Repointing Fieldstone Foundations
Repointing Fieldstone Walls and More
Ram Jack New England can expertly repoint your fieldstone foundation walls. We understand what is needed to strengthen these types of foundations. We remove all loose materials between the fieldstone, paying close attention to maintaining the walls’ integrity. When these fieldstone masonry walls were originally constructed, the stone builder would use small stones of different sizes. These stones were called pinnings and were used to secure the larger stones. This would also lock in and make sure to transfer the load to each stone.
Our crews are trained to mix our own recipe of lime mortar. We never recommend a Portland cement based mortar to repoint fieldstone foundations.
There are several reasons why we use our own lime mortar:
- It allows for the stones to experience seasonal changes and slight movement with less cracking between the fieldstone;
- It lasts and protects the walls much longer.
When should repointing be done?
It should be expected that the mortar used in fieldstone foundation walls will deteriorate over time. Repointing is something that is usually required every 80-100 years if done properly.
Repointing should be done when the mortar joints are crumbling and loose. Sometimes even small stones will fall out. It is important that a fieldstone wall be repointed before the wall is allowed to weaken and collapse. If left unattended ground water passing through the foundation mortar joints and cause structural damage.
One problem we run into as a MA Foundation Repair company is when an inexperienced DIY or contractor repointed the walls with a Portland cement type mortar sometimes in the past. This mix is very strong, that is the problem it is too strong. Fieldstone foundations move because of seasonal changes. This type of mortar is actually too rigid. It is best to use a hand mixed lime mortar that adheres to the fieldstone better.
- Lime mortar repointing should not be done during periods of heavy rain or in the case of the exterior, freezing weather.
- Move all items away from walls at least 3 feet. Cover items with plastic.
- Safety precautions should be taken to ensure a safe work area. It is important for workers to wear protective safety glasses and gloves.
Cleaning Out Joints
In order to do a good sound repointing job it is vital that the loose mortar be removed and if at some time in the past Portland cement mortar was used a hammer and chisel may be necessary to clean this off the wall to get down to the original lime mortar.
A foundation repair from Ram Jack New England would be happy to answer any question you have about chimney repair or retaining wall repair.
DO NOT use power tools like hammer drills to remove the mortar joints as you might disturb the pinnings (small stones used to lock in the larger stones). We do not use power tools in removing the old mortar. We prefer to do this work by hand, so as not to damage your foundation wall. We make sure these pinning stones are wedged in with a gentle but firm tap with the wooden handle of a hammer.
- Using various sizes of thin metal tools a worker can rake out the decayed mortar. Many times it is advantageous to wash out these joints with a fine stream of water.
- It is important to make sure all roots and vegetation are removed from between the joints.
- It is a good practice to take pictures of all sections of the walls prior to repointing.
This is the process of pushing new mortar back into the joints. Using various metal tools this mortar will be tamped into the joints. This first coat or tamping coat should be batched by mixing the following – 7 parts sand, 1 part lime, 1 part cement.
Final Pointing Mortar
This mortar should be batched by mixing the following 6 parts sand, 1 part lime, and ¾ part cement. This mortar should be used to fill the finish pointing. Carry should be made to clean the stone of any excessive mortar.
The work area should be broom cleaned, then remove the plastic from items and make sure to leave the work area clean. A clean job is a great job.
It is all about having the right tools and understanding the right lime mortar mixes needed for the fieldstone wall being repointed. The pricing to repoint a fieldstone foundation is usually based on the size of the stones and how many joints in a square foot. An average fieldstone foundation can usually be completed in 1-2 days.
To learn more about our repointing services, call Ram Jack New England today!