Framing windows, what are the rules?

[Yokosukadweller]

Hello everyone,

Finally I got my mini frame up. At the moment am waiting for a quotation for wood for the roof deck and a roof. But then walls and windows would be next.

I have never framed windows (or doors for that matter). So I am an absolute beginner.

I've got a lot of window glass in various sizes from my father in law, and I also have several windows. I also have some double glazed glass which I plan to use on the loft. My plan is to have windows pretty much all around the frame on the ground floor between the horizontal 'nuki' braces (if that works). I also plan to have 120mm space counting from the outside of those horizontal braces to the outside of the structure. This is for 12mm ply, vapor barrier, 100mm insulation, and around 5-8mm spacing to allow air flow and outer shell. So I guess I have around 120mm for window frame, double glass and also mosquito netting as the summers here are pretty intense on that front. I realise 120mm (about 5") is not much, but it is just a small workshop/mancave type of experiment here.

I was wondering if some of you more seasoned experts here could point me to some instructions or 'rules' as to how one should go about framing for windows with the above in mind. Or if my thinking regarding insulation and walls is ok. I have indicated on the photo where I could put windows, and I suppose I could just close it all off with plywood and vapour barrier first and then measure and cut holes for windows afterwards? 

Also, I realise I could (or should) have planned this better in advance, but admit that this project has grown organically ever since breaking ground for the wood fired oven that is hiding under the silver sheet inside the frame.

Thanks very much in advance,

Simon



 

[Don P]

I didn't see dimensions for the "outer shell", I'm assuming another 12mm ply, a weather resistive barrier (Tyvek), then some form of siding?

All depending on desire the jamb usually starts at the outer face of the siding or the outer face of the sheathing. It ideally runs to the inside face of the finished material. I typically rough frame the opening 1/2" wider and taller than the window jamb dimensions.

It sounds like not only are you framing the openings, you are building the windows... and with screens, these are operable? Just how deep is the question? 

[Yokosukadweller]

Thanks Don P,  Tbh I really don't know. There are many ways to skin a cat I guess? I talked to a Danish architect, who said I could put the insulation and then just a windbreak membrane (I guess like Tyvek) and then the outer shell. As for the outer shell, I was thinking to put 12mm cedar boards horizontal, so they overlap each other on the bottom - those are relatively easy to come by around here.

You say you rough frame 1/2" wider and taller than the window, you then put 1/2" stick to create an edge the window closes up against? Just trying to imagine it...

[Ljohnsaw]

The 1/2" allows you to use some thin shim pairs (long, very shallow taper) to get the door or window perfectly plumb and square so they operate correctly.  You would drive a nail or screw through the window or door frame, through the shims and into the rough frame.  Whatever gap is between the rough frame and window/door frame can be stuffed with fiberglass insulation.  You could use spray foam but need to be careful it does not expand to much and warp the window frame. Then your trim molding covers between the window frame and the rough frame, both inside and out.

Your windows from scratch need to be built as a stand alone unit with some nice wood that will paint or stain nice.  Different then rough framing.

[Don P]

If you have glass you need some type of frame for the glass. For an operable window or door that is usually built in the shop as a component and set into a "rough opening" a structural hole in the wall. There are a number of types of operable windows. Single and double hung where just the lower or both window "sashes" slide up and down. Horizontal sliders, the same as sliding doors, casement, a single large sash that swings like a door, awning, a casement that swings from the top. All of those have a sash frame that holds the glass and a window frame that includes the side jambs, header jamb and sill. In other words the "window unit" is a good bit larger than the size of the glass. So it really starts with the glass you have and the window sizes desired. Don't let your build be dictated by the glass available, it isn't really that expensive, the window is.

These are some double hung simple period windows for a job.
A bunch of upper and lower sashes leaned up around and the first frame being fitted to make the completed window unit. It sounds like the siding is similar. We have a flat outer siding surface so I'm running the window jambs out to the face of the siding and applying the casing trim on the siding... there is head flashing detail.
In the lingo these would be craftsman style  2-0 x 4-6 double hung 3 over 1  single pane windows.


 

Fixed glass is another beast. Better built as a separate unit but I have framed the rough opening, lined it with the finish glass frame and direct set the glass. Not as good, I would say never direct set glass inside of heavy timber, there is too much wood movement. So really, shop build any frame and set it in a rough opening in the building frame.

[kantuckid]

 I built my timber frame living room addition and talked to a glass guy who was also sourcing the custom insulated panels for the end of my room. I paid him to transport on a glass truck as part of the deal.  Room was finished in 2005 and given that the room end faces deep forest I didn't bother with UV resistant glass-it's plain. I went with heavier glass and as I recall was 5/8" spacing. Glass folks have the edge spacers . My design for a 16' wide room is a small triangle stacked on top of a square with two side triangles glassing the gable end. Has 4x6's between all glass. Double French doors in center with a fixed French on either side. 

I do wonder at what age I not be the guy who cleans the glass ;D. I also get to hang a huge wreath soon as it's holiday time again. 

My current cabin project I bought 4 slightly used Pella wooden double hung sashes from an OH window/door guy. I refinished them as they had one coat of screwed up- what looked like poorly applied Minwax on them. 
That gave me my opening sizes for when the walls are built. Same with door-bought off of a covid DIY guy who bought the wrong size and waited too long to take it back. 
As for drying concerns with my room job, the timbers were EWP 4x6's and well air dried before I planed them. Larger beams I'd be more careful. 
 

[aigheadish]

That's a neat looking little building and I love your oven!

[Yokosukadweller]

Thank you @Don P , @kantuckid , @ljohnsaw  for your very valuable information on considerations I need to have before going ahead. I need some time to digest all of this including how to make the rough frame and make space for a finer window inside. 

I have a few double glazed windows from an old display fridge, which I think I can pull out. I suspect I would put those on the loft between the king post on either side of the triangle. I also have a variety of old timber, some of which I imagine can be used if I pressure clean it first ha.



 


 

 



 

Then as you can see I have access to a lot of glass, and I can try to cut it, but to an extent the sizes I have dictate the sizes of the windows. In any event they need to fit in between those horizontal 'nuki' braces, which is the Japanese way of bracing to retain some flex/sway on the building in the event of an earthquake. I need to figure out the appropriate size of the windows relative to the space between those horizontal braces, both in terms of rough frame and window - and to keep that 1/2"of space as you have mentioned.

Another consideration I have is: I guess it is theoretically possible to make double glazed windows (no vacuum between glass), simply just two layers of  glass with a bit of air space between if I route a channel for the glass into the frame. Would that make any difference from insulation value perspective or am I fooling myself here?

If the above makes sense, I would do a window on the outside of the building (at the outer edge of the shell) that opens out - either with hinges at the top or on either sides, i.e. two halves that swing in and meet in the middle. Then on the inside I would put another frame with a mossie net, either sliding, or totally mobile that could be kept against an offset (whats the right word?) in the window sill with a peg and some pressure.

If there are any no-no's to my thinking please let me know, otherwise I shall go ahead to consider this task more deeply, and how I can make windows that are strong enough to hold what for some of these glass sheets is a considerable weight of glass.

Best

Simon

PS: @aigheadish thanks - it has been a lot of fun work so far:)

[Ljohnsaw]

Then as you can see I have access to a lot of glass, and I can try to cut it

Be careful there.  You might be dealing with tempered glass.  If you try to score that and tap it to snap it, it will shatter into a pile of coarse sand.:(

I guess it is theoretically possible to make double glazed windows (no vacuum between glass)

In theory, a good idea.  Back in New York, we had single pane, double slider windows.  Two sets of windows in one frame.  They would condensate but we had the option of opening one to dry it out.  If you permanently mount two panes, you WILL get condensation between them in the winter.

[Don P]

I think non sealed double pane has a lot going for it vs seal failure every 10 or so years, where is the energy efficiency if you lose the glazing every decade. If I did it the inner pane would be removable for cleaning. 

If the gap between panes is greater than about 1" there is room to set up a convective loop between panes. It is more efficient to limit the space between panes to 5/8-3/4".

From what I'm seeing I don't think you are cutting any of that glass. Tempered should have a "bug", an etched mark in one corner.

A single swing casement sash is going to be easier to seal vs a "french" double swing. You can find the crank hardware, locks, seals, etc online. You can eat up a lot of money right there.

[kantuckid]

Didn't Pella used to make double paned sash with a vent? 
I'd be careful using old stuff that might cloud soon after your work is done? Lots of clouded door glass is thrown away at glass companies as it doesn't meet public housing regs. They haul it to their dumpster and nick an edge with a file and crumble lots of it each year. 

[Don P]

That's where I first saw it. We did one with their commercial line, the doors had thin louvered blinds in the gap between panes, the cords came through hole in the inner pane and the inner pane was just held in with small turn buttons spaced around the edges. It was vented to the interior and cleanable. You do give up some R value but I'd bet in the long haul it amounts to less energy than scrapping and replacing clouded glass.

If you're ever in Monticello notice the windows. It's been a long time but I think I remember Jefferson did double pane windows, inner and outer about a foot apart.

[Tom King]

The 1980 Pella casement windows in our house not only have vented double panes, but you can take out the inside glass with little lever clips, much like some screens.

I don't know that they have been the most efficient, as far as heat loss, but we have no complaints with them, and I don't think we've ever even taken one of the inside panes out, except once as explained below.  Certainly, not a single one has ever become fogged up between the panes.

It looks like the gap is about 7/8", but that's just a guess as I'm sitting here looking at one.

Once I broke two of the panes in one window by a lawn mower throwing a rock.  I borrowed one of the inside panes from another window the same size, and carried the aluminum frame to my glass shop to replace that glass.  I cut the broken outside one out, and glazed in a new piece of glass myself.  I never did switch the original inside glass back to it's home window.

[kantuckid]

That's where I first saw it. We did one with their commercial line, the doors had thin louvered blinds in the gap between panes, the cords came through hole in the inner pane and the inner pane was just held in with small turn buttons spaced around the edges. It was vented to the interior and cleanable. You do give up some R value but I'd bet in the long haul it amounts to less energy than scrapping and replacing clouded glass.

If you're ever in Monticello notice the windows. It's been a long time but I think I remember Jefferson did double pane windows, inner and outer about a foot apart.

We have been there but missed that one. So much to take in there overall. His gardens sparked my brain too. Maybe we all need to visit there before they tear it down?-I'll stop at that point to keep things nice here.
I've had a similar thought on all this throwing away windows & doors that goes on in our country. The all wood sash Pella's I bought for my cabin are an e.g. for sure. I doubt they are 5 years old and cost and arm and two legs at that! The current oil prices will drive that mania further down the road to the landfill.  

[Yokosukadweller]

Thank you to everyone for your replies. I am overwhelmed by the information presented here. 
 
The glass I have my father in law got for free from a neighbour. The neighbour was a glazier and when he retired he had a large amount of pre-cut glass and just gave it away. Yes some is nicked, and some is tempered and others is not (at least some has smooth edges and others have sanded/no clear edges). There is what looks like modern machined glass (totally flat), and old school glass, which is...not sure how to explain, but slightly distorted when you look through it. The glass has been sitting for at least 10 years already and some cannot be used but I am quite sure I can find what I need there.  I would love to do my own vented double panes, but I am in too deep already and probably I have to find the right sizes of glass and some hardwood and just go for simple single sheet windows for now where one can install a second set of panes in the future.
 
I have done the additional studs now on Sketchup, you can see where I would like to put windows and what sizes they should be. Does this look alright or are there any alarm bells in this drawing?



 
 
Next I have to meet with the local sawyer and order OSB+ 30-40 studs, and try to figure out a cost effective roof. For the roof I want to use oldschool roofing boards (t&g) and then studs and some insulation, but I have not uet been able to decide what kinda roofing should go on there. It has to be decided by price and feasibility.

Must be methodical and do step by step so it is not overwhelming.


Best regards

Simon

[Don P]

 :D :D I've been working in sketchup all evening, I tried to grab your pic and spin it around.

Looks ok from here. With that shape of rough opening I would make horizontal sliders.

[kantuckid]

Did I miss something- are you making woodfired pizzas in the woods?  :D
 Appears to be a VERY hot place to hang out in there? 

[Don P]

Good Point! Some low intake and high opposite exhaust?

[Yokosukadweller]

Thanks for your responses. @ Don P I am not sure my screengrab was spinnable in Sketchup ;) I would send you the file for you to check, hang on I am trying to attach it here - it seems to work, is 2017 version ok?

About heat @ kantuckid - well yes in the summer its gonna get hot there for sure. The oven though is very well insulated - we can cook with leftover heat for up to 3 days after a pizza night. But I agree that eventually some heat would emanate from the oven over 2-3 days. I should think about some windows in the loft area as well that can let out hot air. Actually my father in law wants to give me a big industrial exhaust fan, I laughed it off but it may be a good idea to put one in the wall behind the oven, so heat can be drawn out during summer cooking.

[kantuckid]

For starters, we don't know the climate involved. I'm assuming it's Japan based on your subscript saying- "Dane living in Japan". 
Even in a cold climate that masonry stove/oven should heat a building many times that size?  :-\

My off-grid cabin of exact same size as OP's design will eventually have solar but only heat will be from a small Vermont Castings wood stove. In our home the similar small Jotul stove will run you out in an open ceiling living room if not really cold outside. 

[Yokosukadweller]

Yes, it is zone 9 i.e. subtropical. We get long hot and humid summers and dry cool winters, almost exclusively above freezing. If it ever freezes here its a flash freeze with a degree below zero (C) and quickly back to positive. Most problems here are related to mold and humidity which means people here generally accept very inefficient (bad insulation) buildings and use 'kotatsu' in the winter rather than having very insulated homes that get too much mold in the summer. 

And for sure I would have loved to make the structure bigger than it is but was constrained by the hill (dug out by hand) it is sitting on and so this will just be a mini studio heated by a big WFO...

[Ianab]

Your climate sounds very much like much of New Zealand. Heating and insulation aren't as important as in the colder areas. Ventilation and controlling damp is though. Summers are warm and humid, winters are cool and humid.  :D  

Might just be getting to me today, should be a nice Spring day, outside temp is a quite reasonable 19C. Humidity however is 100%. Doors and windows are open, but I don't think it can do much to keep the house dry :. This is why we don't dry wood down to 6-8% for furniture here. We need to run a dehumidifier to keep the house Down to ~70% R/H and stop mould growing.