ᐅ Garage slab not level with ground – grind down surface

Created on: 11 May 2022 07:25
X
XAMMAX2
Hello everyone,

I had my foundation slab made by someone, and it now slopes down by 4 cm (1.6 inches) over 7 m (23 feet) (I know, this shouldn’t happen).
To properly install the sectional door, I obviously need a level surface.
The foundation slab was then surface sealed, meaning it was smoothed with a round trowel, and it is quite smooth.

What tool can I use to grind down 4 cm (1.6 inches)?
Thank you very much.
B
Benutzer 1001
11 May 2022 12:36
Is the slope angled the wrong way? Or is it across the gate?
X
XAMMAX2
11 May 2022 13:09
Thank you for looking into my issue.
The height difference is not in the depth but in the width. This means the gate (not yet ordered) would already touch the ground on one side, while on the opposite side it would still be 4 cm (1.6 inches) short.
S
Simon-189
11 May 2022 15:25
Hello,

this is rarely an issue for the gate manufacturer, as long as they are informed before placing the order. You can have the bottom sections made with the required slope. Yes, it will cost a few more euros than a standard section, but grinding down the concrete slab is not really an option. Your concrete slab has at least 30mm (1.2 inches) of concrete cover over the top reinforcement; if you grind down 40mm (1.6 inches), the steel will be exposed. Cracking, rusting surface, structural issues... right?

I estimate that the modified bottom section will not cause more than 100€ in additional costs.
T
TmMike_2
13 May 2022 11:47
It looks like the structural builder was short by about 1 cubic meter of concrete; otherwise, this wouldn’t be possible. You could grind the concrete surface and create a proper primer using concrete bonding agent or a two-component epoxy resin, then level it with industrial floor leveling compound. (However, this is expensive, costing 60-70€/m2 (5.6-6.5 USD/ft2) just for the materials.) Alternatively, you could fill it with cement screed. I would recommend adjusting the gate if budget is a concern.