Adding More Insulation to the Ceiling worth it?

minnesotaguy28January 12, 2011

Building a new house and I am always finding out what additional items cost with the builder.

2 Story house, 2200 sq ft finished, building in Minnesota, a pretty tight budget that was made even tighter with a required retaining wall in the backyard.

The attic currently will have a R44 14 3/4 thick blown in insulation.

To upgrade to a R50 16 3/4 it would be an additional $328.20.

Is this a smart upgrade? Will I get my money back from doing this in heating costs? If so, anyone know how long the payback time would be (ballpark guess?)

I also asked him to find out the cost to spray foam insulate just the bathroom walls (around 17 feet of wall x 8ft high with a good sized window in one of the bathrooms). Since he already has the guy coming to do spray rim joists I figured it wouldn't be that much more.....He came back with the cost at almost $600. Kinda pricey I thought.

Like many of the people that post in the monthly progress, I picked one heck of a month to start building....Snowiest Decemeber in Minnesota on Record. Builder said he still is on track for a 3 month build...start to finish...I hope so since we did a early lock on an interest rate before they spiked up again and don't have many days to play with before the lock expires.

They are going to insulate the ceiling Friday afternoon or Monday.

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The numbers are arithmetic-derived and do not necessarily represent reality (reality, as measured by performance.)
R44 14 3/4
R50 16 3/4
Did you say what material this is?
Did you say what else you have? in terms of radiant barriers and vapor barriers and ...
This is important to include for people to comment on the $330 difference.

The foam is a good deal. Foam is not the same animal as blown-in, in the attic. Is one of these bathrooms going to be in a corner?

    Bookmark   January 12, 2011 at 8:20PM
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I think $330 sounds like a lot. My memory serves me that going from R-30 to R-40 for a 4000 sqft house (2x2000) was $200. That was such a no brainer just as your is. I am getting ready to up it to r-50. Mind you I have a very efficient heating system and live in NC. Even still, it is worth it to go to R-50.

In Minnesota, I would think the question would only be going above R-60. Anything up to that is probably worth it.

    Bookmark   January 12, 2011 at 8:28PM
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Material is Cellulose
Not sure about Radiant Barriers/Vapor Barries...It is a 2x6 Exterior Walls w/OSB/Tyvek/Siding (Typical) R-19 Batts.

What I saw today was that they have a Clear Poly up on the 2nd floor ceiling with Taped joints. They also spray foamed any hole that enters the space through the wood top plate.

The Roof is 30 yr Architectural Shingles with a Ridge Roof Vent under Engineered Roof Trusses.

Hope that is what you are asking

    Bookmark   January 12, 2011 at 8:36PM
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Dr. Lstiburek of Building Science Corp. recommends R60 for the roof. The payback calculator below may be of help.

Here is a link that might be useful: Payback calculator

    Bookmark   January 12, 2011 at 9:35PM
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it would be best to delay the
insulation install and invest time in air sealing any
openings between the attic and living space.
an easy way to determine where you need to air seal
is to go into the attic and look for light from living
space below.
while in the attic you should also check around hvac
supply boxes into the house. often when supply box is
installed the screws from the supply register attached
to the living space side of the supply will raise the
supply box off the attic flooring. this leakage will
cause supply grills to condensate because of hot and cold
air meeting on a metal surface, and it also allows insulation particles to enter the living space.
this should be mastic sealed, then check out the
ducts where they take off from the plenum..this should
be mastic sealed..plenum connections to mechanicals
and coil or air handler to heating system should be
mastic sealed.,
mastics..not duct tape

look at bath vents..sheetrock cut is usually larger than
housing for bath vent fan..I use mastic tape to seal these areaa. Make sure that back draft damper on bath fan is installed correctly. flap should close off damper when
fan is not in use. use mastic tape to attach back draft damper..metal dryer venting to back draft damper and
vented as per code.

thermal bypasses like fireplace inserts are often left open
from the attic you should not be able to look down and see fire box.

the goal is to create an air barrier so that air doesn't move from attic to living space through the insulation.
if air is moving thru the insulation it reduces the r-value.
it also allows attic air and insulation particles to circulate through out the house.

once the air barrier is complete then you add the thermal barrier.
make sure that under any mechanicals is insulated, also under mechanical service areas and walkway to these mechanicals.

if you used ICAT lights for recessed lights it is only the
gap between the housing of the recessed light and the sheetrock that needs to be sealed. these cans are insulation
contact air tight.
if your cans are IC only..the holes in the housing into the attic will have holes in them unlike ICAT..then you need to
address with air tight inserts and seal sheetrock cut.
one IC only recessed light equals one sq ft of uninsulated attic. (LA DNR) that is HUGE.
to retrofit the lights to air tight is expensive
we have used ice chests in some homes. the ice chest has to have 4" clearance on all sides and top. it is cut to fit tightly to sheetrock and caulked in place...time consuming.

the recessed lights and other thermal bypasses are often over looked. these have a huge impact on the performance of the insulation and the house.
saving upfront costs longterm..your builder builds and moves
on, leaving high utility bills and poor comfort and iaq for you to deal with.

before insulating seal these will never have as easy of an access to these areas as now..
remember...air barrier first..
thermal barrier after air barrier.
there is plenty of info for this at
and southface institute has an excellent air sealing

in my personal experience with cellulose
it creates a fine 'dust' of borates
and newspaper..your air barrier should be as perfect as
you can get it. and invest in 4" pleated media filters for
your hvac system

best of luck

    Bookmark   January 13, 2011 at 9:17AM
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Thanks, I did the calculator and it is a 30 year payback assuming I entered all the info correctly.

Thanks Energy Rater, I will try and get up there today and look at these areas. Since the sheetrock isn't up I can't do the light test.

Only 1 Can above the shower, Fireplace vents out the side of the house. I know they foamed all the plumbing/electrical/mechnical punchouts that go between the 2nd floor and attic, but will look to make sure they taped around these areas in the attic as well to keep the air barrier tight.

Sheetrock is going up Friday so if they don't blow in the insulation in the same day and wait till Monday, I can get in there this weekend and do the light test.

Thanks again

    Bookmark   January 13, 2011 at 11:15AM
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That calculator does not differentiate between attic and wall which is a significant problem. It isn't the only one that does that. There is no question that attic requirements are much higher and paybacks are much better in upgrades.

I'd venture your payback is less than 10 years.

    Bookmark   January 13, 2011 at 12:38PM
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Do it. Nothing will get better relative to energy as time goes by so it is important to increase your bragging rights. There is little that is more important than that as you get older.

    Bookmark   January 13, 2011 at 7:49PM
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Epiarch Designs

I would be more concerned about your "r-19" walls (really more like an r-13)....for your climate, you should consider alternatives then the bare code min...

    Bookmark   January 13, 2011 at 8:28PM
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We did spray foam in ours here in Arkansas. But we are building a country triple dormer home. The 3 bedrooms upstairs have partial sloped ceilings. In our old house we had a bonus room with sloped ceiling and it was always warmer in the summer and cooler in the winter in that room. Our insulators quoted foam and blown in. When I asked about half and half(foam upstairs and blown-in downstairs) he gave me a price break on all foam so that he would have to bring out 2 different sprayers.

If we hadn't had that bonus room to learn from we probably would have done blown in and regreted it.

    Bookmark   January 15, 2011 at 12:32AM
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Wish I had room to have did Spray foam and all the other things suggested on these boards, but reality is we don't.

They did do spray foam rim joists, which I seen the framers already had to chisel back in some areas to add some more bracing (not happy to see that).

    Bookmark   January 16, 2011 at 10:21PM
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I'll only comment on the bathrooms: I think insulation is good on the interior walls too, for a sound damper or barrier. If you have a bathroom near the kitchen or DR, I'd definitely insulate it well so noise doesn't travel when someone's using the loo while you're enjoying a nice meal. If anyone in the house has a different bedtime/wake up schedule, it would also be nice not to hear them in the restroom when you're trying to sleep.

    Bookmark   January 19, 2011 at 1:02PM
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