Job of the Week
Flagstone Walkway nightmare
Tuesday, July 28th, 2009I recently looked at a flagstonejob in my neighborhood and once again came across a really bad work. Time and time again I see stone masonry projects that people are not qualified to handle. They don’t even have the basic idea of what there masonry base should be constructed of. This particular job was done but some fly by night contractors who took the money and ran.
They set indoor slate on the outside of the steps and walkways. They used bar sand to set the slate tile on top of the concrete. They didn’t even have the thought to use some bonding agent against the concrete. If they did it probably wouldn’t of work because they didn’t clean off the original concrete steps to begin with. Bonding agents can only be applied after a proper cleaning has been accomplished. Even if they did everything I mentioned it was still doomed to fail. Slate is not the most porous stone, but if you have to use it at least mix up some cement and water paste. If you paste the backs of each stone then maybe you could get a decent bond.
But not to worry they didn’t use any anyway. At least they came off pretty easy. In the walkway they again used the existing concrete but wanted to extend it from three to four and an half feet wide. So instead of tamping down the earth and setting crushed stone. Then adding a four inch slab of concrete for the new slate walkway. They decided to just throw some dirt and debris on top of the earth and call it tight. They however, put down a little mortar on top of the debris to level things up.
I feel bad for these people, they just spent thousands of dollars for a walkway that looks terrible and is falling apart. Should of went to help with masonry .com and got some input. Look for an article on how some bozo used stacking block and natural stone together on a porch. John the mason out.
Improper slope towards stone foundation
Wednesday, July 22nd, 2009This weeks job has a few different spins to it. The first part of the job includes a improper slope in the landscaping towards the stone foundation of the house. The poor slope in the grade has been sending rain water into the stone foundation and has undermined the earth. This has caused a void around the stone and caused water to pentrate the stone. When this happens in the Northeast part of the country it will freeze and cause major expansion between the mortar joints that it penetrated. This expansion will cause stone mortar joints to crack and fall out. After the stone mortar joint falls out then the water comes in the basement. That’s not Good!! The crack itself has also traveled up the stone wall and has seprated quite large.
What to do? Cawley is on his way!! We have to first get to the stone joint crack that is under ground. We will remove all nescessary earth to get to the stone crack. Clean the stone joints where the crack is ( no major debris in the joint) and mix a four to one mix of concrete sand and cement. Not to wet or dry. I like a sticky texture that will stick to my trowel but not too wet so it runs off the trowel. I also use concrete sand over bar sand because of it’s overall cured strength. Make sure you pack it out tight and don’t be afraid to go over the stone a little bit. The only time i’ll recommend going over a stone a little is when no one will see the stone joint or if it’s underground. Let the mortar joints dry and then apply a tar base waterproof agent to the areas. After the tar has become sticky enough to back fill then begin to back fill. Don’t throw all the earth back into the hole and then try and tamp it down. It won’t work, it may look good at first but the earth will settle down and you’ll be back to a reverse grade again. So with that said back fill your foundation in 4 to 6 inch layers. Throw some dirt, do some tamping. This way you’ll be sure to get good compaction in your trench. keep large stone or debris out of your hole. They can cause uneven compaction and cause voids under them. When you get to the top of your grade, remember you have to add more earth for your proper slope away from the stone foundation. Don’t go to the store and buy top soil for regrading because top soil will absorb the water that falls on it and won’t be much help. If you have no other choice then try and mix it with some earth from around your property. I know this might not be possible but it will help. If you can get a truck then ask your local guy or gal about some compactable soil to be delivered. Good Luck and I hope this helps. John the stone mason
cobblestone boarders
Saturday, July 4th, 2009the job of the week brings us to historic Philadelphia and the use of cobblestone for a driveway boarder. Cobblestone make great use of their strength when used in high traffic areas. Cobblestone are granite and come in a many shapes and sizes. In the Philadelphia area where they are abundant many are historic stone that our fore fathers walked on.
This particular job we used a yellowish cobblestone with a grey speckle look. The cobblestonerange slightly in size 9×5 and 10×5. When using cobblestone for your boarders try and get the same thickness in the cobblestone. They will line up alot better and look more professional.
This job we started out by removing 10″ down of earth7″ wide and tamping the soil down as tight as possible. If you have a gas powered tamper than use it or if you can rent one I suggest you do. If that’s not possible then you must use a hand tamper and slam the tamper straight down onto the earth. Once you have the earth tamped then add your concrete base. Add at least 4″ of 3500psi concreteto your trench and let sit. Make sure when your pouring your concrete base that your pouring the concrete level. You can drive a stake at one end of the boarder and one stake at the other end. String a line up one end and put a line level on the string and that will tell you if your string is level.
Hint: You have to make sure the string is pulled tight or you won’t get an good reading on the level. The string height must be the height of your concrete. Now you can pour your concrete nice and level. Let the concrete harden over night and in the morning your ready to set your cobblestone.
You’ll need three parts concrete sand and concrete sand only to set your cobblestone. Use one part type I cement and three parts concrete sand. Mix dry first and then wet. Make sure not to add too much water it will ruin our setting bed. I even like to add a slurry coat of cement and water mixed to a pastie texture. I will dip the bottom of my cobblestone into the slurry right before I’m going to set the cobblestone. Once set in the wet bed of sand and cementand the bottom slurried. Your cobblestone are set so well that it can withstand the occasional car bumping into them. If the job calls for it, we will point the joints between each cobblestone. Sometimes I’ll point the stone flush or do a concave design. Either way it helps to hold each stone. If I need for water to flow through the stone then we will lay them as tight as possible to one another.
Cobblestone boarders are great around landscaping areas. Cobblestone can be used flush with other materails or be raised above surrounding materials such as flower beds or patio’s.
The only time I won’t use a cobblestone is when clients ask about building a wall out of cobblestone. I find that cobblestone are not great stacking stone and don’t bond as well as I would like when stacked. I’ve seen mortar joints fail sooner than they should be when people use them to build walls.
If you use the cobblestone for a area that has to absorb water then set the cobblestone in a dry manner. See the page How to set a patio it will give you different bases you can use. Hope this helps Johnny Mason