# How to repair gaps around firebox



## Rndy_918 (Oct 24, 2015)

We've inheirated my grandmother-In-Laws house and I want to use propane gas logs in fireplace.  There is about a 2" gap on both sides and top between the firebox and the bricks on the front.  Cold air blows in every winter.  I'm going to shoot Dap polyurethane fire block foam sealant in first.  Then I plan on inserting firebricks within an inch of the edge of the firebox.  Then finish the edge, bring it flush with the box with firebox mortor.  Is there any suggestions or comments that anyone has?  I want it sealed and insulated good to prevent cold air in an to prevent heat loss up the back side of the walls.


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## Grisu (Oct 24, 2015)

That could be a prefab zero clearance fireplace and then the gaps are there to cool the firebox and keep the fire from igniting any close combustibles behind it. I would certainly hold off on your modifications until you have determined whether it is safe to do. Can you post some pics? What kind of chimney do you have; masonry with clay liner or steel pipe? It would also not hurt to consult a professional before; the chimney may need a cleaning anyway before you start burning in the fireplace. You can search here: http://www.csia.org/search or http://nficertified.org/pages_consumers/consumers-1.cfm


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## Rndy_918 (Oct 24, 2015)

The fireplace was added to the end of the house after it was built.  It just has brick on the 3 outer sides of the fireplace.  I know that at one time, the cracks were sealed in with mortar, because there's still pieces here and there.
      As for the stack, it has a masonry type, but I'm planning on using ventless, so my damper will be closed reguardless.


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## begreen (Oct 24, 2015)

Why use ventless when there is a flue?


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## Rndy_918 (Oct 24, 2015)

Well, I debated but after talking with several reps and techs from different local companies and weighing pros and cons, the ventless seemed like the best fit for what we're wanting.


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## Rndy_918 (Oct 24, 2015)

Plus, the flue needs repaired I'm sure, as it wasn't maintained good. Cost for that as well as an insert for a vented unit is more than we want to pay, and with the vented, we'll get the better heat that we want.


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## bholler (Oct 24, 2015)

Rndy_918 said:


> we'll get the better heat that we want.


Do you mean you will get better heat with ventless?  

I think we need some pics to advise you better not entirly sure what you are referring to yet.  But i will tell you that ventless units are not ventless they vent all of the products of combustion into your house.  Most also are not meant to be real heaters either I would look allot harder at vented units


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## Rndy_918 (Oct 24, 2015)

Yes, I meant ventless..dang spellcheck. I have it closed off, but planned on opening it up today and applying the fireblock foam, so I'll get pictures and post.


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## bholler (Oct 24, 2015)

Rndy_918 said:


> Yes, I meant ventless..dang spellcheck. I have it closed off, but planned on opening it up today and applying the fireblock foam, so I'll get pictures and post.


Do not use fireblock foam it is extremely flammable and even with a ventless unit is would be very dangerous.   And are you talking about gas logs of an actual insert?


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## bholler (Oct 24, 2015)

Post pics before you do anything if it is a zero clearance unit which it sounds like you absolutely cannot block those vents they are needed to use that firebox in any way at all.


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## bholler (Oct 24, 2015)

Rndy_918 said:


> but planned on opening it up today and applying the fireblock foam


Again do not use foam it will make the fire place unusable


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## Rndy_918 (Oct 24, 2015)

I'll be using the fire block foam, deep inside the crack, where flames won't be close to it.  Then I will have firebrick embedded in refractory cement. The firebox is steel.  The foam is basically being sprayed deep inside cracks to stop drafts. I call them cracks, but they're actually spaces on each side of the firebox, where it buts up to the rock wall on the inside wall.  They had mortar originally but it fell out.  I just want to remotor the seams, but want that added I insulation to prevent heat loss inside the walls,  I will send you pictures though.


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## bholler (Oct 24, 2015)

Rndy_918 said:


> I'll be using the fire block foam, deep inside the crack, where flames won't be close to it. Then I will have firebrick embedded in refractory cement. The firebox is steel. The foam is basically being sprayed deep inside cracks to stop drafts. I call them cracks, but they're actually spaces on each side of the firebox, where it buts up to the rock wall on the inside wall. They had mortar originally but it fell out. I just want to remotor the seams, but want that added I insulation to prevent heat loss inside the walls, I will send you pictures though.


yes you are proposing putting a highly flammable material in an area that needs to be completely non combustible.  DO NOT DO IT it is a very very bad idea!


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