Is a DPC needed for small garden wall?

phil-007_3

Hi,

I'm going to build a small raised bed in the garden, probably only about 4-6 bricks above ground level, I've read various different tips some say you should put a Damp Proof Course in, other say that for a single wall under 4 ft a DPC isn't needed and would actually weaken the wall.

I'm leaning towards not having a DPC in between a row of bricks but applying a wider sheet to the back of the wall so that soil is sat directly against the brickwork.

Does anybody have any suggestions as to if any of the above is needed?

Thanks

Phil

sneekymum

If you are going to fill the bed with soil over the level of the dpc then there's no point in having one - as you'll be providing a bridge for the water to go up.

leveller2911

No need for any DPC on a garden wall unless the wall joins into a wall of the house. If it does then you will need a vertical DPC to stop damp bridging the existing house DPC... So if the raised border is independant of the house then no need for any DPC.

I went round the houses a bit there but I have had a pint of "Scarecrow" bitter...... so I hope you get my gist.;)

dampdaveski

No DPC needed, it would definately weaken the wall if you put one in.
If you want to be really saucy then instead of using a mortar plasticiser in the mix use a waterproofing additive instead,(you can get it from most builders merchants) this will also weatherproof the joints a bit more than normal plasticiser.

DD

tony6403

Smooth finish and not really made for facing, but class B engineering bricks have only 7% water absorption.
Some facing bricks such as London Stocks can have 22% water absorption which could lead to saturation and the faces blowing due to frost.
I used Ibstock type B for a retaining wall without a dpc and there is no sign of any problem after many years. The link below is worth a click.
www.ibstock.com/pdfs/get-it-right/getitright7.pdf

phil-007_3

Thanks for the advice guys!

Furts

No garden wall or retaining wall should have a dpc built into it. As previously stated this causes a plane of weakness in the wall.

The addition to the posted comments is good building practice. This would be a brick dpc course, typically two courses of solid blue engineering bricks laid in 1:3 mortar. Blue engineering bricks are virtually waterproof, solid and impenetrable. That is why the Victorians favoured them for bridges and viaducts - that and the small fact that reinforced concrete was a twentieth century innovation!

27col

As above, blue engineering bricks do the damp course job well.