On Fri, 27 Jan 2012 19:24:06 +0000, claire2965
wrote:

I have just acquired some old bricks. I thought I would make myself a
cold frame on my allotment. Can anyone give sme advise on the size plz.
I am Klingon at 3-5 bricks high

Size is basically whatever fits your space and the materials you have.
I constructed mine about 33"D x 61"W, 20"H at rear and 13"H at front
(the height allows me to put potted plants inside). Top is split
hinged (hinged at the rear, plus a set of hinges in the middle so it
bows up). The lid isn't lightweight, so I don't need to fret about it
blowing around.

Something to consider with your bricks is the need to mortar them -
not merely dry set them. If they don't seal well, you're going to
have a draft in your coldframe. This is especially true of used
bricks which may have chunks of mortar on them, be chipped, or more
irregular in size. You'll have a bit more trouble setting up a sloped
top for the cold frame as well - I can't offer any pertinent
suggestions there because I didn't use brick for mine (but it also
doesn't get all that cold in my medditerranean climate in Northern
California near San Francisco - it was 70'F/21'C today).

Not gardening related, but in the summer, when it's too hot to keep
anything in it, it doubles as a solar oven - I can put a pan with wax
in there, it'll melt in a few hours, and I can pour that off into
candle molds. I have honeybees (and thus, beeswax), and also have
hundreds of pounds of vegetable wax, plus one can melt stubby candles
and "slag", to make new candles.

I've considered spraying adhesive on the interior of mine and affixing
aluminium foil to it - both for the solar oven purpose, but also to
reflect diffuse sunlight on the opposite side of the plants inside.