[TCates]

Went and met with a client this morning for a short but long retaining wall. It's going to be 138' long and 2'-3' tall straight down the side of their house. Of course the client wants to match what their neighbor had done which is some sort of flagstone. Looks shotty and is already cracking and moving in a lot of spots. My idea is to start with a gravel base about a foot down with a concrete footer. Lay our cinder blocks on that level em out, the first one being below ground level. Then offset each additional block with a piece of rebar going through the center of each then filling them with concrete or mortar. After the wall is complete I'll go through and mortar flagstone around the outside face purely for looks. We're going to put a french drain along the backside with a sleeve to divert water away from the wall. Does this sound like the best way to go about it? what should be done differently?

[Squizzy Taylor]

G,day TCates

Does this sound like the best way to go about it?

Nope, not if you have a choice and the economics work for you.

The method you propose is essentially building a mortared retaining wall from Man-made products and dressing the face with a natural product if I am reading you right. This is a practice that I have done a number of times. However, it is not one I favour. When people ask why I always reply that the terrace walls at Machu Picchu are still standing strong.

The reason why the neighbouring walls are failing is because of the construction method employed for the situation or the workmanship (which could have been driven by budgetry constraints). No matter, the wall is not good enough.

If you can source a supply of a the same or similar stone then this is what I would recommend. I can't be specific on the dimensions because I can't see the site or know the soil conditions:

Excavate the footings to the appropriate depth and compact. If there is fall on the site work level and have steps, do not taper the footing. Install about 5" of compacted roadbase. Build a footing from the same stone and mortar that the rest of the wall is to be built from. The top of the footing should be about 2" below mean ground level and have 3" scarement. Then set your base width appropriate for the height and build up the wall in 12" courses. The rule in traditional mortared stone walls is to not make the mortar stronger than the stone. A traditional friable mortar mix (sand/lime/cement) will allow some movement in the wall and prevent fractures as occurs with modern high strength materials.

I avoid using concrete footings for natural stone walls because of the mis-match in physical properties between the man-made and natural materials. A properly constructed natural stone wall will move and act as a whole and will rarely suffer serious failure. The requirement for drainage will be determined by the site but its probably a given.

I have also found that by the time I pour concrete and let it cure, then build the man-made backing etc, then install the face stonework......with all the different supplies/materials required to be sourced...I could have just got a load of stone, mixed some mortar and got on with it.

Thats just the way I would like to do it...if it was me. The technical details (such as width and depth of footing) need to be worked out appropriate for the site and the surcharge.

Good Luck

[brooks]

You say face it with flagstone- have you looked into snapped (cut) flagstone wallstone? We build these kind of walls with it all the time- dry laid. I'll post some photos if I can locate them.

Here's one from our portfolio:

Retaining walls : Arcadia Gardens, LLC

[zullo-design]

Originally Posted by Squizzy Taylor

G,day TCates



Nope, not if you have a choice and the economics work for you.

The method you propose is essentially building a mortared retaining wall from Man-made products and dressing the face with a natural product if I am reading you right. This is a practice that I have done a number of times. However, it is not one I favour. When people ask why I always reply that the terrace walls at Machu Picchu are still standing strong.

The reason why the neighbouring walls are failing is because of the construction method employed for the situation or the workmanship (which could have been driven by budgetry constraints). No matter, the wall is not good enough.

If you can source a supply of a the same or similar stone then this is what I would recommend. I can't be specific on the dimensions because I can't see the site or know the soil conditions:

Excavate the footings to the appropriate depth and compact. If there is fall on the site work level and have steps, do not taper the footing. Install about 5" of compacted roadbase. Build a footing from the same stone and mortar that the rest of the wall is to be built from. The top of the footing should be about 2" below mean ground level and have 3" scarement. Then set your base width appropriate for the height and build up the wall in 12" courses. The rule in traditional mortared stone walls is to not make the mortar stronger than the stone. A traditional friable mortar mix (sand/lime/cement) will allow some movement in the wall and prevent fractures as occurs with modern high strength materials.

I avoid using concrete footings for natural stone walls because of the mis-match in physical properties between the man-made and natural materials. A properly constructed natural stone wall will move and act as a whole and will rarely suffer serious failure. The requirement for drainage will be determined by the site but its probably a given.

I have also found that by the time I pour concrete and let it cure, then build the man-made backing etc, then install the face stonework......with all the different supplies/materials required to be sourced...I could have just got a load of stone, mixed some mortar and got on with it.

Thats just the way I would like to do it...if it was me. The technical details (such as width and depth of footing) need to be worked out appropriate for the site and the surcharge.

Good Luck

exactly how I would do it.

[fakie99]

Originally Posted by Squizzy Taylor

G,day TCates



Nope, not if you have a choice and the economics work for you.

The method you propose is essentially building a mortared retaining wall from Man-made products and dressing the face with a natural product if I am reading you right. This is a practice that I have done a number of times. However, it is not one I favour. When people ask why I always reply that the terrace walls at Machu Picchu are still standing strong.

The reason why the neighbouring walls are failing is because of the construction method employed for the situation or the workmanship (which could have been driven by budgetry constraints). No matter, the wall is not good enough.

If you can source a supply of a the same or similar stone then this is what I would recommend. I can't be specific on the dimensions because I can't see the site or know the soil conditions:

Excavate the footings to the appropriate depth and compact. If there is fall on the site work level and have steps, do not taper the footing. Install about 5" of compacted roadbase. Build a footing from the same stone and mortar that the rest of the wall is to be built from. The top of the footing should be about 2" below mean ground level and have 3" scarement. Then set your base width appropriate for the height and build up the wall in 12" courses. The rule in traditional mortared stone walls is to not make the mortar stronger than the stone. A traditional friable mortar mix (sand/lime/cement) will allow some movement in the wall and prevent fractures as occurs with modern high strength materials.

I avoid using concrete footings for natural stone walls because of the mis-match in physical properties between the man-made and natural materials. A properly constructed natural stone wall will move and act as a whole and will rarely suffer serious failure. The requirement for drainage will be determined by the site but its probably a given.

I have also found that by the time I pour concrete and let it cure, then build the man-made backing etc, then install the face stonework......with all the different supplies/materials required to be sourced...I could have just got a load of stone, mixed some mortar and got on with it.

Thats just the way I would like to do it...if it was me. The technical details (such as width and depth of footing) need to be worked out appropriate for the site and the surcharge.

Good Luck

good detailed response......he can get away with this method in TX - here in MI, we would need a full frost depth concrete footer (42" down) before even thinking about mortar.....

[Squizzy Taylor]

Originally Posted by fakie99

good detailed response......he can get away with this method in TX - here in MI, we would need a full frost depth concrete footer (42" down) before even thinking about mortar.....

Something that doesn't crop up too often in Western Australia.

[FungusMudGrub]

Veneered walls just never look right to me, so another vote for a natural stone wall. Pure aesthetic snobbery, I know.

By the way, what the heck is "scarement", Squizzy?

[Squizzy Taylor]

Originally Posted by FungusMudGrub

By the way, what the heck is "scarement", Squizzy?

It should read scarcement. The ledge formed when the wall is set back on the footing. If you wall footing is 16" wide and your base of wall is 12" then you have a 4" scarcement...or 2" either side for a free standing wall.

[TCates]

Thanks Squizzy for the in depth response. We've talked to the clients and they've agreed with doing natural stone all the way through. Thanks again everyone for the support!

[Stoneman705]

Great thread, darn nice work there brooks.

What would the mortar mix be? 2 cement, 1 lime, 9 sand?

[Squizzy Taylor]

Originally Posted by Stoneman705

What would the mortar mix be? 2 cement, 1 lime, 9 sand?

I use 6.1.1 Sand/Lime/Cement and vary it a little to suit the conditions. Sometimes you get some masons sand that has a little more clay in it than it should so you add more lime to keep it more workable. If you are within a mile of the ocean increase the cement IAW Portland recommendations or paint the mortar with boiled linseed oil when finished.

Sometimes I will add a fine aggregate to give the mix a more antique appearance. The fines should be no bigger than about 5/32" and from the cruahings of whatever stone is being used for the wall although I have used fines from old clay fired bricks to put a fleck in the mortar. Substituting some aggregate for sand often produces a more "fluffy" mix that works easier. This is because the fines are less even grained so it can be very soft (too wet) but it still holds up and can be worked. (I'm giving away trade secrets here)

If I'm building limestone I use limestone fines in 5.1.1.1 mix. A little complicated but very worthwhile if looking for an old style finish. Also the fines help you get the mortar to the same colour as the stone without using artificial colourings which I despise.....but just a personal view. And thats all great if you can get your hands on the fines without driving around the country with your seive all day to extract a wheelbarrow full of fines.

[Squizzy Taylor]

Originally Posted by fakie99

here in MI, we would need a full frost depth concrete footer (42" down) before even thinking about mortar.....

I have'nt been able to stop thinking about this advice. We don't have freeze/thaw cycles here so I wouldn't have a clue how to deal with it. I do however, well remember looking at some beautiful 300 year old plus walls in Scotland and Ireland. Some of the castle walls I looked at where 90 feet high and looked as good as the day they were built. These walls were built with lime mortar and well before concrete came well into being in the late 1850's....and it really only was the American's in the 1920 & 30's that made concrete "commercial" as such. The retaining walls in Ireland, often in horrendous conditions (for wall building) were simply founded on larger stones.

I pour concrete footings for manufacture stone (block) walls but I try and stay well away from it when using natural stone. Just thinking out aloud.