Jump to content

Roof Lights: glass or polycarbonate


Recommended Posts

We plan to have about 5 square meters of roof light. It's above our Winter Garden. (1720 by 3200) On a partially protected South West face

The darkish area below the roof is an open, barn-style set of baffles. ... I'm thinking about our equinoxial gales, and the occasional hoolie. The area to the right of the glazing is meant to represent solar PV

 

rooflight.jpg 

 

I'm wondering whether polycarbonate is the best choice? Or maybe 4 toughened glass sheets?

I have no experience of polycarbonate at all. I've looked at too many videos.

I'm all over the place and wonder what your experience is?

Ian

 

Link to comment
Share on other sites

What about 2 large roof lights or 4 small to get the size you need. They come with all the bits needed to make the roof watertight.  Easy to fit and easy to open and close, long pole cheap option or motorised for the expensive version. 

 

 

Link to comment
Share on other sites

You'll want to use glass. Polycarbonate has some useful properties but ultimately glass will look the part and weather far better. Its just a case of specifying the glass to be sufficiently strong and then looking at the implications for weight & cost.

 

 4 toughened sheets wont help strength if that's your concern. You'll want thicker individual sheets to resist wind, gravity and (depending on pitch) snow loads. That span could even be done in one sheet but splitting it as you've done is the sensible way to go for cost.

 

Off the very top of my head. It will need to meet a design wind load of at least 1.5kN/m2 in an open barn style structure though i could be mistaken. Your glazing supplier should be able to advise on this and help you specify the glass.

Link to comment
Share on other sites

A gallery and studio was built near my parents house, the studio part being fitted with fixed glass in the roof to give the artist enough light. Chatting to him not long after it had been built he said his biggest regret was not fitting Velux roof lights, firstly as he would then have the option of being able to open them (something I would have thought useful given the garden use of the space in question), and secondly, that the final cost of fitting the bespoke opening he had turned out the same as buying 4 Velux Windows that had the same coverage. As Declan says, make it easy and install roof lights.

Edited by Stones
Typo
Link to comment
Share on other sites

lAs people have said glass is better than polycarbonate.

 

Also i would specify 3G roof lights, it makes a considerable difference to the amount of noise you will get when rain hits the roof, otherwise it will be very noisy on there. Plus heat is going to rise and leave via the roof so the more insulation the better.

 

If you look at the spec on the velux site it shows the difference it makes depending on what kind of glass you use to both the U-Value and sound transmittance.

 

These are the electric and manual roof windows if you want an idea of sizes and prices.

 

https://www.roofingsuperstore.co.uk/browse/pitched-roof-windows/velux-roof-windows/centre-pivot/white-painted-electric/triple-glazed-206621u.htm

 

https://www.roofingsuperstore.co.uk/browse/pitched-roof-windows/velux-roof-windows/centre-pivot/white-painted-manual/triple-glazed-2066.html

Edited by AliG
Link to comment
Share on other sites

3 hours ago, recoveringacademic said:

The darkish area below the roof is an open, barn-style set of baffles

 

Do you mean hit and miss..?? So the wind will be able to blow through them..??

 

If so, then a single 6.4mm laminated sheet would be fine - either in 2 parallel panels (so you don't need to sort out how water runs over the mullion) or use 4 and overlap the top to the bottom by 75mm with a gap over the mullion bar.

 

If its an unheated space then seems pointless having DG or TG.

 

Other thing to consider is cleaning as I'm sure @MrsRA will want it on your weekly list of things to clean so you may want to get self cleaning glass or use something like Rain-X on both sides to stop it getting too mucky

Link to comment
Share on other sites

Hmmmm,

 

5 hours ago, PeterW said:

[...] So the wind will be able to blow through them..

If so, then a single 6.4mm laminated sheet would be fine - either in 2 parallel panels (so you don't need to sort out how water runs over the mullion) or use 4 and overlap the top to the bottom by 75mm with a gap over the mullion bar.

Other thing to consider is cleaning [...]

 

Yes, the wind will circulate. No need for 2 or 3g

Why the top to bottom overlap, Pete?

 

I cleaned windows for seven years to pay my way round my first degree. Should be fun doing the insides at that height. 

Ian

Link to comment
Share on other sites

2 minutes ago, recoveringacademic said:

Why the top to bottom overlap, Pete?

 

Classic old greenhouse thing - beaver tail glass from one pane to the next and then the water runs down the middle of the panes and doesn't rot the glazing bars. Lower glass rests on a mullion and the upper straight on the glass below. 

 

In a modern set up if you have anything stopping water flowing down freely then it will find a way through the joint or you need some way of making a gutter to go round the lower pane. 

 

 

Link to comment
Share on other sites

So how are you going to clean them?

 

With that shallow roof pitch it could be .. er ..  difficult from the outside. I have a cleaning pole that extends to about 9-10m but even that would be pushed. As for the inside.My solar panels are 3m off the ground and run upwards for 7m at 55 degrees and that is tricky.

 

I think I would want that upstairs glass window I can see with the wintergarden view to be a solidly built Juliet Balcony for the inside, and I would want a system for the outside - turn a solar panel into a velux?

 

(Update: Hmm. 1st floor level sitting out balcony below the slope of the roof, which would also give a sheltered garden feature / tea terrace and afford access?) 

 

I love the winter garden, though. And I am sure you have far better ideas than I do B| .

 

F

Edited by Ferdinand
Update and correct typos.
Link to comment
Share on other sites

5 hours ago, Ferdinand said:

So how are you going to clean them?

[...]

I love the winter garden, though. And I am sure you have far better ideas than I do B| .

 

Eye bolts in the rafters, and some strapping on the top ladder rung - attached to a carabiner. Same method as when I cleaned windows to keep the wolf from the door when I was a student. 

 

The Winter Garden was Sam's idea (architect) and @MrsRA fell hook line and sinker in love with it. I like it too, perhaps more from the point of view that the light from the garden will filter into every room in the house except the loos and the utility room. It certainly gets people talking. It's such a small house, and to devote so much space to a garden inside the building means that we will have to be really super careful about its maintenance.

Link to comment
Share on other sites

  • 3 months later...
On 1/24/2017 at 09:12, Ferdinand said:

[...]I can see that you will be one of those 92 year old tightrope walkers :P.

 

I'd missed this comment @Ferdinand. I am annoyed to find that I can only last 5 seconds balancing on one foot with my eyes shut now. (standard old-fogey test). Try it somewhere safe, and then try it again a few months later. Useful indicator for old codgers like me.

Link to comment
Share on other sites

On 5/16/2017 at 10:30, recoveringacademic said:

I'd missed this comment @Ferdinand. I am annoyed to find that I can only last 5 seconds balancing on one foot with my eyes shut now. (standard old-fogey test). Try it somewhere safe, and then try it again a few months later. Useful indicator for old codgers like me.

 

Dancing is said to do wonders for the balance. I have always been awful at balancing.

 

I can last longer but with lots of adjustments.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...