For smaller jobs pre mix mortar is available that is used right from the container.
What type of mortar for chimney crown.
Many bricklayers build chimney crowns the wrong way.
The different types of mortar.
For very severe weather applications consider a type s mortar mix made from 1 part cement 1 2 part lime and 4 to 4 1 2 parts sand.
The basic mortar ingredients remain the same.
In almost every cases i ve seen no overhang no reinforcing steel in the top and no flashing under the crown.
While the mortar rests prep the area by clearing away any loose debris.
The most common type is called masons mortar which is used for building chimneys and repairing them.
For very severe weather applications consider a type s mortar mix made from 1 part cement 1 2 part lime and 4 to 4 1 2 parts sand.
The nps describes type n mortar as a mixture of 1 part cement 1 part lime and 5 to 6 parts sand.
A mortar cap or chimney crown that has been improperly constructed or one that has become deteriorated over time may be the cause of water leaking into your attic through cracks or broken mortar in the crown when this happens it is sometimes better to replace the crown than attempting to repair it.
It s very rare when you come across a chimney crown built the right way.
Mortar however is not the best material to make a chimney crown with because mortar crowns will often crack due to shrinkage enabling water to penetrate the chimney beneath.
The first tip to remember when mixing chimney mortar is the four different types of mortar that are commonly used in building projects.
Portland cement to bond water to turn it into a paste sand and hydrated lime.
The nps describes type n mortar as a mixture of 1 part cement 1 part lime and 5 to 6 parts sand.
It is a layer of mortar hopefully pitched properly 3 slope for every 12 of a flat surface applied over the top course of bricks.
National parks service also recommends type n mortar for the majority of chimney applications.
I show you all the steps i used chipping out the old crown cutting plywood if you are worried about moisture use 1 2 hardie bac.
When applying the mortar to the crown form the mortar into an apex with the peak at the middle of the crown sloping down toward the edges.
I ve seen hundreds of chimney tops that are just made from the same mortar used to lay the brick or stone.
Diy chimney crown repair.
Characteristics of an effective chimney crown.
The idea is to have the water drain away from the crown image 1.
These types are type o type s type m and type n.
Think of it like a roof.
National parks service also recommends type n mortar for the majority of chimney applications.
