Thread: Gas Fireplace Vent Hood - options when building deck over top

Hello,

I am in the process of building a new deck on my house but I have a Nat Gas Fireplace Vent cover located in an area that the deck will be going over. Do I have any options to add an extension to the vent and run it under my deck and vent it out the side of the deck.

Can I build a box under the deck floor joists and run a chimney out the side of the deck or how do I deal with this vent.

The fireplace is located in the basement below grade and it vents up and out of the house threw the floor joist in the basement.

Any suggestions on how to deal with this vent would be appreciated

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I think when you say "vent hood" you mean the horizontal termination cap. Let me know if I am incorrect.

Yes, you may extend the venting if you keep within the venting and termination parameters of the fireplace installation manual. Some things to look for:

1. Maximum horizontal run. Most direct vent fireplaces allow up to fifteen feet of horizontal run with some vertical rise. Check the venting diagram in the manual to be sure.

3. Clearance from the vent pipe to combustible materials. Some fireplaces only require one inch clearance in all direction, but some require 3" from the top.

4. Required rise in venting. Some, but not all, require a 1/4" rise per foot of run.

5. Clearances from the termination cap. Other than clearance to combustibles, most terminations require clearance to inside and outside corners, soffits, operable windows, etc.

Originally Posted by Tom Parks

I think when you say "vent hood" you mean the horizontal termination cap. Let me know if I am incorrect.

Yes, you may extend the venting if you keep within the venting and termination parameters of the fireplace installation manual. Some things to look for:

1. Maximum horizontal run. Most direct vent fireplaces allow up to fifteen feet of horizontal run with some vertical rise. Check the venting diagram in the manual to be sure.

3. Clearance from the vent pipe to combustible materials. Some fireplaces only require one inch clearance in all direction, but some require 3" from the top.

4. Required rise in venting. Some, but not all, require a 1/4" rise per foot of run.

5. Clearances from the termination cap. Other than clearance to combustibles, most terminations require clearance to inside and outside corners, soffits, operable windows, etc.

I have a picture but can't upload. Yes I believe we are talking about the same thing essentially it looks like a stainless steel chimney about 15" inches in diameter that stick out about 10" inches from the house and says "HOT" on it.

It is in a location where I would like to build a new deck right over top. Actually it is at the same level as where I am going to have to put the face plate that needs to be bolted to the foundation to hang the joist for the deck.

Can I take off this cover, connect a fire rated chimney and run it about 15 ft under neath the deck floor joists to vent off the side of the new deck?


Thanks for the help

When in doubt,check with the manufacturer.

Originally Posted by Harry Janssen

When in doubt,check with the manufacturer.

Te manufacture says 3"clearance from any structure. What I need to know is if I need to vent this out the side of the new deck or just leave as is venting under the deck. Is there code for this or best practice. My logic is telling me to extend and vent out side of deck I am not sure what the best way to do this is or what material to use.

This sounds like a gas direct vent fireplace. As always, refer to the mfrs. listed instructions. You can use only the venting listed in that manual and only within the venting charts therein. Now, some mfrs. have some units approved for power venting so that may be an option. Regardless, this is NOT a DIY project and you'll need to hire a pro to advise you about your specific unit, get the approved parts and do the job.

Originally Posted by Kevin Sachvie

Can I take off this cover, connect a fire rated chimney and run it about 15 ft under neath the deck floor joists to vent off the side of the new deck?

Don't do this. This is most likely a direct vent gas unit, which is a balanced system. What this means is it isn't just a vent, it's also an air intake. Get a professional to do this. There's too many "what if" situations that could lead to a fire if this is not done properly, if it can even be done at all.

Originally Posted by lou curley

Don't do this. This is most likely a direct vent gas unit, which is a balanced system. What this means is it isn't just a vent, it's also an air intake. Get a professional to do this. There's too many "what if" situations that could lead to a fire if this is not done properly, if it can even be done at all.

I wasn't planning on doing this myself, I am planning stage of the deck build and am just trying to figure out my options. My big question, is can it be done, can I just leave it and build over top, what is the best thing to do. I was hoping someone on here might have seen this before and could offer a solution so I know it is manageable prior to calling a professional out.

What I have seen is the deck stops well clear of the fireplace vent and a railing goes around the hole, so it is a well with a direct vent in it. With plenty of air circulating around it, you can leave the vent where it is.

Originally Posted by John Kogel

What I have seen is the deck stops well clear of the fireplace vent and a railing goes around the hole, so it is a well with a direct vent in it. With plenty of air circulating around it, you can leave the vent where it is.

So no building right over top and then venting or just leaving?

I can't be the only one with this situation?

Originally Posted by Kevin Sachvie

So no building right over top and then venting or just leaving?

I can't be the only one with this situation?

I give up--what do the listed instructions say?