Dedicated Room for Penetrations?
Hello,
I am designing a single-level, 1000 square foot PGH in coastal Maine, zone 6. Its a 3/12 chicken shack on a concrete free slab with foot wide walls, dense pack cellulose all the way around, and mostly open floor plan (except for the bathroom and utility room). I have several non-traditional systems; including a composting toilet, grey water pump, water catchment off of the roof and storing water in a 500 gallon tank in the utility room.
Here are my penetrations: ERV, composting toilet vent, grey water pump vent, water tank catchment inflow, radon vent. I may also need a stack for my pressure tank, not sure. I am planning on putting everything in the conditioned utility room, and air sealing, vapor sealing and insulating (for sound) so that the overall living space is not negatively affected by the sieve like nature of the utility room. I will probably install an exterior door on it as well. There will be a small electric heater.
Is this a sound strategy? Is there anything else to do about this?
Thanks, Stephen
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
One trick I saw on a Matt Risinger Youtube video was to make sure that you follow the "one hole, one wire or pipe" rule. Don't run a bunch or wires or pipes through a larger hole in the exterior wall because it's a lot harder to insulate around them.
Also, another trick is to run a piece of PVC pipe that is a bit larger than the wire or pipe through the wall, air seal around the PVC pipe, run the wire or HVAC pipe through the PVC pipe and spray foam the interior of the PVC pipe. This way, if you ever have to replace the wire or pipe in the future you can pull it out of the PVC pipe but the PVC pipe is still in place and sealed to the wall.
Lastly, you kind of limit yourself with regards to roofing materials with a 3:12 pitch roof. A lot of shingle manufacturers (and esp metal roofing manufacturers) prefer a minimum 4:12 roof pitch.
You may have to install an air grill between the main living space and the utility room in order to reduce pressure imbalances between the two spaces. Also, is your tub/shower on an exterior wall? If so, you might consider finishing the exterior walls in the bathroom with drywall (air sealing them to the framing) and build a second interior wall against the exterior walls in order to run plumbing or vent pipes. This keeps all plumbing pipes out of the exterior wall.
Thanks Rockies. Those are great tips for air sealing the penetrations. I am doing a vented 3/12 sarking membrane roof assembly with metal, possibly standing seam but maybe corrugated metal. I am not concerned about the pitch, although i realize I am at the limit for a vented roof assembly and the pitch limit for safely using a metal roof. There will be taped zip sheathing over sleepers and pro clima mento WRB underneath the sleepers so I feel like I have some insurance. Also, the penetrations will be at the lowest point of the roof.
I have a double stud wall assembly with drywall and possibly membrain with all plumbing (there's not much of it and the runs are short) either in the interior wall studs or inboard of everything.
Regarding the grill suggestion and the pressure imbalance...this was kind of where my question was pointing at. I am not sure if sealing the utility room off and making it air tight from the rest of the interior space is a good idea.