The concrete floor in our garage continues up to the door, then there's a step down of about an inch and the concrete continues for about eight inches, and then the tarmac starts. The tarmac people were I think supposed to tarmac up to the step, but they didn't.

It looks crap partly because there's a builder's footprint in the lower bit that should be covered, and there's also a gap under the door which isn't good for insulation or security.

What could be done? I am thinking some kind of tiles or stones or something laid along it, but does such a thing exist? Even a plank would be better I think.

Is that adequately described or are picures needed?

Sounds rubbish, ideally the concrete would meet the tarmac with just one seam. And without some builders footprint!

My garage has about 5 inches of concrete outside the door (continued from inside) which is sloping to stop water getting in so maybe thats what they were allowing for?

Perhaps.. it looks like it's meant to be tarmaced over but the rest of the driveway kerbs etc are all on the level of the lower concrete but not all the way up to the door.. if you see what I mean. So tarmacing to the higher level was not an option when they came round otherwise I@d have made them do it.

Would Ultracrete Tarmac do the job?

Sounds like your door has been mounted too far inside the frame or the step has been cast in the wrong position – the step is there to provide a tolerance for the door / floor and to give the door something to stop against. Also means you can't see any gaps when the doors closed. Is the house new?

It's a new build, and it looks like a cockup with the builders. The tarmac goes up to the door threshold on some of the others, but not all. It could well be that the door was intended to close against the lip, but it didn't, which is what allowed burglars to get their fingers underneath it and rip it open. The replacement door would only fit resting on the level of the garage floor which means there's a similar gap.

>It's a new build, and it looks like a cockup with the builders.<

Simple then – your recourse is to snag it with the builders / invoke the NHBC guarantee