Rain can bring a lot of damage to various structures of the house. Homeowners may have many things to worry about during heavy rains; one area they may not know about is chimneys. So, does rain go down the chimney?
In the absence of a cowling, rain can trickle down a chimney’s comparatively tiny opening. But nonetheless, every chimney has a bend built into it to stop downdraughts. Any usual rain will be soaked up by the chimney’s interior and stopped by the smoke shelf.
Before we can fully understand how rainwater can go inside chimneys, it’s important to understand how they work and their anatomy. This article covers all of these details. Keep reading below for more information.
How Do Chimneys Function?
The term “draught” describes the upward movement of air and smoke within a chimney. The phenomenon of draught results from the fact that hot gasses have a lower density than cold ones. Because heated gasses in a chimney are lighter than atmospheric air, they are pushed upward into it.
Simply put, more of this hotter, lighter gas means more updraft. So, it stands to reason that a chimney with a greater vertical height would also provide a greater flow. However, more friction in the chimney and the tendency for the gasses to lose heat as they rise tend to cancel out the enhanced airflow inherent to a taller chimney.
It’s probable that a very unclean, shoddily lined, towering chimney with poor insulation and potential air leaks will perform less effectively than a shorter chimney with a good design.
Another physical aspect also impacts the effectiveness of chimneys, but in a less significant way. There is a decrease in pressure as air is pushed across the end of a tube. The draught created by this is comparable to that created by wind blowing over a chimney.
There are strict guidelines that must be followed for a chimney to function properly in order to maintain a high temperature in the flue and decent airflow. For instance, insulating chimneys is crucial since it keeps the smoke warm and reduces the likelihood of condensing as tar deposits.
Because wood burns cooler than coal, this is crucial when using wood-burning appliances.
Does Rain Go Down a Chimney?
Yes, it is possible for rain to go down a chimney. However, it is really difficult for the rain to travel all the way down to the fireplace. This is due to a couple of reasons, all of which we have discussed in this section.
The chimney caps have a slight bend to them. Therefore, it is difficult for the rain to fall at an angle that allows the water to go inside the chimney.
The chimney has a relatively small aperture, which also prevents a lot of rain from going inside, especially considering that rain is often accompanied by winds that keep changing the angle of its fall.
Most of the rain that goes inside the chimney is absorbed by the walls due to the rough and porous masonry, which leaves very little rain to reach the fireplace. After a while, the built-in upward ventilation effect of the chimney that we discussed in the previous section will dry out this rain.
In the event that you had a fire burning in the fireplace, the heat and exhaust fumes would be enough to dry out and evaporate any rain that did manage to get inside the chimney.
Most chimneys have a built-in damper and smoke shelf inside the smoke chamber, which prevents the rain from going further down the fireplace after it has entered the chimney.
Is Rain Bad for Chimneys?
You may be wondering what the big deal is if a little rainwater does manage to get inside the chimney. Well, a chimney could face a multitude of problems due to rain. Rainwater may combine with creosote within your chimney walls if rain is permitted to enter your chimney.
This mixture has the potential to spill into your fireplace, discolor the masonry, and leave an unpleasant smell.
When water is permitted to pool on your stonework, a bigger problem may arise. Your bricks can absorb a lot of water through their minute pores, despite the fact that this may not seem to be the case. Water that has penetrated a brick may pool and gradually damage your masonry from the inside out.
Also, during the winter, water within the brick may freeze and rapidly expand, resulting in the cracking and crumbling of your masonry. This poses a serious safety risk and may affect the airflow through your chimney.
How Can Rain Be Prevented From Falling Down a Chimney?
To keep rain from getting into contact with your chimney, the chimney industry employs a number of methods. In most cases, chimney caps and chase coverings are the first layers of protection against rain.
Before deciding on purchasing one, watch this video to learn how to install a chimney cap:
These items serve as a cover for your chimney’s aperture. A mesh cage is placed on top of a cover in a chimney cap. This keeps the chimney entrance closed while allowing smoke and hot air to exit your chimney.
A chase cover is intended to hide your chimney; however, it features a cutout in the middle where your flue would normally be positioned. In order to stop future rain penetration, a new chimney cap or chase cover should be installed if one is missing or damaged.
The crown of your chimney, which lies on top of it, is often built simultaneously with your chimney. It is made by applying mortar to the top edge of your chimney top to create a waterproof seal.
Rain is more inclined to bounce off the chimney’s edge than its interior since the mortar has been shaped into a steep slope.
It is difficult for rain to enter a chimney and even more difficult for it to go all the way down to the fireplace. However, we recommend that you follow the appropriate precautions to make sure that rain does not get into your chimney.