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    The Victorian-era windows in our roof are past their best, but seems difficult to find a modern replacement that is narrow enough.

    The rafters are 50mm thk on 450mm centres so the widest window frame that could fit between is 400mm. Modern roof windows seem to be at least 550 wide, which would mean cutting some rafters, which is best avoided for many reasons.

    The new windows do not need to open. Reasonable thermal performance would of course be good, but maximum glazed area is also important.

    Has anyone found such a window?
    It is possible to make your own e.g. http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14984

    Or get a local chippy to do it - If they don't have to open then it's not rocket science.

    And I think Tony has posted details somewhere
    What about 'conservation roof lights' which are designed to mimic just to mimic just this sort of roof light?

    Ah, just checked - min width 460mm of the few I looked at.
    • CommentTimeApr 8th 2017
    Yeah but the roof window doesn't fit between the rafters - it spreads wider, has substantial part sitting 'on top of' and a fair bit above the rafter, both sides. I think you could make a 550 work - all glass area would show, anyway. Maybe a top hinged one, not reversible.
    • CommentAuthorEd Davies
    • CommentTimeApr 8th 2017 edited
    If they''re not to be openable then think about the rules on being able to clean them:

    • CommentTimeApr 8th 2017
    Posted By: Ed DaviesIf they''re not to be openable then think about the rules on being able to clean them:

    http://www.gov.scot/resource/buildingstandards/2013Domestic/chunks/ch05s09.html#d5e14026" rel="nofollow" >http://www.gov.scot/resource/buildingstandards/2013Domestic/chunks/ch05s09.html#d5e14026

    "Rooflight in dwellings - however within a dwelling, any rooflight, all of which is more than 1.8m above both adjacent ground and internal floor level, need not be constructed so that it may be safely cleaned. " ?
    • CommentTimeApr 8th 2017
    The rules don't seem to allow the use of a very long stick with built-in hose, as commonly used on commercial buildings. Or have I misunderstood something?
    Is the "built in hose" for cleaning them? :rolling:
    Posted By: djhThe rules don't seem to allow the use of a very long stick with built-in hose, as commonly used on commercial buildings. Or have I misunderstood something?

    I think a long pole with a brush connected to the hose (I have a 26ft version for doing my solar panels twice a year) falls within option B:

    Any window or rooflight, all or part of which is more than 4m above the adjacent ground or internal floor level, should be constructed so that any external and internal glazed surfaces can be cleaned safely from:

    "b) a loadbearing surface, such as a balcony or catwalk, large enough to prevent a person falling further or"

    I would say you can argue that the ground falls within 'safe loadbearing surface' that is difficult to fall further from.

    On the window, I would probably be tempted to go for a fixed UPVC unit with a coloured frame on a "fix and forget" principle in this case.

    (Dons tin helmet).
    • CommentAuthorowlman
    • CommentTimeApr 9th 2017 edited
    Investigate the aluminium conservatory roof market. Some companies fabricate their own roof lights.
    Other companies supply the extrusions only but you may be able to fabricate your own from standard components. You can certainly do that for fixed lights.
    If you created a 450 centre open box, or less if you packed out the inside faces of the existing rafters, height TBD, to sit atop and between, the existing rafters and flashed into the tiles you'd then be left with a projecting opening onto which you could easily fix a pre fabricated light.
    Thanks all, good tips there,

    Getting bespoke windows will be Plan B if there really isn't an off-the-shelf product out there - it does seem to be a gap in the market... Surely others had the same problem? Plan C is a sun tunnel..

    There is Velux GVK about the right size, but single glazed Uw=5.1.

    @Tom, that's a great suggestion. Velux suggest the window frame should be 40-60mm narrower than the hole to allow insulation, but as you said it is mounted on battens up above the rafters so could instead be wider than the gap. The smallest 550 wide window has a glazed opening 370 wide which might work here. I will see if the conservation windows that @Nick found work the same way.


    Off topic: Building Standards don't require these particular windows to open for cleaning or escape, but cutting any rafters would require a building warrant with plans and calcs - £££ .
    Possible, but not cheap:

    412mm wide, Uw=1.5

    http://www.therooflightcompany.co.uk model CR-6
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