I’m doing an addition on a 105 year old mansion that is on a historic registry and the HO wants to maintain the architectural integrity of the house with the new mods. The foundation is a CMU block that is odd sized and has chamfers on all edges. The wall caps are made from cast concrete.Problem #1 is we can’t find a CMU block or wall caps off the shelf to match so we are looking at having them custom made to match. We have this dialed in/no problemo.
Problem #2 is we have to remove one of the existing blocks and wall caps and take it/send it to a fabricator out of state.
Question is: anybody have any great ideas for removing a CMU block from the middle of a bearing wall without busting it or adjoinging blocks to pieces or damaging the edges?
Same with the wall caps?
Pic’s attached:
Thanks
BjR
Replies
Why in the middle of the wall? Just go to a corner of that wall and locate a "half" block. Best way to remove blocks is to cut the motar joints with a saw. Once the joint has been "sawn", use a pry-bar and gently pry up the blocks. Mortar is weaker than the concrete block, so attack only the mortar joint itself. IF you do crack the block make a replacement for it and put that back in it's place.
Best way to remove blocks is to cut the motar joints with a saw
In the past, I've used a diamond blade on a grinder, working from both sides, with good success. Had to replace a damaged block in the middle of a wall.View Image bakersfieldremodel.com
The idea is we're trying to remove a full one intact that is going to be used to make a mold for the new ones. Grinder doesn't go all the way through the 10" thick blocks even from both sides so there's still mortar out of reach with grinder wheel. Thought about a gnarly,dead sawsall blade tonight and will try that tomorrow. Other ideas have been suggested have been to use a 3/16"x5 " rotohammer bit and make relief holes in the mortar joint and try my damnedest not to stray onto the block itself.
sawzall makes a diamond blade also - for finishing up the vertical cornersView Image bakersfieldremodel.com
Why not take a reverse casting of the existing block and cap, and use that to create the mold for the new ones?
View Image
"Why not take a reverse casting of the existing block and cap, and use that to create the mold for the new ones?"
This was my first suggestion but the casting company requires the whole block and the HO feels more comfy sending them the whole block too to get as close to exact as he can.
I'll see if I can find this diamond Sawsall blade locally.
BjR
do a cast in place concrete wall with the right mold chambers on the inside of the form.
You might try and see if you can get this brick/block saw in the US somewherehttp://www.masonrymagazine.com/4-06/saws.html'Man who say it cannot be done should not interrupt man doing it' ~ Chinese proverb
View Image
Might this work ... ?
http://www.readingrock.com/rockcast/product.aspx?productid=78
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Yeah, that was my thought. There are rubberized casting materials that would probably work pretty well: Paint on a release, paint on the rubber, apply a burlap backing and more rubber, peel off when set.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
There is a company that makes a saw specifically designed to cut out mortar joints in brick and block.
Rather expensive, but it will do the job.
I think those CMUs would look great with a nice flat parge coat to match your new work. Problem solved and at a lot less cost.
Sometimes older isn't better its just older.
That sounds like something my woman friend would say.....
They can't get your Goat if you don't tell them where it is hidden.
Well, somebody has to say it - we always do - Multi-Master ! ! !
Greg
I'd make my own forms for these blocks and cast one each. Take these to the block supplier and say "Here ya go." I had a great-uncle who wanted to build a garage, about 20 x40 in size. He MADE his own forms for the blocks to build the walls for his "little shed". Cast every block and laid them up himself. That "little shed" still stands today, 70 years later. Your forms would have that champfered edge top and bottom, plus any "voids" in the center you want. The cap block would also have the strips, top and bottom, to mimic the cap block. Seem to me this would be a lot easier than trying to remove the originals out of the walls.
For sawing them out you might contact the local concrete cutting specialist and see what they have in their toolbox. The chainsaw is probably too thick, but they might have a large circ blade or some such.
looks like cut limestone block. you should be able to get a form liner to match that. it may cost you alot of money to have costum CMUs made. i would do a cast in place concrete wall with a form liner to match existing. might be cheaper to go that route.
man o man, where have i been all these years
Carnegie Mellon U, core memory utilization, change management utilization, charismatic/mortician/undertaker, etc. ; then to see the pix and guess its a concrete molded underpining, aka cinder block, cement block, press block, etc. heard of those but not as a cmu ....
really, never heard or seen'em referred to as CMU before..... say what???
can't tell if you are joking or not, if not : Concrete Masonry Unit though some say it means Concrete Modular Unit
They can't get your Goat if you don't tell them where it is hidden.
Arbortech Brick and Mortar saw:
http://www.toolsnob.com/archives/2007/05/arbortech_as160_brick_and_mort.php
"Arbortech Brick and Mortar saw:
http://www.toolsnob.com/archives/2007/05/arbortech_as160_brick_and_mort.php"
YES...........YES........
Thank you. Iwas sure somebody had to have thought of this problem before.
I'll try to find one locally.
Thanks
BjR
Just bid it into the job :)
"Just bid it into the job :)"
The beauty for me is it's T&M.
Thanks for the link.
BjR
I suspect that the reason they want an original block and that casting off the wall itself is a waste of time is that they have to dimension the block to consider curing shrinkage as well. They'll take dimensions, make a block maybe 2% oversize and see if it cures to match the size of the sample.
They could do the same thing with the casting.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz