# Forum Home Renovation Brickwork  back fill + Ag pipe for retaining wall

## jags

Hi all 
I was hoping somebody could help . 
I have recently got a retaining wall built at the front of my house about ( 25m across ) and have allowed it to set for about a week   . Now i want to back fill it as the builder did not do this . The blocks are 1000 x 350 x 350 and 240 kg recon limestone  
The soil is sand and the wall is four blocks high and double back blocked with half the first block and backing block as a footing . 
Do i need to use Ag pipe and should i just use the sand i have to back fill i was going to lay back plastic over the back of the top two blocks to stop any water getting into the them . But feel this is not needed for the bottom two as there are two blocks thick .   
As the soil is sand and the blocks reno limestone what is required .
Any help would be greatly appriciated .
Thanks 
Rob j.

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## Bleedin Thumb

as long as the sand is free draining I wouldn't worry about the agpipe. Theoretically I suppose you should put one in but.....

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## chipps

Off topic. 
That tree on the high side may be a problem. 
How much of the root system got cut & how deep?
It has possibly lost it's anchorage on one side & with heavy rain, then strong winds, it may topple. 
Also, roots may upset the wall footings.

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## Terrian

I would pt in an aggie pipe, and lay some weed mat over it (not the plastic woven stuff, the marix weed mat) then fill over that with 14mm agg (not scoria, the red colour may leach out onto the wall) just my 2 cents worth  :Smilie:

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## jags

thank for the replys  
The my plan is to not worries about the ag pipe as we do not get much rain and the soil is very free draining But to still  use the  plastic sheet to cover the back wall . the reno block are 350 cm and 65 % dencer than limestone so there is really not much chance that water could get  through to the front but for the cost of the sheet and the little time it will take it seem worth while   
As for the tree the roots on one side where cut back and the tree is about 1.5m away from the wall which is 750 cmm at the base so think it we be fine for the next 10 year before it becomes somebody elses problem . 
thanks again 
Rob

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