Retaining Wall Questions

[sanku]

Hi All,

I am just about to commence a fairly large retaining wall. It is an 'L' shape, 10m x 8m, 1.050 high and c/w a 2m set of steps in the centre of the long wall.

The footings are down and I have completed detailed drawings for the wall. I am just costing up the blocks at the moment and intend to use natural limestone on all exposed brickwork and reconstituted seconds for backing and fillers.

I have a couple of questions related to finish and drainage. I am a big fan of the joint being flush with the face brick and then 'scored' (not sure that is the correct termionology) however I am unsure on how to achieve this finish. Is this finish created as the job progresses or is a gap left and the whole wall jointed flush and then joint 'scored'? What tool is used to score the joint? How hard must the mortar be before scoring it?

My other question is related to drainage. The filler behind my wall will be very soft and fine black riversand. People from Perth will no doubt be familiar with the type of sand I refer to. It drains very well. Will I need to add additional drainage? Perhaps blue metal? If so, how much? Piping?

I have buit a few smaller retaining walls that have gone well and look good but this is a much bigger project and it is in a highly visable area so I am determined to get it right....

Many thanks in advance...
Sanku

[Brickie]

I am a big fan of the joint being flush with the face brick and then 'scored' (not sure that is the correct termionology) however I am unsure on how to achieve this finish. Is this finish created as the job progresses or is a gap left and the whole wall jointed flush and then joint 'scored'? What tool is used to score the joint? How hard must the mortar be before scoring it?



I think you are after a raked (http://www.brickwork.net.au/Finishing.html) joint. Achieved with a raker (http://www.brickwork.net.au/Basic_Tool_Kit.html).

[Gingermick]

Depends how big the wall is. Water is a big killer of walls as it exerts more pressure sideways than soils.
We usually leave the perp grout out of every other block on the bottom row.

[sanku]

Thanks Brickie but its not a raked joint I refer to. I am familiar with a raked joint. This joint is flush with the facebrick but then horizontal anbd vertical lines are etched into the joint....

I will try and post a photo of a few walls in my area...

Cheers...

[Cementer]

Hi Sanku,
Is it tuck pointing you are refering to???
http://www.tuckpointing.com.au/

http://www.heritageceilings.com.au/how-do-I/re-pointing-bricks.htm

Maybe one of these is what your after.

Cheers,
Neil

[joe greiner]

It sounds like sanku is after joints tuck pointed with a square bar bent so as to present the bar to the joint on the diagonal of the square. There's probably a name specific to that style, but dashed if I know what it is. Sometimes might be done with the point of a trowel, but the point of the trowel is subject to wear.

Over time, fine soil particles in the parent ground can migrate into the backfill and destroy permeability. To prevent overload due to water pressure, it's best to line the cut with filter cloth and backfill with well-draining material. Soft sand may not be ideal for this. Coarse hard gravel is probably better. For a wall this high, I'd place perforated drain pipe at the bottom of the backfill, with an exit to daylight or a rock pit, also lined with filter cloth.

For "belt and suspenders," weep holes, as Gingermick suggests, are advisable.

Joe

[jags]

hi sanku .

I am looking at doing a similar thing but the wall will be about 21m and about 0.7 high . so am very interested in how you are going to biuld yours . can i ask who did your enginnering approval for council and did you do the drawings yourself ?As bayswater council are a bit anal and need engineering approval for anything over 450mm.

as for the finish you are after i think i know what you mean it is the one that is done a lot in W.A the join is made flash with the brick face and once the mortor is nearly set a line is scribed into the middle of the joint.


http://www.limestone-resources.com.au/com-image-retaining.htm

this web site is very helpfully and informative when i rang them the price i got for 500 x350 x200 for linestone blocks was $8.20 and the seconds where $7.04
thanks rob

[sanku]

Hi Rob,

Thanks for the great info....I will be sure to check out Limestone Resources tomorrow..$8.20 is cheap!

You know the joint I refer to! It is quite common in Perth. A number of walls in Mt Lawley / Maylands/ Bayswater have this finish. I will post some photos soon and hopefully someone may be able to suggest a tool to achive the finish as I am doubtful it could be achieved with the end of a trowel (I could be wrong though!).

As far as my wall goes, I completed the drawings (sketches) myself. They are obviouisly not of professional quality but are detailed enough to get the job done. I was not aware of the 450mm requirement and have only been going on what my bobcat guy (lives in the area) told me....1.2m! I will have to look into this tomorrow....


Thanks all for info and help to date...

[jags]

Hi Sanku

where abouts are you in perth ? im on katanning st in baywater finally move in in 1 week after 7 months of renovating ... :-)

the lines you mention can be done with a trowel or a large nail on a bit of wood ould do the job .I resently watch a guy do them on the wall at my fokes place he placed a straight edge on the wall face and scribed along it , looked prity simple ?

have you already got council approval for your wall ? just thought i would ask as from your reply it sounded like you had not .

if you go to your local council they will give you a information sheet with the requirement for the wall . if it is going to be over 1m you will have to back block the wall ?

the plans for my place are in feet and inches as it was biult in 1973 which make drawing plans for the lay out of my wall a right pain .

also what kind of rate are you looking at for the bob cat hire as this is also what i will be needing .
sorry for all the questions but i thought some might help ....
thanks
rob

[autogenous]

I am a big fan of the joint being flush with the face brick and then 'scored'I would call it struck but thats not what you would refer to as a real struck joint. Its done with a trowel. :)

These are limestone tiles. Poorly illustrated as the photo was taken from about 30 feet

http://www.limestonerender.com.au/random_limestone.jpg

[Planned LScape]

I've seen random rock walls done with a flush joint, then have a trowell or other sharp object score a line in the middle of the mortar joint defining the joints more.

Havent seen it in a wall with plumb courses but would give a different effect.

[autogenous]

Heres something Ive done in limestone render but a bit closer

http://www.limestonerender.com.au/limestone_render.jpg