I'm building a 5ft high retaining wall against a garden banking. So far I have dug out a 2ft x 2ft trench and filled with ready mix. I plan to build a double skin brick wall in class b engineering bricks and common at rear.
I have had delivered a ton bag of MOT to fill behind the wall for additional strength. The MOT delivered was not what I expected. Is this the same as crusher run? It just looks like a bag of dirty sand and stones!
Am I ok in using this with a mix of cement, or would it be better just to use ordinary stone chippings?
Any thoughts appreciated
Banking Wall
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alan ditchfield
- Posts: 203
- Joined: Thu Jan 01, 1970 1:00 am
- Location: Preston / Lancashire
You would be better using a single size stone (20mm)behind the wall and be sure to put weep or drainage holes at the bottom of the brickwork to prevent blowout in freezing weather, have you thought about using block at the back of the wall instead of commons it will be much faster, and i sorry but i dont know what you thought MOT was but it is meant to be 40mm to dust,(usually limestone) ie.. ministry of transport specified hardcore for road use, all the best Alan.
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84-1093879891
Again, I have to agree with Alan. DTp1 (what used to be MOT1) is fine as a sub-base material, but it's not intended for use as a 'free-draining material' at the rear of retainer walls, and it will do nothing to increase the strength of the wall.
Get a delivery of clean, single sized, no-fines, non-limestone gravel to use as backfill for the wall, and include weepholes or land drainage to help relieve any hydrostatic pressure.
The DTp1 might be useful if you're laying a patio or need to back-fill at the front of the wall, but it's the wrong product in the wrong place at the back of a wall.
Get a delivery of clean, single sized, no-fines, non-limestone gravel to use as backfill for the wall, and include weepholes or land drainage to help relieve any hydrostatic pressure.
The DTp1 might be useful if you're laying a patio or need to back-fill at the front of the wall, but it's the wrong product in the wrong place at the back of a wall.
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Rovernut
- Posts: 8
- Joined: Fri Jun 11, 2004 12:18 pm
- Location: Gtr Manchester
Thanks Alan and Tony for your replies.
The wall has gone up today to about 3ft. high with commons at the rear. Whilst this wall appears quite sturdy, I would have thought that the addition of any stone/ sand/ cement behind it would have been the main strength of the wall. It has a good amount of re-enforcement bar behind the wall and weep holes are in place.
I plan to chuck the MOT with a mix of 6:1 cement behind the wall and am surprised you think this is wrong.
I will use 20mm stone next delivery as you suggest, but the MOT was specified by a professional structural engineer.
I am told the MOT is normally this colour and is probably recycled. I was expecting 40mm to dust stone of a limestone appearance.
The weep holes also seem irrelevant as the ground is very porous and would drain past the back of the wall foundation rather than build up behind the wall.
Many thanks for your thoughts and suggestions, they are very helpful to a newbie wall builder.
Come and have a look Tony, I'm only 6 miles from Leigh!
Great site many many thanks,
Chris
The wall has gone up today to about 3ft. high with commons at the rear. Whilst this wall appears quite sturdy, I would have thought that the addition of any stone/ sand/ cement behind it would have been the main strength of the wall. It has a good amount of re-enforcement bar behind the wall and weep holes are in place.
I plan to chuck the MOT with a mix of 6:1 cement behind the wall and am surprised you think this is wrong.
I will use 20mm stone next delivery as you suggest, but the MOT was specified by a professional structural engineer.
I am told the MOT is normally this colour and is probably recycled. I was expecting 40mm to dust stone of a limestone appearance.
The weep holes also seem irrelevant as the ground is very porous and would drain past the back of the wall foundation rather than build up behind the wall.
Many thanks for your thoughts and suggestions, they are very helpful to a newbie wall builder.
Come and have a look Tony, I'm only 6 miles from Leigh!
Great site many many thanks,
Chris