Bi-folds/Slide and Turn Patio Doors in a New Build

[Tony99]

I am looking at patio door options for a 5m wall in the gable end of our new build. Keen to have it open fully rather than have a sliding door option so that leaves me with bi-folds or the rather newer 'slide and turn' doors which do seem to be a neater option. I noticed that some of the popular window companies e.g. Internorm, Rationel, Norrsken etc don't make bi-folds/slide and turn doors and it made me wonder, why not? Looking at some threads on here I have seen various people stating that they have been warned against having bi-folds but I really wasn't too sure why. Apologies if I have missed the thread that explains this (I've tried having a good search) so could I ask the community:

Is it an air tightness issue (we are looking at MBC Timber Frame-probably the blown cellulose option so should be well insulated and air tight). 

what about the slide and turn doors-when closed, the doors seem to be pushed/forced together so I would have thought they would be good in terms of air tightness

any good 3G bi-folds/turn and slide doors recommendations-(Green building store do 3G bi-folds-anyone have them?)

Many thanks. 

 

[nod]

I have fitted bifolds over a 4 mtr opening 

But worked on sites with slide and turn 

The later are absolutely fantastic and in my opinion worth the extra money 

 

[gravelld]

Yes, the problem is with the weight on the hinges over time causing air leaks.

 

Lacuna make the only Ph certified bi-folds I know of - https://www.phstore.co.uk/lacuna-passivhaus-suitable-triple-glazed-bi-fold-doors . How good they are long term I don't know.

[joe90]

I had bifolds made by the same company that made my windows, they used a German hung slide mech (don’t know the name) and I insisted on compression seals as I don’t like brush seals because of the air leakage issue. They work very well, look good (oak) and yet to have an air test but feel positive it will be fine.

[Vijay]

I tried asking a door company who raved about bi-folds about their air tightness warranties. They declined to give any. So might be worth asking any suppliers you look at.

[nod]

Ours are pretty airtight 

But is airtightness a bit of an obsession There I’ve said Thought it for a long time 

We where forced to have trickle vents on every window 

22 downstairs alone and they are definitely not airtight 

The test guy taped them all up prior to testing 

We don’t like the look of them But we leave them open most of the time 

[ProDave]

2 minutes ago, nod said:

Ours are pretty airtight 

But is airtightness a bit of an obsession There I’ve said Thought it for a long time 

We where forced to have trickle vents on every window 

22 downstairs alone and they are definitely not airtight 

The test guy taped them all up prior to testing 

We don’t like the look of them But we leave them open most of the time 

Only because presumably you don't have mvhr?

[Jeremy Harris]

1 minute ago, nod said:

Ours are pretty airtight 

But is airtightness a bit of an obsession There I’ve said Thought it for a long time 

We where forced to have trickle vents on every window 

22 downstairs alone and they are definitely not airtight 

The test guy taped them all up prior to testing 

We don’t like the look of them But we leave them open most of the time 

 

If you have trickle vents and no MVHR then yes, airtightness can be a bit OTT.  If you have MVHR, though, then airtightness becomes far more important, so much so that any leaks, such as those that will always appear, sooner or later, as bifold seals stop working, will make a significant impact on the total heat loss.

 

Ventilation heat loss in a house without MVHR will always be pretty high, so whether a bit of leakage makes much difference is debatable.  Our house loses around 220 W of its total heat loss of 1600 W  in cold weather from ventilation losses, but if it was less airtight, had trickle vents and no MVHR it would lose around 1,500 W to ventilation from a total heat loss of about 3,000 W.  Having good airtightness and MVHR just about halves our heating bill.

[nod]

9 minutes ago, ProDave said:

Only because presumably you don't have mvhr?

Correct Dave 

It was one thing I had no exsperience of We followed the advice of a friend who does have it 

Like is he is near a busy main road and told us he’s does use his due traffic fumes 

He switched his on for our benefit when we visited While I didn’t have any issue with the trafick 

The farmer was burning in a nearby field and it was starting to get a bit funky indoors 

So he switched it off 

On the next one I will probably add MVHR 

Though when the weather is nice we have both lots of doors fully open to the garden 

So I’m not sure how that would work 

 

We have sash windows throughout 

so never giing to be competitive airtight Though the airtest guy did say that nothing is escaping anywhere else 

Our home never drops bellow 18 and the Up and  down 

and as I’ve already stated We do have the bifolds open as soon as the weather allows 

[ultramods]

Has anyone had any prices for the tilt and turn doors?

 

I like the idea of them as I have 3 3000mm wide windows in the open plan area, but only 1000 mm in each of the windows slides open. Having the middle window opening fully would be nice.

[vivienz]

Our decision against bi-folds was for a rather different reason. Our site is quite exposed and windy and we know from experience at work where we have the factory roller door up in the summer just how much stuff blows in, even when there is only a light breeze. Bi folds would replicate this and I would prefer our bew build to have less housework, not more.

[Ralph]

We have about a 5 meter span and I think we're going with sliders from Rationel. We decided against bi-folds mainly due to the amount of sightlines and the thickness of them. Also given our location I can't imagine that we would have them fully open on more than a couple of days.

[jack]

We have a 5.4m slider, and to be honest I'd rather have gone for a pair of wide French doors in the middle with horizontal windows along the rest of the space. In our case, such a large window drastically limits our options for furniture placement. That may not be an issue for other layouts.

[gravelld]

I thought the maximum slider from Rationel was 3.5m? Maybe a three door slider?

[Tony99]

6 hours ago, jack said:

We have a 5.4m slider, and to be honest I'd rather have gone for a pair of wide French doors in the middle with horizontal windows along the rest of the space. In our case, such a large window drastically limits our options for furniture placement. That may not be an issue for other layouts.

I know what you mean! Our initial design had so much glazing, often full length windows that it was difficult to see where any furniture, bookcases or Tv could be placed!

[Sue B]

We will have French doors - furniture placement for me.  Previously had bi-folds and  whilst they were lovely, no actual benefit to simpler French doors.

[Tony99]

Thanks for all the replies...so: bifolds are not intrinsically 'bad' but their weight and mechanics mean the seals wear out and air tightness is lost. 

So....perhaps if we only use the doors a few times over the summer (likely) we should be OK for some time if the windows are well made....

 

Is it obvious if the seals are not working well and air tightness is being lost e.g. would you feel a draft on your hand if held up close on a windy day or is the loss of airtightness more subtle than that?

[Jeremy Harris]

5 minutes ago, Tony99 said:

Thanks for all the replies...so: bifolds are not intrinsically 'bad' but their weight and mechanics mean the seals wear out and air tightness is lost. 

So....perhaps if we only use the doors a few times over the summer (likely) we should be OK for some time if the windows are well made....

 

Is it obvious if the seals are not working well and air tightness is being lost e.g. would you feel a draft on your hand if held up close on a windy day or is the loss of airtightness more subtle than that?

 

The issue with bifolds is that the geometry of the door fastening system means that it's really difficult to get enough force on the seals to maintain adequate airtightness over time.  Usage isn't really the issue, as the seals are in compression all the time that the doors are closed.  The best way to see the issue is to look at how the seals are compressed with bifolds, particularly, the means of applying closing force at the intermediate hinged sections, as this is the primary weak point in the geometry, as there is nothing at this point to directly pull the sections either side close to the frame.

[Tony99]

@JSHarris I think I understand?! We have old bifolds-3 doors. the right hand side is traffic door which opens outwards. When we close the doors, the left and centre doors are pulled tight by handles and secured shut by pushing 2 latches into the frame-1 at the top of the door and the other at the bottom. There seems to be good compression between these 2 frames. But there does seem to be less compression between the right traffic door and the centre door....is that where the problem is? (if you managed to follow my description!). 

I did see some slide and turn doors at a show and they seemed to be very tightly compressed when all shut-do you think they are better in terms of air tightness?

[craig]

 

18 hours ago, gravelld said:

Yes, the problem is with the weight on the hinges over time causing air leaks.

 

Lacuna make the only Ph certified bi-folds I know of - https://www.phstore.co.uk/lacuna-passivhaus-suitable-triple-glazed-bi-fold-doors . How good they are long term I don't know.

 

They aren't certified, they are PH suitable. Not a bad thing, as long as the values can be proved. Others also supply PH suitable bi folding doors but Lacuna are not certified.

[Adam2]

We had 5m or slide and turn doors (some company in Kent curtain wall or something on those lines). Really liked them - 2cm rubber strip between glazing makes for great viewing into the garden. Seemed incredibly good - though was a retro-fit so no air tests done. The handle turn really compressed the glazing. We were really happy with them. Only issue was when ordering the chap with us wrote down the wrong RAL colour for the frame so instead of anthracite they were beige!! Could have been worse. At the time felt like a disaster but like many disasters we realised soon enough that really didn't matter - would have been more of a drama of course with bi-folds. Price was high, I think 40% more than the double glazed bifolds we were getting prices at the same time from Shuco supplier.

 

[Ferdinand]

On 03/05/2019 at 13:05, jack said:

We have a 5.4m slider, and to be honest I'd rather have gone for a pair of wide French doors in the middle with horizontal windows along the rest of the space. In our case, such a large window drastically limits our options for furniture placement. That may not be an issue for other layouts.

 

As a cheapskate, I never consider anything except French Doors.

 

Until I build my Para 79 Haese in the Peak District.

 

F

[gravelld]

On 04/05/2019 at 01:58, craig said:

They aren't certified, they are PH suitable

 

Thanks for confirming.