# Can caulk be used on the fireplace surround with a woodstove insert?



## breathebeast (Oct 28, 2010)

Sorry if I missed this somewhere, but I just did the tile job on our fireplace surround before the woodstove insert gets delivered next week.  And there's definitely a gap at the top, between the top tiles and the mantel - not huge, maybe 3/16", but it'd be nice to fill it.  Sounds like I'd be better off using caulk than grout (more give for a mantel moving separate from the chimney?), but it sounds like inserts can get the local brick pretty hot - do y'all think heat-resistant caulk be stable there?

now off to try to find the stuff about putting in inserts for better efficiency....wondering if our old, broken-baffled, Nashua wood furnace (provided forced hot air to the upstairs, local heat to the garage and it's pipes) would be more efficient after all....


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## breathebeast (Oct 28, 2010)

Ah, yeah, the blocker plate, once I finally figured out its function, makes a lot of sense.  Especially since we not only have a chimney on an outside wall, but protruding into the outside, and on the north side of the house!    I'll have to call the installers tomorrow and see if they know what I'm talking about and how we can make one happen.  Too bad I tiled the surround for the insert (not quite fully to the edges of the original brick surround, since the panels would extend so far to the sides), 'cause I like the idea of leaving the panels off.  (Hey wait, I think I could do some clever tile edging potentially and make that idea work...but it'd definitely not be as sharp looking as it would've been if I'd seen this earlier, did some rough edges...)  

Now to go soothe DH...not sure he can handle another project going on so soon after the dramas of this one..!


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## breathebeast (Oct 28, 2010)

Oh, and if I'm reading right, it sounds like certain silicone caulks can be used INSIDE the fireplace, so they'd probably be fine on the fireplace surround.  Am I following okay?

Man, I am SO going to blame this site for my sleepy head tomorrow!  (thanks for the fascinating stuff!)


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## oconnor (Oct 28, 2010)

In the end, it all depends.  Given the amount of caulk you would be using, and it's likely distance from the stove itself, it shouldn't be a problem.  If it was, then the mantel would really be too close.  As long as the mantal is outside the clearance to combustibles, then you should be ok.


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## begreen (Oct 28, 2010)

Should be ok if it is just under the mantel. Check to see if the grout company has matching caulk. They often do. Use silicone for the blocking plate.


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## breathebeast (Oct 29, 2010)

I'm so off-topic here, but talked to my woodstove installers today about putting in a blocking plate.  The guy essentially said it wasn't possible to get a good fit and that just putting some insulation in there would do the job better.  From reading previous posts, it does sound like this is common practice.  However, it also sounds like at least one person could tell that their stove heated the house better with a blocking plate, and I'm guessing that several others could, too, since there is so much interest in them.  In other words, it sounds like there is at least a group of people who have tried the blocking plate (low) and been impressed with the results, though that wasn't said directly.  

ANYWAY, my basic question is, could I put the blocking plate on while the installers are here?  It doesn't sound like it would be too hard, but does the furnace cement need to be left for a while before the stove is attached?  Or ditto with the silicon application?  I'm guessing I could ask if they would split up the installation if needed.  

And thanks for setting me straight on the caulk thing.  Someone posted about how hot it got around their insert and it got me worried, but it makes sense that the clearances should hold.  I'll post when the whole deal is done, the hearth looks SO much better than it used to!  I'm pretty darn proud of it....


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## begreen (Oct 29, 2010)

Many installers want to get in an out as quickly as possible, so they avoid the complications of a proper block off plate. The blockoff plate could be cut, fitted and ready to install before the installers arrive. Then it is a quick matter of shooting some silicone on the back of the mounting flange, popping it in place and attaching it with tapcons. Put it in while they are on their lunch break.


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## flyingpig (Oct 29, 2010)

I remember my installer use some kind of black caulk  to seal the damper block plate and the connection between liner and insert. But I'm not sure about brand or type.

Cheers....Som


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## breathebeast (Nov 1, 2010)

i haven't found local furnace cement yet, but did find a fiberglass gasket kit that includes "cement" that is labeled as withstanding 1000 degrees.  Is that sufficient?

Also, is any silicone caulk okay to use?  The one I have right now is labeled for use up to 400 degrees.


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