rigid foam insulation on exterior
dccarp
| Posted in Energy, Heating & Insulation on
I’m in the planning stages of a big remodel project on an old home in the upper midwest. The home does not have any inuslation in the walls, hence the 1600 gallons of propane that were used this past winter (!). I plan on pulling the siding and windows, then covering the whole place in rigid foam, including the foundation above grade. If you have done similar, I’d like to here how it went. As far as building paper, I prefer to use felt on most of my projects. Is it even necessary to use building paper? Or would the foam itself act as a secondary drainage plane? Thanks, Dan
Replies
Dan,
Nothing wrong with wanting to insulate walls and replace windows, Remember though, most heat loss is through the roof. Depending on a multitude of factors, air infiltration may or may not play a significant role in the heating cost of your home. Certain areas of WI do get very windy for days (weeks) at a time. If money matters, concentrate on the roof if it's deficient.
Jon
Ah dog gone it , WorkshopJon, I could have sworn, it was always the doors and Windows, not the Roof. I suppose you believe that the heat loss is thru the roof/ ceiling?? Hmmm, hmm, nope, I have to dissagree with that one. Jim J
44,
Sometimes it's easy to forget that this is supposed to be a forum that exchanges useful info about homebuilding and remodeling techniques, and not something strictly logged onto for recreation.
When I saw that the poster lived in the same state as I (similar weather) and burned 1600 gal of propane in the winter, and was contemplating changing his windows, the first thought I had was that all that energy can't be escaping just through the walls and windows. (Unless they are really bad)
You are right in implying I got off the topic of the question and stated the obvious. Everyone knows that on a dollar for dollar basis, extra insulation in a roof often does more to lower heating bills than changing windows and adding insulation to the walls.
Jon.
WorkshopJon, No Harm , no foul, Piffin, I thank you. This Forum, this forum here, the one called Breaktime, I love it. It's just about equal to my bowl of Ice creame, that I treat myself to just before shuteye. Be safe out there Jim J
Before you two guys get into a full blown flame war here, mind if I interject a moderate explanation why you are both right - sort of?
If you are ignoring the opennings, then yes, the ceiling insulation is the far more cost efficient return on your insulation dollar. And since convected heat rises, more heat is lost thru ceilings - all other things being equal.
But
The insulation package is like a chain. It will break at the weakest link. So you can insulate the ceiling to R60 if you want but leave one window open all winter and guess what? The fuel bill will be high.
So the place to start is with all the weak links. Identify them first. If the windows are drafty and single paned, by all means change them. If you lean up against the plaster wall and feel cold radiating off it, get some insulation in or on it.
As to the rain plane, you will need to tape and or foam the joints in the sheets and furr out for a rain screen drain plane to give water somplace to go. If the siding is tight to the foam, the water will "bunch up" and find a way to come in. give it a place to go instead.
Excellence is its own reward!