Floor screed

[addz307]

hi there

Wondered if anyone could give me some advice, I have a rough concrete floor in my outhouse and i was going to use self leveling compound but for a area of 11.5m2 its not worth the money,

I was going to use a sharp sand and cement mix (ratio not sure) as this would work out cheaper but i only need it for a depth of less than half an inch. 

would this be possible or is self leveling compound better.

I know what im doing its just not 100% confident in what to use (if you know what i mean)

thanks adam

 

[Ferdinand]

Welcome.

 

It would be useful if you could post an introduction in the Introduce Yourself forum here:

http://forum.buildhub.org.uk/ipb/forum/1-buildhub-guide-information-about-the-site-introduce-yourself/

 

Does your floor have a damp-proof course?

[addz307]

Hi there 

 

just done the introduction on the other form, I'm not quite sure, if I get a pic would that help? 

 

Thanks for for the quick reply

[addz307]

Heres a pic of the floor

[Dudda]

I’d be afraid a half inch sand cement screed would just crack and break off. It’s too thin. Then the issue with the levelling compound is if the floor is damp that won’t last either. If the floor isn’t damp and doesn’t have a door with water getting in (ie where rain is coming in onto to the floor like some outbuildings) then this, while more expensive, is probably the best option.

Another option if the existing floor is fairly good concrete would be to hire a large grinder and just grind down the existing floor making it flat. This would be the strongest most durable finish but my only concern with this is you’re floor might be so rough it could take a long time to grind flat and smooth. 

[addz307]

thank you very much for replying I did think it might of been a bit thin myself, self leveling is the way to go then il do that. grinding would take an age plus there are a few dipples in the floor lol. thanks again 

[Onoff]

We used to use a grey powder you mixed with water, it got hot and set rock hard. We used it thin too to repair concrete bearing surfaces that trolleys rolled over. I think it was called Tero Tech or similar it was from IMG I remember.

[Jeremy Harris]

2 hours ago, Onoff said:

We used to use a grey powder you mixed with water, it got hot and set rock hard. We used it thin too to repair concrete bearing surfaces that trolleys rolled over. I think it was called Tero Tech or similar it was from IMG I remember.

 

I've seen that stuff used to repair workshop concrete floors, it's pretty impressive.  I have a feeling that something similar is used to patch up concrete pavements, too, but I've no idea what the trade name is.

[Onoff]

2 hours ago, JSHarris said:

 

I've seen that stuff used to repair workshop concrete floors, it's pretty impressive.  I have a feeling that something similar is used to patch up concrete pavements, too, but I've no idea what the trade name is.

 

It was brought in by the IMG rep about 20 years ago.  (They did some great chemicals). Proper old school he was who'd arrive with coffee and doughnuts for the buyer and whoever was passing in the office.

 

I remember he came in with some disposable plastic cups and poured some of the powder in. Added some water and I seem to remember the ratio wasn't that important. He then had us poke in an M16 bolt threads first. It got hot and had set by the time he left. It just popped out of the cup perfectly smooth. It was called something different then but think it's evolved into Newcrete. Application thickness 0 - 12mm.

 

http://www.img-limited.co.uk/product/new-crete/

 

Think I've the original tech spec sheet on a drive somewhere.

Edited July 25, 2017 by Onoff

[nod]

10 hours ago, addz307 said:

hi there

Wondered if anyone could give me some advice, I have a rough concrete floor in my outhouse and i was going to use self leveling compound but for a area of 11.5m2 its not worth the money,

I was going to use a sharp sand and cement mix (ratio not sure) as this would work out cheaper but i only need it for a depth of less than half an inch. 

would this be possible or is self leveling compound better.

I know what im doing its just not 100% vconfident in what to use (if you know what i mean)

thanks adam

 

Ive levelled a floor  at home From 50 mil down to 15 mil I used grano chippings It set rock hard Its been down about three years and is still ok 

[Nickfromwales]

As said, half inch is way too thin for sand and cement. You can lay a dry screed with fibres if the layer doesn't get thinner than 8-10mm anywhere, but you then need a particularly fussy resin primer / bond coat which cannot be walked on during application and laying. 

Self leveller with fibres is what I'd go for, but I'd be quite concerned about getting good adhesion to the existing floor as it's clearly been down for a while and is likely to be contaminated with things that SL won't want to stick to very well. Scrub the floor and soak it first with a 75% water 25% flexible tile primer, then when that's dry, say 2-3 hours, apply another coat at 50/50 ration prior to laying the SL. Have the floor absolutely saturated with the primer solution, literally soaking, and that'll help the SL to flow easily and ensure a great bond too. Never pour SL onto a dry floor as it'll just bite and not flow anywhere. 

[addz307]

whats grano chippings and do you mix it with just water. thanks

[Nickfromwales]

I'd only use an aggregate if it's 25mm or over. For the thickness you need I'd just use SL out of the bag. 

2-part SL is best, and each 20kg bag comes with a 5 litre container of add-mixture which gives you an exact mix every time. . The water mix ones aren't that good TBH and don't 'flow" as well imo, so stick with the 2-part.  

This is what I use....Link

 

[Ferdinand]

12 hours ago, addz307 said:

thank you very much for replying I did think it might of been a bit thin myself, self leveling is the way to go then il do that. grinding would take an age plus there are a few dipples in the floor lol. thanks again 

 

I put self-levelling down in a concrete floored former attached former coalhouse at the back of a terrace.

 

It was concrete(?)  floored and no dpc, and the stuff just came up again in chunks. Was an attempt at a quick solution which failed.

 

Given there was no prospect of it drying out, in the end I just put a painted on dpc down, and dropped a sheet of ply on top loose as a slight protection - knowing that it will have to be replaced before long. But it was basically a bike and tool store.

 

Ferdinand

 

[nod]

9 hours ago, addz307 said:

whats grano chippings and do you mix it with just water. thanks

Grano is very fine granite chippings about five mil I  mixed it semi dry at a rate of 4-1 with cement and used tapering bitterns 3 mtrs apart screwed to the concrete floor and simply removed them the following day and filled It sets like iron

Ive laid thousands of mtrs of semi dry sand and cement and would never go less than 50 mil

But in this case my options were limited as I needed to match to the existing asphalt I forgot to mention that I coated the floor with SBR sealer on two separate  days and also added it to the mix I waited a few weeks before tiling    Three years on no cracked tiles or loose grout

 

 

[Onoff]

I've been quite impressed using SBR instead of water to make a "resinous" mix to infill the slab where I knocked it out to get a feed to a towel rad.  Did 5:1 ballast to cement. You don't need much SBR I found. It's as sticky as but finishes ok. One side of the wall it's under the bath and the other in a cupboard in my case.

 

 

 

 

 

Edited July 26, 2017 by Onoff

[addz307]

by the sound of it a good coating of sbr is a definate and i think its a toss up between grano chippings which i can get from travis perkins fairly cheap or the ballast mix my next question is whats better at about 10mm (the only reason why i have to have it so thin is because of the door) thanks gain for all your ideas would never of thought of half of them

[Onoff]

1 hour ago, addz307 said:

by the sound of it a good coating of sbr is a definate and i think its a toss up between grano chippings which i can get from travis perkins fairly cheap or the ballast mix my next question is whats better at about 10mm (the only reason why i have to have it so thin is because of the door) thanks gain for all your ideas would never of thought of half of them

 

Some good info here ref a 1/2" thick topping using SBR:

 

http://www.kebur.co.uk/product/everbuild-sbr-bond/

[addz307]

Thanks