The oldest portions of the Great Wall of China date back 2,300 years. It’s an awe-inspiring architectural and engineering marvel. Some of the oldest portions of the wall are still standing today. What has contributed to the longevity of this wall? The mortar!
With the butt and pass style of log home building, the horizontal joints formed by stacking wall logs require chinking – and lots of it depending on the quality of your logs. For the bunk house, I decided to use a time-proven mortar recipe. It’s cheap compared to the synthetic products on the market today. I estimated the cost of using the synthetic chink for the bunk house to be $1,500. The mortar chink was batched for less than $125 in material – all bought at the local hardware store.
The materials in the mortar for the bunk house are almost identical to those used in the Great Wall. An additional ingredient was found in the mortar that many experts claim have added to its longevity – rice flour. Although I didn’t use rice flour in my batch, I will be experimenting with some test batches for the house build. Hopefully I can incorporate this into the chink.
The recipe for the mortar chink consists of 3 parts sand, 1 part Portland type I-II cement, 1/2 part hydrated lime, and water. I purchased a used electric mixer for $50 that makes the perfect batch size. It takes about 15 minutes to batch the mortar.
Before the mortar is placed in the chink joint, the joint was prepared with bonding nails and insulation. The nails bond the hardened chink to the bottom log of the joint. When the logs shrink they maintain their horizontal axis as they shrink towards their centers. This does open gaps between the logs. By bonding the mortar to the bottom log with the nails, the gap always opens at the top – making for easier maintenance down the road.