puntloos Posted June 22, 2020 Share Posted June 22, 2020 Clearly they're all the rage nowadays, having 5m wide bifolds whoaaaa. Great selling point for real estate agents I'm sure. But.. I see a ton of practical issues: - Day to day, moving a 5m door out of the way to get into my garden feels.. hard... even with well-made ones. - Fire regulations, perhaps - Where do you 'store' the folds? They don't vanish But currently top of my mind: The 'bifold' system kind of feels iffy to me. You have a massive weight hanging forward to one side of the connection (runners?). I'm no mechanical engineer but that feels like a lot of strain on a small area - will that start to bend? Do we have to replace them, or worse, would it possibly damage the surrounding structure? TL;DR: will well-made bifolds stay easy to open/close, and will the framework stand the test of time without major maintenance? Link to comment Share on other sites More sharing options...
daiking Posted June 22, 2020 Share Posted June 22, 2020 One of the leaves just opens as a door. Where that leaf is and how it opens is to be configured. Examples of all in one or split bifolds in fully open. Link to comment Share on other sites More sharing options...
joe90 Posted June 22, 2020 Share Posted June 22, 2020 My 3 mtr bifolds work very well, made locally in Oak with German running gear. Fully adjustable hinges etc I specced solid seals as I had heard brush seals leak badly (mine came with both!). We love them. Link to comment Share on other sites More sharing options...
Thorfun Posted June 22, 2020 Share Posted June 22, 2020 Think I’ll follow this thread with interest as we discounted bifolds due to possible degradation in airtightness over time (if that’s even a thing) and are looking at sliders instead. But I’m interested in the responses to see if I can be persuaded to look at them. (full disclosure; I’ve not researched this area in detail yet and I’m sure there’s a bifold vs slider thread on here somewhere which I’ll definitely get around to reading at some point soon! My reading list just keeps growing.) Link to comment Share on other sites More sharing options...
timsk Posted June 23, 2020 Share Posted June 23, 2020 We are in the process of replacing all the windows on the south facing elevation of our 60s bungalow. There are many considerations but, for us, there are two really big ones . . . 1. Being able to open the doors for ventilation and to have that sense of connecting to the outside and 'bringing the outside in'. Bi-folds address this concern perfectly. 2. To maximise the glazing and to minimise the framing - so that the latter doesn't interfere either with the views or cut out light. (The current uPVC French doors that open out onto a terrace are only 75% glazing, i.e.a full 25% of the overall aperture is plastic!) Bi-folds score poorly in this regard - large sliders win hands down. Living as we do in Devon, we concluded that the number of times each year that the doors will be open will only be a fraction of those that they are closed. So, for us, it was a no-brainer; large sliders it is. If we lived in the med' - or in a warm climate where the doors would be open more often than not - we'd may well have gone with bi-folds. TIm. 2 Link to comment Share on other sites More sharing options...
Conor Posted June 23, 2020 Share Posted June 23, 2020 We put in 3m wide bifolds in our last house about 4 years ago. Loved them If you have an odd number of leafs you normally have a single opening door. Dead easy to operate. No issue with BC regs- fire or otherwise. Our 3m folds took up about 400mm at the end of the run. They open outwards so don't take up any space inside the house when open. The running gear is really solid, even on ours which was mid range. Didn't notice any issues in the 4 years we had them. Occasionally vacuumed the rail, and I think I greased the running gear once and adjusted the hinges once in those 4 years. Airtightness and U values aren't as good compared to lift and slide doors. But, there are some that are comparable. We're going for Lacuna, that have class 4 airtightness and use an top hung system so no stress on the floor channel seals. Also are triple glazed and really low U values. After living with biflods, I'd find it really hard not to have them in our new build. Link to comment Share on other sites More sharing options...
Thorfun Posted June 23, 2020 Share Posted June 23, 2020 5 minutes ago, Conor said: After living with biflods, I'd find it really hard not to have them in our new build. You see lots of photos with them open and they look lovely. But as @timsk said, this is the UK and they’d be closed most of the year and you’ll lose a lot of the view from the frame at those times. Do you find that is the case? Link to comment Share on other sites More sharing options...
Conor Posted June 23, 2020 Share Posted June 23, 2020 8 minutes ago, Thorfun said: You see lots of photos with them open and they look lovely. But as @timsk said, this is the UK and they’d be closed most of the year and you’ll lose a lot of the view from the frame at those times. Do you find that is the case? Not at all. We had them open on a daily basis from spring onwards. Even in winter we'd open them on a good day to blast fresh air through the house. They were certainly well insulated - condensation on the outsides. No issue re the view... It's only about 400mm over 3m. We're picking them for the new build for the "framing" aspect in order to match the fixed frames above. A lift and slide door would clash with the vertical frames above. Link to comment Share on other sites More sharing options...
Thorfun Posted June 23, 2020 Share Posted June 23, 2020 1 minute ago, Conor said: Not at all. We had them open on a daily basis from spring onwards. Even in winter we'd open them on a good day to blast fresh air through the house. They were certainly well insulated - condensation on the outsides. No issue re the view... It's only about 400mm over 3m. We're picking them for the new build for the "framing" aspect in order to match the fixed frames above. A lift and slide door would clash with the vertical frames above. cheers. I read your blog btw. the new place looks stunning! looking forward to reading how it develops. Link to comment Share on other sites More sharing options...
daiking Posted June 23, 2020 Share Posted June 23, 2020 (edited) They don’t seem to be the best technical solution if you want a low energy home but they have other benefits. And you’d be surprised how often you’d open them. Size is relative as well. A small 3m bifold has a significantly bigger opening than the opening in a 3m slider but once you’re at a 4m+ opening, a 2m wide opener in a slider might well be big enough for you. Edited June 23, 2020 by daiking Link to comment Share on other sites More sharing options...
Ralph Posted June 23, 2020 Share Posted June 23, 2020 The reason we discounted them was the number of sight lines you need in a 5 meter run compared to sliders. Also being in the north of Scotland we couldn't see them being fully open very often. Link to comment Share on other sites More sharing options...
Thorfun Posted June 23, 2020 Share Posted June 23, 2020 12 minutes ago, daiking said: They don’t seem to be the best technical solution if you want a low energy home but they have other benefits. And you’d be surprised how often you’d open them. Size is relative as well. A small 3m bifold has a significantly bigger opening than the opening in a 3m slider but once you’re at a 4m+ opening, a 2m wide opener in a slider might well be big enough for you. 3 minutes ago, Ralph said: The reason we discounted them was the number of sight lines you need in a 5 meter run compared to sliders. Also being in the north of Scotland we couldn't see them being fully open very often. yeah, cheers guys. this is where my thinking is coming from. we have a garden room where the whole corner of it will open. one slider is 5m and the other is 2.5m so it's a pretty wide opening when both sliders are open like this. but I can't help thinking that bifold would make a bigger impact and a better job of 'bringing the outside in' as they say. anyone know if bi-folds are generally cheaper than sliders when you get to this size of triple glazed sliders? Link to comment Share on other sites More sharing options...
Conor Posted June 23, 2020 Share Posted June 23, 2020 2 hours ago, Thorfun said: but I can't help thinking that bifold would make a bigger impact and a better job of 'bringing the outside in' as they say. anyone know if bi-folds are generally cheaper than sliders when you get to this size of triple glazed sliders? IMHO, yes, they do. You end up with a much wider open area. Price wise, the doors I'm looking at seem to be the best in the market - triple glazed, 25 year frame warranty, class 4 airtightness, and looks like around £9k for a 4.6m opening. I know lift and slide for that size are around £5k - so almost double the cost. BUT, our doors will be 2.7m tall and I've yet to find a lift and slide locally that comes in anything taller than 2.4m. For comparison, our "standard" double glazed 3m bifolds in our last house cost £3250 including side windows and installation. I'm sure you can get a good product for aronud £1k/meter. 1 1 Link to comment Share on other sites More sharing options...
puntloos Posted June 23, 2020 Author Share Posted June 23, 2020 Interestings stuff so far. One builder we've been bouncing ideas off of (paying a ittle for consults) says that his experience is mostly bad with them, primarily because he keeps on having to come back to fix them. Hence my mechanical point. The idea of having a bifold act as a 'normal door' is something I didn't realise and does change my opinion somewhat. We have a sliding door currently and fact is that while 'fine' it definitely doesn't let you through as smoothly as a classic door. A bifold could be best of both worlds in that case.. My bifold brand of choice was/is Centor 400-line since they have built-in fly screen as well as built-in blackout screen. The fly screen I'm not completely sure "is a thing" in Passivhaus style since leaving doors open sort-of breaks the carefully maintained temperature inside. Or? Link to comment Share on other sites More sharing options...
puntloos Posted June 23, 2020 Author Share Posted June 23, 2020 (edited) Optimal Panel Size: Seems to me if I want to hit standard accessibility reqs AND I want the door closest to the kitchen to be usable as a 'normal door' I need the door gap to be 838mm wide, so x3 is 2514. From https://centor.com/uk/doors-and-windows/400-series/405-integrated-folding-door I'm assuming that the frame is actually 1434 - (575*2) = 284mm so my best guess is my gap should be exactly 2798 - okay 2800? mm wide? Would this work: Edited June 23, 2020 by puntloos Link to comment Share on other sites More sharing options...
Vijay Posted June 23, 2020 Share Posted June 23, 2020 6 hours ago, Conor said: IMHO, yes, they do. You end up with a much wider open area. Price wise, the doors I'm looking at seem to be the best in the market - triple glazed, 25 year frame warranty, class 4 airtightness, and looks like around £9k for a 4.6m opening. I know lift and slide for that size are around £5k - so almost double the cost. BUT, our doors will be 2.7m tall and I've yet to find a lift and slide locally that comes in anything taller than 2.4m. For comparison, our "standard" double glazed 3m bifolds in our last house cost £3250 including side windows and installation. I'm sure you can get a good product for aronud £1k/meter. That's a bit of a concern. I was told that sliders would be made to measure, so I didn't know there was an issue with anything over 2.4m Link to comment Share on other sites More sharing options...
puntloos Posted June 23, 2020 Author Share Posted June 23, 2020 One further issue with bifolds: The Centor ones have an U value of 1.0 and Air Permeability Class 3. Is that okay for passivhaus or am I going to struggle? Presumably the size of the door matters too - was thinking 2.8(wide)*2.4m(tall) -M Link to comment Share on other sites More sharing options...
puntloos Posted June 24, 2020 Author Share Posted June 24, 2020 Comparing it to this one: https://www.greenbuildingstore.co.uk/products/lift-slide-doors/ they are 'proudly claiming' a 0.98 but class 4. Is air perm a big deal at this level? Link to comment Share on other sites More sharing options...
Conor Posted June 24, 2020 Share Posted June 24, 2020 4 hours ago, puntloos said: Comparing it to this one: https://www.greenbuildingstore.co.uk/products/lift-slide-doors/ they are 'proudly claiming' a 0.98 but class 4. Is air perm a big deal at this level? That's the thing, I'm not really sure how air tightness class relates to air leakage under test conditions... Seems more of a wind resistance measure than anything else... Which is probably more relative to the real world! Link to comment Share on other sites More sharing options...
puntloos Posted February 19, 2023 Author Share Posted February 19, 2023 FWIW at this point we went with slider doors. The reasons were: 1/ A lot more maintenance, of course(?) sliding doors offer a much more balanced load/weight, straight down, rather than trying to shear the frame out of the wall. 2/ Lower U-values/airtightness on the sliders. Our house is very bright so we need to compensate somewhat to hit passivhaus 3/ Somewhat cheaper Link to comment Share on other sites More sharing options...
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