Secondary glazing for skylight.

[ I could just pay someoen to do this, but it looks like it might be an interesting small project ]
I have a skylight in a small room. This is basicly a pyramid shaped 0.8m square window at the top of a 0.5m vertical tunnel.
I know from last winter when I was decorating and had the radiator off that the room loses heat and gets cold quickly in winter. So, it is probably worth working out how to insulate that skylight.
What occurs to me is to build a frame and put a couple of sheets of clear plastic `glass' at bottom of the `tunnel', ie at ceiling height.
This is not beyond even my limited abilities, probably, on a good day, but I suspect condensation in the chimney between bottom and top windows might be a problem. Is there an obvious solution to this which hasn't occured to me?
I'd rather not do _anything_ to the external glass part as that would involve going up on the roof which in turn would involve going up a ladder next to a 4 floor drop, and, being one of those who has to build up courage before changing a lightbulb, frankly I'd rather freeze to death.
Quick diagram: _^_ / \ / \ <- Glass / \ -------------| |--------------- ROOF #############| |############### #############| |############### -------------o=========o--------------- CEILING ^ New Plasic Window
--
Mail me as snipped-for-privacy@MYLASTNAME.org.uk _O_
|<
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Firstly Richard. Does the existing window have an open vent at the ridge ? I mean, does it have any open vent at the very top part of its frame work ?
If it isn't open to the elements, then I think it would be quite feasible to frame the tunnel at ceiling level, then, as long as it is sealed air tight, which is really what you want it to be, it shouldn't have any problem with condensation.
If the ridge does have an open vent, then I think I'd first try to find a way of being able to close it up during the winter months.
--
www.basecuritysystems.no-ip.com
Outgoing mail is certified Virus Free.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
spamguard (s) writes:
Thanks for the reply.
s> Firstly Richard. Does the existing window have an open vent at the ridge ? s> I mean, does it have any open vent at the very top part of its s> frame work ?
Not so far as I can see from where I can get to with a step ladder (high ceiling plus height of roof plus height of pyramid means there could be somthing in a side I can't see) I strongly suspect it is just a wooden frame with triangluar pieces of glass. Way back when when this building was put up I think keeping out the cold was a priority and ventilation wasn't.
(they also aparently had not invented the right angle, which may make the frame building more fun).
s> If it isn't open to the elements, then I think it would be quite feasible to s> frame the tunnel at ceiling level, then, as long as it is sealed air tight, s> which is really what you want it to be, it shouldn't have any problem with s> condensation.
That sounds good.
I suppose there is a limited amount of air up there, so a limited amount of water to precipitate out. Maybe throwing a small bag of silica gell up there might be a worthwhile belt and braces move.
--
Mail me as snipped-for-privacy@MYLASTNAME.org.uk _O_
|<
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

ridge ?

feasible to

tight,
with
That idea sounds good to me.
--
www.basecuritysystems.no-ip.com
Outgoing mail is certified Virus Free.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I am wondering about doing this when I install a skylight in a future project. I'm inclined to use glass instead of perspex since it won't become opaque/scratched as easily - although the safety kind that has two sheets laminated together & won't shatter when broken. Perhaps some grilled vents could be put in the 'chimney' sides allowing a (slow) exchange of air with the loft space? The next question is whether or not to insulate the sides of the chimney? And how to make the sheets removable for cleaning?
And I've got the same reservations as to the validity of the whole thing!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
dh> I'm inclined to use glass instead of perspex since it won't become dh> opaque/scratched as easily
Mine is so high that nothing inside is going to touch it, and of couse, there is no access to the other side, so simplicity of cutting made me think of plastic.
dh> (slow) exchange of air with the loft space? The next question is whether or dh> not to insulate the sides of the chimney?
I'm assuming that even if the space gets down to exsternal termperatures, a double layer of plastic at the base will provide reasonable insulation for the room.
dh> And how to make the sheets removable for cleaning?
Removable frame on some kind of removable fastening?
I was seriously considering velcro. I have a trestle table I hold together with high-strength velcro and quite small amounts happily hold a heavy trestle when the table top is lifted. Certainly heavier than a frame and perspex I was thinking of. Glass would be another matter.
/| /|--------- /| | W /| wooden | A /| batten | L /| | L /|--------- /| ######## <- velcro /| --------- /|| |============================================= /|| wooden | Glass/Perspex /|| frame | /|| |============================================= /| --------- ----
Perhaps a more conventional attachment on the same lines would be to put the kind of rubber draft excluder used around doors where the velcro is above and use (reasonably presentable) bolts through the frame into threaded fixtures in the batten.
--
Mail me as snipped-for-privacy@MYLASTNAME.org.uk _O_
|<
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That looks like a workable solution. I'll go with using bolts and hide them behind some architrave - attached using your velcro idea. Thanks!

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
_

I have seen small pseudo nuts (ok they probably have a real name) which are basicly a narrow tube with an inside thread with a flat collar at one end, the collar having a couple of prongs sticking down. In crosss section, something like
___ ___ \/ |//| \/ |//|
The tube goes into the hole the bolt will come up through, the prongs get hammered into the top of the batten and so stop the whole thing from rotating.
Alternatively, there are fixings Ikea seem to be in love with which are basicly short pieces of steel rod with a threaded hole through them cross ways, the bar goes into a horizontal hole, the bolt comes up from below and through the threaded hole in the bar. These also presumably have a real name. Have to find my Screwfix catalogue. I suspect these would be fiddly to get right when you can't get to rotate the bar to get the bolt in to it, because the glass is in the way.
--
Mail me as snipped-for-privacy@MYLASTNAME.org.uk _O_
|<
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.