Author Topic: Insulating my house  (Read 1502 times)

secondcor521

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Insulating my house
« on: January 05, 2018, 04:11:41 PM »
Hi,

I'm probably going to be improving the insulation on my house.

My house is a single level with a bonus room over the garage in Boise, Idaho.  The insulation report in the garage claims that it has R-38 in the ceilings, R-13 in the walls, and R-19 in the floors.  The attic is blown-in fiberglass.

The house overall seems draftier than my last house, but it's not bad.  My utility bills aren't bad.  But there is about a 5 degree temperature gradient between the main floor and the bonus room, and the interior just feels cool even when the temperature is reasonable, especially if you're within a few feet of the exterior walls.  The temperature is particularly colder in the two bedrooms furthest from the furnace.  The furnace is gas forced air.

I'm thinking about:

1.  Adding more fiberglass blown-in insulation to the ceiling with a borrowed blower from Lowe's to get it up to R-60.
2.  Adding fiberglass batt insulation between the floor joists in the ventilated crawl space.
3.  Taping and insulating the ductwork in the attic and crawlspace.
4.  Sealing any holes and gaps I can find in the attic and crawlspace.

Which of these are likely the best bang-for-the-buck?  Any general advice?

mustachemountain

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Re: Insulating my house
« Reply #1 on: January 05, 2018, 06:55:09 PM »
air seal, air seal, air seal

by far the best bang for your buck, most of the work is you and a caulk gun, and the rewards can be amazing.

next is your insulating your attic, and insulating the rim joists where your haus attaches to its foundation. huge place for air leaks and conducting warmth out of your house.

when you are up in the attic, pay attention to how the drywall of the ceiling meets the walls- often there is a gap, covered only by a piece of paper and a bit of mud, that allows a significant about of heat to escape.

plastic over the windows or good storm windows, shutters, and heavy, close fitting curtains will also help. usually windows/doors are the major heat leaks in a wall. *anything* you do to make them tighter will reward you with a warmer house

secondcor521

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Re: Insulating my house
« Reply #2 on: January 05, 2018, 09:34:05 PM »
Thanks.

I know there is insulation already in my attic, and I think there may be fiberglass batt insulation on the underside of my floors.  In situations where there is insulation, do I try to move it out of the way to air seal, or do I trust the original builder to have properly air sealed before installing the insulation?  My house in general was decently built by a reasonable builder, but it is of medium quality overall.

Eucalyptus

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Re: Insulating my house
« Reply #3 on: January 05, 2018, 10:02:18 PM »
Yep air sealing always comes out top. Don't forget gaps around windows and doors as well.

From there probably getting some clear plastic to add a "secondary glazing" to your windows is probably the next best bang for buck in most circumstances.

zolotiyeruki

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Re: Insulating my house
« Reply #4 on: January 05, 2018, 10:04:11 PM »
You might consider renting a FLIR camera (Home Depot rents them) or getting one that plugs into your phone, and walking around your house.  That way you can more precisely identify where the cold is coming from, where insulation is missing/settling/etc.

mustachemountain

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Re: Insulating my house
« Reply #5 on: January 06, 2018, 06:07:23 AM »
air sealing, both during construction and especially after, is tedious, time consuming, and needs to be pursued with an obsessive zeal.
99.999% chance your builder didn't give a f@#$
you should not trust their work. move insulation out of the, pull off window/door casings, baseboards, and especially crown molding.
years before i bought my haus, a leaky roof over the kitchen forced the replacement of the entire ceiling. the drywall had an 1/8" gap where it didn't quite meet the walls, covered by cheap crown molding. when i pulled it off, the back side was black from years (decades?) of air being sucked through the gap- under quite a lot of pressure i might add due to natural stack effect. no wonder i could never keep the kitchen warm!
a blower door test is the best for finding air leaks, if you are that serious about it. google for more info about it, an awesome tool/method to seal your house!

TomTX

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Re: Insulating my house
« Reply #6 on: January 06, 2018, 08:35:27 AM »
While I fully agree with the "seal, seal, hunt around and seal some more!" sentiment...

When you get to blown insulation, I far prefer cellulose over fiberglass. With fiberglass it is far too easy to "over loft" - meaning that the fibers are so far spread out that you get actual air currents through the insulation. Cellulose is dense enough to self-pack and prevent this. Adding a cap of blown cellulose over fiberglass (or rockwool, etc) - works just fine to seal it up.

Actually, now that I think about it - this really fits the "Seal it!" theme....

secondcor521

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Re: Insulating my house
« Reply #7 on: January 07, 2018, 08:38:34 AM »
Thanks all for the advice.

Since I just got my bill I thought I'd mention that I used 4.62 therms per day of natural gas with an average regional temperature of 43.  I am not sure but I think that is reasonably good?