Ventilation on suspended concrete floors

[eandg]

Needing to confirm the number and location of periscopic vents asap before groundworkers' brickie is out. Scottish Building Regs require:

 

 

Presume it's floor area for the ground floor only? A standard 220x215 vent like this appears to give 6600mm2 air flow so by my reckoning my 14m wide walls would require 4 on each side (1500x14/6600=3.18). Is that right?

[nod]

I did ours at 1800 apart 

and left letter boxes out of the internal support walls 

[ProDave]

Our house has 8 along an 11M wall, so either mine is over ventilated, or yours will be under ventilated.

[eandg]

10 minutes ago, nod said:

I did ours at 1800 apart 

and left letter boxes out of the internal support walls 

 

Is the letterboxes just belt and braces good practice? Can't see anything on the regs but would appear to make sense and allow airflow through. 

[nod]

No you definitely need them to circulates the air and in case of flooding will stop the water getting trapped 

I also added a drain with a none returned valve 

Thatme looking miserable spreading four cube of concrete on my own in the rain 

Real simple I chopped a concrete lintel up and left a couple of bricks out 

 

[TonyT]

Plus one on the letterboxes.

[Dave Jones]

you cant choose randomly it will be specified on the the beam drawing so check it.