Advice on glasshouse roof design : glazing

[sebmaster]

Hi,

Following from my previous post, I want to construct a small glasshouse and would appreciate any comments/advice on the design from the pros.

masona and ^woody^ have been very helpful in getting the roof to this point; its a very tricky one because the stone base is already built and the span of the gable over the porch is slightly different to that of the main house, so the two planes of the roof don't quite meet up.
The image below (looking from the end of the valley to the apex) shows what I mean:

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• sebmaster
• 16 Sep 2010
• 1

However, I think I have the configuration of the rafters as good as it can get without knowing the specifics of the glazing so thats what im thinking about now.

I looked at some of the glazing supporting kits but I am not sure they are what I want.

Instead I was thinking about installing the panes in one of two ways shown below:

Untitled

• sebmaster
• 16 Sep 2010
• 1

In both cases the panes are supported between two slim wooden frames and seated with glazing sealant (such as http://www.screwfix.com/prods/57735...nts/No-Nonsense-Glazing-Silicone-White-310ml)
On the right there is a single sheet supported by a lower rafter while on the left there are two panes. Where they meet a thin strip of wood sandwiches them and join is covered by flashing.
(Or alternatively use something like this: http://www.greenhousewarehouse.com/...lazingbar-timber-supported-glazing-bars.html) The important thing is that the join is as 'flush' as possible because I don't want to create a pool where the common meets the valley.

All comments on the glazing and the roof are appreciated as nothing is finalised and i've not done a roof before; am I close to the mark with this design?

Thanks!

 

[masona]

I think I've read it right, you can buy a galley glazing bar or roof glazing bar kit made to measure which yours is known as P shaped roof, do a search on P shaped roof glazing bar for more info

 

[sebmaster]

Hi masona,

I didn't realise they did entire precut kits, thanks for letting me know.

I've had a look and I'm not sure about a couple of points though.

Below is a shot of the entire thing (I probably should have shown this alot earlier!), so its not acctually connected to the house.

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• sebmaster
• 18 Sep 2010
• 2

Also the window seat isnt a proper semi-circle, its more of an ellipse (that part took a long time to work through!).
This coupled with the differences in pitch mean its a fairly odd roof, how much play do I have with the pre-cut designs? Could they accommodate these odd angles or are they intendeded really for just varied floor area?

The final thing is the colour, this probably sounds a little silly but I like to try and think of every detail before I start, and the intent is to paint the frame as opposed to staining the wood, so I want the roof to be able to match. (This is half the reason I was wary of the glazing strips I linked)

 

[masona]

Is it possible to do a drawing with pen & paper and highlighting the problem, I'm still a little confused

 

[sebmaster]

Hi masona,

Sorry I wasn't very clear! I don't have a problem so much this time round as I was just wanting some second opinions on the design.

I've never done a roof like this before and I wasn't sure whether my plans for installing the glass were best practice or even workable, so I thought I would just double check on here before I order the wood, build it and 2 weeks later the panes fall out

I've attached some hand drawn diagrams, I hope these are clearer.

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• sebmaster
• 19 Sep 2010
• 1

Untitled

• sebmaster
• 19 Sep 2010
• 1

In short what I have planned is to construct a set of thin window frames to sandwich each pane, which will be sealed in place with glazing sealant.
The exception is the intermediate common rafters which for the reasons stated before cannot be the same height as the end rafters, so in their case the glass will sit on top on either side, with each pane and its sealant seperated by a thin wood strip and the join covered by flashing tape (so to remain as flush as possible allowing drainage on the triangular panes flanking the valley rafters).

 

[^woody^]

You may want to rethink the design of glazing to the rafters and covering with tape

There is going to be a lot of movement and temperature variation, so you need to be sure that this design will accomodate that. Also think about how its actually going to be applied - stretching up over glass panels to apply sealant and tape is inherently problamatic

A proper glazing bar fixed to the timber may be better?

 

[sebmaster]

Hi ^woody^,

Thanks for your reply.

I was expecting a little pain when building , but the problem with movement and temperature variation was just the kind of thing I posted to get comments on, as I didn't know how much of a problem it would be.

I'll go with a glazing bar like the one in my first post if you agree this is best.
If I used glazing bars on the intermediate common rafters would this allow sufficient play if I were to glaze on the other edges using the thin wood frames as in my drawings?
I would use timber supported glazing components on all edges but I'm having a suprisingly hard time finding suitable supports for the edge and ridge board. I would expect to find something like this: http://www.greenhousewarehouse.com/...l-acc-fsectionmaster-aluminium-f-section.html that provided support in same way as the regular bar but these are proving hard to find as most are self supported (I also want something fairly discreet since it will be plastic or aluminium and so painting won't be much of an option).

I was considering routing channels into the rafters instead of building frames (the frames were my first choice as I don't have an angled routing jig); I was thinking of this more for asthetics, but will one method or the other have a significant effect on the performance of the roof?

 

[^woody^]

Have a look at the site or download the catalogue from C&A Supply www.casupply.co.uk as this has some good illustrations of roof components

There is no actual problem in using timber frame, but you have to be very careful in the actual detailing to ensure that it remains water proof. Your indication of sealing with flashing tape raised a few alarm bells as this is not really a long-term solution.

IIRC, one of the regular (older ) posters on here has a timber roofed conservatory and I recall a photo of the timber glazing bars, but I don't rmember the glazing detail or who it was.

I'll see if I have any technical details of this type of roof, but you need to decide on a timber or timber/glazing bar design and work from there

Also, make sure that you are not doing too much CAD work which may complicate things. As you are making this up on site, you may not need exact drawings as its likely that things/dimensions may alter slightly.

EDIT

BTW, have you tried Google Sketchup for your design/conceptual design - its free and will be very good for allowing you to visualise your roof. Just try not to get bogged down in too much detail. But you can import your CAD drawing to give you a head start

 

[sebmaster]

Thanks for that link.

The flashing tape came about simply because I saw it on the conservatory and thought that it must be an acceptable method and so was a good starting point, but your posts and others here suggest it isn't too popular anymore, so thats out!
The use of the tape was really about creating as flush a seal with the glass as possible because of the drainage, which I wouldn't be able to do with wood. Glazing bars seem ideal for the intermediate rafters so i'll definately use these.

I am still having trouble finding a bar that can join the glass with the gable end rafters, as all the edge components seem to be just trim.
What I am thinking of is routing a channel into these, sitting the glass on a bead of rubber for support (much like the glazing bars use) and sealing on the top.
This will hopefully allow some play and make installation easier as the glass can 'slot' in then be placed 'down' on the glazing bar at the other edge.
I won't need an angled jig for this and so long as the seal remains watertight there shouldn't be any problems with leakage or the roof coming apart. What do you think, is this an OK plan?

For the tops of the panes I was thinking the Glen centre bars on C&A. Its hard to see from their site though (do they have more detailed drawings in the catalogue?) what the centre bar does exactly, does it provide support for the glass or just cover the meeting with the ridge board to create a watertight seal?


I agree I tend to go overboard a little with the precision when using the CAD package, and probably with the level of detail aswell, though at least the latter is a little defensible; this project is a bigger than my usual ones and i'm trying to model as much as possible to avoid any unpleasant surprises - the meeting of the odd pitched planes springs to mind, as do some implementation details with that semi-elliptical window seat

I have not tried Google Sketchup yet, i'll download it later today and have a play.

 

[masona]

I know Mr Plastic do quite few difference type of glazing bars including edge type but their website is upgarding at the moment, ask for their free catalog

Also they can deliver if any good

http://www.mrplastic.org/where_find_us.php?osCsid=898b0156328ee8edcf942aa2ba94b2fc

 

[sebmaster]

Thanks masona, i've just given them a call and they are sending out a catalog.