Closing In an Alfresco and Opening Up the Back of the House

I want to close in my alfresco — what do I use?

It's normally a combination rather than one product: a large sliding or stacker door where you want to open the space up, fixed lites where you want the view and the best energy performance, and an awning or two for ventilation.

Two things we'd settle first, and neither is a window decision. The structure is your builder's and engineer's call — whether the existing posts and beam can carry a glazed wall is determined by them, and we design and supply to the opening they give us. And whether enclosing the space changes its status under the building code — whether it becomes a habitable room, with energy or glazing requirements attached — is your building surveyor's determination.

What we contribute is the glazing: sizes, the wind and water performance for that elevation, and the energy figures.

Will an enclosed alfresco be weathertight if it's exposed?

This is the question we'd most want you to ask, because an alfresco is usually on the weather side of the house and it's where the numbers get tight.

Water resistance requirements go up with your wind classification and with exposure. At N4 a sheltered window needs 200 Pa and an exposed one 300 Pa. At N5 it's 300 and 450 Pa.

Now hold our tested doors against that. Our thermally broken open-out hinged door reached 500 Pa — the strongest we supply, and the only door we hold that clears N5 exposed. Our Comet two-panel slider tested 200 Pa. Our Comet three-panel stacker tested 150 Pa. So a stacker that's perfectly compliant under a deep verandah may not be in an exposed opening at N4.

There's a legitimate route the other way: where a wide verandah or eave genuinely shelters the opening, a lower water figure can be specified. That's a design decision to document, not an assumption to make.

Stacker or sliding — and how wide can you go?

A sliding door has panels that slide past one another, so at best you open about half the opening. A stacker collects its panels against one another, so much more of the opening clears — it's what we recommend when you want the wall to genuinely disappear.

On size, our Comet stacker goes to 2400mm high by 3600mm wide as a three-panel, and 2400mm by 6000mm as a six-panel centre-opening unit. That 6000mm is the widest residential opening we make. Our apartment door system goes to 3000mm high by 4500mm wide with heavy-duty interlocks.

The trade-off is weather performance, and it's real — see the table above. On a sheltered alfresco a stacker is fine. On an exposed one, the slider or a hinged door is the stronger specification.

Can I get bi-fold doors?

We build them, and we'll give you the honest performance picture rather than the marketing one.

Our Windsor bi-fold runs from two up to eight panels, with the stack splitting either way — so a six-panel can go three and three, or five and one, or all six to one side. Panels over 2100mm high need pivot snubbers fitted, and the maximum panel weight is 90kg, which matters because double glazing is significantly heavier than single.

Here's the part worth knowing: on weather performance the bi-fold is the weakest door we make. Our Windsor bi-fold tested to N2 in both general and corner positions, with 200 Pa water resistance. Compare that with N4 for our Comet sliding door and N5 general for our thermally broken hinged door.

For a sheltered opening a bi-fold is a lovely thing. For an exposed rear elevation catching Melbourne's southwesterlies, we'd steer you to a slider or a hinged door and tell you why.

Does closing in an alfresco change the building rules?

We won't approximate this one. Whether an enclosed alfresco becomes a habitable room, whether that triggers energy requirements, and whether a permit is needed are all determined under the National Construction Code by your building surveyor. Our technical library contains the window and glass standards — AS 2047, AS 1288, AS 4055 — not the NCC provisions that decide change of use.

What we'd say practically: get the surveyor's answer before the glazing is specified. If an energy target arrives late, it changes the glass, and glass is the long-lead item.

How big can you make it?

For the openings an alfresco creates, generally big enough — and it's usually hardware capacity or glass weight that sets the limit rather than the frame.

The widest we make is our Comet stacker at 2400mm high by 6000mm wide as a six-panel centre-opening unit. Our apartment door system reaches 3000mm high by 4500mm wide with heavy-duty interlocks. A single hinged door leaf goes to 2600mm high, though only at 800mm wide — the width comes down as the height goes up.

These are maximums, not recommendations, and the constraint behind them is weight. The rollers in our stacker are rated to 40kg and 100kg depending on which is fitted; our bi-fold panels cap at 90kg. Double glazing is much heavier than single, so a panel that works single glazed may need splitting double glazed. Send us the opening and we'll size it properly against the hardware.

Adding a back door — hinged or sliding?

Both work; the decision usually comes down to exposure and floor space.

A hinged door needs clear swing space on one side, but it seals better and carries the higher wind ratings. Our thermally broken open-out hinged door tested to N5 in the general position and N4 in corners, with 3000 Pa ultimate and 500 Pa water resistance — the strongest residential result we hold in any system.

A sliding door takes no swing space and suits a wide opening. Our Comet two-panel slider tested to N4 with 200 Pa water.

For an exposed rear elevation catching Melbourne's southwesterlies, we'd lean hinged and we'd say so even though it's the less fashionable answer. Either way we'd want your site's wind classification first, because at N4 exposed you need 300 Pa water resistance and not every door we make clears it.

French doors or a sliding door?

French doors are a pair of hinged leaves meeting in the middle with no centre mullion, so the whole opening clears when both are open — which a two-panel slider never does.

We build them across several of our systems, including our thermally broken range, with dedicated French lock stiles and hardware. Size is governed per leaf, and a pair doubles the width but not the height: a single glazed leaf runs to 2600mm high at 800mm wide, 2400 at 950, or 2100 at 1200. Double glazed leaves are more constrained — 2400 by 900, or 2100 by 1000 — because the glass is heavier.

The honest gap: we hold no AS 2047 test report for a French door specifically. Our tested door results cover hinged, sliding, stacker, bi-fold and apartment doors, and none of them is a French pair. So for an exposed opening we'd work through the wind classification with the manufacturer rather than borrow a neighbouring door's class.

How big can a single door leaf be?

Height and width trade against each other, and double glazing costs you both.

Single glazed, a leaf runs to 2600mm high at 800mm wide, 2400mm high at 950mm wide, or 2100mm high at 1200mm wide. Double glazed the ceiling drops: 2400mm high at 900mm wide, or 2100mm high at 1000mm wide.

Hardware follows the size. Up to 2100mm single glazed we fit three hinges; above that, up to 2600mm, it's four hinges and a three-point lock. Double glazed leaves take four hinges from the start, and a three-point lock above 2100mm.

For a wider opening than a single leaf allows, the answer is a pair — French doors or a slider — rather than a bigger leaf.

Can I have a flush threshold with no step?

You can, but you should know what it costs you, because this is a genuine conflict between two standards and neither of them yields.

Accessibility requirements want a level transition — a design step of zero, with a threshold ramp of no more than 35mm rise at no steeper than 1 in 8 where level can't be achieved. A weathertight door sill under AS 2047 works by having an upstand and a drainage geometry, and that's what earns its tested water resistance. Take the upstand away and you've removed the thing doing the work.

The standards themselves resolve it by handing the problem to the building rather than the product: where a level threshold is used, the building design has to provide the water protection instead — shelter over the opening, a graded and drained approach, or a drain across the threshold.

So we won't quote you a tested water figure on a flush sill it wasn't tested to. We'll flag it at quote stage and it becomes a design decision, recorded on the drawings.

Can you cut a new opening in my back wall?

Not a question we answer, and we'd rather be clear about why than be vague about it.

Whether a wall can be cut, what lintel it needs and how the load is carried are structural determinations made by your builder and, where required, an engineer. We're a window and door manufacturer — we don't assess walls and we won't offer an opinion on one. The industry position is unambiguous that windows and doors are not load bearing and must never carry the weight of the structure above.

What we contribute is everything from the opening inwards: the door specified to your wind classification and exposure, sized to the structural opening your builder gives us, with the reveals, flashing interface and certification to match.

Do I need a screen or security door too?

We make them, and they're worth planning at the same time as the door rather than afterwards.

Our barrier door range covers single hinged, double French hinged, single-track single and double doors including centre-opening, and double-track stacking doors — so there's a matching screen for most door configurations, including a French pair. On the infill you can have a diamond grille, or security mesh in galvanised, perforated or vision-guard types, with flyscreen or DVA mesh as an additional layer.

Two honest limits. Our documentation states no maximum sizes for the range, so we confirm your opening against the manufacturer rather than quote a limit we can't substantiate. And we hold no forced-entry test data, so we're describing the mesh options rather than making a security claim.