Garage floor upgrade - Block and Beam floor

Sorry for the slightly long explanation/ post...

We are in the process of upgrading the garage floor as part of a conversion.

Having broken/ dug up the concrete slab we found a lot of loose bricks - which I thought was weird (I'll come on to that in a bit)

Most of the material (mud/ hardcore/ the bricks) were removed to reduce floor level so that it can be built back up with hardcore + DPM + concrete + insulation + screed to meet floor level in the rest of the house. We got to the stage of compacting hardcore + sand - when the general builders returned the next day (to lay DPM and pour concrete), they found the sand was notably wet as it had rained overnight.

It then dawned on us that the bricks were there to soak water and release it slowly when it stops raining. The garage was built with the house so must have been an old method of doing things (albeit apparently not recommended/ considered ineffective nowadays)

ANYWAY, we have now decided to go for a block and beam floor (yes I know, far more cost) as we're too far in to turn back now. A few days have passed and I noticed that in some areas the water was even puddling after prolonged periods of rain.

We have a block and beam floor in an other part of the house where the extension was build during the summer so I never saw the effects of prolonged rain.

The garage has a single skin wall so the builder have suggested creating an internal foundation + engineering brick wall for the block and beam to sit on.
I know there should be a bed of hardcore, sand blinding and then DPM with a 150mm void under the block and beam floor - however should I be concerned that the water rises so much during winter? Flooding under the B&B floor may be unlikely but the water sitting under it/ rising/ falling - is that a cause for concern or normal?

I think you would need your beams laid out to take the block work within them long ways (215mm) if a car is ever going to go in there.

Not sure why engineering brick would be specified, unless the foundation is narrow - my b&b is supported on concrete blocks laid flat.

It's a conversion so no longer a garage. I've opted for engineering bricks just because the opportunity is there. Though some of the beam sits on existing/ previous wall which wasn't engineering brick.

But my question was more about the water pooling under the floor - is this normal or should I be concerned?

So because of the dimensions of the room the final beam has about a 30mm gap against the wall. (The alternative would have been to install another beam and cut down blocks etc - which seemed like an overkill).

The floor build up will have a 150mm PIR insulation before another 60mm odd of screed, and the (internal wall) is to be plastered as well which closes some of the gap - is this gap between the beam and wall an issue?