Retaining wall advice needed

11fernsroad

Hi

We need to build 4 feet high x 8 feet length retaining wall.

Will hollow concrete blocks over 6 inch footing do the trick or do we need to have interlocking blocks?

Many Thanks

weeg

There are a lot of variables involved in retaining walls, but unless it's basically a solid rockface, then no. Hollow concrete blocks don't weigh enough. The starting point is generally about 2/3 width to height at the bottom of the wall. And you need drainage at the back of the wall.

You need proper advice.

11fernsroad

sorry.

no to concrete hollow blocks or interlocking blocks?

stuart45

The idea of hollow blocks is that they have rebar reinforcement and are filled with grout to give the wall maximum strength.
LABC recommend that retaining walls over 900mm are engineer designed, while the NHBC say over 600mm.

Section62

11fernsroad said:

sorry.

no to concrete hollow blocks or interlocking blocks?

You need to talk to a structural engineer to get a design appropriate for your situation.

gm0

Sadly Modern BR tend not to be "like for like" for old amateur hour retaining walls.  Digging a deeper and a wider foundation to build back up properly and doing drainage renewal is very typical.  More cutting back on one or both sides may well be needed to do the wider than the old one base properly.  Before building a "to spec" wall on top of the improved and now "to spec" foundation.

Rules have tightened due to unfortunate incidents of various kinds.  The rules are there to cover higher and more dangerous situations than the typical gardens and drives on a slight slope scenario.  But you get wrapped in them just the same.

Bodging again in situ can create a legal exposure at future sale. Even if it would work in context as well or poorly as the previous single skin/wrong materials version from 30 years ago. 

thebikemechanic

@11fernsroad whats the context of what you're doing/what you're supporting? 

We used gabion baskets to add further support to a relatively stable bank, rather than building a block wall. Because space was not an issue, we were able to use 1m x 1m gabions, and being a cube shape this makes them very stable. They also allow free drainage through them and filled with nice rock sourced from local farms, they're more pleasant to look at (imo) than a block wall.