Still more drystack stonework

This time last year, I started work on my 21 foot high, 6 foot wide fireplace and chimney that I’m doing in “Buck’s County” drystack ledgestone.   At the time I began, I thought perhaps this project would take a month, two at the outside.    Back in July, I provided the last update on the project and was only about 8 feet up at the time and hoping that it wouldn’t take six more months to finish.  Six months has passed and  I’m about 2/3 of the way complete.   In truth, I haven’t worked on this as diligently as I had intended to, and some months have passed without any work being done at all

I recently found some time during the rainy days of the holiday to resume work.   Here’ s a recap of a few things I’ve learned along the way.  

 1)   Use Type S mortar, and mix in about 15% of an Acrylic fortified thinset mortar like this versabond product.  There are probably some liquid add mixes you could use, but I had this left over from the slate tile I did earlier and found it works really well. 

The addition of the thinset mortar makes the resulting mix very sticky – it holds the trowel well and also helps hold the stones in place better.    When using the straight type S mortar previously, I could only work two courses at a time, especially when using some of the larger stones, as the weight could make the lower courses buckle and fall off while the mortar was still wet.  With the revised mix, I can build up several courses high in one area rapidly, without fear of a collapse.  This is more important on the sides where each course may require only 3 or 4 stones, so it goes up faster.

2) Work short batches of mortar.    Laying block or brick, or other standard size pieces, a person can work quickly enough to use up an entire bag of mortar before it starts to set up.  Because it takes extra time to select and fit each stone, a full pan of mortar would likely begin to set up and become unworkable before it was completely used.   I usually use about 1/3 of a bag at a time, and this provides enough mortar to put up about 3 – 4 courses of rock – enough to cover about one course of standard 8 inch concrete block.  

3) Plan your work time.  It takes about 3 hours to select and fit the stones to make up these 3 – 4 courses.    Since there are about 32 courses of block, not counting the hearth work, this fireplace will take about 96 hours of rock laying to complete.   Add in the time to move the rock inside, mix the mortar, hand up the materials, build up the scaffolds, etc, etc.    One person might accomplish this in a month if it were his full time job.   

I will complete this project during the winter so we can use the fireplace.