# Forum Home Renovation Retaining Walls  Building Limestone Wall with Mortar

## wicksy

Hi,
I am building a limestone wall in my backyard in Melville, Perth and am in need of some info/tips as it's my first large wall attempt 
The blocks I have bought are 500L x 350H x 200W.
The wall heights from ground level will be approx 450mm min (garden beds) to 2m max (feature walls) 
1) What is the best foundation/footing to use in this case? How thick? How deep should top of foundation layer be to ground soil level?  
I have a mixer and plenty of 200 x 200 old solid pavers...
I was going to pour a concrete mix (2 part blue metal, 3 part sand, 1 part cement?) of about 100mm thick with pavers knocked in and leveled every 300mm to same level as concrete to save on concrete mixes and get rid of my old pavers.... 
For the 500mm high walls, was just going to dig 150mm trench for concrete foundation (100mm thick concrete). For the 2m walls, having one full block in the dirt for better strength...? 
2) When using the mortar mix, is it best to apply a fairly dry mix to be able to support the 80kgs blocks without the mortar totally pissing out?
Is 4 parts sand, 1 part cement, 1 part lime a good mix for this work? 
3) Once each course is laid, what is the best time and way to clean up the mortar on and around mortar joints? 
4) What is the best to way to get rid of lime stains on block faces before I seal the blocks? 
Any advice and help would be much appreciated guys
Cheers

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## jago

This is a big job especially the 2 metre high walls... generally has to be engineer specified and certified for councils, there is a lot of mass invovled in a 2 metre wall and liability IMHO seek out the advice of a qualified builder landscaper or engineer. :2thumbsup:

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## Black Cat

I would skip the concrete in the mortar mix and just go four parts sand to one part lime (slaked lime that is). That mix will take a while to go 'off' so you will have ample time to remove any spills and such like from the face of the stones. It does, however mean that you can only do a couple of courses in a session and leave for a few days before the next go on, as the weight of the stone in the taller sections may squeeze out the mortar from the lower courses. The 450mm walls will be fine done all in one go. If it is hot or dry weather, cover the work with wet hessian until it is dry (the mortar not the hessian) to ensure it goes off evenly and does not simply dry out at the surface.

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## wicksy

Cool, thanks for the info fellas. 
Any reason not to use cement in the mix? 
Any info on the footings for the 450mm height wall?
Is it good practise to use black plastic under the fooundation concrete? 
Will standard acid product used on bricks be suitable for lime stains on limestone blocks? These are not mortar stains, they are stains from moisture in the blocks coming to the surface of the block.

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## Black Cat

Concrete sets hard. Limestone is a soft rock. The mortar should always be weaker than the material you are building with or you will get cracks forming.

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## an3_bolt

> mortar mix and just go four parts sand to one part lime (slaked lime that is)

  1:4 might be a little high for slaked lime - it might exceed the void space ratio of the sand.
Generally I thought anywhere up to a 1:3 would be more correct depending on aggregate sizing and workability (considering a fat lime / slaked lime putty). 
Using an engineer specified wall - I would be very interested if they know anything about using lime mortars and stone walling........I hope it has not been lost....

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