[JayG]

Glad you've been able to sort out the way you want to go Yana - for anyone else contemplating a similar project I can recommend "common" concrete bricks which can be used both above and below soil level.

You can buy them either "frogged" or smooth, and the main advantage is the price compared with clay bricks of the right quality to do the same job. As with concrete blocks, avoid the aerated types which are not weather and frost-proof.

[bravemurphy]

If you use bricks with frogs in then make sure you lay them frog up. If you lay them frog down then the frog could fill with water and in the winter it could freeze and blow the brick apart.

[hamsterhead]

Is using second hand railway sleepers not a good idea?  I was going to go for this option as my winter project is to build a greenhouse recently claimed from Freegle.

[makedoandmend]

Folks,

The previous tenant on my plot buried everything - and I mean everything. Digging out the plot I got enough decorative pebbles for foundations plus a skip full - honest - of buried concrete, kerbstones, bricks, old paths etc.

I used reclaimed concrete blocks (skip diving!) to form a base and then screwed timber batons to the blocks using sleeveless concrete anchors (same thing the double glazing fitters use - they are great for timber construction in the garden far better than woodscrews!)

The base of the greenhouse can then be easily screwed to the timber baton.

On the outside I have used cement to fasten roofing slates to the concrete blocks to give a tiled effect - both decorative and functional - it helps absorbs the heat.

Bottom heat comes from a 'sealed' convection central heating system made from a car's heater system filled with antifreeze. Pipes are buried in slate pieces on the insulated floor and suspended under the germination trays.

Ground in the greenhouse (and coldframe) is insulated with large sheet of 50mm polystyrene.

Germination trays on capillary matting are fed using a peristaltic pump and moisture meter controlled by a microcontroller.

I hope to use the microcontroller to control heating and ventilation. A solar panel and back up battery powers the microcontroller which uses next to no juice.

Make do