Bricks for retaining wall?

[Peter500]

I need to build a small retaining wall (about 300mm above ground level). I have loads of bricks left over from building my extension, so they wouldn't cost anything to use, and match the extension perfectly. They are rusticated bricks and only ratted F1, S2. If I use these, are they likely to have problems, or are they likely to be fine?

I've used these same bricks below DPC for my extension, so is the risk for a retaining wall the same? I used these instead of engineering bricks so that they matched the existing house. The existing house has used similar bricks and only one has blown in 40 years.

 

[23vc]

Double skin it and face it with these and engineers/blocks behind? And dpm up the back

 

[Peter500]

Double skin it and face it with these and engineers/blocks behind? And dpm up the back

I will double skin it, and I was considering a DPM. Would I need a perforated land drain behind the DPM to let the water out?

 

[stuart45]

It's a good idea to have a drainage system behind a retaining wall.

 

[Ivor Windybottom]

Absolutely essential, otherwise you're building a very inadequate dam.

But just rubble is often good enough. Just ensure there's a way out for the water, and a porous path to it.

 

[^woody^]

Don't overthink 4 courses of garden wall.

 

[Ivor Windybottom]

Oh aye! OK, it's not going to burst open with a torrent of water.

But decent drainage will vastly reduce the chances of frost damage to your bricks. It's freezing water that blows them, cold air alone won't harm them if they're dry.

 

[Peter500]

I think I will do engineering bricks on the side that isn't seen, some weep holes along the bottom course (below ground level), and pea gravel behind the wall.

What size foundation would be best for this? There is a large tree near by, and clay in places, but some places may be sandy. I built an extension, where this wall will be starting, and the foundation depth was 1m. House foundations in this area are always a minimum of 1m in this area, but maybe that's excessive for a small wall?

 

[Ivor Windybottom]

You need to dig down to clay, sand or rock at whatever depth they happen to be. Don't build on anything black. Brickwork is brittle, it will crack if there is any movement, and topsoil will definitely sink over the years.

You can then either fill it with concrete to just below ground level, or put just enough concrete in to be structurally strong enough then build up from underground to ground level and beyond.

Alternatively, do what the previous owner of my house did... Just slap a bit of mortar on the soil and chuck some bricks on top. It was cracked all over the place and I pushed it over with one hand.