Raised bed against party wall/garage

7 Mar 2011
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United Kingdom
Hi all. I want to place a raised bed in the corner of my garden, the problem being is that a neighbours garage forms part of the boundary. What are my options here? Can I use sleepers directly against the garage wall or should I add DPC between them?

I contemplated just fencing parellel with the garage to give myself a boundary of my own but wouldnt know if digging footing for the posts would interfere with the garage. Plus the expense is also a factor as it would only really be giving me something that was already there, however at least I'd have complete control over what I did to it..any ideas?


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I would definately say DPC as a minimum, and something durable at that. My neighbours did it to me in my last house (same thing as you want to do) and used a rubber pond liner as DPC which continued way down below ground level. It was then trapped/sealed front and back by sleepers and I have to say never had a problem - although don't forget the DPC must also extend upwards above the finished level of the soil and not trimmed off flush as soil touching the wall about the DPC will cause damp to seep through.

One other thing to thing about is drainage for the bed - if the soil below the bed is well draining you should be OK anyway but if not then the water sitting in the bed will cause stress on the wall (if say you are putting the bed on a concrete base/old patio then this will be a problem). In this case you need a good method to get the water out of the soil - I have used drains built into the raised bed (short lengths of waste pipe) with a vertical gravel layer behind separated from the soil by a membrane. At the very least leave weep holes to let the water out.....
Sounds like it may be a bit of trouble, I dont mind leaving a gap between the bed and wall, last thing I want it to damage someone elses property, what would be reasonable so as to negate use of DPC? 2-4"?
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A 2" gap should suffice providing you don't block it off at the front and back with something (sleepers etc) as it may end up filling with rainwater. The other thing to think about if you leave a gap (which is a good iideaif you can) is to cover or cap the gap at the top so it is not open to elements. Being a raised bed means it will 100% certainty fill up over time with dead leaves, grass, bits of soil etc that will start to rot. Thats forms a moisture path through the the wall and again equals one unhappy neighbour!

So to recap - a DPC will be fine providing you sink it in the ground and don't trim it off level with the top of the raised bed. Having said that it does also depend on how deep the raised bed is? 12 -18" will be OK if the area in contact with the wall isn't huge.

If you go for a gap then either make it small enough you can cap it with something (decking board, slate etc) that nearly touches the wall but not quite, or make it big enough to get in there with something to clear out the crud that will fill it up over the winter.

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