DPC and Screed or Concrete Garage Floor


22 Apr 2006
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West Midlands
United Kingdom
I have two questions......

We need to raise the garage floor up by an inch or so to be level with the driveway outside. The front of the garage, where the door is, would then be 2 bricks below DPC level, but the back of the garage would only be 100mm below DPC. This is because the existing floor is sloping upwards-

1) - We know that the ground level has to be 150mm (2 bricks) below DPC, but would this apply to an internal concrete garage floor that has no DPM?

2) What material would we use to do this screed or concrete?

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The floor is intentionally sloping away from the "back" of the garage towards the garage door - this is a Building Regulation (I assume there is an internal door adjoining the garage and house).

DPC/DPM levels/issues aside, is it your intention to "level" the garage floor?
No, our intention is to keep the slope but if we increase the floor level at the front (by the garage door) by an inch and a half, then we need to increase the back of the garage, thus making the gap between the garage floor and the DPC level at the highest point 100mm.
However, the front of the garage would remain 150mm below DPC.
OK. The fact that you intend to keep a fall is good. The fact that increasing the height of the garage floor will leave it 100mm below DPC in places as opposed to 150mm is negligible. In fact due to it being in a "sheltered" location you could push it closer if required IMHO.

The main problem you have is getting a stable substrate @ 25mm-40mm that will hold up to traffic at that minimal thickness, because a traditional concrete / screed mix will not work. At that thickness it will just break apart when trafficked. I'll have a think........
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OK, thanks for the advice so far.

If you can think of a solution, that would be a great help!
I think you will have to look into resin screeds, but that could get £££££. Maybe Ardex do something you can use @ 25mm/40mm depth - I'm not sure. I'll have a dig around their tech specs. What m² have you got to cover?

I think oldun's pretty clued up on screeds maybe he'll have some other suggestions.
Allowing 10% for waste / contingency you need ~ 0.6m³ of screed then to cover 13.5m² at average depth of 40mm.

Just found this on Ardex's website which says it can do 15mm-40mm which would be ideal for you. Need to rush off now but will have a gander through the specs later and post back if I get chance:-


Thanks for all your help and advice so far.

Had a look at the technical data sheets and am I right in thinking the Ardex FastTrack EB2 would be the better option due to it's higher strength. Would I still have to use the Ardex B2 as a bonding agent to the existing concrete floor?
Yes, I came to the conclusion that Ardex EB 2 was the correct product out of that lot for your requirements, because you can have a 20mm-40mm screed and it gives you the additional strength you require. If you use it a 1:4 ratio with sharp sand it will suffice for heavy loads according to the tech specs.

So for 0.6m³ you will need 800kg of sharp sand (grab bag) and 8 n.o 25kg Ardex EB 2. Might not work out too expensive after all. Specs say to use Ardex B2 bonding slurry - I would use it, but then I'm not familiar with the product, so would always follow MIs. They are always trying to make extra £££££'s. Really depends on the condition of the existing floor, give Ardex a call they're very good:-

Thanks for all your advice, really appreciate it. I'll give Ardex a call on Monday and double check about the B2 slurry mix.
No problem. Let me know how you get on, I would be interested to know.

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