Screeding garage floor?

[KevDIY]

Hi everyone,

I've got a garage floor thats very unlevel (some parts up to 40mm below others) and also some parts are powdery and cracked. I'd like to make it flat and also smooth enough to later paint with garage floor paint.

I was intending to level it with deep base levelling compound, but that seems very costly, it says that it requires a DPM in the subflloor (which I haven't got) and also that it needs a good bond with the sub floor (but mine is soaked through with years of oil).

So I'm now thinking perhaps a plastic DPM and then screed would be better. The roof is already quite low though so I'm hoping that a 2" depth would be thick enough (there are no heating pipes in it or anything like that).

Does that sound like the right decision, and do you think 2" would be okay for a garage?

Many thanks,
Kev

 

[softypaint]

Hi Kev, I had similar problems, in the end I broke out the old floor and laid a new screed with dpc. It's a pretty big job I know, but it's the best job in the end and you might even gain an inch or two instead of losing it. Two of us hired a breaker for the day though carting the stuff away wasn't so easy
I would lay three inches at least for garage floor, I think two inches over a wide area would crack especially if you're not sure of the existing base.

 

[KevDIY]

Thanks, thats really helpful. I'd seen things saying anything from 2" to 3" was the minumum; but I guess for supporting a car I should go with 3" like you suggest - the last thing I want is it cracking up after all that effort.

Thanks again,
Kev

 

[softypaint]

Glad to help Kev. If you decide to replace floor, I'm sure you will remember to arrange fall towards the door. Even half a bubble is enough to clear water & melting slush in the winter we may well be getting! Good luck

 

[mointainwalker]

I believe that for a garage you should not be looking at screed ( sand and cement ) but concrete ( sand, cement and stones ) with a re-inforcing mesh.

Also think 100 mm is normal, but not sure

 

[KevDIY]

Glad to help Kev. If you decide to replace floor, I'm sure you will remember to arrange fall towards the door. Even half a bubble is enough to clear water & melting slush in the winter we may well be getting! Good luck

I think I may be able to get away with that without digging up the whole floor - maybe just some of the high spots or something. With all the screed over that it should be a decent solid job, hopefully. And yes, getting a slope to the door was definately one thing I'm keen on, too. Thanks again!

I believe that for a garage you should not be looking at screed ( sand and cement ) but concrete ( sand, cement and stones ) with a re-inforcing mesh.

Also think 100 mm is normal, but not sure

Ah, thats interesting. so much for me not needing to dig up the floor..

If there's an important reason for concrete over a sharp sand/cement screed then its definately good to know in advance. Can you remember why?

100mm plus reinforcement is a bit off-putting, though; thats getting towards making a new slab really. Which I guess is an option, but beyond what I was really wanting to do - it'd make deep base levelling compound look attractive again, if I can find some that doesn't need a DPM anyway..

Cheers,
Kev

 

[mac391]

If your existing base is solid then a 60mm (2.5 inches) sand/cement screed should be fine.
A 100mm concrete screed is only necessarry if you are laying direct to earth/hardcore.

 

[KevDIY]

Thats really excellent. As it happens I was diliberating over the weekend and had decided that 2.5" over the higher end may be a good compromise if iI could get away with it. Most parts would then be about 3" or so and the lower parts up to about 6".

Its mainly the lower parts which are in poor condition too, the higher end is indeed solid and in good nick, so for once that sould work out well. I'll probably cover the bigger crevices/holes with some sand or maybe a soft mortar mix before the DPM sheet, and then screed over that.

Thanks for the advice - really appreciated.

Cheers
kev