How to Increase Chimney Draft

Having been in the chimney business for so long, I have come to realize how widespread the issue of poor draft is all across the country. Poor chimney draft can be extremely frustrating, especially when you light a fire in the fireplace and you get smoke pouring into your living room. There are many steps you can take to fix such a problem, but understanding the cause of a chimney draft problem is the key.

The root of your chimney draft problem may be one of many. To start with, you may be lighting a fire that is too hot and expecting it  to vent up a flue that is too cold. If this is the case then fixing the problem can be quite easy. Prior to lighting your fire burn newspaper, holding it up in the flue system to allow the flue to warm up. Do  cautiously of course and wear protective eyewear and gloves.

Another common problem lies in the chimney height. If the chimney is not tall enough to create a good draft then problems can arise. A chimney must be a certain height in proportion to the size of the firebox in order for optimum draw to occur. The width times the height of the firebox cannot exceed ten times the flue opening. These dimensions should be two to three times the depth of the fireplace and the width of the back of the firebox and the firebox’s depth should be equal. If your dimensions do not reflect these recommended dimensions you may want to consider purchasing a Smoke Guard, a metal strip that you attach to the front of the firebox to change it’s dimensions. A way to test to see if a Smoke Guard will resolve your issue is to tape aluminum foil to the top boo make the firebox smaller.

If you or a professional determine that the height of your chimney is not sufficient to create proper draft and resizing the firebox using a Smoke Guard does not help you may have to make the investment of adding few courses of brick to the chimney. This is an expensive endeavor compared to the other options. Your existing chimney crown will have to be removed, courses of brick added, and the crown replaced. If you are committed to resolving your draft problem this solution is what you may have to resort to.

Consulting with a professional before making any expensive repairs to your fireplace will prevent you from wasting money as well as ensuring that whichever step you choose to try to stop your draft problem is the most appropriate for your situation. Remember that tall trees very near the chimney or other tall structures near the  top of the chimney may affect the draft. Take all factors into account before making any decisions and follow any and all building and fire codes in your area.

This smoke guard can help resize an improperly sized firebox and improve a draft problem.
This smoke guard can help resize an improperly sized firebox and improve a draft problem.
Clay Lamb
Latest posts by Clay Lamb (see all)

4 thoughts on “How to Increase Chimney Draft

  1. Hello, Our chimney is 27″ wide by 25″ high by 23″ deep. The chimney is in a relatively new home ( 4 years ).
    We have a special air system installed by the builder. There is a vent under the grate that we keep open when operating the fire. The fireplace working really, really well and we use it a lot. If we could make one wish, it would be to make the opening to the fireplace bigger. All of what I am reading is that “if” this is even possible, it would be a big job and quite expensive. We are just about to reface the fireplace and wanted a firm answer from an expert on whether such a change is recommend and safe, and also the cost involved.

    Thank you

  2. Because all of our homes are so darn airtight, this could be a complex (re)-design situation.
    There are many factors that can effect the “draft as well as the air balancing in our homes today.
    Design factors must be taken into consideration for the fireplace to draft properly.
    The height and shape of the flue tiles will all draft differently (round, rectangle or square). Location of the fireplace (on an outside wall or in the center of the room),ceiling height and the shape of the room that your fireplace is located in. Location of HVAC supply and return vent can be crucial. Also the location of staircase(s) as well as whole house attic fans
    Proposed changes to the fireplace opening open must be able pass your local building codes in your araea. Concern of “other fireplaces” located in the your home and how they might function after the modifications have been made. That “special air supply” that you mentioned that is located under the grate may need to be evaluated.
    There are way to-many variables for me to give you a firm answer or estimate of cost here online.
    The original home builder may provide insights as well as your HVAC contractor may shed light on this project. I would also consider speaking with a designer/architects as well.
    You may find a reputable Chimney contractors that may be interested in your project in your area, by using this link to the National Chimney Sweep Guild locator:
    It is very important to go online and read their customer reviews from Google, BBB and AngiesList.
    Personally, I love taking on projects like this and I have successfully completed many of these projects, but I and have walked away from just as many, as well.
    Yes “it would be a big job and quite expensive” but I’ll bet this a is very do-able.
    Please send me some pictures (when) this project comes about.
    Here are two fireplace projects from our (Ask The Chimney Sweep video) library.
    * See Through Fireplace 7 of 7 Final

    * Fireplace Resurfacing

  3. Hello. My Wife and I purchased a home recently and love fires. However our fireplace seems to have a relatively small floo opening. (A small round Floo opening). And the problem we are having is smoke leaking out the sides on top. It looks like we have a liver that is not sealed. (The liner peices move freely, the back peice and the 2 side peices). I was wondering why the smoke escapes on the side of my fireplace. I can adjust the fire and get the smoke to stop rolling out on the top side. But I feel there is a better solution somewhere. Any help is appreciated. Thank you.

  4. Not being able to see this I think you have serious fire hazard that should be addressed before you continue burning your fireplace. Smoke should not be coming out what they call the breast wall of the chimney. This may be a major repair or a minor repair. I would recommend having a chimney inspection completed by a member of the NCSG. A level-2 inspection would be a full observation of your chimney that would suggest what repairs you should probably get. Just so understand the chimney and fireplace, where we put the wood is called the firebox. A damper is mechanism used to open the smoke chamber which is an upside funnel made of masonry material. In most cases, you would have a flue liner attached at the top of the upside down funnel venting out of the top of the chimney. A good service provider should be able to resolve this for you. Visit to find a certified chimney sweep in your area. Burn safe and warm, Clay.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.