Hello all, I am new to the forum after reading a lot about everyone's projects in the past week. My wife and I are planning to do some serious updating to our ugly white 1970's colonial and wanted to get some opinions on the best ways to do so. After living through our first winter in our house, I am noticing some drafts and what sounds like air infiltration in the walls when a large gust hits the house. For the most part, I have sealed everything I can (outlets and switches) but I highly doubt there is any insulation under the floorboards on the second floor. For example, in our newborn son's room, you can feel a draft and coldness around the exterior walls. The house is mainly aluminum siding with one portion of it being ugly white stained brick. My thinking is to side over all of the brick when we replace the existing siding and wrap the house if possible (maybe add foam as well?) to cut down on the drafts. Does this make sense to do so? I know that stopping air leaks is the biggest way to cut down on that drafty feeling but besides ripping out all of the carpet and foaming around the studs, I am not sure what to do. I thought about getting spray foam into the exterior walls but I heard the foam eventually shrinks and is not airtight. Does anyone have some tips for me? I really want to know what you recommend to increase efficiency if you were to remove all of the current siding from the house and also add siding to the bricked portion. Hopefully the attached picture allows you to see what I am talking about. Thanks in advance!

It might be a good idea to get an energy audit by an independent auditor who can measure leakage rate in the house and examine the insulation levels, and give you a comparison to current recommended insulation levels. This should be an independent auditor who is not trying to sell you any services beyond the audit. In many places, the utiltiy will subsidize the cost, so net cost to you might be $100 to $150 or so.

I would not expect insulation under the floorboards on the second floor. Rather, you would like to have the outside of the house sealed and insulated. If you replace the siding, that would be an excellent time to add rigid foam insulation, poly isocyanurate, XPS, or EPS outside the sheathing. Poly iso is about R-6 per inch, XPS about R-5 per inch, and EPS about R-4 per inch. However, as Dana1 points out, the XPS made in the US uses a blowing agent that is much worse than CO2 for global warming potential, so polyiso or EPS is preferred from that point of view. If you could wrap the house with 2" or so of rigid foam and tape the seams, that would add about R-10 to the wall insulation, and cover over thermal bridging by the studs. It should also cut down on air infiltration. You could also use two layers of 1" foam with offset seams, but at increased labor costs, and that should cut down on air infiltration even more.

If you can get to the rim joist, which is easy if you have an unfinished basement or crawl space, it would be good to see if it can be sealed up with spray foam, probably professionally, with some added rigid foam cut to fit, in order to finish the insulation job. The energy audit will help identify if there is leakage at the rim joist.

Adding insulation in the ceiling is usually pretty easy if the insulation level is less than the IECC 2012 recommendations for your area. Cellulose is more effective than fiberglass in reducing the air infiltration.

An energy audit is definitely the way to start. Expect to pay up to $600 for a thorough report if your utility does not have a program. One caution - some utilities have agreements with contractors who do the audit for a minimal amount, then recommend solutions. You are much better off if, after the audit, you talk to several contractors about the report and potential work they propose doing. Typically around here they look for relativelty simple projects like air sealing and adding insulation to the attic, all of which will likely be helpful.
If anyone recommends adding insulation to the attic, make certain they are removing (or moving) the existing insulation and "air sealing" the ceiling below. Insulation does very little if there is air moving through it - a common scenario in most houses - so a coat of spray foam on the top of the drywall helps a lot.

On the walls, if you remove the siding, you'll need to air seal the existing wall first, by spray foaming holes and adding a layer of Tyvek or similar. (Remember to tape the seams and the top and the bottom - this layer must be air tight!) Also a good time to cut a hole & check your existing wall insulation. Then add 2" or more of polyiso (the foil faced yellowish crumbly foam), then strapping then your siding.