Is a Lean-to Greenhouse Right for You?

Building a lean-to greenhouse may be an excellent solution if you are trying to fit a greenhouse into an awkwardly shaped garden or back yard. The idea is to use a wall, either a garden wall or a free standing wall surrounding the garden, as the back wall of the greenhouse.

Advantages of a Lean-To Greenhouse

Apart from the space-saving element of this type of garden building there are other advantages. The wall gives you a solid basis against which you can mount shelves, lights and heaters in ways that you wouldn’t be able to in a conventional greenhouse.

If the rear wall happens to be part of the house or garage then bringing electrics, heating and even running water through to the greenhouse may be a lot easier too. You may even be able to construct a lean-to greenhouse in a way that incorporates a back or side door, then you’ll be able to get in and out without going outside.


A south-facing wall will give the best results for raising plants, or at least easterly. This won’t be as good as a south-facing wall but it will still allow plants to thrive, you may need to heat the greenhouse more in the winter and early spring.

You can buy a specialist lean-to greenhouse or make one by taking a conventional greenhouse and splitting it in half. If you take this second route there are a number of things to watch out for. The first is that the door is almost always central in a conventional layout so either look for one where the door is offset or that you can move or modify.

Getting More Headroom

The second is to build a dwarf wall of brick or block to raise the overall height of the greenhouse a foot or so. The headroom in a conventional greenhouse is always in the centre and if you convert one to a lean-to format it will be hard to avoid bumping your head. Raising the whole building will make it a lot more comfortable to work in.

An obvious trick to get the best value for money is to make the greenhouse longer, putting the two halves side-by-side. Of course you may not have the space for this, but if you do, you can end up with a very grand looking greenhouse.

Use Flashing to Prevent Damp

Whether you convert a conventional greenhouse or buy a purpose-built the most-important aspect will be sealing the gap at the pitch of the roof, between the supporting wall and the glazed roof. Make sure there is a run of substantial batten, fixed to the wall, to provide rigid support both for the spars of the greenhouse roof and the walls at either end.

Then put proper flashing over the join, securely embedded into the wall just above it. Don’t be fooled into thinking that just because a greenhouse is a relatively cheap garden building you can skimp on construction. At this point you should treat a lean-to greenhouse as if it were a proper extension to the house and put the same care and attention into preventing water entering.

If you do this you will have a lean-to greenhouse that will be useful and attractive for years to come.