Moderators: Random Orbital Bob, nev, Noel, Charley, CHJ

By tim_n
So a few things are about to happen to my workshop.

First of, it's being knocked down. It's being replaced almost exactly the same - about 4ft longer and with foundations and a proper concrete base, slightly higher roof, less rotted door & non lethal electrics.

Plan is to leave all my gear out of the garage until I've got all the basics in place. One of those basics is a decent paint job (maybe not paint, maybe resin etc) on the bare concrete to keep down dust. Any suggestions? Any interest in a vblog or just some pictures?
By novocaine
I'm thinking of doing similar so I'd be interested in what you do.
are you replacing the slab completely or tieing in to increase the size?
By screwpainting
Hi Tim, regards the floor Finnish. There is a way of getting a very smooth rock hard surface onto either concrete or a thick or thin bed screed. Once you have poured the slab and its at the stage where it is just starting to stiffen up, either dust it with straight Portland cement which will take up a degree of moisture from the mix, or if the mix is a little dry (like a typical sharp sand screed) mix a slurry of neat cement and water and pour this onto the surface. You then simply need to trowel either application flat and smooth. You ideally want about a 3/4mm thickness of neat cement to ensure the surface will hold up to long term abrasion, but a little thicker won't hurt, just not much more than about 6mm. We used to tile Supermarket floors using this method and I have always applied a cement slurry to any screeding I have done in the past, it stops them from dusting up and the surface from wearing during any work done on top of them. You will not believe how strong this surface is and how cleanable the finish is and if you get it right, it wont need paint or any other sealer etc. You can literally wash a floor laid in this way and for a basic workshop it is well worth the cost of a couple of bags of dust and an hour or so with a decent laying on trowel.

Nothing to lose on the day of the pour or as it is screeded and you can end up with what is very similar to a granite floor. You don't (or should not) need expensive leveling compounds etc if you are involved at the initial laying stage of a floor, just a bit of knowledge and a smidge of skill.
Just pay extra attention to your shuttering, get that completely spot on and float off of it with a good straight edge and its a piece of pizz.
By tim_n
Thanks for the advice, I'll raise it with the builders I have doing this bit of the build.

It's a complete rebuild - there's no damp proof membrane on the floor so rising damp and cracks haven't helped keeping the dust down. Saw no point painting it when it was so cruddy to begin with.
By colonel-cueball
I did mine last year, mixed the concrete by hand (with the aid of a mixer)
4-5" thick, 1,2,4 mix, levelled with a batten, let the water vanish off the top and trowel smooth, not had any dusting issues (well apart from what blew in under the door and what falls off the car (workshop / garage) Mine was laid in 3 pours to make it more manageable to do, its also helped as its cracked exactly where the pours meet and only hairline cracks.
Lot drier inside (albeit took a while for the humidity to come down inside the garage while the concrete cured out)
Now even on damp winter days I'm running 70-80% humidity inside, and no more wet spots on the floor every time it rains
I'd let the builders get on with it their way, from being a sparky, there is nothing tradesman hate more than joe public giving them "advice", put it this way - you wouldn't give your dentist advice on how to do his, would you? If you doubted his skills, I'd hope you'd find a different dentist, same with tradesmen, if they look and sound like they have no idea what they are doing...chances are they don't.....