A client of mine has recently had a brick raised bed built, it is approx 1.2 mtr square and 600mm high, its free standing so the brickwork can breathe on four sides, there are small drain holes incorporated near the base, although they are not that large, probably about 20mm in diameter
The builder recommends sealing the brickwork internally where it will be covered by soil, i would agree perhaps if the brickwork was holding in a large volume of soil and thus damp ie a retaining wall, but in this case all sides are open to the air for evaporation, plus the soil will be a free draining, compost and topsoil mix.
I advised the client it was unnecessary in this instance but wanted to check i was infact correct in my assumption
Cheers, anthony
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Any amount of moisture will be detrimental to the brick. You would be well advised to treat the inside of the brickwork with a bitumen sealer. The problem for the brick work is that any moisture that enters the planter will inevitably pass through the brickwork by capillary action. Any salts in the bricks will then be left on the surface of the brick as the moisture evaporates. This is known as efflorescence and is difficult to remove. The increased moisture in the bricks will also make them more vulnerable to frost damage.
For the cost sealing the inside its not worth the risk
Clive
www.thehandmadegarden.com
Yes, a bitumen paint is to be recommended, available at most DIY sheds.
Nick
Why not just do it? We always bitumen this type of wall. Will also help retain the moisture in the soil and help the plants.
Hi Anthony,
i would have to go with the guys above,
we usually, construct the inner skin in concrete blocks to as near to the ground level on the high side as not to show.
coat the wall in Black Jack or similar - usually 2 coats to stop stones from penertrating the sealant.
cover with DPM plastic, put a perforated pipe to soakaway or french drain beyond the wall.
cover with shingle and then top off with planting medium.
probably over the top, but never get problems or call backs
Peter
Ok thanks guys, the client has actually had it sealed anyway by the builder, but was asking my advice as they werent sure it was necessary either
Cheers
Just another thought, i assume with jobs like this you would use some sort of water proofer in the mortar mix instead of just a plasticer, or are they much the same thing?
No need for waterproofer as the liquid or pyshical dpm stops the majority of penetrating water. Plasticiser and waterproofer are different, plasticiser is to aid workability i.e without it mortar feels dead a bit like wet sand. Waterproofer is more self explanitory and commonly used in scratch coat of some rendering but not that common in mortar unless on a building site for things like flaunching chimney pots etc