Wednesday September 30 2015, Tuesday November 10 2015, Friday May 13 2016, Monday November 21 2016
Windows – eek. They have been the bane of this project. What started out as a design generator – four double glazed units, roughly the same width as an apple crate, picked up for free – has turned into a costly and drawn out component of the building. It’s amazing flicking back through the photos I’ve taken for this project (and trust me, I’ve taken heaps) – it certainly has come a long way. But it’s also taken much longer, and cost more, than anticipated. The first windows were delivered at the end of September, 2015; the final window was installed on November 21, 2016 – fourteen months later!
I managed to arrange the first batch of windows by discussing this project with the sales rep sitting next to me at the Tasmanian architecture awards in 2014. I had heard of ‘mistakes’ with windows – unpaid orders or incorrect measurements or slight damage that the manufacturers are unable to sell. Sheree found me four, fixed, double-glazed units (DGUs) stacked in their warehouse and agreed to give me the DGUs if I bought the frames – done deal. We discussed a range of frame options as I tried to balance U-values against the glazing calculator. In the end I opted to pay for a Thermal Performance Assessment to save money on more expensive window frames (see the post ‘Consultants’). It turns out I paid for a frame with a larger profile that was more expensive and less energy efficient – a hang-up from previous discussions about better performing framing. Oh well, the big four windows were delivered, Greg and I installed them, and I began to shop around for the other windows. It was around about this time Sheree left, and windows became more of a problem…
My Bushfire Attack Level is BAL-19 – this is about mid range, and fairly common for many rural properties. A requirement for ALL houses with a BAL rating is that ALL operable windows (windows that open) must be fitted with either a fixed metal flyscreen or a bushfire protection shutter. Nobody I have spoken to knows what a bushfire shutter is, let alone specify and use them. That means it’s flyscreens all round. They are good at keeping flying embers and mosquitoes out of your house, and trapping flies inside (they fly in through the open doors, which don’t need to be fitted with flyscreens at BAL-19).
To open or not to open
The second batch of windows I was looking to order were operable windows – windows that open. I wanted a casement window (hinged on the side and swing like a door) for the bedroom and another for the study/living. I was told this wasn’t possible for two reasons: the width (around 1100mm) was too wide; and there was no means of fitting a fixed flyscreen to them while still being able to open the window from inside.
Because I wanted the window to be full width this also ruled out sliding windows, meaning my only option left was awning windows (hinged at the top). That wasn’t too bad – it’s what I had drawn for the kitchen windows – until I found out how far they open. Or, should I say, how little they open. The maximum opening for an awning window is determined by the length of the chain winder – typically 300mm. That’s not a lot of opening.
* Its worth pointing out that any operable window more than 2m above the ground with a sill below 865mm above the floor is limited to an opening of 125mm. This is a similar requirement for stairs and balustrades – to prevent children falling or getting their head stuck. *
I went to another aluminium window manufacturer to see if they could do any better. Different manufacturers use different frame profiles. Their windows wouldn’t open any further, and the winder didn’t even fit on the profile without it hanging half off!
Dissatisfied with the winder options and the aluminium manufacturers I went to speak to a timber window manufacturer. He was working on another architect’s house where the windows alone cost $60k! He showed me Truth hardware – a scissor winder that opens slightly wider than a chain winder – at considerable cost. Timber frames were also significantly more expensive than aluminium frames, and the frames wouldn’t match. Here’s a critical moment in the development of this project: it was then I realised how important looks are to me. I didn’t only want an affordable and efficient house – I also wanted one that looks good.
I went back to the original manufacturer and ordered awning windows with chain winders – a result I wasn’t happy with but could live with. Most window manufacturers I dealt with had a real ‘no can do’ attitude – which I find utterly frustrating. There must be a market out there for people wanting windows that actually open! Consumers are limited with the options available.
* Update – Mick the energy assessor just put me onto a company in Victoria who design and manufacture casement windows up to 600mm wide and can be fixed with internal flyscreens! *
Everyone who came to my birthday party last year commented on how great the view was out from the bathroom (at that time there was only a temporary sheet of Perspex with the top left open). So great was the view that I took for granted I didn’t even take any photos! Those comments influenced my decision to have some clear glazing – until then I had always intended for all of the bathroom windows to be polycarbonate.
I had grand ideas for the bathroom windows – large, translucent polycarbonate shutters with gas struts that would swing open to horizontal, affording views out to the surrounding valley while lying in the bath. Alas they remain only dreams, because I encountered all of the same problems as before. I considered for a long time having a fixed internal flyscreen and open the window from the outside. Another factor was the windload on a large, lightweight hopper window supported by gas struts – this was the windy side of the building, a fact becoming increasingly obvious as we built.
I went to see Thomas an architect friend who designs some really nice houses – including the house with $60k of timber framed windows. He had used Danpalon (a product with impressive thermal performance because of the pockets of air trapped in the multicell cross-section) for many of the windows in his own house and had a stockpile of leftover sheets (the result of a mix-up with the supplier). A guiding principle for 60k House was to source materials as cheaply as possible, such as this. However the sheets weren’t wide enough for my windows. I contacted the local supplier who just happened to have some left over from a big job and was willing to part with a couple of sheets for a slab beer. Tom suggested designing the window frames myself using steel angle, having them fabricated, and fitting the Danpalon and gas struts myself. It sounds like a nice idea, but I was pushed for time and unsure of the details. Maybe in the future, once 60k House is finished. Again I chickened out and took the safe option – awning window with chain winders, but this time using Danpalon instead of glass.
The BAL level for my site is 19, which equates to a radiant heat index of between 12.5 Kw/m2 and 19 Kw/m2 as defined in AS.3959. Danpalon has been tested and fails at approximately 50 Kw/m2: therefore the product should perform adequately at the expected maximum of 19Kw/m2. It is definitely not a Deemed to Satisfy solution – for this it would need to be fleshed out in a detailed report to qualify as Performance. But for me the Building Surveyor accepted the logic!
Of course the window manufacturer had their doubts – they didn’t like anything outside the norm. Window manufacturing is symptomatic of the building industry as a whole – inefficient and set in their ways. Anything slightly different, a little bit out of the ordinary, and it’s labeled either too expensive, too hard, or can’t be done.
I delivered the sheets of Danpalon to my original window manufacturer. When I picked up the windows a few weeks later I was surprised that the window with the glass only had one sheet of glass installed! Apparently they were waiting on a supplier (I hear ya mate!). Running out of time I took the windows and had them installed only a few days before I went overseas. Before I left, while I was away, and once I returned, I was onto the window manufacturer to come down and install the remaining sheet of glass. It took them over six months to finally get another DGU made and a guy to come down and install it onsite – it took him all of 10mins. This delay has held up the issuing of the Occupancy Certificate from the Building Surveyor (all of the essentials need to be in place, including all of the bushfire construction regulations such as glazing).
I’m still unsure if I’ve made the right decisions with the windows for 60k House – only time will tell. I’m not entirely satisfied with the compromises that I’ve had to make but have learned a lot from the process.
Costs: 4 large fixed – $2,355; 3 medium awning – $2,518; 3 bathroom awning – $1,590; Danpalon – slab of beer
Disclaimer: Any advice contained within this blog is of a general nature only and cannot be relied upon. Details provided are in good faith and relate specifically to this project. Any author will not be held responsible for advice or information presented.