footings for brick pillars and concrete grinding

[cyberhonky]

Hello all,

I'm about to embark on a carport/garage project (standard carport then panel door on front, hardi plank/weather board sides) on an existing stenciled concerete driveway. and i was hoping the experience here could help me with 2 questions;

1. carport will have brick pillars at each corner, non load bearing other than supporting the tracks for a panel type garage door. (see hyperlink for pic of carport) for a 2 brick square pillar approximately 26 courses high, what is the recommended footing dimensions? (ground here is hard clay)

http://www.aussiemade.com.au/images/...rports8lge.jpg

2. given the existing driveway is stenciled concrete and i have to make some alterations , has anyone every had (or known this to be) sucessfully ground off using a standard approach (im not too keen on having stenciled concrete for a garage floor.

Any advice or recommendations would be much appreciated.

[Wood Butcher]

Hi Honky,
In Regards to the footings I would recommend that you contact an engineer, although if you are buying the carport? the plans should dictate the footing size.

I have seen people grind off concrete stenciling with a concrete grinder available at most hire shops. I may take a while but can leave a good smooth finish.

[Tools]

I think that grinding the stencilling off would take a hell of a long time,and the surface wouldn't be too flash.You would be better to lay a new screed over the top,or rip it up and lay a new slab.

Tools

[Wood Butcher]

If the grinding is done properly it wouldn't take too long. We had to grind some high spots on my Dad's rumpus room (15m x 7.5m) because the concreter left it too long to put the helicopter over:mad:. The finish was really good, a lot smoother than I thought it would be. For a workshop I think that the finish may be too smooth unless you can get really coarse grinding blocks?

[cyberhonky]

Hi Honky,
In Regards to the footings I would recommend that you contact an engineer, although if you are buying the carport? the plans should dictate the footing size.

I have seen people grind off concrete stenciling with a concrete grinder available at most hire shops. I may take a while but can leave a good smooth finish.

thanks for the replies guys. As for buying the carport, yes i am. they dictate 500x500x500, which sounds fair for a ~100mm post (load bearing). the brickwork is non load bearing, but i'd presume they'd still need something more substantial than 500mm3 (given that the pillar themselves would be ~470mm2), but i could definately be wrong.

As for tools comment- im not overly fussed about the time it takes (it wont be my time) but id prefer to keep it, if its financially viable- as it doesnt sound right to rip up ~50m2 of concrete only to put it back down again next week. saying that though, if grinding it costs more than redoing it, its a no brainer.

Cheers- honky

[ozwinner]

because the concreter left it too long to put the helicopter over:mad:.

Ehhhh! whatsa wronga you ahh?

You noa wanna paya fora proppa joba, now youa complaina?

Alfonsa.

[thebuildingsurv]

Add 50mm to either side of pier so for 470mm pier have footing at 570mm square go about 600 deep min 100mm into firm natural clay. In regards to stenciled concrete, probably easier to pour another thin 30mm topping slab which you could put some heavy gage chicken wire in to re-inforce.

[silentC]

I'd be reluctant to top a driveway slab. It has to stand up to being driven over every day by a car. You might get away with it if you used a proper topping compound like something from Ardex but I'd check with them first to see if they have something suitable for that application and it wont be cheap - about $70 for a 20kg bag.

[thebuildingsurv]

Assuming the slab underneath is ok ( 100mm thick f62 or f72 mesh) which can be verified when he cuts it for the pads, i would see no harm in a topping slab, you could order 32 MPa with a smaller aggregate, and to be really conservative scabble the existing surface and use boncrete. I have seen this used in a commercial carpark when there where drainage issues.

[cyberhonky]

well, updates thus far. Had a guy come around to quote on grinding the slab. the 42 odd sq mtrs i wanted to keep will cost me around 2k to grind, so i'm ditching that idea. got a brickie to quote the pillars, with me suppling the bricks and the footings, i'm looking at 2.4k.

it all adds up, thats for sure.