Double-glazing as replacement for slate roof

[pembrokestephen]

Ah, you know how it is...one unguarded comment, and all of a sudden you've got a Project on

This is the situation: we have a kitchen extension, above half of which is a bedroom, and the remainder of which is covered by a sloping slate roof. In the bedroom, a small doorway under the window leads into the roof void above the kitchen ceiling, and beneath the roof.

Because of the layout of the house - we have a steeply (upward) sloping garden, and there's a 1.5m wall 3 feet from the back of the kitchen, not a lot of light gets in. So stupid here says "Well, I don't think it would be impossible to have that slate roof off, and glaze it with double-glazed units - that'd let lots of light in, and we could take away the kitchen ceiling up to the bit where the bedroom ends.

So, what we're talking here is replacing a slate roof some 3m wide by about the same front-to-back, and at about a 30degree angle, with double glazed units. If the rafters (at 44cm spacing) will support slate, I'm guessing double-glazed units wouldn't be too much of a problem. I would need to find some kind of spacer to fit to each rafter that would hold the glass, and I need to worry about the join between the glass and the slate roof below the bedroom window, and probably a million things I haven't thought of yet.

But the obvious and big questions are:

Is this even feasible?

Are there buildings control implications?

Am I going to have to go for special glass (eg toughened, etc). I'm aware of Schedule L, or whatever it's called, and would be intending to put glass in that was of a suitable U value (this is part of the reason - that bedroom gets DAMN cold in the winter, and I suspect that it's draughts from the roof).

Have I missed some critical thing that's going to cause my house to explode, or flying badgers to come down the chimney?

And where would I go to to get hold of suitable DG units and the necessary spacers/fitments?

 

[breezer]

isnt what you are suggesting more commonly called a conservatory?

 

[pembrokestephen]

isnt what you are suggesting more commonly called a conservatory?

Well, I suppose it'd end up being like a conservatory roof, yes.

But it's an existing structure whose roof I want to change - my instincts tell me that that could well make rather a difference to the whole thing...

 

[breezer]

i am not a builder so dont take my word for it, but would not the rafters have to come out? since the dg units cant be fixed between them, A, it would look terrible and B the rafters outside would get wet.

if you put the dg units on the rafters it will still look terible since from underneath you would see them

hence conservatory.

all rooms / buildings i have seen with glass roof you cant see that much of what is holding the glass there

 

[noseall]

in order to expose the roof timbers you will need to remove the ceiling joists, which form your lateral restraint for the rafters and they also support the insulation.

so by opening up the roof you do indeed create a few problems which contravene building control regulations, particularly with glass per floor area.

have you thought about installing velux roof lights?

 

[pembrokestephen]

in order to expose the roof timbers you will need to remove the ceiling joists, which form your lateral restraint for the rafters and they also support the insulation.

so by opening up the roof you do indeed create a few problems which contravene building control regulations, particularly with glass per floor area.

have you thought about installing velux roof lights?

I was going to leave the ceiling joists, for the reasons you mention, but call them a "feature" (the other half can hang saucepans from them ). I'd have to remove the insulation (as I'd be taking away the ceiling as well), but the hope was that, by putting in sufficiently good DG units, I'd at least maintain the levels of insulation, and possibly improve it: certainly, judging by the heat in summer and cold in winter that that roof void provides to the room adjacent to it upstairs, there's plenty of room for improvement.

But the glass-per-floor-area issue looks like it might be a showstopper - can you tell me more? As it happens, it's a HUGE room - about 3m x 5m - which might have a bearing. And, thinking on it, the glazed area is more likely to be 3 x 2m, not the 3x3 I originally said...

Regarding velux lights, I think that, to be quite honest, if I were going to go to all the trouble of taking out a ceiling and everything that goes with it, it's a bit of an all-or-nothing proposition: it wouldn't really be worth doing for the sake of a couple of rooflights. What I could do, though, is consider adjusting the area of glazing to conform to regulations, and see if that still works.

 

[RichA]

I reckon velux will be cheaper, easier and better.

Pretty standard to use them for roof of kitchen extension/side return.

Looks good and works well. And easy to clean (from inside).

 

[JohnD]

Tell your wife what it will cost, and say how keen you are to get it done.

 

[pembrokestephen]

I reckon velux will be cheaper, easier and better.

Pretty standard to use them for roof of kitchen extension/side return.

Looks good and works well. And easy to clean (from inside).

I may not have explained the situation terribly well.

[code:1]
|
BED |
ROOM |
.\
. \
. \------ slate roof, which I want to
-----. \ replace part of with glass
-----,,,,,\
| U---- gutter (in the interest of detail )
KITCHEN | E----W
|

[/code:1]
The bit marked with dots is a partition which stretches from below the bedroom window to the floor.

The heavy floor joists end at a cross-joist which runs across the bedroom in line with the partition, and from there to the kitchen wall (to the West), it's smaller (100x50mm, at a guess) joists for supporting the kitchen ceiling.

What I was thinking of doing was replacing part of the roof bit (the bit shown with "\") stretching from below the bedroom window down to the roof edge with glazing, and removing the kitchen ceiling (the bit shown with ",") from the bottom of the partition of the bedroom to the wall.

I'm not planning to remove any joists! Or rafters. I don't think Velux will really work, because it would mean opening up the void above the ceiling to a whole load of not-very-pretty underside of slate roof and insulation type deal just to put a potty little window in, and removing a whole chunk of ceiling for no great benefit - indeed, I think if the idea of glazing a fair chunk of the roof (as a minimum, I'd say 2m x 2m) isn't on, then it's simply not going to be worth the bother. The idea here is to go for Lots Of Light And Airiness.

Also, the kitchen ceiling is currently about 4m high. The velux windows would be a good metre above that. "Easy-to-clean" becomes a relative term at those altitudes and, in this case, it would actually be much easier to clean from outside.

 

[JohnD]

There's a thing called a "light-pipe" (I think) which seems to be a sklylight with a reflective tube leading to a panel in the room below, to let the sunlight in. Anyone know what I mean? they're alleged to be very good though I've only seen it in the press.

 

[breezer]

There's a thing called a "light-pipe" (I think) which seems to be a sklylight with a reflective tube leading to a panel in the room below, to let the sunlight in. Anyone know what I mean? they're alleged to be very good though I've only seen it in the press.

take your pick

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