Author Topic: more on insulation  (Read 3855 times)

Jill the Pill

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more on insulation
« on: March 20, 2013, 06:36:13 PM »
We just found out that the insulation in our attic is inadequate (has settled).  Of course we should put in more.  But, we are no-air-conditioning people.  I am concerned that keeping the heat from rising out the attic in the winter will also make the house hotter in the summer.  Can we avoid this?  The online advice is mostly about a.c. or fans/vents. 

Mountainman75

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Re: more on insulation
« Reply #1 on: March 21, 2013, 06:59:36 AM »
If you were to stick a thermometer up in the attic during summer you'd find it to be 120-130 F.
Adding insulation will keep that heat from heating the ceiling downstairs and re-radiating that heat into your living space.

Interior ventilation with the windows open will feel cooler if you re-insulate the attic space, it won't pick up the heat form the ceiling and bring it down to your level. If I had it to do over again, I'd make the attic conditioned space and insulate the roof itself with a spray in closed cell foam insulation product. Really makes a difference in the summer for keeping the house cool, and retaining heat in the winter.

Spork

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Re: more on insulation
« Reply #2 on: March 21, 2013, 08:25:09 AM »
If I had it to do over again, I'd make the attic conditioned space and insulate the roof itself with a spray in closed cell foam insulation product. Really makes a difference in the summer for keeping the house cool, and retaining heat in the winter.

That is what we did and -- ohmygod, what a difference.

Insulation will always help, though.  If you've already got blown in insulation, adding more is generally a low cost "win".  We tend to open all the windows during times of the day when it is comfortable outside, then close them as it gets uncomfortably hot or cold.  The insulation really helps to maintain a temperature.

Mountainman75

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Re: more on insulation
« Reply #3 on: March 25, 2013, 03:55:23 AM »
It can be an easy DIY, and plenty of kits out there from Tiger Foam, etc.
At the end of the day, it may be cheaper to hire it out though. The installer usually gets such a deal on materials that they can install it for about the same cost as you'll pay for materials.

My brother lives in the DC NOVA area and hired a contractor from 2+ hours away (Waynesboro, VA). The contractor had done our barn on the farm out there, and was delighted to come to NOVA and do another job... ended up being about 30% cheaper than hiring a local DC NOVA contractor for the job. Gave him some extra beer and gas money, and everyone was happy.

If you are going to DIY, and are wanting to be cheap as hell, only spray in 1-2" of foam, then back it up with rigid styrofoam sheets or sheets and batting. The best part of the foam is that it seals ALL the airgaps as well as insulating. 1 inch is all it takes to seal the structure, and then you can get the R value from the cheap stuff beyond that.

You can also get a tax credit for adding insulation, even if it's DIY.
http://www.energystar.gov/index.cfm?c=tax_credits.tx_index

One thing to note, if you go this route put a temp and humidity gauge up in the attic to monitor moisture. If it gets too wet or humid you can get mold up there. Running the HVAC to dampen (just the fan typically) that is all that is needed.

Zaga

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Re: more on insulation
« Reply #4 on: March 25, 2013, 06:22:39 AM »
We insulated the attic and exterior walls, and it's made our house much more comfortable in both summer and winter!  Well worth it, even paying extra to have it done for us.  We've had it for a year and a half, between that and the new windows (ours were over 50 years old and single pane) we got several years ago it feels like a whole different house!

superspeck

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Re: more on insulation
« Reply #5 on: April 02, 2013, 06:34:58 PM »
Insulation always helps. You can't go wrong insulating a house unless you screw up the vapor barrier.

In an attic, you can blow in more insulation - either Greenfiber or pink fiberglass. It takes two people to run the blower (one to operate the hose end and one to feed the machine), and both will want to be dressed in tyvek suits and will want to be wearing respirators and goggles -- if you are willing to spend the money, full face respirators are best. Don't just get dust masks; they don't work. Not wearing the tyvek suit is a foul; you will itch for days and your bed will itch for weeks no matter how much you shower. Not wearing a good respirator that is properly fitted (And I'm NOT kidding when I say that mustaches are OK in this department, as are goatees, but the bearded need to shave down to a goatee for a proper fit) is a serious foul because you can't itch inside your lungs to get the fiberglass fibers out. So you just get cancer instead.

Or if you don't want to go there, you can just roll out more batt insulation over the blown-in insulation.

But before you do either of those things, buy a six-pack of those cans of spray foam, and wearing rubber gloves because that stuff is evil on skin, find all the places that wires come up out of the top of walls, all the places where A/C vents penetrate into the attic, and all the place that plumbing goes down into walls, and fill up the holes with spray foam. This keeps air that's in the house from going up into the attic, or hot air in the attic from overpressuring when the wind blows and coming down into the house. For bonus points, also get one of those tent things for your attic hatch. It seems like a dumb idea, but then...

The main thing you need to make sure if you're "no A/C people" is that you maintain good attic ventilation. This means that air should be coming in through the soffits of your house and leaving through vents in the peak of your house -- either turtle vents, turbines, gable vents, or ridge vents. The right combination of these things depends heavily on the design of your house and where you are in the world/country, and you need to have a professional in the roofing or architecture trades tell you what's right for your area. The one thing that's uniform that everyone screws up when they have blown-in insulation is that they block the soffit vents. You need to put baffles in there. There's a lot of cheap baffles that you can buy off the shelf at Home Despot or bLowe's, but they suck and are hard to put in if they don't already exist. The really good ones are called Berger Accuvents and cost a little more. They have to be ordered at the contractor's desk or online.

The thing that most people don't realize is how much having a ton of insulation in the attic will quiet your house if you have a single story house. Neighbors have barking dogs (or, like me, geese)? They go from "nuisance" to "unnoticeable" when your house is properly insulated and sealed. Having filled my attic with insulation to R-60, replaced the wall insulation (was R-9), added a rainscreen siding build with proper sheathing and housewrap, and replaced the windows, I can't even hear the geese in my neighbors' backyard until I go outside. Geese are LOUD. It's a huge quality-of-life improvement that also pays off in reduced energy costs.

Mustache tip: If you're blowing in insulation, you use a machine to do it. The machine rental price is usually waived if you buy enough bales of insulation material. Most people will need the minimum to get the machine rental waived. However, if you don't, you can buy the minimum (usually 20 or 25) and then return the ones you don't use when you return the machine; they don't charge you retroactively for the machine rental as of the last time I did it early last year.

Jill the Pill

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Re: more on insulation
« Reply #6 on: April 02, 2013, 07:47:20 PM »
Wow, great advice, thanks!