SIP level performance on the Oregon Coast

[MikeT]

Given the climate at the Oregon Coast, is it worth it to have nearly a SIP level performance from my walls?  I am building with 2x6s and will fully insulate, of course.  I am trying to figure out the merits of adding 1" of blueboard insulation to the wall in addition.  I know you (John) have liked this as a general principle, but I wonder if it is worth it for my climate? Do you have a sense that this is money well spent in a damp climate that typically ranges from 30 degrees as a low to the 70s as highs.

Thanks,
Mike

[jraabe]

Mike:

I used to do such calculations and try and find the most cost effective level of insulation for a specific climate. Cost effectiveness can best be defined as the point at which the mortgage payment increase of an upgrade is just a bit less than the savings that upgrade produces in terms of utility bills.

You can quickly see that for a given climate, mortgage rates and fuel costs play as big a roll as the cost of the upgrade - and these have to be projections to some extent. (For cash building you would use the "opportunity cost of money" - what you would get in savings or the T-bill rate.)

In general I would guess that the base R-21 wall in a coastal climate might be cost effective choice with something like wood heat but that the R-5 foam upgrade would be cost effective for hydrocarbon fuels or electric heat.

Higher insulation levels are more cost effective today than they were 20 years ago. That is because fuel prices have inflated faster than other things we buy like insulation. This might be even more true 20 years from now. :-/

[MikeT]

Thanks, John.  One of the more interesting aspects of this building process is managing the variables and trying to figure out what is that elusive "best" way to go.  With this issue, I guess I can go either way.  We will have both a wood stove and electric baseboard heat.  This will not initially be occupied all the time but we may put it into the local weekend/holiday rental market.  Choices, choices.  

The reason I am pondering this right now is that soon we will have the walls framed and can start placing boxes for the electricity.  I suppose I could just invest in the adjusting kind and make a decision later, but if I could land on a clear cut decision, I would know where I can set the boxes in relation to the thickness of the studs.

I appreciate your advice.

mt

[builderboy]

John, you're starting to sound like an accountant here. Maybe there's hope for me as a builder.