Can a double wall direct vent intake/exhaust pipe run through a hole in the roof SIP? Does the pipe need to have a space separating it from the combustible, not directly in contact with the SIP? Thanks

This should be addressed by code, but you're likely going to have to separate the pipe from the SIP just as you would with regular framing.

Posted By EdW on 14 Aug 2016 04:42 PM
Can a double wall direct vent intake/exhaust pipe run through a hole in the roof SIP? Does the pipe need to have a space separating it from the combustible, not directly in contact with the SIP? Thanks

If the SIP core is EPS, then I would be VERY cautious and check code/manufacturer on that. EPS melts at 200F and a fireplace flue will easily get over that temperature.

It can/has been done but just follow the manufacturers recommendations to keep the metal flue insulated/far enough away from the EPS core.

We built a steel SIP house for a customer in North Florida. They wanted a fireplace. We hired a fireplace company who installed a natural gas fireplace. It is vented out of the 4" SIP wall using the manufacturer requirements. I would recommend a fireplace expert to properly answer this question based on the building material that you are using.

Thanks for the feedback. I'll due further research per the above recommendations.

Main thing is to always keep heat/flames away from exposed EPS. When the EPS is protected by drywall it is reasonably safe but it's when exposed EPS is near heat/flame above 200F, that is when EPS will begin to melt and fail.

I would use Roxul Insulation around any flue heat source since its 2,000F + rated, not 200F like EPS


EPS FIRE SAFETY

EPS FIRE TESTING

If this is a concentrically vented direct vent unit, I would propose that the temperature of the outer wall stands a very good chance that it is below 212F, the softening temp of EPS. This for the main reason that your stack is at one end of the flue where the incoming air is the coldest and the exhaust has also lost much of its temperature. The longer the run, the more significant that cooling will be.

That said, unless it's using a PVC vent system, I would still provide some small distance as specified by the manufacturer for combustible surfaces. To my knowledge, code doesn't specify more than relying on the manufacturer's specs which will have passed various jurisdictional bodies in their approval on the equipment.

And yes Roxul is something that can be used for fire rating, but I have a problem that it passes a considerable amount of air if you are trying to tighten up your house

More good info. Thanks.

Well, Roxul or not, there will be something like a stainless or galvanized collar where it passes through the roof.

Jelly:
Can you further describe the collar. Is it separate from the pipe? How large of a hole needs to be in the roof panel (relative to the size of the vent pipe)?

EdW, those details are going to be specified by the residential code to which you have to adhere. Do an image search of "direct vent firestop" to get an idea of what it will look like. Duravent and Duratech are common manufacturers.

The same flue clearance specs that apply to wood framing apply to SIPS