Insulation (update)

[Dr K]

I did a search and read the prior insulation threads, and the insulation part of Pookie's attic fan thread.

We had a home energy audit because our electric bills are both high and the same throughout the year (we have gas heat, so the bills should be higher in the summer).

The largest item on the audit, likely the most helpful, but the most expensive estimate-wise is to improve the insulation in our attic.

I'll go into the specifics first, and then post my questions:

Currently, we have 4-6" of cellulose insulation, going to the eves (no baffles), not sealed on the tops of the walls (suggestion to do that in the report with baffles) and without covers on the recessed lighting allowing significant airflow through the light fixtures.
There is also installed 3/4" plywood "flooring" (4x8 sheets) through about 1/3 of the attic, going end-to-end (approx. 70 feet) and the width of the bottom of the W-shaped rafters (8 feet).
There was also significant leakage around the drop-down door.
There are 2 sky tubes which are neither sealed nor insulated, and 2 bathroom vents which are also not insulated (one is a single fan remote fan drawing two low-noise vents and would be very difficult to insulate other than insulated flex tube, and I don't want to make Jesus cry).
There are vents (about 2 x 2.5") at either end of the attic, plus when we recently replaced our roof, we installed a ridge vent running the length of the attic

The recommendations are;

Seal accessible top plates and end walls with foam
Seal and insulate sky tubes
Seal all penetrations through attic floor (plumbing, etc.) with foam
Install covers on recessed lights so the are insulation compatible and airtight
Insulate to R49 (16" of insulation) with fiberglass or cellulose
Install baffles so the eave vent air goes over the insulation
Install an attic tent over the door
This would involve installing 2x6's and raising the flooring to accomodate the added insulation




Questions:

Is there denser insulation available to install beneath the flooring as I'd hate to lose 5" of height (I'm pretty tall...)?
How much insulating value is the 3/4" plywood itself?
Is the attic tent a good solution, or would the experts here weatherstrip the door?
How much of the above can I do myself relatively easily? The estimate is quite a few sets of Hoosiers worth!
Is this a job I should just plunk down the money because it's hot as blazes up there and much of it is a crappy job, or is it one of those things like changing brake pads -- "I can't believe I paid somebody that much to do this job?"

[Richard Curtis]

Peter: several years ago, we had another foot of blown-in cellulose insulation added to the amount originally in the house (12 inches? 8?) plus the necessary baffles and and increased number of eave vents. It's difficult to describe the difference that made. Not only is the house warmer in winter, cooler in summer, it's also much, much quieter from street noise and storms. I don't remember it being particularly expensive. My wife reports that heating/cooling bills have been noticeably less.

[Dr K]

Thanks, Richard. Because of the floor needing to be raised, we're being quoted thousands of dollars.

I had a different thought - what do people think of insulating the inside of the roof to, like, R39, and 6" of insulation on the floor surface? I got this idea reading the installation instructions for the soffit baffles, which gave 2 options.

Peter

[Trak Ratt]

If you don't use the attic for storage you don't need the plywood and because of that the raised floor. Can't believe you actually use the attic other than stashing stuff in it

[Dr K]

We use the attic for storage. Old records, boxes from just about everything we own (unfortunately, boxes from lots of stuff we no longer own - need to clean that out). Off-season stuff like hammock, market umbrella...

[Vicegrip]

Expensive storage

[Dr K]

Expensive storage

Yes, but law requires maintenance of medical records for many years. Almost all of what I would actually need is in my computer (and backed-up to 2 sites) but since it's not 100%, and scanning what is missing would require scanning everything there ($$$$$$), that is not an option.

But given that we have to insulate for many reasons, can anyone answer any of my questions? I believe I have the answers to some:

Denser foam insulation is about 1"=R5 (so for our desired R49, about 10"). And, that is much more expensive than blown-in or fiberglass (would need 10" x 500 sq. ft.).
Plywood isn't going to be enough of an effective insulator to make a difference.

Therefore, if we want flooring, we're going to have to raise it.

But how about the other questions? Thanks in advance. The expertise I've seen on Dorkiphus has been impressive, and I'm hoping to learn more.

[Richard Curtis]

Have you considered total foam insulation? Much more efficient than batt or cellulose but more expensive. Mike Holmes of TV fame uses it exclusively in all his home improvement programs. I'm no tax expert, but I would think that this entire project would be deductible as a necessary business expense (storing medical files). Dunno if it's still applicable, but when we did our home there was an appreciable tax credit.

[BlackTalon]

Mike Holmes is in Canada, eh? Their climate is different than ours here in the DC area. They love spraying urethane foam on the bottom of the roof sheathing up there and making 'compact' roofing systems.

The issue with that is if you ever get a roof leak you could suffer a lot of sheathing damage (especially if you have particleboard sheathing) before you even realize you have a leak. The way we typically handle things in the DC area is to leave an air space below the sheathing and circulate air through it, so the sheathing has a chance to dry out some if a leak does occur.

Frankly we have too many cooling days in the DC area for the compact system to be a good idea. That being said, it is getting more popular as people hear about it and see it on TV, although they often do not realize it is not optimum for our geographic area.

[Richard Curtis]

FWIW: I've only seen Holmes spray it on walls and attic floors, never on the bottom of roof sheathing. He's a big advocate for adequate air floor through the attics.

Is particleboard sheathing even allowed by code in this area? Kinda dangerous if it gets wet.

[DonNewton]

Mike Holmes. . . The people in my peer group out here (architects) have started a drinking game: Every time he mentions "structure", that "thing" of undefined value, take a drink. By the end of the show, you're hammered. One of the more unkind things said: "He wouldn't know structure if it bit him on the ass." Now, having said that, he's a great proponent of obtaining permits (there's a reason, over readjusting your assessments) and of using contractors who're licensed and insured. He's also got his heart in the right place (or he's found a niche that allows him to talk the talk and make money). I'm pretty sure he's not doing pro bono work on all those sites.

[Dr K]

Bump.

Despite the activity on the thread, I still could use some more help answering my initial questions, or at least the last 3 of them (I think I've figured out the answers to the first two, so the list has been renumbered).


Is the attic tent a good solution, or would the experts here weatherstrip the door? Is there a better solution to insulate the drop-down attic door?
How much of the above can I do myself relatively easily? The estimate is quite a few sets of Hoosiers worth!
Is this a job I should just plunk down the money because it's hot as blazes up there and much of it is a crappy job, or is it one of those things like changing brake pads -- "I can't believe I paid somebody that much to do this job?"


Thanks in advance.

Peter

[jerome951]

I went through almost this same scenario a few years ago when I bought my current house.
Defiinitely weatherstrip the attic access door. Depending on the type of door/ladder, you may be able to attach some foam pieces to it. I'm not sure about the tents, but I would think that at least laying a piece of foam board over the opening is better than nothing assuming your door/ladder doesn't prohibit it (mine does in that it has counter-weights that swing upward).

I added insulation (R13 fiberglass rolls) and a walk surface to my attic during August. Was hot as blazes. The smallish opening of the attic access door meant I couldn't take full batt bundles up there so had to use smaller rolls (didn't want to get fiberglass particles strewn throughout the house by carrying up individual pieces). Getting 4x8 sheets of plywood up there was also a pita.

Frankly, I think you have better things to do w/ your time than roll out insulation and build an elevated floor, though at some price point the cost/benefit isn't there.

[cmartin]

Wait until fall and it's not a bad job. Way too hot up there now for me.

Rolling some unfaced batts is cheap. Blow in some fiberglass for the areas you dont want to roll or want it done faster. Takes 1 to load the machine and 1 to work the business end.

The energy audit folks like to tell you to add more insulation not matter how much you have. There is plenty to read if you are inclined but after ~r20 the benefit just isnt there. I added r30 as readily available and the cost delta was minuscule.

I built a box from foam sheet to cover the attic stairs. Some weather stripping on the base and tape on the seams. Simple and there is no draft around the door anymore. Buy a cheap smoke tester if you want to geek out. Similar for an IR thermometer.

[Dr K]

Thanks, guys. And I'm a race car driver. I gots an IR thermometer!

[Vicegrip]

Don't overthunk this. You want to slow the movement of heat. insulation does not stop movement just slows it. It does so not by the material itself but by the material stopping the circulation movement of air. You want high air to material ratios but still not have the air moving around. Compressing the stuff down lowers the air to material ratio and lowers the R value. Direct air flow from the condition space is to be avoided as it bypasses all insulation and brings unwanted stuff with it like moisture, dust, pollen and bugs. Spray foam is wonderful stuff, in the right places under the right conditions. It has some very strong downsides.

Maintain air flow from eave to ridge. Stop direct air exchange. Add as much fluffy, lofted insulation as you can where you can. Saving money by storing stuff in those conditions rather than improving a prime energy loss zone is nuts.

Insulated attics are crappy storage places. Everything in them is subjected to extremes in temp from subzero to 150+

[cmartin]

Everything in them is subjected to extremes in temp from subzero to 150

A great point worth repeating. There was some cool stuff left in my attic at this place. A military uniform, house blueprints, books... some in boxes, some in metal storage containers. Everything was junk when I checked it out.

Don't overthunk this.

I have a habit of doing this too. I might have went a bit overboard with the air sealing and insulation at my place. Thing is, after talking to a few contractors I realized they werent going to address the details I was interested in. Standing in the center of the attic with a blow in machine isnt hard if that's all you care about. I'm sure I could have dont more but my works seems to have paid off. I took care of the low hanging fruit and then a little more where I could.

[Dr K]

Spray foam is wonderful stuff, in the right places under the right conditions. It has some very strong downsides.
We were recommended to use it to seal the tops of the walls and around any other places with air leaks (but to put covers over the light fixtures). What are the downsides?

Maintain air flow from eave to ridge. Stop direct air exchange. Add as much fluffy, lofted insulation as you can where you can. Saving money by storing stuff in those conditions rather than improving a prime energy loss zone is nuts.
Such as using baffles up from the soffets before putting in the insulation? That was what was recommended. Looked at them at Home Depot - pretty simple, it seems. Do I put the baffles up just 48", or should I run them all the way up to the ridge vent?

Insulated attics are crappy storage places. Everything in them is subjected to extremes in temp from subzero to 150+

I hear ya'. Mostly just boxes (which I've used in the past to send things back). I figure we'll get rid of about 50% of the stuff when we bring it downstairs to do the attic work - lots of the boxes are for things we no longer have...