The Appearance of Stonework

Jose Garcia has been a landscape contractor for 24 years and has gravitated to doing a lot of rock work. He has built innumerable retaining walls of timbers, boulders, drystacked and mortared stone. He has built foundations out of stone and mortar and put rock veneer around the base of a straw bale building to raise the level of waterproofing. He lays about 20 tons of flagstone a year in patios and walkways. Over the last couple of years he has built a half dozen mortared flagstone staircases. In Colorado we are blessed with a wonderful red flagstone with great tensile strength that he uses to make benches. He tries to work with the stone's shape as it comes, and can generally lay out a patio with a minimal amount of cutting or chipping, and the benches are free form and distinctly shaped. Mostly he's out rolling boulders and flipping flagstone on a daily basis.

Questions and Answers

Q: I have a lava rock wall and fire place that I want to concrete over. Is this possible? How?

A: It is possible to concrete over a lava rock wall, and maybe even fairly easily. You'll need to have a solid wall and hopefully a concrete or stone footer to build on. I would probably suggest an expanded metal lath over the existing rock wall attached with molly bolts or lead shields. The new facing will be heavy if made of concrete so make it as thin as possible. A troweled on masonry mix will probably be less problematic than a thick formed concrete wall. But then your looking at a concrete wall, it would have to be an ugly lava rock to justify all the work. If it were me I'd consider an earthen plaster over the lath instead. In and of itself the earthen wall will look better than concrete and is a much better medium to plaster or paint over. Good luck.

Q: I just bought a home in Santa Rosa Beach, Florida that is in a flood zone and is up on pilings (about 4 ft off the ground) It currently has lattice skirting around the bottom and reminds me of a mobile home. I would like to give it a natural rock skirting, but I don't know if I could glue the rocks to treated plywood, mortar around them, then attach them to the bottom of the house (or how I would do this exactly)...I want something that looks nice and natural. I don't have a lot of money but will do the work myself, any suggestions?

A: I understand how that lattice can look so tacky, but I'm not sure it would be a good idea to enclose the area under you house. It can be an endless task trying to fight the flow of water. I think it best to let the floodwaters go where they will with your house safely above the fray. Enclosing the pilings with stone of any sort, a dry stack wall or a faux stone veneer over plywood, would likely end up with you searching for the materials downstream after each flood. If the materials stayed in place you are faced with the fact that the saturated soil under your house would retain moisture long after the surrounding landscape dried out. Better to let the water and air flow under your house as it was intended when built.

I approached a couple of friends with your dilemma and came up with answers based on their orientation. A carpenter suggested a finely built lattice work with quality materials that would add to the look of the house rather than detract. A young at heart friend with a decorator's sensibilities suggested a playful arrangement of plastic flowers on the trellis.

My background is in landscaping so my suggestion is to plant the trellis with vines, around here I would use sweet peas in Florida you might look for a flowering edible, and start some shrubs out in front to eventually hide the underside of the house. Use enough variety to stager bloom times and to give height and color variations. A decorative boulder or two with shrubs, flowers, and maybe a bench can do wonders to draw the eye away from the functional but less appealing trellis.

Q: Can you help me with some information as to what I can remove cheap emulsion paint from granite walls on the inside walls of a 200 year old cottage which I recently purchased. Sand blasting has no effect whatsoever which leads me to presume that something has been added to the paint. At the minute I am trying to remove it using a chisel which is proving to be very time consuming and labor intensive.

A: (Kelly) It sounds like a difficult situation to deal with. It would appear that the paint has managed to work its way into the pores of the granite over time, since sand blasting doesn't remove it. I don't imagine that ordinary paint removers would the job either. Actually removing the outer layer of the rock may be your only solution, which means chipping with a chisel like you've been doing, or possibly grinding it with an abrasive grinder. Good luck.

Q: We have a large front yard and would like to break it up with several rock gardens. My husband feels he would like to build each one out of a different kind of rock. I wonder if this will look like a hodgepodge with no planning. I believe in adding interest to the rock gardens but should there be some continuity either in color, shapes of rock, etc? The house is moderate in size and made of brick that has red, shades of orange, dark gray and black. The main question is should there be a theme carried through all 3 rock gardens or does it really matter?

A: (Kelly) The answer to your question is purely aesthetic...what appeals to you and your husband the most is the best. From a sustainable point of view, you might choose rocks that are locally available, rather than need to be transported long distances to arrive at your yard. This might result in a certain uniformity because local rocks resemble each other. This also might mean that the rocks would seem to fit into the landscape better, because they actually come from the landscape.

Q: I live in the Hills of West Virginia. I own a red brick house. We want to tear out our driveway and add an additional parking space. When we do this we need to add retaining walls. I also have a 60' wall in the back that will be 4 - 5 feet tall. We were going to use the interlocking blocks due to drainage problems when you live on a bank or a hill. The previous 60' wall in the back was brick and because of the water, rain, freezing, etc. the brick has shelled and cracked and is falling apart. My question is this. We can only buy 6 colors of block and nothing matches the brick on our house. I do not want this block to look like a commercial driveway. I called sherwin williams and they said we could paint or stain the block but I also do not want the upkeep down the road. What can I do?

A: (Kelly) Trying to match the color of your bricks is going to be difficult, even with a stain, and paint would certainly need upkeep. I suggest choosing a color of block that is complimentary with your house color, rather than trying to match it.

Q: I need to find an insulating material for my stone wall basement. I don't want to cover the stone with dry wall. I would consider adobe or some other natural material that might provide some warmth.

A: (Kelly) Adobe would not make a good insulating material, so unless you left an air space of several inches between it and the rock wall, it would not do very much good. Of course doing this would diminish the interior size of the room noticeably. Most any insulating material, natural or otherwise, would need to be covered with something else to make it look good. One approach would be to put a relatively thin layer of insulation (such as blueboard) over the stones, attaching it as firmly as possible, and then put wire mesh over this and plaster the wall with an earthen plaster. This would give you the adobe look and feel without taking up as much space. The best approach would be to dig around the basement and insulate the wall from the outside with blueboard or something similar, although this may not be feasible. This way the interior natural stonework would remain the same, you would not lose any space, and the thermal mass of the stone would work to your advantage on the inside, being insulated from the ground.

Q: I bought a house that has a rock shower wall. It appears to be the type that most people use to form ponds...larger gray rocks. There was some sort of sealant on it when we first moved in, that made the rocks shiny. Now that has faded and we are left with dull looking rocks with white water stains. What do you suggest to clean it, and to coat it with?

A: (Kelly) It is hard to say what was originally used to seal the rocks. It could have been urethane, or something else. I have a rock wall in my shower that I sealed with a bit a pure linseed oil that brought out the color of the stones and sealed them from absorbing much water. I would say it will take a bit of experimentation to figure out what will work. First you might try cleaning the rocks with a brush and some cleanser to see if you can remove any stains or film. Then rinse and let it all dry. Then you might try a dab of linseed oil just rubbed onto some obscure corner to see if you can bring out the luster again. The nice thing about the oil is that it doesn't chip off and it can be renewed over time.

Q: We have a brick house with an addition built out of wood. We want to put a rock facade on the entire house. How do we do this? (We want to do it ourselves) Are there any resources? What type/size stone would be best?

A: Your project sounds complex and on such a large scale that I would recommend not trying to do it yourselves. The weight of the rock veneer could put more stress on the foundation and existing walls than they were built to take. I am sure that you could mortar on the fabricated stone with out much trouble but I don't see how that would improve the look of the house. If you find some one that will help you with this use a thin stone over tar paper and metal lath screwed into the siding and bolted into the brick. There are another thousand or so considerations so please find a mason to give you a hand.

Q: We have a cabin in the woods and wanted to use the river rock (I swear it multiplies daily) to do the outside walls. Is there any way to rock the outer walls using the existing house...similar to putting siding on an existing house...Hope this question makes sense. What we would like to do is take the siding off and replace it with rock walls...is this Possible?

A: You may need to add some support to your existing foundation to hold the weight of the rock. I would leave the siding if convenient and cover with tar paper and a metal lathing. You will have to work on the details around the windows and doors including headers and sills. It is sure not an easy conversion when the house is built to accommodate wood siding an easier task might be to rock up a few feet along the bottom of the house and leave the siding up over the windows and upper reaches.

Q: I have a beautiful basement that I want to finish. The walls are my houses foundation and they are made of stone and some mortar. Problem is that it often flakes and is the cause of dust. Is there a clear seal that I can put on it and keep the beauty of the stone?

A: There are any number of clear sealers for stone work and mortar to protect your wall. I am sure that you can find something locally. A sealer won't protect your mortar much if it is already starting to degrade. You may have to chip out the flaking mortar and replace it. This is a process called tuck pointing. I would hope that you don't have to go too deep to get at solid mortar. Try and do small sections at a time using a fairly dry mortar mix in the newly cleaned joint.

Q: I have several samples of granite from all over the world in various sizes and color. (3x5 to 12x12) I would like to know how to adhere the granite to an existing building which is made from pressed wood only on the front.

A: You will need to put tar paper over the existing wall and expanded metal lath over that. Don't expect the lathing to support the weight of the stone by itself, you will probably need some sort of foundation.

Q: I would like to put a rock/stone veneer on the exterior of my house, over the area of the poured concrete foundation that rests above grade, to simulate the look of a fieldstone foundation on the exterior. I have read that when adding a brick or stone veneer over siding, an air gap, flashing and weep holes are required to prevent moisture problems. Is the gap and/or a moisture barrier necessary when veneering the foundation, or could I simply set stones in mortar coated directly onto the foundation wall, using wall ties to secure the veneer?

A: No need for any air gap or weep holes when putting a veneer over your concrete foundation. I would probably apply some masonry glue to help the bond between old concrete and new mortar to go along with your wall ties, and pay special attention to the top of the veneer to insure any water sheets off the masonry and doesn't puddle.

Q: We have a wall in front of our house made out of rocks 3 feet by 1 1/2 feet wide. You can see the full 3 feet of rocks from the driveway but when you look out the front door you only see about six inches of stone, since it is built with the grass and ground close to the top on one side. On one side of the pathway it has a wooden top on the other side it either wasn't finished or it was taken off. Is there some other option to top the wall off? We like the finished feeling not just the wall of stones. These stones are flat on the top but on the side they look round.

A: Mortared stone retaining walls and wood don't mix well. I always put a stone cap on such a wall if I can. I use cut flagstone mortared to the top of the wall with a little overhang. It's not the easiest thing to get a cap to adhere well to the top of a flat wall. If you can, gouge out some indentations in the mortar on the top of the wall to give the new mortar a tooth. Set a good bed of new mortar for the flagstone and the joints between each one. I have drilled holes and set bolts in the bottom of my flagstone to get a good bond before but would rather reset a stone that might come loose than go through the pain of drilling and epoxying bolts to keep it in place longer.

Q: We purchased an older home (75-115yrs) with a stone foundation. The previous owners spray-painted the outside of the house. While doing this they got quite a bit of the paint on the foundation. I'm not sure yet what type of stone this is. The blocks are large and asymmetrical, they have a course surface, and are of diff rent colors. We were hoping you might have an idea of how we can remove the paint, without damaging the surface of the stone?

A:Try a wire brush first and then test a small area with paint thinner. If that doesn't discolor you should be able to clean up the mess with the thinner. If the thinner has an effect on the stone try using soapy water and elbow grease with a stiff brush.

Q: We built our fireplace out of "river rock." We are in the Blue Ridge mountains of NC. The upper part of this 20ft. high fireplace gets moss growing on it, mostly on the north and east sides. Do we have to have it pressure often? Would it be advisable to seal it with something? If so what do you recommend?

A: Are you worried about the moss deteriorating your fireplace? I am not very familiar with wet climates, around here the moss is sought after and causes little damage. I don't see how sealing the stone work would help keep the moss off. I have seen where moss can shorten the life of your mortar and scraping and sealing the mortar every year could prolong it's life but I would have to think that re-chinking the mortar every ten years would be an easier solution.

Q: My daughter just built a waterfall in the back yard and used flagstone and concrete. It looks great, except there are some places where the white, dried concrete looks unsightly. Is there a product that gets off unwanted concrete from the flagstone?

A: Chip off as much of the concrete as you can with a chisel, then attack the remaining with a wire brush and rinse. Next try a stiff brush with soapy water. That should get most of it off but may still leave some staining. Muratic acid is sold as a concrete cleaner and works well but please be frugal with it's use and careful as well. Rinse with water and watch out for the waste. You don't want acid water in your pond or on your landscape. I really hesitate to use the muriatic acid myself and find that a little elbow grease works wonders.

Q: I was advised to use a sealant on my stone wall tiles in my kitchen to resist stains and bring out the grain in the tile. The product is extremely environmentally unfriendly. Do you know of an environmentally friendly product that does a similar job?

A:I am regrettably uninformed about natural sealers for stone. I have used shellac on a rock wall in the past. That brought out the color of the stone but yellowed over time. I will have to try a linseed oil treatment and see how that works.

(Kelly) I have used a light coating of linseed oil to seal stones and bring out their color. Just wipe it on and let it stand for a few minutes, then wipe off all excess oil before it congeals.

Q: I have a small patio wall made of some kind of sandstone and mortared together. I'm wondering if its possible to stucco over this??

A: I think it can be done but may be problematic. Make sure you get any loose material off the wall to start with. You may need to get some masonry glue to get a good bite on the sandstone if it is smooth at all. I think it is well worth the try.

Q: My husband and I have built a concrete earth sheltered home and would like to put a veneer of river stone on the outside, using slipforms. Can you please tell me if there's a good way of doing this? The idea is to stack up the stone and pour concrete in behind, but I'm not sure how successful this will be, and whether the end result will look OK.

A: River rock as a veneer is a little on the thick side and therefore puts more strain on the bond between mortar and concrete wall. A slipform application seems inappropriate to me. I think I would be more comfortable mortaring each stone to get a good troweled bind to the concrete wall. Perhaps if you used an expanded metal lath lagged to the concrete you could get away with the slip form technique. On second thought the round stones against a flat form will leave little of the rock showing when you remove the form. I think river rock, veneer and slipform are words that probably shouldn't be used together. Try mortaring some river rock against your concrete wall one at a time and see how you like it. In general rive rock goes up pretty quickly.

Q: I am thinking about putting some lava rock accents in the area above my shower. Do they make a faux lava rock for this? I'm concerned about the weight and cost of using regular lava rock. Also will typical drywall material hold the weight.

A: I really don't know much about faux lava rock but the real thing seems inappropriate over drywall. I doubt that the cost would prohibit the use of natural stone but you're right the weight of the stone would be problematic. I also wonder about all the cavities in the lava rock in a shower environment.

Q: I have a large quantity of black polished river rock that are any where from on to three inches. My Idea is to embed them into poured concrete incorporating this new look into our new brick patio that I have laid and purposefully left some interesting shapes to play with. My husband has suggested two things. The first is how do I get them in fast enough before the concrete sets? And the second is what's keeping the rocks from popping out over the winter? He has really put a damper on my project but I still want to do it. Can you tell me how to over come these obstacles?

A: Overcoming obstacles is my main occupation. I think you can do this project by using an exposed aggregate technique. Pour your concrete sections in the normal manner just shy of the top of the form. Set your stones and top over everything with with a wetter concrete mix screened of large aggregate. After the sections have set up for a while you can wash the top layer of concrete away from around the stones with high pressure water or even a wet sponge, leaving them exposed on top. I would try some test squares to make sure you can master the technique before attempting the final product. The rock should be embedded in the cement to the extent that freezing won't hurt them.

Q: I have bought a house built in 1973 that has a huge wall in the den covered in lava rock. Is there anything I can do to help the look of the rock? If not, how do I remove it? Any comments/suggestions will be appreciated. This wall has a window and a fireplace, and lots of mortar and rock.

A: (Kelly) I'm not sure what you mean by "help the look of the rock." Lava rock tends to have a characteristic "frothy" or aerated appearance, that perhaps you don't like. If this is the case, there is probably not much to improve that, or make the stones smoother looking.

Removing the rocks could be a huge job, depending on how well they are mortared into place. If they are just cosmetic, with the structure of the wall not depending on them, it might be possible to get in there with a crowbar and hammer and pry them all out of place. This would be a big job, but possible. If the wall is basically built with these stones, then you are looking at completely reconstructing the wall...which is even a bigger job.

Perhaps if you give the situation some time, you can come to accept the stones as "rustic" and appropriate  for the den area...

Q: We have bought a house that has a river rock patio out back that is mostly in the shade. A good portion of the patio has begun to grow moss on it. What would be a good way to clean off the moss or kill it so that it does not come back and then re-seal the river rock? I was thinking of power washing, using Seven or something like that and then sealing it.

A: I would think that your power washing idea would be easier than hand scrubbing to get the moss off. I'm not much into toxic chemicals, so I would try a strong bleach to discourage the moss, and then your sealer. I suspect that time will eventually allow the moss to return, no matter what you do; so it may require periodic attention.

Q: We are remodeling our downstairs and the whole lower half of the walls are concrete and rock, with unfinished areas. I do not like it; it is uneven, gathers dust and spider webs. How do I get rid of it? I read the plastering idea, but some of the rocks jut out a lot further than the others.

A: (Kelly) It sounds like what you are describing is an old stone foundation for your house, and you certainly don't want to disturb it very much. You might be able to chip off part of the rocks that stick out too much, but plastering over them is about the only to make the wall smooth. Or I suppose you could frame in an entirely new wall inside the foundation, but that would be a lot of work and use up space.

Q: We have tons of rocks on our farm in Oregon. I would like to make a field stone wall using some of them. However, they are rust colored from the clay soil. Is it possible to wash them and get the rust color off? I hope this is not a silly question! I would like to use them but they look . . . dirty.

A: Sure you can wash the rocks. Scrub them with a stiff brush and get all loose material off of them, especially any clay soil. Hopefully cleaning will solve your color problem.

Q: I have a doublewide home and am wanting to get rid of the ugly cheap skirting that surrounds the bottom of the house. I have a lot of rock/stone and want to rock the bottom of this house instead of this cheap skirting. What would be the best material to use to properly hold the stone. should I use wood/mesh? Type of mortar to use?

A: (Kelly) I happen to be living in a double-wide manufactured home myself, and plan to do the same thing. In my case the skirting is an insulating foam material that goes way down into the ground and really helps insulate the space under the house. I plan to leave that insulation in place and build up a rock wall just outside of it.

I suggest that you dig a trench wide enough to accommodate the stone that you have, and fill the trench with gravel as a foundation for the stone. This will keep any frost upheaval to a minimum. As long as your skirting is not supporting your home, then replacing it with a stone wall should be pretty easy. Just lay up the stones with standard mason's mortar. If you are not familiar with stone work, you might get a book to explain the basics. Such a small wall should easily be self-supporting without the need for wood or mesh.

I plan to stand up rock instead of stacking it, similar to the way you do your hearth/wall for a wood stove. So that is why I was asking about the wood and mesh because it will have to have something behind it to support it.

Perhaps you can attach some mesh, like diamond lath, to your existing skirting to give support to your stones.

Q: I just built a glass porch that I want to cover the skirting with thin natural stone. I have h-beams for joists and welded angle iron frames to hold pressure treated 3/4 plywood to cover the sides which I bolted to the angle iron. The skirting is only about 2 ft high. I have some natural stone that ranges from 1/2" to 1" thick and was hoping to cover the plywood with. My question is what's the best way to go about this? Do I need to prep the plywood with something first?

A: (Ed Hartz) Waterproof the plywood and screw an expanded metal lath to it. Use a type N masonry cement with masonry glue in it.

Q: We recently had our fireplace refaced using full depth natural stone, after having been cut to veneer. We had a dry stack installation. The stone is rustic which left bigger gaps than we can appreciate, and an unfinished look. Can we have the fireplace mortared over the existing mortar? And can this be done using a different color mortar? The installation is 4 weeks old.

A: (Kelly) It is much easier to mortar stone as it is built, but it could be done later very carefully. Getting the mortar in the joints without making a mess on the stone is the challenge. You might try a canvas cone with a hole in the end (like a cake decorating tool) to squeeze the mortar into the joints. These are sold for tile work sometimes. The color of the mortar doesn't matter...whatever you like.

Q: I live on the coast of CT where our home was just hit by 2 consecutive hurricanes requiring us to elevate our cedar shingle home approximately 10 ft with a poured concrete foundation. We have beautiful rounded rocks on our beach that I would like to cover the concrete with. What size rocks would work best and which method would you recommend? I have spoken with the foundation guys who say they can leave a 4 inch shelf. I also spoke with a mason who says he would use mortar but no mesh. Would a wire mesh improve the stability?

A: (Ed Hartz) A 4 inch shelf will be just the thing, and if they leave a rough surface on the shelf all the better. I don't think an expanded metal lath would be appropriate for your application. A little masonry glue might help the mortar adhere to the foundation stem wall better. If you are going to do the work yourself some brick ties might help also. You should be able to fasten them fairly easily while the cement is fresh. Working with round rock takes some skill, I would recommend varying the size to keep from getting rows and columns, and use as large a stone as you can on the bottom. Ten feet is a lot of rock to lay I hope you can get help from the stone mason, this is quite a challenge. Good luck.


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