Best way to build 2 layer modular decks?

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I am working on my first building and just realized that my deck is curving upwards because I built it with 2 layers of plates completely covering each other. The reason for the curving probably have to do, with lego plates kind of functioning like a box turned upside down. That way the "top" of the box where the studs are, is more rigid and less flexible. This was my first attempt for a 24 x 32 deck with a 4x10 hole for stairs:

Layer 1

Layer 2

Now after looking at some instructions for the modular buildings, I see that Lego usually build something more like this

Layer 1

Layer 2

Where no plate that is larger than 6 studs in one direction, is larger than 6 studs in the other direction ( So 6x16, 6x12, 6x8 etc. but not 8x8, 8x16), with 2xX plates in the "middle" connecting as many plates as possible, and 1xX plates covering up the edges.

But what are your preferences when building modular? Do you have any guidelines, rules or suggestions on how to build decks?

[alois]

The problem almost always is solved when you put nine layers of bricks on the floor, so I do not really pay attention to this problem and have various ways to build floors, depending on the kind of house I'm building and the plates I have.

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Well for this level there isnt 9 levels above, since its a roof, and so it bends like a curve when put together like in the pictures in the first post. Also this bending is neither good for the bricks or for the stability, since its not possible to attach it properly to the level below it (all bricks are new by the way, and not damaged in any way).

Also there is cost and availiblity of bricks to consider, so it isnt as simple as it might look.

[Venunder]

The Lego designers have years of experience building Modular buildings so you should not go wrong by following their example.

If you must have a flat "ceiling" , try making it three plates deep, that might stop the bending issue ???

Following your pictures this would be :-

Layer 1

Layer 2

Layer 1

Edited March 1, 2014 by Venunder

[dollesterdy]

right,Also there is cost and availiblity of bricks to consider, so it isnt as simple as it might look.thanks

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Okay so I have looked at the digital models for all the modular buildings, and been doing some testing. To be able to build on top of the deck, all edges must be supported by a plate below. Also the "holes" in layer 2 shouldnt be wider than 4 studs for a stable surface. Lego have used a 16x16 plate in the cinema building, but that was without much building on top of the deck. This is the layout I´m going for now:

Layer 1

Layer 2

The 3rd layer would be the flat smooth plates the deck rests on, on the level below. This solution uses more, but less rare parts and fewer different ones. Also I like symmetry .