Will the courtyard be paved? How big is it? If I had a courtyard, I'd probably plant a tree in it, so no basement.

Basement or not, you are wise to consider drainage. I don't know where you live or your roof layout, but if half the rain that hits your roof ends up in the courtyard, that water will have to go somewhere.

Looking at either 25x25 or 35x35. If the basement is under I would pave it. If not I would leave some grass and yes, probably a tree.

Yes, anything is possible, with sufficient budget!

Curious as to why you wouldn't put the basement under a portion of the occupied house? Stairs and access might be easier.

Regardless of where you put the basement, you will need exterior drainage of the enclosed courtyard, unless you desire a large swimming pool during your monsoon season! :-)

Oh yes. The basement would go under everything. Including the house part. Just wondering if we would need to "exclude" that center part in the basement.

Though highly impractical due to cost, with proper structural design, anything is possible. Basement ceiling (courtyard floor) will be a challenge unless using rcc, which can get very expensive, also requires taking extensive waterproofing measures however prone to cracks and leakage; I should know, we've build homes in other countries with brick and rcc. For drainage (assuming rcc ceiling slopes to perimeter), one would seamlessly cover entire perimeter of courtyard with trench drains such as ones made by LTEC. No planting trees :)

While in London, I watched a show called "Basement Millionaire's Wars". On this show, it showed a basement that went under a terrace in the back garden. It had glass circles here and there, supported by bronze, so light would come into the basement. The entire show was astounding as it truly proved that if one is willing to spend enough money, almost anything is possible.

I doubt what you want to do would be financially wise as the houses in London where such was being done, were in the £20 million+ range. At that price, what's another million or two!

think about HOW you will move the water out of (essentially) a donut hole- that water is going to have to go OUT THROUGH the basement to drain - otherwise - you'll building a swimming pool and not a courtyard.

Can it be done? Yes. SHOULD it be done? Probably not.

Might you consider digging out the courtyard so that you have a sunken patio? I have seen at least one very nice (and expensive!) house like this.

How big will this house be?

Everything is possible but a courtyard that size, enclosed on 4 sides will not be that great. It will be just as a large room with no roof.

What you want, will be like a humongous shower in the middle of the house, and in theory, it could be built just like a shower. Waterproofing a custom shower is expensive (per square foot).

Did you consider an "u" shape house? The courtyard can be enclosed on 3 sides but you do not need a drain in the middle.You can always add an evergreen tree line at the 4th side for privacy, or a fence.

last night, I saw a show for a few minutes and they talked about this house with a rooftop tennis courtyard - hamptoms house - not the same case but they said they spent millions.

Green roofs are the law in large new commercial and residential projects where I am, so it's not an unknown undertaking.

But for a single non-luxury home, be prepared for a large bill. The two-storey courtyard would be more feasible. The last one of these I saw was done as a walkup from a below-grade ballroom to Roman gardens and fountains fed by a 100,000 gallon reservoir. The owner went bankrupt after a couple of years and the fountain garden was converted to a swimming pool.

Slab. Trough drains about 36'' from the perimeter. The paving was pitched towards the drains. The basement was a square doughnut. It drained to several sump pits that were pumped through the exterior foundation walls.

The courtyard surface would be a "plaza deck system" with a thick layer of extruded polystyrene insulation over a waterproofing membrane and pavers on pedestals above it so water could drain below the pavers to internal drains. The structural deck would be concrete poured on temporary forms or metal decking. The space below, if habitable, would probably need a fresh air ventilation system.

The waterproofing membrane and insulation should be specified by an experienced design professional or a manufacturer's rep since protective separation materials may be needed to prevent membranes with plasticizers (PVC) from contacting polystyrene insulation.

This would be a very expensive way to build a poor quality space. You would get more for your money by building above grade.

I've designed two buildings with underground connectors, one in Manhattan under a street between a dorm and a library and one in NJ between college dorms under a plaza. Waterproofing required a lot of consultation with the reps at Grace Products who are the best at this kind of thing as well as advice from large construction companies who do this kind of thing often. IMO this is not a task for most builders, designers or architects.

Be aware that the courtyard slab would be lower than the main floor of the house and would be designed to support the weight of ponded water up to the level of overflow gravity drains around the courtyard. That water would need to go to dry wells. That deck drop would lower the ceiling of the space below a foot or more.

For this idea to be feasible, you should have a very important use for a low ceiling, windowless space with beams and columns that can't be located elsewhere.

Without additional information I would have to say this is a really bad idea.

When inspecting a downtown century home that had at one time been a food store, I was struck by how the basement was so much larger than the house above. It had been expanded under the adjacent four-car parking pad. I somehow doubt the owners followed the elaborate procedures described above. We demurred on an offer!

• It only gets complicated when the underground structure abuts a building and/or adjacent roofs drain to i and/or there is limited drainage by gravity. Some towns might require a large dry well. The expense is worthwhile for major universities and museums but not for homeowners.

Overall, I think U shape is a ton better than an "O". The completely surrounded courtyard never gets much in the way of a breeze, it tends to concentrate the heat and stagnate, and drainage is an issue even without a basement.

The U shape gives you access to light, wind, better visual sight lines, etc. AND gives the water somewhere to go.

I have just found this thread and I am wondering what you ended up doing as we are building a house and considering building an atrium above our basement. I would really appreciate the feedback. Thank you