corner) because I know that there’s a second-floor column directly below the old corner of the building.

I went down to the second floor to look up at the ceiling (roof), at the same distance from the corner/column. There was a BEAM in that location along the edge of that depressed slab area. Well, these steel pieces could be some kind of stirrup holding the beam, or they could be the vertical legs of angles holding concrete, or something different entirely. But, since this steel on the roof was exactly in alignment with that beam, and the beam is crucial to the structural integrity of the depressed area and the roof next to it, it meant that I needed to leave them alone entirely and minimize any concrete removal around them.

Okay hopefully no more distractions – back to demolition…

About half done with the wall.

More than half done with the wall.

More smashing, more hauling. See the brick pile in the distance growing?

As I got closer to the end of the wall, I needed to make a strategic vertical cut along the brick. In the next photo, the yellow dashed line is where I want the demolition to stop. The corner is going to remain, but it won’t look like a corner, it will be a new end-of-wall. So if I kept smashing with the hammer, some of the bricks that tie into the wall being removed could loosen the bricks that I want to stay.

Line where I want brick removal to end.

Line where I want brick removal to end.

So I grabbed that big “spinning wheel of death” and made a full-height cut into the bricks, as deep as I can get it. In hindsight I should have grabbed a face mask – it was very dusty.

Brick cuts easily...

Brick cuts easily…

...but makes a lot of dust.

…but makes a lot of dust.

Since Sue was up on the roof taking pictures of that cutting, I asked her to stay and take some action pictures of the smashing. A few chunks of mortar came close to her head. Sorry Sue.



Tom smash MORE!

Tom smash MORE!

Since the chunks DO fly everywhere, I placed a bundled-up tarp over the old roof drain and weighed it down with chunks of concrete. If mortar or brick bits got in the drain, they could collect in a bend or trap deep inside the drain and could cause a major blockage.

Gotta cover the roof drain...

Gotta cover the roof drain…

More smashing!

Getting close to the end...

Getting close to the end…

Around the old drain, a well was constructed. I don’t know why, or what it was even made of, but I wanted it gone. So first was to cut through the tar & roofing with the circular saw.

Cutting up roofing at drain well.

Cutting up roofing at drain well.

Then I peeled it off, just like I’ve done with the roofing everywhere else. This was a piece of cake compared to the brick walls. But still hot sweaty work.

Prying off the tar & roofing.

Prying off the tar & roofing.

That well was made of a few rows of brick, with a concrete cap. Not sure why that was necessary. It came apart easily.

Just a little more smashing!

Just a little more smashing!

Just a few more whacks and I’ll have this wall totally removed. Good thing too – because my brick pile in the distance was growing close to my comfort zone… (Even though I planned the location of that pile to be right over a large beam below.)

Callin' it done.

Callin’ it done.

Essentially done for now – I’ll leave that rough edge of the wall for the masons to clean up.

So here’s a view from standing on the last bit of parapet looking out over where the low parapet and high parapet have been removed.

Overall roof view sans brick parapets.

Overall roof view sans brick parapets.

Feels good to have all of that finally demolished. But there’s still a lot to do before the masons can start their work!

6 Comments leave one →
  1. December 10, 2014 4:36 pm

    I’m an architect working on reroofing a public school building built in the 1950’s. The original drawings show raggle blocks — mostly in the relationship you have here (inside face of brick parapet wall) but sometimes the back side of the coping stone is cut with the same profile. No one in my office has ever heard of the term; neither has the roofing manufacturer’s technical department. Thanks for sharing your forensic experience and photographs 🙂

  2. Brian permalink
    February 16, 2014 7:29 pm

    raggle block. a manufactured masonry unit, usually of terra cotta, having a groove for receiving flashing.
    1880–85; origin uncertain

  3. Jim and Laura permalink
    February 16, 2014 9:33 am


    They all thought we were crazy when we started on the project build our contemporary dream-house around a 50s ranch…after following your project for the last several years; I will let you finish that…

    But seriously, I am really enjoying the story and look forward to the updates. Thanks for taking the time and efforts to chronicling this adventure.


    • Tom permalink*
      February 16, 2014 5:43 pm

      Hey Jim,
      People call us crazy all the time! Just last week I stepped out the front door, a stranger asked “Hey what is that?”, and when I answered “My house, I live here…” he looked totally befuddled.

      I’m glad you enjoy following along and I’m certain you’re the type to appreciate the detail. If you ever want to “appreciate” it up close, there’s always room for another sledgehammer!



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