Glasshouse / Greenhouse roof design

[garethharvey]

I have pretty much built all the walls of my new glasshouse but now struggling with the roof. My wife want's some windows up on the ridge this time.

I have seen some pictures of other timber glasshouses but can't get my head around how to make the ridge water tight. I was thinking of going down the route of a traditional build with a ridge board, but then how would the glass fit against this?

Any help would be greatly appreciated

 

[Myfordman]

Fix battens to the ridge board, chamfered to suit the roof pitch on which the glass can rest with putty, butyl or sealant of your choice.
You could fit some inverted gutter onto the top of the ridge boar to help shed the water onto the glass for belt and braces or strip of lead flashing bonded onto the glass with leadmate if you are in a windy location.

 

[garethharvey]

Thanks, that's pretty much the way I see it, I may try substituting the guttering for a piece of wood though, would need to cut two pieces then glue them to form a V

 

[AJB Temple]

If you think of a typical aluminium greenhouse frame, the glass just rests on a rubber strip stuck to the aluminium frame, and is then held firmly in place by spring clips. There is no reason why this should not work on a wooden structure I suppose. I would be interested in how you do this as I am thinking about building a lean to cedar glasshouse.

 

[Random Orbital Bob]

Thanks, that's pretty much the way I see it, I may try substituting the guttering for a piece of wood though, would need to cut two pieces then glue them to form a V

Personally, I would avoid that for two reasons:

- you've joined the wood at a critical place for long term waterproofing and despite modern glues, that's not its strong suit.
- Wood moves considerably, particularly when subjected to moisture and UV/heat

If you look at typical solutions for waterproofing the hidden join on a ridge they're almost all waterproof materials that span the joint and cause water to sheer off onto the pitched sections. Plastics, rubber, lead, copper, curved ridge tiles with cement between etc.

I think you'd get away with wood for a couple of years but long term its not the right solution.

 

[garethharvey]

Thanks Random, I will probably put a strip of lead over the ridge than add something a little more decorative over the top.

Next issue, I have a gable on the front of the glasshouse, the roof pitch is 48 degrees.

How on earth do I calculate the angle on the base of the valley?

Picture attached showing what I mean

 

[screwpainting]

I am looking to build more or less the same and have been thinking about fabricating the ridge/valley to glass connection from say 6 or 9mm medite Tricoya mdf clad in pond liner. It might sound a bit heath robinson but I think a flexible rubber that can be bonded to glass is a good option for a timber greenhouse and to be able to create more or less any fiddly or small profile yourself has to be worth a look at. I'm going to test this out for the actual glazing itself, accurately cut strips of rubber wrapped over the top edge of the actual rafter and into the groove routed to receive the glass and hopefully form a waterproof gasket and bombproof protection to the top edge of the rafter.

Theres probably a good reason why I haven't seen this done before and it will probably won't work but It's worth a play with. Painting the outside of a greenhouse roof is such a faff and if I can build that requirement out of mine I will be well pleased. Lets face it, the top of the rafters is what gets all the wear and tear so for the tiny amount seen from outside to be covered in a neat black replaceable material is neither here nor there cosmetically.

The only thing is sliding the glass up to the top inside that rubber groove :-k ....

Its looking like it will be a nice one Gareth, I can't wait to start mine.

 

[screwpainting]

Forgot to add this link.

This guy inspired me to build mine.
https://www.youtube.com/watch?v=P0ZkM9tWXtA