ᐅ Change in the size of roof windows after building permit approval
Created on: 27 Mar 2019 10:20
C
chrisw81
Dear forum members,
We have planned to install four roof windows from Roto in our house (two on each eave side), all sized 65x118 cm (26x46 inches).
I recently visited friends who have similarly sized double casement windows, and the width seemed rather narrow to me.
So my question is... is it even possible to change the size after the building permit / planning permission has been granted? I assume the structural calculations won’t be a big issue, since we have a purlin roof, which should allow a width greater than the rafter spacing without much difficulty.
Now regarding the optimal size... Roto also offers widths of 74 cm (29 inches) and 94 cm (37 inches), and the height can go up to 140 cm (55 inches). I think the height of 118 cm (46 inches) is fine, but would 74 cm (29 inches) width look good, or is 94 cm (37 inches) better? Three of the double casement windows to change are in the rooms Kid1, Kid2, and the bathroom. It would certainly look better to have a more generous amount of natural light rather than a small opening, right? The rooms measure about 360 cm (12 feet) in length along the eave side.
In the hallway, where our fourth double casement window is, we want to install an additional double casement window next to the existing one to make the hallway brighter (this would be a kind of “twin installation,” called “Velux Duo” by the manufacturer).
What do you think about this?
Thanks so much in advance!
We have planned to install four roof windows from Roto in our house (two on each eave side), all sized 65x118 cm (26x46 inches).
I recently visited friends who have similarly sized double casement windows, and the width seemed rather narrow to me.
So my question is... is it even possible to change the size after the building permit / planning permission has been granted? I assume the structural calculations won’t be a big issue, since we have a purlin roof, which should allow a width greater than the rafter spacing without much difficulty.
Now regarding the optimal size... Roto also offers widths of 74 cm (29 inches) and 94 cm (37 inches), and the height can go up to 140 cm (55 inches). I think the height of 118 cm (46 inches) is fine, but would 74 cm (29 inches) width look good, or is 94 cm (37 inches) better? Three of the double casement windows to change are in the rooms Kid1, Kid2, and the bathroom. It would certainly look better to have a more generous amount of natural light rather than a small opening, right? The rooms measure about 360 cm (12 feet) in length along the eave side.
In the hallway, where our fourth double casement window is, we want to install an additional double casement window next to the existing one to make the hallway brighter (this would be a kind of “twin installation,” called “Velux Duo” by the manufacturer).
What do you think about this?
Thanks so much in advance!
What exactly do you plan to do with the windows? Do you want to lean out of them and use them as a lookout? If they are just for lighting and ventilation, you can skip the gymnastics. Windows designed for installation within standard rafter spaces are completely sufficient for that purpose. You shouldn’t compare double-hung windows with façade windows of the same glass area – the mistaken fear that they might be undersized probably comes from this misunderstanding.
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11ant schrieb:
What are you actually planning to do with the windows? Are you going to lean out of them and use them as a lookout? – if they are only meant for lighting and ventilation, you can skip the gymnastics. Windows designed for installation between standard rafters are perfectly suitable, and you shouldn’t compare double casement windows with facade windows of the same glass area – probably that’s where the mistaken concern that they might be undersized comes from. No, I don’t intend to lean out of them, nor are they really intended as a lookout. I was more thinking about the effect of a "panoramic window," which can look very nice, for example, in a bathroom, so that the double casement window doesn’t just look functional but also attractive and harmonizes with the room.
Of course, you’re right that the current size would also work, but I think wider windows would create a better atmosphere in the room?
M
Mottenhausen2 Apr 2019 09:28Or several (e.g., three) narrow double casement windows side by side, with only the thickness of the frame separating each. The visual effect looks quite nice overall and may not be much more expensive than one large window, with less effort in aligning the roof truss.
Mottenhausen schrieb:
Or multiple (for example, three) narrow double casement windows side by side, with only the width of one mullion between them. The visual effect looks quite nice, and it might not be much more expensive than one large window plus the additional work involved in framing the roof structure. I found in the structural calculation of the house that the rafter spacing is apparently 1m (3.3 ft). If the carpenters stick to that, a double casement window could be a size larger than currently possible – so 74x118cm (29x46 inches) instead of 65x118cm (26x46 inches). A width of 94cm (37 inches) wouldn’t fit, though. But it’s something.
You’re right, two double casement windows side by side also look very good; I’ll reconsider that for the hallway or bathroom.
chrisw81 schrieb:
that the rafter spacing is probably 1m (3.3 ft). If the carpenters stick to that, With some tolerances, yes, but they do stick to it. After all, the standard double casement window sizes are based on typical rafter spacings. But keep in mind: this is a center-to-center measurement, not a clear span measurement.
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11ant schrieb:
There are tolerances, of course, but the sizes are generally adhered to. After all, the standard double-wing window sizes are derived from common rafter spacings. But keep in mind: this is a center-to-center measurement, not a clear opening dimension.From which rafter spacing is the 94 cm (37 inches) supposed to be derived then? The rafter spacing would have to be quite large for that. Yes, unfortunately it’s not a clear opening dimension, otherwise it would fit.
With a bit of luck, maybe one rafter could be removed and overlapped, which would gain a few centimeters. But it would still be very tight for a 94 cm (37 inches) double-wing window.