Hi,

Just looking for suggestions that I might not have thought about.

I've been trying to cut a pit into my garage floor and so far after making a huge amount of mess have managed to cut just 4 inches through the 8 inches of the floor with my large petrol stihl saw, tbh I was quite disappointed at my lack of progress after so much work. In a good and bad way the concrete is a really hard grade and is back breaking to do any thing with it such as a hammer & chisel or just whacking it with my sledge hammer, which just bounces off! I actually started this about a year ago and gave up, I was also annoyed at just how much mess it made of everything in the garage. However as I am currently in-between projects and the garage is not being used I thought this a good time to revisit this and see if I can find a solution.


You can see i the photo I have cut the floor into sections with the hope I could just smash them up with a hammer, ha fat chance of that! It's about 15 years ago since I built the garage and just can't remember if I even used any rebar. So what are my options now? all I can think if is to hire a jack hammer...


Suggestions appreciated

Ideally you would want to cut through in one go. Then attach some anchors to the sections and pull them out (engine crane or chain hoist would be good candidates for this as the sections still seem large).

But 8" is rather thick. Not sure you can go this deep. If not, then a jack hammer seems the only option to widen the cuts allowing to cut deeper.

Last year I had to make a smaller hole (about 10" x 40" with HDPE hoses in it which had to remain in tact. Also about 8" thick. It has taken me a good few days with an angle grinder and hammerdrill (with chisel on). I wasn't able to use heavy machinery and had to cut out stone by stone. Just saying this approach isn't going to work for your section.

Last time I had to cut a hole in a concrete house floor, I just bought a massive concrete breaker from screwfix. £150, peak impact 50j, which is ten times more than most sds drills. It was absolutely insane, the concrete seemed to explode in front of it. I don't need it anymore, but being in Leeds isn't much use!

Another vote for buying a kango rather than hiring. When refurbing my house, I hired one which got 10 mins use, a few days later a similar job, so bought one, about £125 at the time. It got used about a dozen times, mostly only for a short time. It has been lent to friends many times since.....
They also turn up used pretty regularly.

ok I've just bought an electric jack hammer and will give it a go. Got new neighbours moving in around the same time as its delivery, so should set a good impression with them

Was thinking it might be a handy thing to have around after blowing up the last smaller hammer drill and sods law I'll need it to breakup boulders encountered when digging down!

Thanks for the advice

I have one of the titan breakers from screwfix (£150) which has taken mega abuse for 5 years. I've got through thicker than 8". Once you have a hole all the way through it'll get so much easier as the bits will have somewhere to go and not be held in tight. A bit like digging a hole, once it's started it's so much easier.

I hired a kango years ago to break up a really thick greenhouse foundation. It's so satisfying you will be gutted the job comes to an end.

You will have that done in about an hour!!

No idea what it would cost to hire, but when I had a floor cut in our workshop premises to put a sunken 4 post ramp in, they had a large, walk along concrete cutter which had about an 8 or 10 inch cut on it & IIRC had water sprayed at the cutting site, so made very little mess, other than sweeping out water.

Once cut round the edge, they were able to break out fairly easily with normal jack hammers, might cost more, but could save a ton of aggravation?

as others have said hire a jackhammer. it us great fun. i took some concrete stairs out and its deeply satisfying . luckilly a mate is a builder so i borrow his, but would probably worth buying one at £150

I went the other way....!

Instead of filling the pit, I went for a HD bearer beam and block approach, leaving the void clear and clean underneath should anyone wish to reclaim the pit. Great pit, huge, commercial vehicle size, dry, nice and deep. I lift the race car with a gantry, so the pit was more of an awkward feature than a useful one.

Nevertheless a recess had to be cut to support the bearers, for which I bought an Evolution 230mm concrete cutter. Then a lot of breaking out (suprisingly solid material) with a Clarke Demolition Hammer. Both tools were circa £150 or so, and have been used for several jobs since, mainly breaking and cutting flag stones (etc.). Dust mask, googles, visor (with ear defenders) and a Clarke air mover and duct are always used as additionals.

I've never had a great deal of success hiring tools, buying has always been preferable, given early experience of the dire state of some of the rental offerings.


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Well my new toy arrived and 20 mins later broke through the floor amazing tool, still hard work but very effective. Now I have an edge to hack away at...

02GF74 has reminded me to install a ventilation system to flush out settled exhaust fumes which is very important. I had a pit a very long time ago and we use to leave the boards off and the garage doors open to flush it but a fan system will be much better.

Turned out I had indeed put rebar mat in it but it seems to have sunk to the bottom of the mix and is quite thin so not an issue. Now I have many weeks of hard graft to go but certainly a good start

Success not bad going and still quite a bit of effort but that's the concrete removed and down to the subsoil, now the real work begins

Totally recommend one of these electric jack hammers, simply would not have been possible to get this far without it..