We're doing the same, 2 sets. Want wood but have been told they "may" warp, even though under a covered alfresco. Don't have a firm cost yet but indication from builder is $10-15k more than powder coated aluminium. Total width of each set is 3250 divided into 3 doors, with stacking security screens. Don't have a price for the aluminium ones yet to compare but +$10-15k has probably helped with the decision. Have bifolds at current house but will be going for stackers at the reno house because they can have the stacking security screens, whereas bifolds are difficult to security screen, you can flyscreen but it's quite a flimsy arrangement.

Thanks Siriuskey for your fotos.... beautiful Parquetry floors, beautiful home and stunning water views! I notice your parquetry floor transitions to grey tiles as well.... which is also very similar to what i will have happening. Im now very much leaning towards parquetry you'll be pleased to know. I collected some samples today, and noticed the store had them in a double formation which i'd never seen layed like that before. Its just 1 block of parquetry layed right next to another to make it seem thicker. I think it looks quite contemporary....check out the pic below from the timber showroom:(top half shows 2 blocks layed together in herringbone pattern) I placed a few of these on my floor as example No1, then i placed some in single herringbone as example No2 below. Which do you think looks better? - examples No1 double block herringbone - example No2 single block herringbone Thanks in advance for everyones input and feedback :-)

extra fascia depth would be dependent on how much you want to spend on extra labour by not using standard steel fascia (which is only about 185mm wide) with all the standard fixings ..A carpenter or plumber should be able to make a wide substitute out of sheets of ribbed colorbond steel and the rest should be standard timber framing and soffit linings but check wit a carpenter or roofer about what you want to achieve (why does it need to be 40cm wide??) and there may be a very simple alternative available

You could add a chaise lounge or a comfy chair and table for a reading nook or an office area if you need one, a computer area but whatever you do don't over clutter it keep it sleek and sexy and or a comfy chair as suggested with a little side table for reading, I also like the idea of a place to put coats, shoes etc if you must enclose it. Maybe even a small wine bar? with a couple of stools. I decided to google is and will give you a link to many pics to give you more choices. https://www.google.com.au/search?q=pics+of+what+to+do+with+space+behind+floating+stairs&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjFy-n9p4vZAhUEF5QKHSvhAOMQ7AkISg&biw=1280&bih=893