This is a long post. Apologies and thanks for your patience.
I am researching how to face a cinder block retaining wall with stone. I have a very modest experience with the materials and methods. I removed some set-in-the-ground timber stairs from the hillside in my yard and replaced them with a cinder block/concrete substructure faced with brick and hand cut stone. It was a lot of work and took forever, but it looks good, and even more importantly, it seems solidly built.
The next project: Facing a cinder block retaining wall with stone. A description:
The wall is about 70 feet long in total, surrounding the front of my rather narrow urban lot. The 40 foot long front face abuts the sidewalk and is broken by a set of cement walkway stairs. A 25 foot leg runs up the driveway on one side and a 5 foot leg anchors the other end. The front wall is about 25 inches (3+ cinder blocks) high. The side walls and stairway are progressively shorter. The wall probably dates from 1940-1960. It was capped with 3-hole brick that had been set on edge. The brick was crumbling and I have recently removed it. The wall has been painted several times. Much of the paint has deteriorated and been removed.
My main concern is avoiding mistakes that could cause problems in the near future, especially mistakes in preparing the wall to receive the mortar.
1) I will need to remove the remaining paint. On the side walls, which receive less sun, the paint is mostly intact. Does 100% need to come off, or will 90-95% do. These side walls are shorter, averaging 12-14 inches high. Suggestions? Paint thinner, scraping, sanding?
2) I had thought that the base layer (the first layer laid over the cinder block) was white paint, but upon closer inspection, it appears to be more like plaster than paint. Of course it could not be plaster (or whitewash), which are too water soluble. It is slightly soft/powdery and can be scraped away with a lot of pressure from a putty knife. It appears too thin for stucco, varying in thickness from .5 to 2.0 mm. Perhaps a very thin layer of colored mortar or Portland Cement? Advice? Ideas?
The point of ascertaining what this substance is, is to find out whether or not I should remove it, also, from the cinder block, before refacing. It would be difficult, if not impossible, to remove it all, as it is embedded in the texture of the block. And it appears to have an absorptive quality, like plaster. I think the mortar will adhere to it.
3) A neighbor who had a much higher retaining wall faced with concrete faux-stone (looks pretty good, btw) said that a professional mason would score the cinder block with saw cuts to provide a surface for the new mortar to adhere to. I have also read of facing being secured by giving the mortar something to adhere to: a) lath (metal lath maybe?) screwed into the wall, or b) metal mesh secured to the wall by screw and washer anchors.
This wall is on the short side, and seems less likely to shed it's stone face. However, it does hold back a fair amount of soil, and that soil is sometimes wet or frozen (Washington D.C. area). This project will require a lot of effort and I don't want to have it fail because I am ignorant of standard practices.
Two additional notes: I hoped to reduce possible water issues by improving the drainage behind the wall: digging out an 8 inch trench and filling it with brick rubble, and cleaning out the three 4 inch weep pipes. This is now done. But I have noticed that the mortared joints on the front of the wall now display numerous cracks. I think this may be caused by the wall drying out, caused by either the drainage work or the removal of the cap, thus exposing the open tops of the cinder block. Some of the cracked mortar may need to be removed, but I hope that applying the mortar for the stone facing will remedy the gaps. Another thought: the center of the cinder blocks is mostly hollow, should I partially fill the interior with cement (and rebar?) before recapping the wall?
Also, as mentioned, the wall is butted directly up against the concrete sidewalk. The stone face will have to extend out over that walk (not more than 4 inches at the base). Although this is a relatively new sidewalk, that doesn't mean the city won't find a reason to demolish and replace it in 5 years. I was wondering if I should run a line of standard size stone or brick along the base of the face, which could be more easily replaced if it was damaged by such activities.
I am also wondering about what kind of mortar/grout to use?
Any information you can share would help me overcome this initial hurdle and would be greatly appreciated. If anyone wants advice on building landscape stairs, I endured a number of travails.
thanks.
I am researching how to face a cinder block retaining wall with stone. I have a very modest experience with the materials and methods. I removed some set-in-the-ground timber stairs from the hillside in my yard and replaced them with a cinder block/concrete substructure faced with brick and hand cut stone. It was a lot of work and took forever, but it looks good, and even more importantly, it seems solidly built.
The next project: Facing a cinder block retaining wall with stone. A description:
The wall is about 70 feet long in total, surrounding the front of my rather narrow urban lot. The 40 foot long front face abuts the sidewalk and is broken by a set of cement walkway stairs. A 25 foot leg runs up the driveway on one side and a 5 foot leg anchors the other end. The front wall is about 25 inches (3+ cinder blocks) high. The side walls and stairway are progressively shorter. The wall probably dates from 1940-1960. It was capped with 3-hole brick that had been set on edge. The brick was crumbling and I have recently removed it. The wall has been painted several times. Much of the paint has deteriorated and been removed.
My main concern is avoiding mistakes that could cause problems in the near future, especially mistakes in preparing the wall to receive the mortar.
1) I will need to remove the remaining paint. On the side walls, which receive less sun, the paint is mostly intact. Does 100% need to come off, or will 90-95% do. These side walls are shorter, averaging 12-14 inches high. Suggestions? Paint thinner, scraping, sanding?
2) I had thought that the base layer (the first layer laid over the cinder block) was white paint, but upon closer inspection, it appears to be more like plaster than paint. Of course it could not be plaster (or whitewash), which are too water soluble. It is slightly soft/powdery and can be scraped away with a lot of pressure from a putty knife. It appears too thin for stucco, varying in thickness from .5 to 2.0 mm. Perhaps a very thin layer of colored mortar or Portland Cement? Advice? Ideas?
The point of ascertaining what this substance is, is to find out whether or not I should remove it, also, from the cinder block, before refacing. It would be difficult, if not impossible, to remove it all, as it is embedded in the texture of the block. And it appears to have an absorptive quality, like plaster. I think the mortar will adhere to it.
3) A neighbor who had a much higher retaining wall faced with concrete faux-stone (looks pretty good, btw) said that a professional mason would score the cinder block with saw cuts to provide a surface for the new mortar to adhere to. I have also read of facing being secured by giving the mortar something to adhere to: a) lath (metal lath maybe?) screwed into the wall, or b) metal mesh secured to the wall by screw and washer anchors.
This wall is on the short side, and seems less likely to shed it's stone face. However, it does hold back a fair amount of soil, and that soil is sometimes wet or frozen (Washington D.C. area). This project will require a lot of effort and I don't want to have it fail because I am ignorant of standard practices.
Two additional notes: I hoped to reduce possible water issues by improving the drainage behind the wall: digging out an 8 inch trench and filling it with brick rubble, and cleaning out the three 4 inch weep pipes. This is now done. But I have noticed that the mortared joints on the front of the wall now display numerous cracks. I think this may be caused by the wall drying out, caused by either the drainage work or the removal of the cap, thus exposing the open tops of the cinder block. Some of the cracked mortar may need to be removed, but I hope that applying the mortar for the stone facing will remedy the gaps. Another thought: the center of the cinder blocks is mostly hollow, should I partially fill the interior with cement (and rebar?) before recapping the wall?
Also, as mentioned, the wall is butted directly up against the concrete sidewalk. The stone face will have to extend out over that walk (not more than 4 inches at the base). Although this is a relatively new sidewalk, that doesn't mean the city won't find a reason to demolish and replace it in 5 years. I was wondering if I should run a line of standard size stone or brick along the base of the face, which could be more easily replaced if it was damaged by such activities.
I am also wondering about what kind of mortar/grout to use?
Any information you can share would help me overcome this initial hurdle and would be greatly appreciated. If anyone wants advice on building landscape stairs, I endured a number of travails.
thanks.