What does this distance mean in architects drawing?

[r_c]

Hello,

I am trying to figure out exactly what is meant by two notes on an architect's drawings. The drawing shows a cross section of an extension being built. They show a distance of 2700 and 2450, but I am not sure if they say "Min 2450" or "WDM 2450". And what does WDM stand for? I am confused as I am not in the building trade. Or does it say "NOM 2450"?

I am asking as it does not look to me like the beam/structure/building has been built to these measurements, and the architect has signed off of the building work. So I'd rather hear your opinion before speaking to the architect.

Thank you

20160807_115248 (1)

• r_c
• 7 Aug 2016

 

[wessex101]

His "N's" look a bit like "W's" so I'd go with "NOM" which would explain why the as built dimension is different.

 

[Hugh Jaleak]

I'd go with 'Nom', as in nominal distance. Seems the exact distance couldn't be given at time of drawing, as this seems to depend on the size of the beam required, which was to be decided by the Structural Engineer, and the finished floor level.

 

[r_c]

Thank you both. So would you say that I should read nominal as "roughly 2450" or should it mean "minimum 2450".

I ask because the steel beam is currently 2230 from the floor, and that is without the double layer of plasterboard, the timber for the plasterboard attaches to, and the plaster.

 

[Hugh Jaleak]

Personally I'd go with 'rough distance', if the Structural Engineer has specced a deep beam, then I'd assume that is for a reason, even though it has affected the headroom below. If my calcs are correct, with the plasterboard, you'll have a bit over 7 ft of clearance.

 

[r_c]

Gulp ... that seems low to me. I am not in the building trade, so can you tell me if it seems low to you?

(The usual response I get from builder/architect from these sorts of questions is "we do this [height/width/distance/size/material]* all the time", "don't be so particular" and "this is normal".)

* cross out where appropriate

 

[Newboy]

Well unless you're 7'1" tall then it shouldn't present a problem!

 

[Hugh Jaleak]

'Normal' ceiling height is 8ft, doors are usually 6'6, so that is a little lower than normal, but if that's the size of beam required, (and not one that's been used as it was left over from another job!), then you have little choice but to accept it I suspect.

 

[^woody^]

It's whatever the height of the existing floor and ceiling is.

You always work to the existing levels when adding to existing buildings and those dimension take precedent, unless there a specific reason not to.