Bi-parting shutter materials.

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It has now occurred to me that I could use cut outs from an extra, dome segment for the bi-parting shutters. I don't want a repeat of the plywood shutter, leakage problem once the dome is well out of reach.

I keep studying the [few] online images and videos of the original animal housing. Trying to understand how its panels are used in its construction. Given the limited evidence the three panels do all look identical. 

Only if the top panel is perforated for a ventilation "chimney" does it become a dedicated top panel. Two images of large stacks of dome segments are shown online. With the manufacturer's claim that they were deliberately designed to be compact and easy to transport in quantity. 

There are examples of animal shelters online having two, large manufacturer's promotional labels. Which suggests two identical panels were used instead of three individuals. Further evidence that they can be freely swapped around?

The semicircular doorway of the original "animal shelter" shortens the top panel too much to provide a full shutter height. The observation slit cannot extend much past the zenith. So there would be no spare material left from the cut out [slit] strip to be able to make even a single shutter. Let alone a pair of bi-parting shutters. 

A spare top panel would provide plenty of material for both shutters. Simply because it doesn't need a slit to be be cut out of it first. While the observing slit cut-out material would easily provide the two spherical triangles. For closing off the gaps on either side of the slit in the original, arched doorway. On that basis I have requested the pricing of an additional top panel.

The domed animal housing donor is designed to be self-supporting. Enough for "robust" use on a farm over an extended period of perhaps decades. So it needs no additional reinforcement beyond the slit ribs, base ring and a strong zenith crossbar. The latter is only needed to strengthen the structure after cutting out the observation slit. Though it is only really required during lifting. 

The rest of the time the loads are evenly distributed throughout the assembled dome. By the time I have bonded a plywood base ring and ribs, the dome should be stronger than the original. The most obvious downside might be the weight of the GRP shutters compared to thin plywood. Though the heavy duty drawer slides I have used previously show no sign of fatigue. 

My present shutters are arguably slightly under-built. Using the original fibreglass panel for shutters will provide an attractive and matching finish. Unlike plywood additions. With the inevitable [serious] problems of matching finish and colour with the rest of the dome.

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