Retaining wall - wrong blocks?

[nearthemark]

I want to build a retaining wall in the garden, just two blocks high, and have got 100mm thermalite shield blocks. Selco websites says they have high moisture resistance, and are good for both external walls and foundations, so I thought fine for a little wall!

A friend has just advised that they are not at all suitable and I should have got 7N blocks.

Would appreciate any advice on here. If they are too absorbent, could I paint the side that will be in contact with the soil?

Thanks,


Mark

 

[nearthemark]

After a bit more research, maybe paint on DPM or similar?

 

[kingandy2nd]

Should have gone with concrete blocks for longevity

 

[kingandy2nd]

Actually, just re-read. For a retaining wall, thermalites are no good at all. They literally have no strength to them.

 

[nearthemark]

Actually, just re-read. For a retaining wall, thermalites are no good at all. They literally have no strength to them.

Thanks for reply. Even only two blocks high?

Looks like I need to go shopping again...

 

[kingandy2nd]

I've been building my extension with thermalite shield blocks on the inside skin. You can pretty much snap them in two with your bare hands. Sorry.

 

[kingandy2nd]

Depending on how much retaining your wall is going to do, you need to consider the foundations and the width of the wall. You may need to lay concrete blocks on their side and build up if you've got 450mm of soil and a slope behind the wall to hold back.

 

[nearthemark]

Depending on how much retaining your wall is going to do, you need to consider the foundations and the width of the wall. You may need to lay concrete blocks on their side and build up if you've got 450mm of soil and a slope behind the wall to hold back.

There's not much behind it, just pond and patio, nothing higher.

 

[kingandy2nd]

So, not a retaining wall then...just a wall

Either way, thermalites will chip and crack with minimal contact.

 

[Notch7]

far too soft -thermalite shield blocks are like a crispier version of polystyrene.

 

[nearthemark]

So this:
https://www.selcobw.com/products/building-materials/bricks-blocks/blocks/concrete-block-100mm

And not this:
https://www.selcobw.com/products/bu.../blocks/thermalite-hi-strength-block-7n-100mm

?

 

[kingandy2nd]

Yes, the concrete block. What's your plan for decorating? Rendering or painting it?

 

[dontbelieveawordofit]

thermalites should be banned.

 

[martin hill]

An easy way is to sink 4ft concrete fence posts in by at least 2 foot and use the concrete gravel boards. For extra strength cut the boards to 3ft lengths with some pea single behind them to help with drainage so the wet soil no constantly against the boards. If you already bought the thermalite blocks you can make a small wall in front of the boards and render it with some capping on top.

 

[nearthemark]

Yes, the concrete block. What's your plan for decorating? Rendering or painting it?

I'm thinking of cladding with decorative stone, something like this, but would prefer something with smaller sections (I think these are 40cm wide) to cope with the curvature of the wall:
https://mydecorativestone.co.uk/epa...c1d-150b-4969-9209-e0c358d3b850/Products/0049