Floor support under wood stove

[CREATIVE1]

What would you suggest under a woodstove like a Vermont Castings Defiant?  I want to make the floor level (not have a raised pad).  Under current code, do I need cement walls, double joists (they would at least need to be notched to sink the base)--or what?

[peternap]

I just added 4- 4X4 piers under my stove and used a section of granite instead of sub floor. It is raised about 3/4" though.

[Redoverfarm]

I am not that familar with Vermont castings and their products. Do you have any idea what the weight on that particular model is.  I doubt it is any greater than my Hearth Stone @ 550#.  I would say that a double joist under that particular location would be more than enough to hold the stove. Depending on where the joist is located in relation to the location of the stove you might have to go with 3 joist being doubled for the weight distribution.  As far as the hearth you would really be comprimizing the joist to recess it. As Peternap pointed out you could substitute the subfloor in that location for a fire proof material but that might create a weak system of the complete floor whereas it would not tie into the rest of the floor and surrounding joist to give a unified strength.  There are natural stone products available with very little thickness 5/8 -1".  As far as that goes there would not be anything wrong with tiling the area with slate. 

[glenn kangiser]

I agree, John -- weight shows 480 lbs.

[CREATIVE1]

I looked up that model, and it's 510 pounds.

[MountainDon]

The Defiant is the largest wood burning stove VC makes. It's 480 or 490 Lbs of cast iron (catalytic or non-catalytic) according to the VC owners manuals I looked at. 

I would not notch out the joists to allow the hearth to be flush to the other floor surface. That would weaken the joists, even though a notch on the upper (compression) side would not be quite as bad as a notch underneath (tension).

How thick is the desired hearth material compared to the rest of the floor? If you want to have the hearth material around the stove flush with the other flooring it would be better to adjust the joist heights under the stove area downwards, although that would complicate the construction. If the joists can't be lowered easily consider using a smaller joist in that area and more of them. Perhaps doubled joists, one size smaller would do the job? I can't say for sure off hand. That way all you'd have to do is build up the other part of the floor on those joists to make everything at the same level. Hopefully the thickness of your selected hearth material allows that to be worked out with minimal fuss

To satisfy my curiosity are you electing the catalytic or the non-catalytic model?

[Willy]

On my wood stove which sits next to a outside wall I put a 4X6 header beam under 3 joists that goes under it. I figured that over time the extra weight may cause the floor to settle some. I just placed the beam right under the joists and used 2- 4X4s shimed tight on top of peir blocks. The ground under my house was packed as hard as a rock before the floor was put on. No settling in 12 years so far. Wood stove 24 ft stack fire wood ect must weigh at least 600 lbs. I put the beam in before the stove so it made the 4X4s even tighter on the peirs. Mark

[CREATIVE1]

The Defiant is the largest wood burning stove VC makes. It's 480 or 490 Lbs of cast iron (catalytic or non-catalytic) according to the VC owners manuals I looked at. 

I would not notch out the joists to allow the hearth to be flush to the other floor surface. That would weaken the joists, even though a notch on the upper (compression) side would not be quite as bad as a notch underneath (tension).

How thick is the desired hearth material compared to the rest of the floor? If you want to have the hearth material around the stove flush with the other flooring it would be better to adjust the joist heights under the stove area downwards, although that would complicate the construction. If the joists can't be lowered easily consider using a smaller joist in that area and more of them. Perhaps doubled joists, one size smaller would do the job? I can't say for sure off hand. That way all you'd have to do is build up the other part of the floor on those joists to make everything at the same level. Hopefully the thickness of your selected hearth material allows that to be worked out with minimal fuss

To satisfy my curiosity are you electing the catalytic or the non-catalytic model?

I don't know all the details yet.  I guess the minimum fireproof underlayment is 1/2 inch?  I think I could box out the area and laminate the joists, maybe double them with plywood in between.  The only reason I'm trying to make this level with the floor (which will probably be flagstone) is for the "trip" factor, as it's in the traffic lane.  Look at Victoria---Lake Cushman in the Owner/Builder forum for the plans.

Don't know if I'm going catalytic.  I've just noticed that slightly used Defiants are for sale at 60 -70% off, and also that they are one of the heavier stoves, so if I build the floor for that weight I should be fine.  Obviously any info here would be appreciated. I'm a Florida girl, so I don't know nuthin' about wood heat.

[glenn kangiser]

There is nothing as good as wood heat, Creative.  It's the only way to toast buns. 

[Willy]

As I sit here and look at the tile under my wood stove it is lower than the carpet and the oak floor. I put my 3/8" tile right on the plywood floor. With the carpet pad and carpet it is now higher than the tile. The oak flooring is also highter. I had to use a Oak Trim Board to go around the spot to taper down to the tile. You must be going to use some real thick slate under your wood stove for it to stick up. You will probley find unless you use Lanolium it will be a wash in the drop down. Measure your floor coverings first for there thickness. I like the lower area because when a small spark comes out of the stove puting wood in it the raised trim board helps stop them from getting on the carpet. Mark

[MountainDon]

Your mention of used VC Defiants caught my eye. Maybe you've checked this out; if so disregard.

There have been two different Defiant series, pre 1988 and post 1998, with the later having both catalytic and non catalytic models. The older models were discontinued in '88 because they did not meet the EPA regs for post 1988 wood burning stoves.

To complicate matters, Washington state has the most restrictive wood stove regulations, stricter than the EPA. The EPA rules calls for 7.5 Grams per hour or less, whereas Washington state limits the emissions to 4.5 grams per hour (non catalyst) and 2.5 gph for a catalyst stove. I believe WA state also requires outside fresh air hookups. I don't live in WA state so I don't know how these rules are enforced; I simply know WA state is more restrictive.

Personally I would opt for a non catalytic model. I have read about problems associated with catalytic stoves. Not just the Defiant, but in general. A replacement catayst unit costs $100-200 plus installation. Improper firing can kill one.

EPA REGS

WA STATE

Vermont Castings products are listed under CFM

[CREATIVE1]

I had checked out and have a list of all stoves that meet Washington State requirements.  To bad the Orleys from Oregon aren't on the list!
They take 24 inch logs, which means less cutting.  And they're really neat.

I probably will steer clear of a catalytic woodstove.  The more complications, the more chance for an expensive failure.

I'll be careful about Model Numbers if I get a used one.  Mason County is PICKY.