Retrofit Insulation - Best Approach?

wanttolearn

Not sure if this is a right forum for this, but I am going to give it a try:

I live in a 90 years old house, that has very inconsistent insulation. Some parts are uninsulated, some have old rockwool, other areas have batt or cellulose insulation. whatever is there is not very effective, and we have big problems with draftiness, etc.

i am redoing the siding of our house, and want to use the opportunity to do a total retrofit of the insulation. I have two methods to chose from: (i) used rigid foam insulation to cover the entire exterior of the house before applying the new siding; (ii) or blow cellulose into the wall cavities through the outside sheathing, before applying the new siding.

the rigid foam approach is more pricey, but seems like a safer bet. blowing cellulose into cavities is tricky, because we can be sure to fill the entire cavity, etc.

i would like to hear the opinion of some experienced people on this. which approach is preferable? and why?

does it even make sense to do what i am doing, or are they payoffs going to be very limited, given that the house is already partially insulated?

any help/opinion is greatly appreciated!

SWEI

The best answer here in my book would be wet-sprayed cellulose. It's applied before the sheathing and includes an acrylic binder in the mix, which is then trimmed flush to the studs using a power rake. It will prevent drafts without sealing the wall so tightly that it can not breathe.

Details of the outer sheathing attachment and layout are somewhat dependent on the climate (specifically the dewpoint at various times of the year.) These are actually critical for all insulation types, but certain manufacturers and applicators are not telling you the whole story on their products' real-world performance.

BobC

I live in a 96 year old balloon framed house and I can tell you the balloon framing causes all kinds of problems that can only be cured if all the bays are sealed so air cannot freely move through the walls from the cellar to the attic. I would consider air sealingto be a vital step in an old house.

Also cellulose insulation does a better job than fiberglass, foam is better yet but expensive and hard to retrofit into old walls..

Bob