There's a shimmer in the glass roof as the wind gusts. You are inside a 2.8m glass cube, a four by four grid on all sides and the roof, with a quarrytiled concrete base.And it is tied back to the house. So what is happening? And then you work it out. It is rainwater just lying there in the 16 glass squares of the dead-flat roof which have been ruffled by a passing breeze.
This is Andrew Holmes' glass house in a back garden in Dalston, east London. Long time an admired AA unit master, he now teaches at Westminster. He is also noted for his extraordinary super-realist depictions of West Coast mechanistic environments and especially those giant road trucks he draws in, for god's sake, coloured pencil.
This man is a perfectionist, obsessed in the best possible way with getting the whole right by agonising over the minutiae of the detail. In some people this is worry ing obsessive compu lsiveness .
In Holmes it is mostly productive of great, serene beauty.
And so too in this Dalston backland. Holmes has created a perfect geometric form. And then comes the surprise: the outer wall opens out; it is two identical doors and you realise why he went for a four by four grid rather than three by three or even two by two. With the present frequency, there is enough steel to stop the doors from flopping and maybe damaging the glass.
Inside you wonder briefly whether this could not have been formed from five giant sheets of thick glass neoprened together.Holmes thought of that too until his supplier told him the cost of such glass - and that there would be the problem of supporting the roof.Out through the big doors you see how Holmes has solved this roof support.Four tubular columns stand just outside the corners of the glass house. Their tops are joined diagonally corner to corner and the roof, an identical frame structure to the two side walls, is hung from it.The side walls span up from the slab edge to the edge of the roof grid and have restraints back to the tubular columns. The back of the glass house connects to a doorway in the house via a big glass collar whose side pieces can be opened for ventilation.
The frames are made from 30mm by 30mm by 5mm painted mild steel Ts and the 6mm laminated glass is held in place by 13mm by 13mm by 3mm angles machine-screwed to the Ts. The doors are the same but each is half the width and the hinges are by Dorma, which, says Holmes, was very helpful, particularly in reassuring him about supporting such a load. The whole structure including the insulated slab, electrics and the planting outside, cost about £16,000.
And what about U values? From the beginning Holmes' client was prepared not to use the glass house in the worst cold of winter, although he had devised a system of golden-coloured duvets which could have been fitted against the glass. But then it would not have been a perfect glass house any more.