Bifold door height?

[puntloos]

My ground floor is 2.7m ceiling height. And, having full height doors and windows is a bit of a statement

 

 

But:

 

1/ Should I worry about U-values? I'm certainly aiming for passivhaus (but not super concerned to miss it somewhat). Will a 2m high bifold

 

....be dramatically better than 2.7m? 

 

(note I'm not too worried about solar gain since I have awnings everywhere..)

 

2/ What about price? I know that the brand I was/am thinking of - Centor 405's does have even 2.8m tall ones. But do they typically have standard sizes or are they made to measure and you're mostly paying by m2

 

3/ What about ease of opening/closing? 2.7m means 35% more weight of the doors presumably.. will this make the bifolds meaningfully difficult to open/close? Any other challenges I should worry about?

 

4/ What about 2m with a 'top window' above it? Probably quite pricey.. not sure if it's a big benefit? Will it be even doable with very deep (465mm) window depth due to insulation?

 

Edited August 8, 2021 by puntloos

[nod]

Full height look good 

But you will have to consider shading Blinds etc 

[Russell griffiths]

If you are considering passive standards then I thought bi folds where something to avoid, I was under the impression that they have poor air sealing that gets worse as they get older. 

[puntloos]

7 minutes ago, Russell griffiths said:

If you are considering passive standards then I thought bi folds where something to avoid, I was under the impression that they have poor air sealing that gets worse as they get older. 

 

I suppose that makes sense but *in theory* the centor 405s, when triple-glazed - are 1.0w/m2k (if the shades are drawn).  Not terrible.. 

[nod]

9 minutes ago, Russell griffiths said:

If you are considering passive standards then I thought bi folds where something to avoid, I was under the impression that they have poor air sealing that gets worse as they get older. 

Ours are the best on the market got airtightness 

 

Bloody rubbish ?

[puntloos]

5 minutes ago, nod said:

Ours are the best on the market got airtightness 

 

Bloody rubbish ?

Not sure what you mean? Are they wrong that they are best on market (not shocking perhaps, which brand is better?)

Or just that 'the best is not good enough'?

[IanR]

18 minutes ago, Russell griffiths said:

If you are considering passive standards then I thought bi folds where something to avoid, I was under the impression that they have poor air sealing that gets worse as they get older. 

 

It's a commonly made point, but there are plenty that are PH Certified. I have Solarlux Bi-folds and gave them special attention during the blower test where I couldn't detect any air leakage around them, (but did around my bowed front door, which had to be replaced and a couple of windows that needed adjustment). After fixes we achieved a 0.089 ACH, so can't be too bad.

[nod]

9 minutes ago, IanR said:

 

It's a commonly made point, but there are plenty that are PH Certified. I have Solarlux Bi-folds and gave them special attention during the blower test where I couldn't detect any air leakage around them, (but did around my bowed front door, which had to be replaced and a couple of windows that needed adjustment). After fixes we achieved a 0.089 ACH, so can't be too bad.

Ours are PH Certified also 

Still leak air like sieve 

4 sets  on the next one Probably use sliders 

[joe90]

21 minutes ago, nod said:

Ours are PH Certified also 

Still leak air like sieve 

4 sets  on the next one Probably use sliders 

mine were made locally by the same company that made the windows, in Oak, with compression seals and during the air test they did not leak at all and no reason they should start to leak because of the compression seals same as the windows. I think bifolds get a bad rap because some use brush seals which (IMO) are rubbish.

[Russell griffiths]

11 hours ago, puntloos said:

 

I suppose that makes sense but *in theory* the centor 405s, when triple-glazed - are 1.0w/m2k (if the shades are drawn).  Not terrible.. 

That’s u value, not airtightness. 

[puntloos]

3 hours ago, Russell griffiths said:

That’s u value, not airtightness. 

Air permeability    Class 3
Water tightness    Class 7A
Resistance to wind load    Class A3

 

Class 3 has been known to pass the Passivhaus airtightness test, but it is advisable to go for Class 4 as I understand it, so .. doable?

[Conor]

Our 2650mm tall and 4600mm wide solarlux went in last week. Triple glazed and class 4 airtightness. 5 figure cost to go with it.

 

 

[puntloos]

Solarlux, Uvalue of 1.5 - not horrid, and air perm class 4

Strange how Centor is better at U (1.1) and worse at air ..

[IanR]

10 minutes ago, puntloos said:

Solarlux, Uvalue of 1.5 - not horrid, and air perm class 4

Strange how Centor is better at U (1.1) and worse at air ..

 

Most of the higher end Solarlux have a 0.8 U value, but wasn't aware any of their Bi-Folds went to Class 4 air permeability.

[Conor]

16 minutes ago, puntloos said:

Solarlux, Uvalue of 1.5 - not horrid, and air perm class 4

Strange how Centor is better at U (1.1) and worse at air ..

Must be for the double gazed units. Ours are definitely less than 1.

[joth]

53 minutes ago, puntloos said:

Class 3 has been known to pass the Passivhaus airtightness test, but it is advisable to go for Class 4 as I understand it, so .. doable?

I think there's also a question of longevity of the airtightness.

even with a totally bog standard PH certified french door from internorm, we find it very fiddly to get it tuned to a sufficiently airtight state that isn't a complete bugger to lock and unlock. Over time I'm sure this will get tougher, and my understanding it bifolds are an order of magnitude harder to maintain.

So - certainly do the completion blower test and insist the supplier fixes any issues to get it to pass, it seems it is realistic to  be prepared for it to become more drafty (and/or harder to use) over time.

 

Edited August 9, 2021 by joth

[puntloos]

18 minutes ago, joth said:

I think there's also a question of longevity of the airtightness.

even with a totally bog standard PH certified french door from internorm, we find it very fiddly to get it tuned to a sufficiently airtight state that isn't a complete bugger to lock and unlock. Over time I'm sure this will get tougher, and my understanding it bifolds are an order of magnitude harder to maintain.

So - certainly do the completion blower test and insist the supplier fixes any issues to get it to pass, it seems it is realistic to  be prepared for it to become more drafty (and/or harder to use) over time.

 

Agreed, I can only imagine the amount of force that plays on these few hinges and rollers that such a huge door is suspended on. And it's not a stable load either, when folding suddenly the weight starts to pull forward rather than just down.. 

[Bitpipe]

Question I'd ask yourself is whether the bi-folds are more likely to be open or shut.

 

In all your renders above, they are open - which creates a lovely uninterrupted view.

 

In reality they are likely to be partially open or closed so you have the vertical bar effect - nothing wrong with this if it's the aesthetic you're looking for.

 

We have 4.5m sliders so can have a 2m ish opening if we want but rarely want to tbh.

 

Obviously if the weather is inclement, they stay closed but on hot summer days we keep them closed to keep cool air (night time purge) in the house and also to keep noise out. Other issue with a wide open garden facing aperture is you can get a lot of stuff blown in (leaves, tree dander & pollen etc).

 

 

Edited August 9, 2021 by Bitpipe

[Ralph]

39 minutes ago, Bitpipe said:

Question I'd ask yourself is whether the bi-folds are more likely to be open or shut.

 

In all your renders above, they are open - which creates a lovely uninterrupted view.

 

In reality they are likely to be partially open or closed so you have the vertical bar effect - nothing wrong with this if it's the aesthetic you're looking for.

This is one of the main reasons we went for large sliders, they would be closed 99% of the time and the thick frames would annoy the crap out of us. Personal aesthetics and all that.  

[Makeitstop]

Agree on sliders 100%.

 

I don't get the mad fuss over bifolds in recent years. I'd bet for the vast majority it's very rare they are opened up fully, and when they are closed, the vertical interruption to sightlines would annoy the crap out of me.

 

The single aspect of bifolds that I see as a potential plus is the inclusion of a slave door to use as you would any other door, but other than that, sliders every time for a wide aperture imo. 

Edited August 9, 2021 by Makeitstop

[Conor]

He's a counter argument for bi-folds. We had 3m ones in our last house and loved them. They were open far more than even we thought they would be. Having the full width open is ideal if you want to use the space as an indoor-outdoor dining/social space. Which was exactly what we did. That's the main reason we're going for them again in this build. The frames aren't an issue for us as we don't have a view as such, and they do frame what is there.

 

Another factor that is unique in our case, is that we have matching fixed units above, and there is a room divide at the second frame. So sliders would never have worked for us as we wouldn't have been able to align the frames above. But that's not a consideration for most people I suppose.

[Mr Punter]

I have had big bifolds in the past and they were rarely opened.

 

The best I had were 3m wide in panes, so you had an every day access door plus the open up all thing.  The downside there was we did not have a window in the same room that could be opened gradually for ventilation, just a big fixed pane.

 

Sliding doors allow adjustable ventilation and are what I have now.

 

Regarding door height, 2.4m is probably high enough.  Do not get them sized near the maximum extremes of what they are able to make, as this will often mean that the running gear / hardware is working at its limits.

[Happy Valley]

We have gone for Sunflex sliders in our kitchen diner at 90 degrees to each other. The 5m and 3.8m widths have 3 pains which when pushed back together are completely flush so looks like you are looking through one window not 3. There are only 20mm sight lines when shut. The compromise we made was going for double over triple glazing. 

 

We have great views so sight lines were the main concern. Also it can be quite windy where we are and I don't like the idea of bi-folds being banged or moved in strong conditions.

Edited August 9, 2021 by Happy Valley

[Makeitstop]

The vent potential (especially lift and slide, where its lockable) is one of the main benefits I see in a slider, as well as better sightlines, less obstruction on opening wide, due to not having a bank of doors protruding maybe 0.8 / 1 metre deep into the outside space, better airtightness and arguably security too.

 

Having said that, on some installations bifolds work well and suit some situations. I think if you've really considered it, and if you've lived with them previously (as Conor has above) and know what you want from them, they are still a great choice.

 

Great looking place by the way Conor.

Edited August 9, 2021 by Makeitstop

[Andehh]

On 09/08/2021 at 15:50, Happy Valley said:

We have gone for Sunflex sliders in our kitchen diner at 90 degrees to each other. The 5m and 3.8m widths have 3 pains which when pushed back together are completely flush so looks like you are looking through one window not 3. There are only 20mm sight lines when shut. The compromise we made was going for double over triple glazing. 

 

We have great views so sight lines were the main concern. Also it can be quite windy where we are and I don't like the idea of bi-folds being banged or moved in strong conditions.

How are you getting on with them?

 

We are going for a similar setup, with a floating corner & doors that seal against each other (so no pillar) - similar overall dimensions to your though.