Concrete Walls

[Fluesheet]

The space for the layout I'm currently planning was slightly too tight for what I wanted to do, so I've decided to tunnel through my basement's concrete block central bearing wall in several places to eliminate some against-the-wall turnback loops and to gain access to more real estate.

(This "natural" barrier has been christened "Wall Ridge" )

I'm curious what experiences others may have had with this type of work (whether for a model railroad or not); that is, best practices for actually doing the tunneling. What types of tools have worked well, how keep concrete dust under control, other potential hurdles, etc.

I've done smaller openings for electrical and communication boxes by drilling holes in the perimeter of the space I'm excavating, then knocking the center out with a chisel. It worked, but was rather slow.

I've also flirted with the idea of having HO scale workers pick an inch or so out per day, but I figure that "fun" would wear off quickly...

Thanks,

Matt

 

[nachoman]

I'd go for the chisel. But what do you if you hit a piece of rebar?

Kevin

 

[doctorwayne]

For drilling holes in concrete block (no re-bar in blocks), probably one of the best tools for the average homeowner is a hammer drill, with a proper bit, of course. If you don't own one, they're not too expensive to rent, either. Try to place the "tunnels" where they won't run into one of the block's internal webs: some blocks have two (in addition to the ones at or near each end), while others have three. It's unlikely that you'll encounter any solid blocks (all concrete, with no internal voids), but they do exist.
The other option might be to remove a complete block, using a hammer and chisel on the mortar, then cut the removed block with an abrasive disk, and replace the re-sized piece(s), leaving only the "tunnel" area open.

Wayne

 

[nachoman]

Oh yeah. I'm thinking of areas with seismic requirements - that have rebar in and concrete in some of the cells

Kevin

 

[MasonJar]

I'd recommend you rent a drill, and buy the masonry bit. My local Home Depot has hammer drills for rent, and for an extra $1 per day, you can add $0 deductable. That way, if you kill it, you can take it back and drop it off no questions asked.

Depending on the size hole you need, you could possibly go for a hole saw, or drill multiple holes and knock out the middle as you have done previously.

Good luck!

Andrew

 

[Fluesheet]

probably one of the best tools for the average homeowner is a hammer drill, with a proper bit, of course.
Wayne

Good idea doctorwayne and Masonjar. Most of my previous efforts have been with a non-hammer drill. I used a hammer drill in concrete a long while back, and now reminded of that it was much quicker.

Try to place the "tunnels" where they won't run into one of the block's internal webs:
<snip>
The other option might be to remove a complete block
Wayne

Unfortunately, all the tunnels will be on curves, so I have zero chance of avoiding a web! :mrgreen:. However, removing a block is a great idea. From what I've seen of the block work (from my previously described forays), there's a good deal of concrete on the interior side of the seams, so chiseling would be tough. However, doing the same with a circular saw (with masonry blade, of course) is another option.

Depending on the size hole you need, you could possibly go for a hole saw
Andrew

This I'm also curious about - less dusty than a circular saw, probably faster than a chisel with the advantage of smooth cut edges; i.e. less block damage. Now whether the make these that will cut a large enough hole to the depth I need is worth researching.

Another option popped up this weekend; on my current design, two tracks tunnel within a foot of a door opening in the wall. I had a discussion with my brother yesterday about widening the doorway so the rails would go around the end of wall ridge, as opposed to through it. He's fresh off cutting a new doorway in a solid brick bearing wall, so this seems to be a no brainer for him :thumb: But the dust!

I appreciate the feedback; any more is certainly welcome.

Matt

 

[MasonJar]

You should be able to find a hole saw up to about 6 inches - or maybe more. This size is sometimes used to put a dryer vent through the foundation.

Andrew