‘Steel trowel finish’ bull float query

[dangti6]

I’ve had a concrete slab laid.

 

The quote stated:

The slab will be left with a smooth steel trowel finish.

 

They went over it with a vibrating bull float, troweled the sides against the walls and then went over with a smaller manual bull float.

 

They have finished up for the day. Water is currently sitting on top and a search suggests that this is supposed to be allowed to evaporate before going over with a trowel.

 

Before I raise, can using a bull float be classed as a steel trowel finish or have I been quoted for a level above what I’ve been left with?

 

 

 

 

 

 

[markc]

Bull float is technically a steel trowel finish, really depends what the finished floor will be....an industrial floor will be left as is so power floating would be done a few hours later .

[dangti6]

It’s only a garage floor. I’m going to probably epoxy resin over it at some point.

 

Appears there was an error in the labour element of the quote and invoice being amended accordingly. They did offer to send someone back if I wanted it smoother than was left with the float.
 

The new concrete joins existing so if the new was super smooth it would still sit next to mediocre existing so the suggestion is to have the lot ground in 8 weeks time which may be a good shout if I decide I want it more uniform. 
 

 

[Gus Potter]

11 hours ago, dangti6 said:

I’ve had a concrete slab laid.

 

The quote stated:

The slab will be left with a smooth steel trowel finish.

 

They went over it with a vibrating bull float, troweled the sides against the walls and then went over with a smaller manual bull float.

 

They have finished up for the day. Water is currently sitting on top and a search suggests that this is supposed to be allowed to evaporate before going over with a trowel.

 

Before I raise, can using a bull float be classed as a steel trowel finish or have I been quoted for a level above what I’ve been left with?

 

 

 

 

 

 

Ah.. dangti6.. can of worms here in terms of floor slab tolerances, quality and variations in level. I have attached a copy of a report that was published on the web that is very informative. It deals with floor level tolerances and flatness. A floor can be flat but not level! Many domestic contractors say a slab will be smooth.. but..!

 

For all.. it's well worth a read if you are into ICF, basements, floor slabs etc. Page 5 onwards could save you a lot of grief. Credit is due in full to Combined Flooring Services Ltd and the author Martin Rogers. 

 

I have found this report to be a very handy reference document. Thank you Martin if you are reading this.

 

If your slab is a structural slab then it is important to control the thickness and variation in thickness. This is where control over the level top / bottom and finish is important.

Floor_level_flatness-survey.pdf

Edited May 7, 2021 by Gus Potter

[dangti6]

Thanks Gus - another British Standard to keep in my back pocket for when the pubs fully reopen ?

 

 

[dangti6]

Stuck my head out to see how it’s looking 24h later.

 

Certainly right about flat vs level. Garage door seal will need some adjustment as it’s slightly higher in the centre. Sunlight makes it look worse than it is, but still frustrating.

 

 

The surface water has dried and left a powdery top layer due to the ‘cream’ I’d assume. Some air bubbles also.

 

 

I have brushed some of it off - not sure whether I should wait until it’s cured further to do that or not. 

 

There is one poor area here:

 

 

Again not sure whether to do anything with that now or not in terms of damage limitation - is what it is now unfortunately.

[saveasteading]

You might be surprised how much variation there is in levels of big commercial slabs. eg in a retail warehouse it may look  very flat, but very likely would hold large puddles if wetted.

There is an official test for such buildings in which a 3m straight edge is laid anywhere on the slab and there should  be no more than 3mm gap at any point. There is then some tolerance on how many such can be  acceptable.

To get better than this you need to grind the floor down after, and it is not normal, as hideously expensive..

Other building types allow bigger variations.

I have not seen your floor, but do not panic, it is probably fine.

 

3 tests for your own satisfaction, best when builder not around.

1. throw a pound coin into the puddle. If the top sits dry above then really, is this an issue?

2. gently roll a golf ball in different directions and see if it deviates a lot. Expect it to curve this way and that, but not to accelerate, or to spiral into a low spot.

3. try the straight-edge test but first  you have to find a really straight edge.

 

I have been talking above about buildings with vast open floors. Presumably you will have smaller rooms, and the variation won't matter so much. and floor coverings also reduce the issue

 

[Ronan 1]

21 minutes ago, dangti6 said:

Again not sure whether to do anything with that now or not in terms of damage limitation - is what it is now unfortunately.

Need to let it cure fully now I'm afraid before you look at it .

[dangti6]

6 minutes ago, saveasteading said:

You might be surprised how much variation there is in levels of big commercial slabs. eg in a retail warehouse it may look  very flat, but very likely would hold large puddles if wetted.

 

The document Gus posted raised an eyebrow as I have just brought in a couple of high reach pedestrian stock pickers and had a load of racking installed in a warehouse. Floor looks spot on but wonder how flat it actually is.

[saveasteading]

Ahh. firstly I see it is a garage, so not exactly warehouse spec.

 

The powdery top is a surprise. The 'fat' that comes to the top should be very hard after  few days, not loose and powdery This looks to have been a very wet mix.

 

Builder should at least brush then stone rub this back to hard surface (not yet)

 

The gap under the door happens a lot, and is a nuisance. I have had scores  of loading doors put in and this is a tricky thing.

My solution was to have the slab on a slope at that point so the water runs away. Too late for that.

option 2. stick some softer rubber under the one supplied, so that it can squeeze to shape.

option 3. fix down a threshold, so the water stops outside, and mastic at the edges...

 

[saveasteading]

Dangti6.   High reach, say 10m or more, with skinny stock pickers, is where the floor might need to be ground flat. 

In 300 new commercial buildings we only did that once.

You are probably ok, but try my suggested tests.

Racking bends to suit, and there is as much variation at every joint as in the floor.

[Ronan 1]

33 minutes ago, dangti6 said:

The document Gus posted raised an eyebrow as I have just brought in a couple of high reach pedestrian stock pickers and had a load of racking installed in a warehouse. Floor looks spot on but wonder how flat it actually is.

I think most of the issue with commercial floors is the people specifying the finishes/ tolerences not understanding what they need I've laid alot of "superflat" floors for 14m high racking and nearly always had to have an argument with the client/ engineer over what is spec'd against what they actually want. Got to pick your Sr level or FM level correctly but problem is most want FM1 or SR1 finished but don't want to pay the premium for it.

 

Same but reverse for domestic floors you have very little comeback unless you spec a proper finish just expect to pay accordingly 

[saveasteading]

Agreed. The tech document being in simple form is very useful. Easily resolves the argument, but doesn't make the client happy who wanted it both ways.....or to avoid paying. Or as likely was being misadvised by consultant. 

[Ronan 1]

2 minutes ago, saveasteading said:

Or as likely was being misadvised by consultant. 

?

[Oz07]

Tilemaster do an external self levelling compound suitable for a wearing surface. My last garage was mint but this one I caught a cold with different batches of conc needed. The flatness is still good but the finish was dog poo so sealed with that.