|Dry stone fence, limestone, Kentucky. Image by Mark Jurus.|
Monday, September 2, 2013
Foundations for walls & related elements....
Why do these dry stone structures last so long? Luck? Lack of exposure to extreme elements? Freeze thaw not present in certain elements????
There are as many theories as there are people who have put one stone upon another. You can go to school and be instructed to build a wall to certain standards of quality. You can also build walls with a naivety to any of those rules. Both walls will have have certain truths that endear them to their own longevity. A friend of mine has said many times in my presence...."a poorly built wall often lives way longer than it should...". They do... wether they are pleasing to look at, or chaotic and terrifying in their relationship to the site.
For me it always starts the same for a new wall. I have to slow down and assess the landscape. This often takes me a while as I try and picture a new wall working in the landscape for the client as they intend it to. Eventually we come to 'yes' for the landscape/client/and myself.
After the site is assessed, the wall is defined to height-length-materials-thickness-drainage... you begin work. You excavate for your foundation. Foundations are to me one of the more beautiful details that hidden within the wall. Many times the only time a foundation is seen by the client is as a line item outlining our scope of work, or by the subtle edge that protrudes 3-4" proud beneath the face of the dry stone retaining wall or fence.
The foundation is, to me, one of the most important details in walls. There is a reason we use that phrase 'solid foundation' in a hundred different analogies in life. We don't want what is above grade to shift, or become insecure because of what is at our feet is not solid. Foundations vary incredibly according to region, site conditions, materials, engineering specifications, surcharge of slopes, and also personal experience of the contractor.
The Dry Stone Conservancy in Kentucky, when I went through their 'Boot Camp' program to obtain my basic certification through them, said that by adding a foundation to our walls of 4-6" thick stones, that protrude 3-4" on the face of dry stone retaining walls/and the same for dry stone fences, will add an estimated 25-50 years for a walls longevity. The foundation! I think this is where I fell in love with working with stone and thinking about the quality of materials and the relationship of the craftsman to a deep timeline long after they mason is gone.
I'll use this site as an example because it was relatively easy.... It is totally clear why the client wanted a 48" tall dry stone retaining wall along their driveway. We chose a blocky Montana slate to work with.....
After digging down, and cutting back into the hillside we realized we were sitting on our local sandstone bedrock. We also had a drainpipe we could remove excess water from below and behind the wall.
This was an easy foundation because we could build right up off the sandstone. We did three things. One was cutting the grade of the sandstone level, and running the back of the wall a few degrees below the front. And the second was to install a 4" drain pipe behind the wall, with a clean out under the lentil detail. We also removed the cedar tree on the edge of the cut to prevent it from growing roots into the wall and pushing it over, and or getting toppled by high winds and wet soils in the winter/spring.
So here you can see a detail of the finished wall with the tree removed(and all the blackberries), and the clean out access detail for water to collect in.
Above you can see Forest building a dry stone retaining wall out of Idaho Quartzite that will finish out at 48" tall. At his feet you can see the detail of the foundation protruding 4-5". In our part of the world the inspectors measure walls height from the bottom of the first stone.
Here is a finish detail of the wall before plants went in.... The pattern language of the foundation stones is picked up with the large cap stones.
We can return to this fence that has a few unique elements incorporated to it.
This site needed to incorporate a passageway for a seasonal stream that appeared during heavy rains, and lintels above the root structure of the 'witness tree' in Shaker Village. The foundation is entirely below water water line. Here I rebuilt the wall the had failed because of the tree and a broken lintel stone. After I stripped it out, I added foundation stones which will greatly strengthen the wall. The tree however will pull it apart again over time as the roots were monsters that should have been removed. By the way... trees love stone walls because the provide shade, and harbor moisture.
In some cases their engineer, or landscape architect, specifies something a little more extreme. In this case the client wanted a dry stone retaining wall look along their man made lake in Ontario. In this project my friend had to build on a concrete foundation and concrete wall behind the stone. The wall had large cap stones 3' x 3' x 6" thick mortared down to the stone. It was designed to show the top 12" in summer when the lake was full, much less in the winter as it receded, but also because of the freeze thaw and heaving.
This project is being built in Bellingham Washington. Our wall was engineered in context to the 'critical slope' behind it, the sandstone bedrock, our desired finish height of 6-7', and drainage. For this project we had to remove all topsoil, and 'toe' our wall into bedrock 6". That was about 11-13" below grade! In the first image you can see our foundation stones for our granite foundation stones. Crazy right? You can see in the second image those stones protruding 3-4". Also note our drain pipes behind the walls to remove excess water content. All the gravel came out as we installed our foundation stones.
I have seen many walls built on gravel of varying depths, on asphalt, over fallen logs/boulders, and stone. Every structure built should be honored with the foundation being properly built. Why waste the time to build a structure without a solid foundation?
As you can see every walls foundation is critical in context to the site, as well as the finished structure.
Monday, July 29, 2013
overview of details.... looking back
|Nick Fairplay & Patrick McAffee looks sum up the weeks hard work.|
It was an amazing week of transferring knowledge in stone to students, to faculty, and to the broader community that participated. This was my 8th StoneFest to attend. The first one I attended lit my passion for a relationship with stone. No where else have I participated in any event that has a focus on one material from so many different points of reference.
Stone & letter carving....with Karin Sprague & Tracy Mahaffey
Stone & Water with Scott Hackney
Stone & Architectural carving/Sculpture
with Nick Fairplay, Alexandra Morosco, Jon Decceles
Stone & Traditional masonry with Mike Schroder & Patrick McAffee
a dry stone retaining wall. Both are Irish walls...
|Entering the inner circle....|
|The Clochan embraced with stone!|
|The dry stone retaining wall from last year with coping on the left, |
and the dry stone fence on the right.
|The view of the dry stone fence, Clochan, and Ditch wall in the back.|
If you are curious about more details of this StoneFest, past StoneFest's, or the instructors....visit the link below.
I felt very lucky to be an instructor again and share in this journey.
A landscape may require stairs, a dry stone retaining wall, an arch, a dry stone fence, or any number of other stone elements to solve an existing transition. Each site is unique to the landscape, design parameters, materials, and budget.
|In this simple transition it is fairly obvious that we needed a retaining wall to hold back soil as well as creating a clean boundary between the driveway and the landscape.|
|We built a 4' tall by 60' long dry stone retaining wall using a Montana Slate, and cleaned up the hillside of blackberries. The cedar was critically damaged by previous excavators.|
|The large boulder is Olivine and the low dry stone retaining wall is Montana Slate.|
|Here our dry stone retaining wall turned into stairs to provide a transition between the patio area and the upper gardens|
Transitional elements in the landscape can function in a multitude of ways...
-They can provide emphasis & contrast between spaces....
|In these cases between the driveway and the entrance .|
Some of these elements are more artistic and architectural in nature and visually draw us in as destinations in the landscape.
|This 11' tall Inukshuk weighs 18 tons. My friend Cameron Scott and I built this for the Seattle Flower and Garden Show in 2008. People flocked here to have their pictures taken in front of it.|
|This large piece of granite we used for a wall end was a great detail for the stairs, landing and bench.|
|This is a dry stone fence I rebuilt in Shaker Village Kentucky . I loved how the small lunky detail allowed for animals and water to pass through, as well as accommodate the roots of the tree.|
Monday, January 21, 2013
I did a site drawing for our client (see earlier blog post October 3, 2011)proposing new walls, stairs, a gothic dry stone arch, and pathways. I love to draw, but not super tight....
|We took 25 yards of soil out from this area to bring it to the proper grade before we|
we began our wall.
Our client wanted this wall to stand out distinctly from the other work we had done, yet tie in with the same language. To do this we used the same Montana Slate materials, from a different quarry there, as well as the same stone from the dry stone retaining wall along the driveway. Functionally I needed to build stairs down from the deck to a path, which evolved to a dry stone arch hidden in the trees, to another set of stairs-which became cantilevered to this wall.
So the wild thing about this project was the staging of 80-90 tons of stone in this space, plus room for machinery, building, access to the mailbox, and keeping the city of Bellingham happy with our water runoff from the site into storm water drains. We got to know the city people quite well working here.
I decided to build a set of stairs down from the deck first to gain access to the slope safely every day. From there we located the arch site in the trees, established a path to the arch, and built the 2' tall dry stone retaining wall along the path which connects the arch to the stairs. To figure out where the stairs where the cantilevered stairs were going to start, I had to set the large piece of granite and establish the line of my dry stone retaining wall with it's base course.
So once that line was established we started with the cantilevered stairs and the retaining wall. I knew we needed to get a lot of big material up on the slope by hand, and with machinery, for the arch so we started building the cantilevered stairs up to the arch.
*Side note here...
This is the medium long version of this whole scope of work for this front area by the way..... Which lead up to the final angled/wedge dry stone retaining wall.
After we had built all those details over some period of time, we could finally begin our wall. We needed the cantilevered stairs, and dry stone retaining wall in to function as our wall end on the left.
So we followed our rules......Each stone in these structures has these rules applied, and then with the angled/wedge wall with get to apply the exceptions!
It begins like all dry stone walls built to DSWA standards...
1)Length in for all stones
2)One stone over two, and two stones on one
3)Largest stones go one the bottom of the wall
4)Stones are laid level and solidly
5)Build to the string line, and heart well!
|So we started with 5-6 pallets of 2-3" thick Montana Slate. We set up our wooden bankers to begin squaring up the stones, and sorting for the build.|
Before we could start building this I had to decide what angle we were going to lay the stone to. I didn't want it to look like it was slipping, or that it was laid casually. We decided a 60 degree angle looked the best and committed to it for 50' long by 4' tall....
You can't 'see the forest for the trees' when you start a wall and this is really when everything seems off.
|And then BAM! It finally snaps together once a pattern language is established!|
|From the side you can see the technique...|
|Another beautiful detail about these walls is the top course. It creates a very beautiful line...|
So here we are almost done.... silt fence still up, bankers have moved with us down the wall, patterns mostly revealed, seasons changing...
|So here is how we end this wall. I had the granite stone on top for|
about 12 months. It is about 30" long into the wall.
|The view from the deck above the wall.|