Talk to me about drilling concrete?

November 22, 2023 7:54 AM

I have a pen and shed on a poured concrete base which is very useful aside from a complete lack of drainage. Here is a photo, with sheep tax. I would like to drill or otherwise bore out drainage channels along the back shed wall and pen fencing so that both pen and shed will drain into the field behind. I have no experience with drilling/chiseling/otherwise destructively modifying hardened concrete. I do have a solid hammer drill, safety goggles, sturdy work gloves, and proper ear protection. What do I need to know to tackle this safely and effectively?
posted by Rhedyn to Home & Garden (8 answers total)

First thing I'd do is get the floor completely clear of all loose bits, then pour a cup of water on it to see which way it wants to flow. Not much point breaking up concrete along the back if it actually has an imperceptible slope in the opposite direction.
posted by flabdablet at 7:59 AM on November 22, 2023 [2 favorites]

Response by poster: Thanks flabdablet, I should add that I have years of frustrating experience hosing it out and then using a yard broom to sweep the water out and through the pen to the field, so I do know the water already tends to collect to the back corner of the shed and along the back edge of the pen.
posted by Rhedyn at 8:04 AM on November 22, 2023

Something else to know is that any drain hole smaller than about two inches in diameter will get clogged up faster than seems credible.

If I needed to smash a built-on corner of a thinnish slab to let water out, and the concrete resisted my attempts to break it with a fencing bar, I'd rent a jackhammer rather than risk letting the magic smoke out of my hammer drill by trying to drill holes bigger than it was good for.
posted by flabdablet at 8:14 AM on November 22, 2023 [2 favorites]

I had a similar situation on an old garage and looked into options then, but in the end we sold the place so I didn't do the work. With that caveat, some thoughts:

A drainage channel (probably with a grate on top) is going to work a lot better than individual holes and will be easier to clean. That would mean saw-cutting the channel, which is noisy but not typically difficult. (It's likely not a concern with a small shed like that, but do give thought to the structural integrity so you don't inadvertently cause yourself larger problems.)

You may also want to cut drain grooves in the floor leading towards the drain across the back wall -- also saw cut.

It's not clear to me from the photo how large the shed is, but you might find it easier to either move or jack up the structure, then remove the old floor slab, and repour it with correct slope and drainage, versus the labor of retrofitting what you have now.
posted by Dip Flash at 8:32 AM on November 22, 2023 [1 favorite]

Best answer: I've done literally hundreds of metres of this. After setting up my line I used a concrete saw to cut two parallel lines the width of my channel - more lines between is good too as it lightens the work, and then an appropriate size small jackhammer to break out between the lines, using something like this, but more like 2000 Watts, with a chisel tip. Your own drill won't cut it. This is a rental tool job.
posted by unearthed at 9:05 AM on November 22, 2023 [9 favorites]

Response by poster: Thanks unearthed, it might actually be worth me buying the tool if I can also use it for removing inappropriate concrete pointing from stone walls, which is likely to be an ongoing rest of my life project. Would I do better to look at one of these SDS drill + SDS chisel, or one of these actual demolition hammers in your opinion? If it's good for both jobs I'd consider up to £400 I think.
posted by Rhedyn at 9:24 AM on November 22, 2023

You want the actual demolition hammer. I've used one side by side with an SDS drill and bit and the demo hammer was much much much faster. It has more weight to it.
posted by MonsieurBon at 9:50 AM on November 22, 2023 [3 favorites]

Yeah, if you're going to break concrete and you don't want the concrete breaking you, the tool you need to use is going to need to be about the size and weight of your leg, not your forearm.

Hand tools are good for making small holes, not big drains.
posted by flabdablet at 9:53 AM on November 22, 2023 [1 favorite]