In reply to johnmctighe:
My house includes what used to be the village shop, and my wife and I have turned that room into our bouldering room. It's accessed off the porch so is separate from the rest of the house, but you still get to it without going outside. Having had a woody in a garage at a previous house, I can say that this arrangement is far, far more pleasant - no issues with it being too cold or damp to use, it's got windows to open for ventilation if it gets too hot, a wee central heating radiator for winter (personally, I like the temperature to be around 10 deg C so that I can still feel my fingertips when I boulder!) and I can shuffle back and fore between the wall and my kitchen for drinks top-ups!
It's quite a big room - we have a 45 deg board, a 30 deg board and in the last couple of weeks, we've just finished building a Moonboard to replace another section that we weren't using so much, but any one of those boards would work if you had more limited space. The Moonboard instructions include details of the space you'll need for one of them so I'll second the recommendation to have a look at that.
The Moonboard does require you to have a ceiling height of just over 3 metres, which is pretty high for a modern house. You can get away with a lower ceiling than that (my garage woody had 2 metres height) but if you can get the architect to come up with the extra height, it makes for much better boulder problems.