The Walipini Project (aka greenhouse shenanigans)

It does, although one section is missing. I'm leaving them in place as I like the look and it adds a bit more character. The firebox is in a dismal state; the front disintegrated and the liner likewise but the box itself is a big lump of iron and not going anywhere!

 

I admit to being curious how they work in practice. The theory is simple enough but how often and long were they run?

I discovered a soakaway in the corner recently after clearing an area of the greenhouse I'd left for a couple of years!

 

That sounds about right. I did poke about in the firebox but didn't find a vent to the 4" piping which I thought odd but I guess it must just use the heat radiated from the lump of iron. The firebox must have had some sort of flue fitted but that's disintegrated by now!

I've been looking and sketching the roofing. I wanted it to have less rafters than originally and have decided (for now!) on 7 panels rather than the original 13. This should mean less work in crafting the rafters at any rate. On the larger end of the greenhouse its about 2m from peak to gutter line and the spacing will be about 61cm / 2ft so a hefty bit of glass. My next choice is in selecting the right rafter dimension - will a 3x2" be adequate?

 

For ventilation I'll create some windows at the side and end walls so the roof won't have any but this should be OK

 

Have you considered Twinwall polycarbonate using their rafter and joint fittings. They must do vent kits as well. How long is the greenhouse?, thinking you probably do need roof vents.

 

One end (larger) is 4.5m and the other 3.5m. with gable openings and side windows it should be ok. If not I'll retrofit something

 

Having modules designed and made sounds very pricey. I'm happy with setting up a ridge beam and doing the rafters in either 3x2 or 4x2

 

I'd go for 4x2 minimum, it's surprising how heavy glass is and you need to allow for a couple of foot of snow once in a blue moon

 

I think you might be right John. The last roof had smaller rafters but nearly twice as many to spread the load

 

Timber arrived on Monday and I have to say I've not been that organised. Anyway, it's taken to today to get the toplate cut, half lap joints cut and mortared in place. Soon I can do the ridge and rest of it...

 

That will be a window. There were 4, two front and two back, but I removed the separating wall at the front for a bit of added light. Assuming the whole thing doesn't collapse of course!