Build It Education House: Part 8
How we specified and installed the windows and roof tiles
With the Build It Education House, we want to show that you can get real wow factor on a relatively standard self build budget. To achieve that, we’re including some finelytuned statement features that give us plenty of bang for our buck. This month, I’m looking at two of the areas that will really set our home apart: the windows, which include a stunning wraparound corner and glazed apex; and the roof.
Specifying the windows
When it came to selecting a partner for this critical element of our build, Kloeber’s reputation for great customer service was a big factor. We’ve chosen them to supply and install the windows, French doors and fixed glazing for the Build It Education House, along with a Funkyfront door for the main entrance. We’re appointing other partners for elements such as the rear sliders and rooflights (more on these next time).
The spec developed over the course of three meetings with sales director Matt Higgs, spread across several months as the house design evolved. I’ve found Matt and his team excellent to work with – they’re proactive, explain technical details in an easy-to-follow way and are willing to go the extra mile. Our initial chat, which included Lapd Architects and our structural system provider ICF Supplies, focussed on design and practicality. We wanted to ensure everyone was on the same page about how the units would be fixed.
Lead times were a hot topic. Most suppliers deliver in six to eight weeks once you press the green light, and prefer to measure up in situ before manufacture starts. But we were keen to specify the windows off the drawings to try to avoid down time on site. Kloeber were happy to accommodate our request; with the exception of the apex glazing, which both Matt and our architect Opinder Liddar (rightly, it has to be said) felt was too complex and should be measured on site.
All our windows are designed to deliver a good U-value (a measure of heat loss, where lower values are better) of 1.3 W/M2K. Working in tandem with the airtight, highlyinsulated superstructure, this will deliver very strong results and low long-term energy bills. Importantly, we can achieve our performance goals using good-quality double glazing at real-world prices; there’s no need for us to buy triple.
We’re opting for factory-painted engineered softwood frames, finished in three coats of microporous paint in RAL 7034 Gelb Grau (yellow-grey). Slow-grown softwood that’s been properly treated can deliver impressive durability, especially in engineered formats, offering a lifespan very similar to hardwood. Kloeber’s timber units also offer better U-values than their equivalent aluminium product. The dualcolour windows can have a different finish inside: we’ll have white for the ground floor and hallway apex glazing; with the natural character of clear-lacquered pine elsewhere upstairs.
One area up for debate was the top lights on the ground floor windows. The planning drawings show dummy sashes, but on such narrow units the frame-to-glass ratio can be a little mean. So would direct glazing work better, or perhaps just full-height windows? Kloeber’s design team inputted our plans into their own software to produce 3D renders showing the options – and it immediately became clear that Opinder had been right to include a top light, as it really does add architectural interest. It was also obvious that a direct glazed version would be best to maintain good sightlines.
At our second meeting, we started to iron out the key order details. The units are in a mix of configurations – some standard casement, others top-hung – to suit their size and location. For instance, sections of the glazing in the ground floor hallway are too heavy for a side-hung casements, so these are all top-hung for consistency. And we don’t need trickle vents because we’re fitting a mechanical ventilation and heat recovery system. Dealing with the steel post at the glazed corner required a joint effort between Kloeber and Lapd to minimise sightlines and preserve thermal efficiency. The solution involves rigid insulation, packing and cladding sections inside and out to match our chosen finishes.
We discussed security, too, including which windows and balcony doors would need to be designed and fabricated to PAS 24 standards (under Part Q of the Building Regs). Any that are considered ‘easily accessible’ must be sufficiently robust to thwart a physical attack. In practice, that means providing good-quality, secure ironmongery and using laminated glass (which Kloeber specifies as standard).
We also finalised elements such as the setback position (how far into the depth of the wall the window will be fixed) and the cill projections (we needed 75mm, the largest Kloeber does, to get 35mm of clearance from the face of the ICF and ensure enough weather protection). Matt and I then agreed and updated our window schedule to ensure everyone on site knew exactly what was expected.
Placing the order
I met Matt over at Kloeber’s Bicester showroom to finalise the order for the first phase. We went through the quote lineby-line to triple-check the window and door sizes correctly corresponded with the planned apertures (which are 10mm bigger all round). We also scrutinised opening configurations, finishes and ironmongery. There were a few small details left to agree – for example, we switched to secure thumb latches on the internal side of the balcony doors, rather than keyed locks. We’ll be sourcing window boards, blinds etc separately (most suppliers don’t actually provide these elements).
With everything signed off, Matt was keen to talk about practicalities on site. The openings need to be completely unobscured by scaffold for access, with working platforms both inside and out. Apparently this often goes awry, which
adds significant delays as scaffold should only be modified by suitably-qualified trades. Window fitting teams get lined up for jobs well in advance – so you don’t want a simple issue like this causing you to miss your installation slot.
Installing the glazing
Fitting the windows was a slick operation. Kloeber had two install teams on site to help us get the house weathertight as quickly as possible, led by site foreman Matt Vickery. One operative preps the units in the order they’re needed, fitting the metal brackets and ironmongery, as well as sucker pads (if required) so they can be manoeuvred without any risk of damage. Meanwhile, the rest of the crew does the install.
Precision is the order of the day with windows – after all, they’ll only look and perform as expected if they’re properly installed. Getting everything level and plumb, foaming the gaps between the wall structure and the unit, and properly finishing them off with silicone seal takes time and patience.
Kloeber’s team had a bit of extra prep to do to the fullheight first floor openings, where the concrete was uneven in places. But a little chipping out and a damp-proof course (DPC) later, and these were ready for the fixed full-height panes and French doors. Getting the glazing upstairs was a slightly nerve-racking experience, as it all had to be handballed up between the ceiling joists. It’s one of those Grand Designs-style moments where you’re just waiting for one person to lose their grip and £600 worth of window hits the deck... but, thankfully, the crew were totally in control.
The biggest job was fitting the first of our glazed corners, which included packing out, insulating and cladding around the steel post. For this section, the cills were deliberately ordered longer than required so they could be mitred on site, and then sealed with a metal corner bead. The team have done a very neat job, and their work here will form a template for the first floor and wow-factor apex glazing above.
By the end of the week, the team had all the pre-ordered windows in and sealed externally with silicone. They look fantastic and, importantly, the Build It House is now pretty much weathertight. That’s allowed us to get first fix work underway inside and out (more on this next issue).
Tiling the roof
Dreadnought Tiles was another supplier we identified early on. We were very taken with their rustic range of machinelocated made plain tiles, where the colour is fired into the clay itself (rather than with applied finishes). This creates a durable tile with a richness and character that can lift and soften a contemporary scheme.
Many self builders go for a straightforward finish in a single colour to achieve a clean, modern aesthetic. Along The Street, for instance, there’s a mix of grey-hued metal and tiled roofs. They look great, but we wanted to bring a little more warmth to our build. The three-ridge design of our roof isn’t as dominant as some, but it will still be highly visible and will thus have a major impact on the overall look and feel.
Dana Patrick-smith from Dreadnought suggested a mix of country brown, brown heather and red sanded tiles. The same blend was recently used to spectacular effect on a contemporary barn-style home. But I was a little dubious at first: after all, our project is anything but barn-like!
Dreadnought sent a sample panel for us to see the blend in the flesh, with some extras so we could also get a sense of two-tile blends. Even then, it wasn’t an easy decision. Lapd Architects kindly reworked their initial 3D renders to give more of a sense of what each of the combinations would look like. Those images, coupled with Dreadnought’s enthusiasm, helped us settle on the original three-tile mix, and I’m glad to say it’s proven to be the right decision.
The Education House is topped with structural insulated panels (SIPS) to give us a pre-insulated attic within a thin roof profile. This has maximised space in the ready-to-convert loft. Our main contractor, Drewett & Hunt, arranged for the tilers to come for a site meeting during the SIPS install. This allowed Zoran Vjestica and his crew from Onpoint Roofing to get answers to their questions about SIPS, and to finalise details with Scott Hunt and I before they started in earnest.
The first consideration was where the breather membrane goes in the roof build-up. Most tilers are used to putting the counter battens down first, with the membrane draped on top. But with SIPS it’s the other way round: the breather membrane gets applied directly to the panels, with the counter battens fixed on top to create the ventilation gap.
Zoran had a few questions for me, too. Should we use verge tiles at the visible sides of the roof (a quick option with no need for wet materials) or cement pointing? A phone call to Dreadnought confirmed the latter route. Next up: what colour should the pointing be? Zoran created test sections in plain cement and various shades to match the tiles. In the end we selected standard cement, as it should blend well with the fascia and will be easier to colour-match in future.
Another key detail would be where the roof planes intersect. We’re using special valley tiles to accommodate the angle. The alternatives are lead flashing, which is slower and tends to give a more traditional feel, and dry-fix GRP. We nearly went for the latter option, until we realised the trough would have got in the way of the flashing for our solar panels.
The tiles don’t arrive pre-blended – so this is a manual task. Zoran’s team likes to get most of the mixing done on the ground, so we agreed to set the palettes in sequence next to each other. The crew could then get small batches up via a bumper (a long, thin conveyor belt). The final mix is sorted up on the scaffold. All of this takes time, of course, and going for a three-tile blend has pushed our budget for the tiling up quite a bit compared to the original estimate.
The PV panels
On the subject of solar, we had a surprise headache with our installation. We planned to include eight photovoltaic (PV) panels across three of the roof slopes to reduce our reliance on mains electricity. In general, it’s best to get at least the mounting system for this installed before the tiles go on, so the roofers know exactly what they’re dealing with.
Unfortunately, our supplier decided to pull out of the self build market just days before we were expecting them on site. It just goes to show that it doesn’t matter whether you’re an individual self builder or an industry magazine working on an Education House – stuff can happen on any project!
Thankfully, Environmentlogic has stepped in at short notice. They’ve been fantastic, even identifying a surprising flaw with the original design. On one of the roof planes, the proposed panels would have actually been too big to fit, as there weren’t enough tile courses to finish off around them. Environmentlogic has re-evaluated the design and will be providing us with a higher-spec system that requires less total area to get almost exactly the same output.