Insulating pantry/utility room against house.
dfvellone
| Posted in General Questions on
I included in my new construction a utility room/pantry (12’×14) on the ne corner of the house. Exterior walls are at r40, heavily insulated slab on grade foundation, and second floor above. I’d like to insulate the two interior walls enough so I can keep the space cool in the winter, but not so much that I’d risk isolating the space making it susceptible to freezing and forcing me to keep the door open. I have access to reclaimed polyiso in all thicknesses. Any thoughts on how much insulation would be a good compromise. My zip code is 13420.
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Replies
This is actually a fairly complex question with a lot of unknowns. Your pantry temperature will be something of a median between the outdoor temperature and the indoor temperature, but it will be a complex relationship based on how much heat “leaks” into the pantry through the insulated interior walls vs how much “leaks” out through the exterior walls. And since the are of all the walls/ceilings/floors between conditioned space and the pantry is probably not the same as the are of all walls/ceilings/floors between the pantry and the outdoors, that relationship also plays a part.
Since you’re just going to have “something colder than the main house” in the pantry, I’d just use whatever size batts fit in the interior walls and leave it at that. If you have stranded 2x4 framed interior walls, that probably means R15 batts is the best you can fit. I wouldn’t try to do anything fancier than this myself, although more insulation would result in a cooler room, in this case.
Trying to calculate exactly what the temperature would be is probably not very practical, certainly not with the information you’ve provided (a lot more info is needed).
If it does get too cold on occasion, you could just leave the door to the pantry open, but my guess is that won’t be an issue.
Bill
Perhaps you could install some adjustable louvers in the door (perhaps top and bottom to allow for convection) so you could tune the rate of heat leakage.
Daniel,
Several mathematical approaches (with examples) to solving this problem are provided in my blog, "Using a Bath Fan to Equalize Room Temperatures."
Are you looking at temperatures suitable for long term storage of vegetables? You might want to look at a means of ventilating from outside.
No, I have a root cellar for vegetables. Just trying to plan an amount of insulation that will be enough to prevent too much heat from the main space from warming it, but not so much that temps might approach the freezing point. It's a walk-in pantry and utility type second kitchen for butchering.