DIY Windows

[paulrockliffe]

I have a loft conversion going in next year, with three wooden windows and all winter to build them. One of them is 1.5m x 2m with a pointy top, so god knows how many thousands to get made, so makes sense to design and build it myself. I've got that book that's recommended on the sticky thread for designing windows coming today and I'll be back with a sketchup design for you all to ridicule at some point too, but in the meantime I'm interested in Building Regs.

Is completely DIY feasible under Building Regs, given I won't be able to demonstrate a U value for the frames, just the glass itself? Are there any quick pointers to how I do this, or do I need to have a conversation with the inspector before I start ordering wood to make sure I'm not pissing in the wind?

Are there any particular design considerations when making to regs? I know the casements will need to have seals and appropriate hardware to lock and restrict falling etc, but not sure if there's anything I need to do to minimise cold-bridging via the frame, and stuff like that?

Any other building regs advice most welcome, I've not done windows before, so I'm sure I'll miss bits here and there.

Thanks

 

[Doug71]

Sounds like you know what you are doing, speak to inspector first and let him know what you are proposing and I am sure all will be fine.

Other things to consider which you have not mentioned are trickle vents and toughened glass where needed.

Doug

 

[paulrockliffe]

Thanks that's helpful.

Yeah, I'm aware of those things but they come under the design spec that I have a professional working up for the wider Building Control submission. Ie I don't need to worry about that, just make sure I follow the agreed spec when I have it.

I'm more concerned if the spec says something like, "frames to ENBSxxxx for thermal performance" or something equally vague. Quick pointers from people with experience on how to design the sections to meet that rather than wading through the regs would be really useful.

Just had an email from Amazon to say my book has been pt through my letter box, so popping downstairs for a look....

Cheers

 

[Doug71]

Building control seem to make allowances when things are bespoke, if your glass has a decent u value I am sure they will not be concerned about the frames.

Doug

 

[mikefab]

My local BCO just wants to know the u value of the DGU and isn't fussed about whole window calculations etc. A quick phone call will tell you how yours feels about this.

 

[Fitzroy]

Our extension has large glazed area so had to up the insulation in other bits to compensate and achieve overall figure that was required. Architects calcs just used u values for glazed area, unglazed walls, roof area etc didn’t go into details of frames etc.

 

[mr rusty]

I have been making windows for an edwardian house restoration. I have had conversations around my diy windows with my BCO while he's been on site, (because we also have an extension ongoing with new windows (not made by me)). Didn't seem that interested that I was making myself, although technically (and very loosely) mine are a "repair" to the original windows re-using some parts of the original window (the weights :lol: ).

You have quite a few things to think about if making your own windows:-

What timber - I used Accoya for dimensional stability amongst other things - a lot of commercial windows are engineered wood.
Seals - you need to design in good weather seals
Glazing system - I internally beaded, using epdm seals and reddiseals dry glazing clips

I designed mine for 24mm DGU with soft coated glass to achieve the correct U values, with my timber sections "inspired" by the CAD downloads that are available from some of the commercial companies if you look at their websites :lol:

 

[Fitzroy]

although technically (and very loosely) mine are a "repair" to the original windows re-using some parts of the original window (the weights :lol: )

Trigger’s broom springs to mind!

 

[paulrockliffe]

Thanks, yes, plenty to think about. I got my copy of Wood Windows - Designing for High Performance in the post today, I've had a quick read and have a reasonable handle on that now, but I'm sure I'll have plenty of questions once I've started pulling together a design. I'm going to use acoya too I think.

I think I'll probably design how I want them to look and then work from there.

 

[mr rusty]

If you are going to use accoya, then IMO you have to plan to machine everything, and not use hand tools. It machines well, but is brittle, and chips and spelches easily. It also drags out on the grain easily when hand planing, and will chip if you knock an end grain corner. My experience is it doesn't chisel nicely, so I wouldn't plan to hand cut M&T joints.

Don't let that put you off though. If you buy the rough sawn to convert to your own sections my experience is it is very straight and only requires a few passes through a cheap thicknesser to finish.

The stability and durability are unsurpassed and it's no wonder so many pro companies are using it for their top-range exterior joinery.

 

[Eric The Viking]

FWIW (I only have a tiny amount of experience doing windows), I used Idigbo to make a missing casement for our French windows (they are all in Idigbo). It was easy to machine and work with hand tools, and took paint well (it _needs_ paint as otherwise it's an insipid yellow colour), but I am told it doesn't have great shear strength - meaning long pieces can snap across the grain.

I know at least one highly respected contributor on here who hates Idigbo (and who did just that: snapped a crucial piece of his own French windows unexpectedly), AND it sounds like you have large areas of glass, so strength is probably the most important thing... but it might be worth considering.

Six months ago, I was considering Accoya for internal frame+panel doors, mainly because of the dimensional stability, but I'm now going to experiment first, particularly with Southern Yellow Pine (my local merchant carries it), as it's more of a known quantity, and I will inevitably end up using hand tools to tweak things. The other thing that was a bit off-putting was the price, but then I'm doing renovation, not a big project where the frame+casements is crucial to weatherproofing, etc.

Do you have time to get some small offcuts or similar to experiment with?

E.

 

[paulrockliffe]

Following up on this, I've got my book and had a good read. I'm not in a huge rush, I don't need it finished until April and I can set aside whatever time I need as Iv'e been stacking up leave from work. In terms of the wider project I have planning and Building Regs approval now, so I'm an initial site visit short of being able to crack on. There's nothing stopping me doing the window other than getting the design checked by Building Regs.

I've got enough ideas to go on for now but had another question that isn't covered in my book.

The main window is roughly 1.5m square, but it has a triangle of glass above that's something like 1m tall at the peak. I have the structural design to accommodate this for the dormer framing, there's a metal tie of 100mm2 cross section to accommodate. But in terms of the window I'm not sure of the best way to approach this.

I want to avoid building it as two windows and it ending up looking like one window on top of the other as an absolute priority because that would look daft with a much thicker frame across the top and my preference would be to use a thicker section around the whole window, with smaller sections between all the glass panels.

From a design point of view it's a bit annoying that this has to open really (cross-ventilation and fire escape) as it'd be much easier and look much better if I didn't need to open it. Are there any clever opening mechanisms these days that'll give me more design options?

Anyway, how would you approach this? As a window planted on top of a window, or as one window? Does anyone have a rough idea of what it's likely to weigh when glazed? Just roughly, as in 2-3-4-5 people to lift?

Thanks.

 

[MikeG.]

........The main window is roughly 1.5m square, but it has a triangle of glass above that's something like 1m tall at the peak..........Does anyone have a rough idea of what it's likely to weigh when glazed? Just roughly, as in 2-3-4-5 people to lift?

Two people will manage fine, but a third to just offer some guidance from the other side of the opening (ie inside if you are outside, or vice versa), or to stuff a wedge in at a critical juncture, would be a bonus.

 

[paulrockliffe]

Thanks, that's handy. In terms of lifting it, I'll aim to assemble it in the loft, then all that;s required is to stand it vertical and then to lift it onto the wall it sits on. Need to make a note to make sure the builder knows it is going that way or we'll have fun!

 

[Trevanion]

I want to avoid building it as two windows and it ending up looking like one window on top of the other as an absolute priority because that would look daft with a much thicker frame across the top and my preference would be to use a thicker section around the whole window, with smaller sections between all the glass panels.

The only real way around this without making a total mess of the joints is to have your frame jambs pass the frames head and work your triangular joints into those rather than trying to fit them into the corners. It would be like the small triangular portions of this window:

From a design point of view it's a bit annoying that this has to open really (cross-ventilation and fire escape) as it'd be much easier and look much better if I didn't need to open it. Are there any clever opening mechanisms these days that'll give me more design options?

The egress friction hinges work well and will allow the window to open to 90 degrees to the frame allowing plenty of room to escape, mushroom espagnolettes also work well to hold the casement tight against the seals and keep the casement from twisting over time.

Anyway, how would you approach this? As a window planted on top of a window, or as one window? Does anyone have a rough idea of what it's likely to weigh when glazed? Just roughly, as in 2-3-4-5 people to lift?

Thanks.

Your glass should weigh roughly 15kg for the triangular piece and 45kg for the square piece if you're going for standard 4-16-4 DG units, 3 people should be able to do the whole frame and glass in one but 4 people would definitely be beneficial.

 

[meccarroll]

Not absolutely sure but I think you may find that egress windows as a means of escape are only considered necessary by building control on the Ground and First Floor (First Floor after the Ground Floor). I think that once you go above a First Floor height you need other means of escape other than just windows. In loft conversions that I have worked on the main stair case had to have fire doors installed into every door opening that leads onto the stairway all the way down to and including the ground floor. This along with other fire prevention methods prevents a fire from consuming the main stairway and gives safe egress from the loft rooms in case of a fire.

Check the fire regulations and means of escape for your stairs leading from the loft rooms and ask about the need for egress hinges on the windows before you go too far. Of course regulations change over time and it's more than a couple of years since I did a loft conversion.

Good luck.

 

[paulrockliffe]

Hello, thanks that's useful. I'm working of the architect's design and building regs submission that includes those windows as fire-escape windows. I haven't checked whether that's necessary, but what you say sounds plausible given there isn't anywhere to escape to from that other than a ladder-rescue.

You're right that the primary means of escape is the protected corridor, I'm regretting not fitting fire-doors when we renovated the house as there's a load of messing about to do on doors that are never closed as a result!

If I don't have to provide emergency egress from this window then that will open up a few more design options, so would e really handy.

Thanks

 

[paulrockliffe]

I've done a check, I don't need the window to open for escape or for ventilation, so I have a free reign. That said I think the room will benefit from cross-ventilation in the summer when it's hot, so I'll aim for some opening.

 

[MikeG.]

........I have a free reign........

Your Majesty.

 

[paulrockliffe]

That's exactly what it's like when you're free to do what you want without Building Control input!

I bet BC didn't visit when Sandringham (?) set itself on fire.