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Green Building Bible, Fourth Edition
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  1.  
    Hi,

    I have some old pvc bay windows on the ground and first floor on the north side of my house. Besides the windows themselves being poor quality, the wall below the ground floor window is thin masonry providing very little insulation. The wall between the windows used to be tiles on the outside, 75mm studs and plasterboard on the inside. I have installed some Celotex in there when I bought the place, but there isn't much room to get a decent depth of insulation. And then the little flat roof on top is shallow too, and covered in old roofing felt.

    Given the poor condition/design of all the parts of the bay window column, I am considering replacing the lot, making my own custom wood windows and designing in some deeper insulation.

    The windows have five sections, and I'd like to keep it like that in keeping with the rest of the street. But elsewhere in the house I have windows I bought in France which open inwards, and have lift off hinges. This has proved excellent for cleaning and painting the windows easily, without needing a ladder. So I was thinking of making sections 2 and 4 inward opening with lift off hinges. Again, this makes window cleaning easy, and I'm planning to varnish the wood - so an annual recoat shouldn't be too difficult.

    I haven't decided what kind of wood to go for. I have a varnished oak front door I made a few years ago that seems as good as new. So I'm thinking oak might be OK. Any suggestions for other timber for good durability and stability at a reasonable price?

    This isn't a conservation area - but perhaps I'd need planning permission to make the windows taller than they currently are?

    And I'm wondering what material I could use between the windows? Something perhaps more interesting than just reusing the same tiles.

    Grateful for any suggestions/criticism/hints.

    Thanks,

    John
    • CommentAuthortony
    • CommentTimeAug 24th 2020
     
    Last time I saw that arrangement wind could blow into the first floor void was open to the tile hanging.

    Oak sounds good but please don’t varnish it 😢 use oil or wax oil, linseed oil etc

    How about 3g

    Warm roof redesigned with 200mm pir,

    G/f masonry with 250mm IWI with nice wide window boards

    intermediate cladding overhanging a bit Again 250pir between and inside studs
  2.  
    Thanks for the feedback Tony.

    What have you got against varnish? I had oiled oak doors on the south side of the house - didn't go well, and I ended up painting over them. The varnished door on the north side of the house is as good as new after 4-5 years - it's just darkened a bit (it does have a small porch roof over it though so it rarely gets wet).

    Whats IWI? And 3g? And what do you mean by window boards? Window cills? Wide so as to prevent rain running down?

    John
    •  
      CommentAuthordjh
    • CommentTimeAug 25th 2020
     
    Posted By: John PedersenWhats IWI? And 3g? And what do you mean by window boards? Window cills? Wide so as to prevent rain running down?

    IWI = Internal Wall Insulation
    3g = triple glazing
    window boards = the typically wooden/mdf boards at the bottom of a window on the inside
    window cill/sill = the stone, slate, metal, wood bit at the bottom of a window on the outside

    wide so as to cover the 250 mm of insulation etc.
  3.  
    Thanks for clarifying things for me.

    I have been considering building some seating at the bottom of the windows to accommodate the insulation. That would be wide!

    I looked into 3g when I was doing the south side of the house, and came to the conclusion that much of the benefit is in noise reduction, which isn't a problem here. Then there's the added expense, extra weight, which would require stronger frames. 2g with argon and coatings and non metal divider between the panes seems most appropriate for this.
  4.  
    John, your windows sound similar to ours and I have been thinking along same lines as you.

    The previous owner replaced the windows with pvc double glazing, unfortunately the pvc frames are quite wide, which reduces the area of glazing and hence makes the room darker. We won't replace them anytime soon but would be looking for thinner frames (Ali? Timber?)

    I think Tony maybe considering EPS insulation for the walls. I am leaning towards PIR (celotex or equiv) which is thinner for the same insulation.

    We have a window seat downstairs but don't use it as a) you have your back to the view and b) the window board sticks into your back. Might go for some sort of storage box.

    The first floor void definitely needs investigation and insulation.

    We can't do much with the flat roof as the height is constrained by the eaves of the main house pitched roof. Possibly slide an inch or two of marmox or even aerogel under the flat ceiling.
    •  
      CommentAuthordjh
    • CommentTimeAug 25th 2020
     
    Posted By: WillInAberdeenb) the window board sticks into your back

    How does that happen? The window board would be what you sit on.
    • CommentAuthorrevor
    • CommentTimeAug 25th 2020
     
    Presume if you are making your own you have the machining gear to do it. Personally I would make out of Sapele it is much cheaper than oak and basically knot free straight grained and easy to work with finishes well ideal for outside use and will be less wasteful than oak. Sandolin or Teknos stain would be a good weather resistant finish. If you use oak oil it, it is open grained and oil will soak in and protect it. Varnishes on oak tend to crack and flake and you say you are willing to maintain it but with oil it is much quicker rub down and wipe over and you won't be doing it that often.
    I think a timber frame would be a good idea making it deep enough to take 100 mm of pir . Don't forget ventilation and avoid cold bridging
    The planners may not like you changing the height of the windows make sure you maintain the means of escape regs. Rather than make windows taller make a pitched roof and have plenty of insulation in the space.
  5.  
    Posted By: djhThe window board would be what you sit on.
    You're welcome to sit on the window board if you are tall enough, but most folks sit on the seat!
      IMG_20200825_183644276_copy_1040x780.jpg
    • CommentAuthorgyrogear
    • CommentTimeAug 25th 2020
     
    nice one -- I see you are on windows 5 - most folks have to run on 10 these days LOL !

    Hope you are virus-free, at least !

    :devil:
    gg
  6.  
    revor - I don't have the machining equipment, but there's a wood engineering place down the road that can turn out any profiles I ask for, so I was planning on drawing up what profiles I need based on some inward opening French windows I have I bought from LaPeyre. And I have a friend who is a carpenter who has what's needed for creating mortises. I figured I'd do the rest...
    • CommentAuthorCWatters
    • CommentTimeAug 26th 2020
     
    <blockquote><cite>Posted By: tony</cite>Oak sounds good but please don’t varnish it 😢 use oil or wax oil, linseed oil etc</blockquote>

    I have a lot of outside oak with a mix of finishes. I wouldn't use "varnish" either but nor would I just use Dainish Oil if you want to retain a honey colour. Too much maintenance.

    If you really want to minimise maintenance I recommend a coat of Sadolins Classic to get the right colour followed by several very thin coats of Sadolin extra durable clearcoat. I do mean thin coats well brushed out or you might as well just slap some thick varnish/treacle on it.

    If you prefer the look of an oil I recommend one coat of Dainish oil then several coats of Osmo 420 UV Protection Oil. The latter lasts at least twice as long as most Danish Oils. If you just use Osmo you will probably find that the UV protection it provides leaves the new oak a bit too white. Hence I recommend a coat of Dainish first which will give it that honey colour.

    I have no connection with this company but they are one of the few that sells very small/cheap sample tins of many of the above so you can try them out. Their prices are usually good as well..

    https://www.wood-finishes-direct.com
    • CommentAuthorowlman
    • CommentTimeAug 27th 2020
     
    Why mess about with two bays,- one lower and one upper with some cobbled together inbetween structure. Build your dwarf wall if you must, you could then go right to the roofline with one tall single structure glazed bay. If the angles are right you could omit the flat roof and pot in a lead pitch roof to match the house roof pitch.
  7.  
    Owlman,

    I am attracted to that idea. However, we're then talking about two storey panels of double glazing. That's going to cost, plus the difficulty of getting them onsite and getting them into place. And there is a floor/ceiling half way up. Carry the glass past that? And are you suggesting using structural glass? I looked into that briefly and found it would be far more expensive than panes inserted into a wooden structure. Unless you can get hold of recycled skyscraper glass panes??!
  8.  
    Posted By: owlmanWhy mess about with two bays,- one lower and one upper with some cobbled together inbetween structure. Build your dwarf wall if you must, you could then go right to the roofline with one tall single structure glazed bay. If the angles are right you could omit the flat roof and pot in a lead pitch roof to match the house roof pitch.


    Posted By: John PedersenI am attracted to that idea. However, we're then talking about two storey panels of double glazing.

    I don't see that one tall single structure needs to be constructed from a two story panel of glass. Divisions in the glass should be possible by properly placed glazing bars.
    • CommentAuthorowlman
    • CommentTimeAug 28th 2020
     
    I'd be surprised if the existing floor/ceiling projected into the midway structure. My guess is you could take down both bays plus the inbetween bit with no structural loss of integrity. So do that and finish the whole like an atrium and then do the tall bay bit.
    If it were mine I wouldn't bother with local joinery firms I'd go straight for curtain walling companies using standard sections. Get them to design your ideas and fit it too. I know of one company that produces a hybrid glazing sections in timber with aluminum facings so no aesthetic interior losses, if a wood finish is your thing. No opening sashes makes it easier and cheaper too.
  9.  
    Ah, if there's no load from the first floor dependent on the bay structure (seems reasonable - just some joists projecting 2-3 feet into that space) that really opens up the possibilities. Great!

    I've never heard of a 'curtain walling company'. Google has helped. Interesting.

    But no opening windows? For ventilation and fire escape?
  10.  
    I maybe misunderstood,

    The unglazed section between the group and first floor windows, which is currently insulation-between- stud on John"s and thin masonry on ours,

    Is the proposal to make that glazing? Even with tiptop 3G the U value would be very much worse than if that section were heavily- insulated stud or masonry,

    John, look for Scottish glazing suppliers, it's normal for windows to open inward here for easy cleaning as you want. Don't understand why they open out in England.
    •  
      CommentAuthordjh
    • CommentTimeAug 28th 2020
     
    Posted By: owlmanI'd be surprised if the existing floor/ceiling projected into the midway structure. My guess is you could take down both bays plus the inbetween bit with no structural loss of integrity. So do that and finish the whole like an atrium and then do the tall bay bit.

    I don't understand what you're suggesting - or maybe I don't understand the existing situation?

    I thought the existing was a two-storey construction with bay windows in two separate rooms, one above the other. So whatever replaces the bay windows needs to maintain that separation between the rooms (noise, fire, air separation).

    I don't see how an 'atrium' or single double-height windows fits into that situation?
    •  
      CommentAuthordjh
    • CommentTimeAug 28th 2020 edited
     
    Posted By: WillInAberdeenDon't understand why they open out in England.

    The traditional windows in England that open outwards are designed to make it easy to provide overlapped seals that reduce or eliminate wind-driven rain ingress, and allow rain running down the outside to drain to the outside. In earlier times it was easier to produce such windows if they opened outwards.
    • CommentAuthorowlman
    • CommentTimeAug 28th 2020
     
    Posted By: John PedersenAh, if there's no load from the first floor dependent on the bay structure (seems reasonable - just some joists projecting 2-3 feet into that space) that really opens up the possibilities. Great!

    I've never heard of a 'curtain walling company'. Google has helped. Interesting.

    But no opening windows? For ventilation and fire escape?



    Any projecting joists will may well be supported by a trimmer or some other form of support at the house wall. If not it would be easy to insert one.

    Once the existing bays are removed you could possibly push the bay footprint out a bit, and left and right a bit also, to wrap around the existing brickwork opening, and create a nice glazed seating area/snug/atrium,- lots of possibilities there.
    You may have to compromise the segmented, ( I'm assuming ), number of segments within the constraints of the glazing system used. Segmented bays are only a series of rectangular windows joined by angled jointing strips. Extrusion suppliers may only have limited angles within any system.
    The curtain wall companies are generally fabricators, find one with a CAD suite to realise your ideas. Most of them deal with a couple of extrusion/glazing section/system, manufacturers. You'll have to shop around.
    If you did go down the local joinery firm route, make sure the sections they use are machined from engineered timber. Anything else would be silly, IMO.
  11.  
    Posted By: djh
    Posted By: WillInAberdeenDon't understand why they open out in England.

    The traditional windows in England that open outwards are designed to make it easy to provide overlapped seals that reduce or eliminate wind-driven rain ingress, and allow rain running down the outside to drain to the outside. In earlier times it was easier to produce such windows if they opened outwards.


    Mmmm... sometimes we have wind-driven rain in Scotland too...!
    But not every day, as some days we have wind-driven snow.

    Fortunately, the windows have always been designed for this, with the same features as the doors, which open inwards in England the same as they do in Scotland.
  12.  
    I've got some Veluxes in my extension roof. Centre hung, which mean they open both in and out! Were they invented somewhere along the English/Scottish border?
    • CommentAuthorowlman
    • CommentTimeAug 28th 2020
     
    The Border Reivers of the window world.
    :wink::bigsmile:
    •  
      CommentAuthordjh
    • CommentTimeAug 28th 2020 edited
     
    Posted By: WillInAberdeenMmmm... sometimes we have wind-driven rain in Scotland too...!
    But not every day, as some days we have wind-driven snow.

    Fortunately, the windows have always been designed for this, with the same features as the doors, which open inwards in England the same as they do in Scotland.

    Sorry, I can't answer for the whys and wherefore of Scottish design choices, only the English.

    There's a history of sorts at https://historicengland.org.uk/images-books/publications/traditional-windows-care-repair-upgrading/heag039-traditional-windows-revfeb17/

    The early frames and casements were simply hung on the outside of the existing structural openings that served as windows before then. The fact that the casement is larger than the opening is what keeps the water out, and especially stops water that falls on the window and drains down from being blown in at the sill. Inward-opening windows need more advanced technology that simply didn't exist as I understand it.

    Maybe the Scots didn't adopt glazed windows until after the English? :devil:

    Another factor was shutters. In England these were originally fitted internally. In Europe more recently shutters are often fitted externally, which dictates that the windows open inwards.

    I seem to remember that front doors in England traditionally open inwards because of security. It puts the hinges on the inside and allows the door to be secured with wooden boards across the back slotted into hooks on the wall (I'm sure there must be a name for the boards but I can't be bothered to find out what it is.) Other reasons for inwards opening include front doors that open directly onto pavements or road, and the wish to avoid collisions. They are notoriously poor at excluding water, relying on water bars that are perfectly sealed.

    Externally-opening front doors are in many places dictated by fire regulations.
    •  
      CommentAuthordjh
    • CommentTimeAug 28th 2020
     
    Posted By: John PedersenI've got some Veluxes in my extension roof. Centre hung, which mean they open both in and out! Were they invented somewhere along the English/Scottish border?

    :bigsmile: :bigsmile: :bigsmile:
    • CommentAuthorJonti
    • CommentTimeAug 28th 2020
     
    Certainly in Switzerland, Norway and Finland shutters have been externally fitted for several hundred years with windows opening inwards. It should be noted that in all these countries buildings have historically had quite deep eaves which reduces the amount of rain actually getting onto the building's walls.

    In Scotland many buildings have no protruding eaves and therefore the walls are exposed to the elements.
    • CommentAuthorowlman
    • CommentTimeAug 29th 2020
     
    Posted By: Jonti It should be noted that in all these countries buildings have historically had quite deep eaves which reduces the amount of rain actually getting onto the building's walls.
    In Scotland many buildings have no protruding eaves and therefore the walls are exposed to the elements.



    In England too and it's a UK design feature I've never understood. Why, in a maritime climate would you not protect walls from rain. The problem is builders are still constructing homes with little or no eaves overhang. Think of all these Barratt and Wimpey homes and many, many others where upgrading with EWI, for instance, is now virtually impossible, at least economically.
    • CommentAuthorEd Davies
    • CommentTimeAug 29th 2020
     
    The only reasons I can think of for not having overhangs are avoiding having something the wind can get a “grip” on and avoiding ice damming.

    https://en.wikipedia.org/wiki/Ice_dam_(roof)
    •  
      CommentAuthordjh
    • CommentTimeAug 29th 2020
     
    Posted By: Ed DaviesThe only reasons I can think of for not having overhangs are avoiding having something the wind can get a “grip” on and avoiding ice damming.

    I think the main reason is reducing the quantity and thereby cost of materials and so increasing the builder's profit.
   
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