Building an off-grid barn in Suffolk

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  • Organic/ natural swimming pond workshop in Norfolk

    In July (2025) I went to a one-day workshop in Norfolk run by David Pagan Butler. Having your own swimming pond is very appealing and some of those that it appeals to clearly have large budgets – judging by the Youtube promotions by companies offering expensive installations. Pagan Butler’s approach is very much self-build with low-cost materials. Here are my slightly un-understandable notes and some short videos.

    Organic Pond workshop

    Also see another self-builder http://www.youtube.com/@manuelangerer-permaculture

    Materials

    UK grown larch can be useful

    Clay can be a source of phosphate. You can buy a phosphate meter

    Rainwater harvesting is the best source of water to fill a pond. Borehole water is ‘generally pretty good’ but run off water from the ground is the worse.

    It is good to wash the gravel or whatever aggregate you use for the planting area before laying. You can use 20mm coarse gravel or 4/10mm pea shingle (https://www.aggregatessupplier.com/product/4mm-10mm-shingle/) and sharp sand mixed 50:50. Gravel is more expensive. Q: how to calculate the amount of aggregate needed? Area by depth?

    You can run a bubble pump/aerator from solar power with a set up like mine in the shed.

    The pond won’t attract mosquitos because of the many predators and because the water is constantly moving. Mozzies like still water (like a standing bucket).

    Basic design principles

    The pool needs to be isolated from groundwater and a plastic sheet is the best way to do it.

    Aim for (at least) 50:50 proportion swim zone to planted zone by area (because it is to do with the amount of sunlight).

    For the skirt/gravel area build with a 1:3 slope with a total of a 1m fall and then a further 1m dig for the swimming zone making the overall depth 2m. A 2m depth helps swimmers not to keep disturbing any sediment at the bottom and causing cloudy water.

    Dig a strip foundation ( 6 inches or so) for the blockwork walls. Walls to be 1m high but with a 400mm barrier/top to stop the gravel of the planted zone sliding in to the water. This can be made out of timber. There’s no need for a concrete floor – just smooth out the ground before you apply the fleece.

    For the inner walls some have used blockwork laid on its side or build in the normal way on its edge (needs 5 courses). Be careful with backfilling behind the wall. Backfill with sharp sand especially if the ground is clay as this can get so heavy when waterlogged it can make the walls collapse. Aim to backfill as little as possible by digging the initial hole as accurately as possible behind where the dig goes vertically down from the skirt/slope.

    Liner: EPDM supplier https://www.pondkeeper.co.uk/pond-products/pond-liners/epdm-pond-liners/?gad_source=1&gad_campaignid=10119464&gbraid=0AAAAAD-TJ1xXD1I5ZGzgyYQPZPx_aHV5N&gclid=Cj0KCQjwss3DBhC3ARIsALdgYxObqXMKHVZYmxGEjBtuvA2jowcUbUpuujfb1cjFXlYfWdiHAVy90xgaAq_hEALw_wcB

    20 by 18 metre liner with half price fleece costs about £4000 from the above supplier.  Alternatively the liner can be made of pvc but this needs to be welded on site by professional installers so is more expensive. Laying EPDM in a single sheet is best.

    Folds can be tricky but you need to fold around your design. More irregular shapes make folding difficult, requiring pleats.

    Laying a concrete base is ‘rock solid’ but expensive (and not needed – because later DPB (David Pagan Butler) says don’t do it – just smooth out the ground). But if your digging takes you below the water table then lay something on top of the liner, otherwise rising water will cause your liner to balloon out. (Paving slabs might work) If clay ground then use a concrete base then the liner then more concrete to sandwich the liner.  

    Do you need the planted/regeneration zone on both sides of the swimming area? As long as there is good circulation this should work.

    The slope of the regeneration zone has to be linear to stop the plants sliding down. It needs to be a 1:3 slope. If there is an end stop in place the gravel will stay in place and not fall into the water. Have 300mm depth of gravel and a 400mm topping to the blockwork (which can be made out of wood/sleepers).  A new discovery is Recy-Edge lawn edging for the top https://www.thegardenrange.co.uk/p/garden-edging/lawn-edging/recoedge-plastic-garden-edging-plank/. 

    You need a design around the rim of the pond that stops run off water from the surrounding area flowing into the pond. One way is a kind of pyramid build of cement (a concrete haunch) with the liner layers sandwiched in the inside and on the outside gravel with a French drain running around it. https://greenfrogwaterproofing.com/why-install-a-french-drain-in-your-property/ and https://www.timberwise.co.uk/blog/what-are-french-drains-and-how-do-they-work/

    Make the edge so that all 3 layers (fleece/liner/fleece/) end up vertical. Hammer in pegs to define the edge. The water is to rise to 4 inches below the top then a plastic strip.

    Another approach to designing this edge is to use lawn edging (as referenced above). This barrier needs to be built all around the pool.  

    Bill’s pond in Norfolk goes to 2m immediately from the house. His approach: dig the hole/shutter for the concrete steps then liner over that then liner and fleece ??

    Insulation (at the bottom) is not needed and is a waste of money.

    Don’t add fish to the water as they produce nutrients

    Planting and Suitable plants

    Pickeral weed  – blue flower

    Purple strife

    Cuckoo flowers

    Fringe Lilies

    Blue Iris or Siberian Iris

    Dragon Iris

    There is no good or bad time to plant.

    DPB has a high density of plants so that the pool is working well because the plants are depriving  the algae of nutrients

    DPB built a floating tyre covered in fleece then hessian to plant in.

    Bubble mechanics and design

    The smaller the pipe that the bubbles rise through the faster and higher the rise of the water. Four inch pipe doesn’t lift water but if its low enough in the water it will move a considerable amount of water. A rule of thumb – one (?3 inch) bubble pump outlet pipe for every 5m linear. 68mm rainwater pipe (its standard drainpipe) is cheap. Koi pipe is more expensive. https://www.elitekoi.co.uk/collections/pipework-fittings because it is purpose made for ponds. Anything that says its designed for ponds seems to be sold at a premium.

    The vertical pipes need to be ?100m high ? from the bottom?

    The compressor pump: no need to be working in the winter. His is on a timer and only runs during daytime in the summer. (One website says keep running constantly) His is a Hailea Air pump https://www.onestopgrowshop.co.uk/products/hailea-aco-super-silent-air-pumps . The pump can be quite remote from the pond – for electrical safety He has six airstones all at the same depth. You need to use airstones in order to create bubbles not just move the water. Have the same length of pipe to each one. Having them all supplied from a loop ensures the same pressure to each one – like a 13A ring main in a home – all have the same voltage.

  • Meanwhile… garden renovation in SE1

    Meanwhile… garden renovation in SE1

    While nothing is happening on the land, or something is happening behind the scenes, we decided to refashion our small garden here in London. It involved learning some major new skills: bricklaying, casting concrete, and cutting things with an angle grinder. We (I) started in December 2024 and finished half way through March.

    The idea was to make better use of the most sunny place in the garden by building a raised bed in the far corner. Our first idea was to build the back of this bed out of gravel board and fashion a curved front from concrete. We realised that piling a few feet of earth against this wooden barrier was not a good idea. It would not take that long to rot, so a rethink meant that, of course, we should build it out of bricks. Enter an account with Selco which is 15 minutes drive away and cue the purchase of many bags of sharp sand, building sand, concrete bricks, engineering bricks, gravel and MOT.

    Foundations did not need to be that deep – between 200 and 300mm. The thing was to make them absolutely level.

    Once the gravel and other aggregates had set, I could start building the walls. The idea was that all the visible brickwork would be of concrete bricks. I’m not sure why we decided this because we ended up painting them a slightly darker colour at the end because they stood out too much. Once we had decided to use bricks we had the idea of having planks of wood to use as benches – one end on the brickwork and the other on piles/plinths, firstly of brick but then we decided of concrete.

    We kept the gravel board in place – and later extended it across the entire back fence.

    We knew the curved front wall would be a challenge but I bought some thin plywood that I could bend to the right shape and keep in place with a mixture of clamps and posts in the ground. First thing was to make a curved foundation.

    Then build the structure for the wall on top – once it had set.

    You can buy rebars at Amazon, believe it or not, and the mesh was something we had lying around, fixed to the brickwork at each end with ties from Selco.

    I put removable barriers inside the form so I could try different mixes of sand and cement and other aggregates like gravel and MOT (not very successful). I could remove them once the first section had set and then move on to pour the next. All the concrete was hand mixed.

    There was a young and fragile cherry tree in situ that made the work tricky. I ended up breaking only one branch in the process. Here are the four different mixes. Looking back I wish I had just used sharp sand and cement (5 to 1). Its the mix on the right. The yellow section is building sand and cement. The top is a layer of sharp sand and cement.

    The next job was to form two concrete plinths for the planned benches to sit on.

    The next job after that was to cut down one of the existing planters (there were two) made of Corten steel and turn it through 90 degrees and move it. This job put a strain on my cordless angle grinder meaning lots of changes of overheating battery. Also PPE was absolutely necessary for this job and even more so for the very dusty job of cutting bricks later on.

    Actually moving the planter once it was reduced in size and bolted back together was not difficult. Once done we started redoing the existing paving before moving on to repave the rest.

    We wanted to lay the paving bricks in curves, around the new raised bed and around the Eucalyptus tree in a circle. This meant cutting about 45 or so bricks which was a nasty job, mainly because of the huge amount of dust it made. I fashioned a kind of dust container inside the planter – lined with ply wood and plastic bags but everything ended up covered in dust including me.

    Working out the layout was not straightforward.

    The more-or-less last step was grouting the paving, in some places with earth where we wanted to grow some ground cover and in other places with sharp sand.

    The circle of bricks around the tree is not quite finished in this picture.