Roof down or Foundation up?

[mr. iagea]

Okay, so this may seem rudimentary and possibly not even the right place to pose it (apologies in advance), but it seems to gather great heated debates amongst my colleagues from conferences to tabletalk.

Roof down or foundation up? Structurally, one might argue that foundation up is best. Aesthetically, another might argue that elevations and floor plans are critical first, thereby determining rooflines, hence roof down (which ultimately decides load paths and future foundation design decisions). I won't posit my opinion now more than to say that I personally feel that each project is unique and deserves a separate approach.

Of course, we all design based on the needs of the structure, the desires of our clients and our own aesthetic, but after all the bubble diagrams and talk of where things should be, how do we start to build our designs, and how are we all the same or different?

How do you design and why?

[islandmon]

In our world roofs are expensive to build and maintain. Therefore, maximizing the material usage , minimizing the waste, and following modular conventions is most cost effective.

Take a look around ... the world is littered with one-off crappy roof designs with ridiculous ' cover-up' detailing .. as if the design was an after thought... "here's the foundation and the walls now figure out a way to put a roof on the thing".

This is especially embarrassing when large multi-unit projects all have the same back-assward design flaws.

[panthony]

Start in the middle and work in both directions. The floor plan...flow patterns and life style space come first. During this initial stage you must be thinking in 3 dimensions...can I roof it? and can it be supported? Once the layout/footprint is generalized it can be tweeked to support the roof with the foundation following.

[mr. iagea]

Excellent comments, both. You both concur with what I (we?) learned in school way back. I particularly like Edward's point on roofs?they certainly do seem to be an afterthought in so many stock designs we see getting built these days, and it's a shame, IMHO.

Anyone else? Keep in mind I'm not looking for a design lesson here, just an interesting topic to discuss.

[HOUCAD]

Start in the middle and work in both directions. The floor plan...flow patterns and life style space come first. During this initial stage you must be thinking in 3 dimensions...can I roof it? and can it be supported? Once the layout/footprint is generalized it can be tweeked to support the roof with the foundation following.

This is how I approach a new custom residential design as well. You need to have a concept or style in mind and think in 3 dimensions. The floor plan layout and footprint dictates how the roof can be built and roofs will vary a great deal between styles. The foundation is the last thing I do usually with custom homes.

With production homes I am often given a foundation plan to start with and have to design from the ground up. The foot prints are usually very simple, rectangular with very few offsets. The roof is usually very basic as well but you can do a lot of interesting things with a box if allowed to.

With commercial design it depends on the project but it usually always starts with the floor plan and space requirements unless you are designing a sculpted concept building then you start with a massing model and define the overall shape of the building then slice it into levels and define the interior spaces.