If the front of the house is west facing in Queensland and you have glass on that side of the house, in summer in the afternoon the sun beats down on this side for hours, heating up the whole house. There is some speculation on double glazing as some think that they do heat up, better than nothing. Once the sun hits the wall you are lost. These image are for north this is worst for west. A more passive means of cooling the house is to install tall enough thick leaves to the base trees on the western side so that they shade that elevation. Problem with that is that in winter, that sun would be nice. So you need trees that drop their leaves early winter and have them back on say September when the sun starts to heat up. Some trees hold onto their leaves till a few weeks before spring, so make sure you do your research and think root barrier up front to protect your footings. Photo below horizontal external shade screens, Another method is to shade the house with screens, i said house not windows. With western sun, it is low when it starts to clear the roof overhangs, so no amount of horizontal shade devices will make any real difference. The screens for western sun in Queensland must be of a vertical nature. So screens that hang OUTSIDE the house to around say 900 mm off the ground would be fantastic. Since the sun travels around the west from more south west in peak summer to west in winter, vertical blades tend to be ideal solution and should pivot, to deal with this moving sun. In the past, Queenslanders used to have these vertical screens on castors and they moved them around to suit the conditions, for some reason we did not learn from the past. This house the screens are not shading the walls at the bottom so they would still heat up. From the plans i see you are building in brick, so western sun and bricks in summer make an ideal oven. Takes bricks 12 hours to cool down depending on the colour. All material heats up in the sun, but bricks take longer to cool, light weight material which is properly insulated is a better choice and against popular opinion, glass is also a good choice, all better if vertically screened. Double brick tends to keep a house cooler and you might as well use the double brick for structure instead of the decorative nature of cavity brick house, but after a while that heats up and takes forever to cool. Studs hold up the roof, not the face bricks. Ever wonder why the house stands up during construction with stud wall and roof? Photo is vertical blades which pivot. A good landscape architect would be worth a look and they will know how to blend your style of house with the garden. North windows in Queensland even with no overhangs, (which is stupid in Queensland) do not get sun into the rooms, but in winter it might crawl in say 2 M which is nice. What are you doing with the roof and concrete tiles heat up nicely and the darker you make them the hotter they get, Colorbond is a good choice with all the hail we tend to get, or keep a stockpile of tiles for when they break. Colour also makes a difference to heat. Make sure you vent the roof space, whirly birds, and vented eaves or gable ends, make sure you fully insulate the roof and also ceiling, and choose a light colour. choose a style of external screens or trees to fit the house. See if that makes a difference to the report which is there to make your life better and we are talking the cost of air con for the life of the house, the reports are there to help save you money, maybe a bit more up front but worth it in the long running cost of a house. Ros

our cavity sliders don't have a track on the floor although the wall needs to be reinforced if you want to mount a towel rail on a wall with a cavity slider inside.. in 35 years we had to replace the fittings on one door (out of five cavity sliders) but you need to make sure that the fittings are good quality but the door will probably be open most of the time and a simple floor mounted door stop installed close to the wall will stop the door hitting anything without being a trip hazzard

Hi Dr Retro, Thank you. I really appreciate the input and the time you've taken to explanation your point of view. I really do want to get an understanding of where the issues lie in this design. So I hope you'll forgive me digging a little deeper. I don't quite follow why you think the design would require a 6m lintel. Yes, it does require a 6m track, but the track can simply be attached to the wall. The weight of the door need not be supported by the top track. It could be supported from below. The whole point of putting the configuration on the outside of the wall is to minimize the need to make structural changes to the building. There currently is no capacity to install a 6m wide external sliding door/window unit. Likewise I don't follow why the door should be any draftier than any other external sliding doors. The cavity is on the outside of the wall, so draft is not going to get in via the cavity. Other sliding doors of the unit type have the same draft problems this configuration would and solve it by using an overlapping flange at the front end of the fixed door and the back end of the slider. The same could be applied here, where we treat the wall as the fixed door.The point at which the doors engage each other has also be solved for other door configurations. It is just a matter of having a loose tongue and groove configuration. Again this is exactly the same as a unit providing center opening sliding doors. Finally the same sliding mechanisms are used in other sliding door configurations, so I don't see why that should be any draftier here either.

SOOOO Annoying....I 100% feel your pain, I've had many "discussions" (read: confrontations) with builders about this - despite clear specification they just don't seem to get that seamless/concealed means we don't want to see that sliding door sticking out AT ALL.........Yes, you can fix it, but the problem with the less invasive option, (which is to pack out the frame so that the door is completely concealed) is the reduction in the opening width.......this detail to pull off well needs to be nailed down at framing stage/ordering of the cavity door units, because the cavity unit really needs to be ordered longer.......it's an expensive fix for the builder if they stuff it up - they'll try and talk you out of it, so if you had it in the contract/spec possibly it's a point of negotiation if there are other variations/extras involved... Good luck Kay! PD :)