Salvaging 105 year old CMU block - Contractor Talk - Professional Construction and Remodeling Forum

BjR · 09-01-2009, 04:25 PM

Hi guys,
I just joined this group today in hopes I could tap into the collective wisdom of your skills and trade. I'm a remodeling contractor in Seattle with an interesting and perplexing problem project.
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 adjoining blocks to pieces or damaging the edges?
Same with the wall caps?
I've tried a cold chisel. I bought a diamond Carbide sawsall blade and will try that tomorrow. But a grinder and a Skilsaw with a diamond blade on it won't go all the way through the grout joint to free it completely because of the chamfers on all the edges only allows about 2 inches of penetration into the grout joint. Entertained using a 3/16" rotohammer bit between the blocks to make some relief cuts in the grout joint but I'm afraid 3/16"(which is the smallest rotobit I can find) will damage the chamfered edges.
Any ideas would be appreciated.
Pic's attached:
Thanks
BjR

rombo · 09-01-2009, 04:40 PM

Possibly a concrete chain saw with a really steady hand.

BjR · 09-01-2009, 04:54 PM

Concrete chain saw?
That's a new one for me......
Got a link to a specific product?

rombo · 09-01-2009, 04:58 PM

icsbestway.com

4th generation · 09-01-2009, 05:29 PM

The last pic looks like a free standing wall, does it come to an end there or does it have a return corner? can you access both sides ? do you know if the blocks are hollow core? If its a freestanding wall with a free end then work at removing from that end with making a purchase point with a chissel then either wedge them out with wood wedges or remove with crowbar, if you have to take from the middle of the wall and can access both sides then run a cut of saw through the middle of the joints & use a hammer & bolster to remove the remaining mortar from the top & bottom /sides of the joints. Why cant you make some shop drawings and send them out instead? I've never used a concrete chainsaw so I cant say anything except would it make too wide of a cut?

BjR · 09-01-2009, 05:29 PM

Thanks, I found a local dealer and called them. The chain appears to be too thick to go between the grout joints and not potentially damage the edges. Not to mention that it looks like a scary machine that would be like using a shotgun to swat a fly.
Good link and info for other occaisions though, thanks.
BjR

BjR · 09-01-2009, 05:41 PM

Quote:

Originally Posted by 4th generation

The last pic looks like a free standing wall, does it come to an end there or does it have a return corner? can you access both sides ? do you know if the blocks are hollow core? If its a freestanding wall with a free end then work at removing from that end with making a purchase point with a chissel then either wedge them out with wood wedges or remove with crowbar, if you have to take from the middle of the wall and can access both sides then run a cut of saw through the middle of the joints & use a hammer & bolster to remove the remaining mortar from the top & bottom /sides of the joints. Why cant you make some shop drawings and send them out instead? I've never used a concrete chainsaw so I cant say anything except would it make too wide of a cut?

The one pic of the wall caps and the CMU block is free standing but the HO doesn't want to take the sample from there. (Already tried to talk him into that.) The location where I will remove it from however does have access to an end section because it's an abandoned window well but tough access for a 55yo guy like me to bend over upside down to work on it and I do have access to the back side of the blocks as well.
The fabricator would prefer an actual block rather than shop drawings. The HO is an architect too but apparently the fabricator won't guarantee the accuracy of the fab'd blocks without an actual sample.

dakzaag · 09-01-2009, 06:41 PM

4" angle grinder and a 7or 8" diamond blade.

gloves, mask, eye protection,

done in 15 minutes.

Special recognition to tkle for that tip from the archives.

Tscarborough · 09-01-2009, 07:05 PM

You are going to ruin some blocks no matter how you do it. I do not see the problem though, since you are having replacements made?!

If it was my project, I would make them onsite like the original builder did at a cost of a couple bucks each instead of what the out of state fab guy is going to charge (10-30$ each, plus freight?).

Rockmonster · 09-01-2009, 08:30 PM

I agree with Tscar....make onsite fairly easily...few pieces of off the rack moldings....The chainsaw would work as well....you can make a jig that would act as a guide, clamp it on the wall....plunge or let in...they are not as beastly as you may think, and the chain could be kept in the joint with care. Pretty cool project-let's see photos of finished product.