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Is roof insulation worth the $3k?? Help!

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Jun 08, 2013, 02:40 PM
Is roof insulation worth the $3k?? Help!
I own a 1958 home and it has open beamed ceilings inside. It is dreadful in the summer and freezing in the winter. I don't want to drywall the ceilings. We desperately need a new roof, and I have been getting bids for a roof plus insulation. The insulation alone is $3k! Anyone done this? Is it worth it? Some say it can help lower the interior temp by 12 degrees... others say its not effective. Any feedback is greatly appreciated.
Jun 08, 2013, 05:12 PM
stop and think a minute.

the idea behind insulating a home is to create a climate controlled zone that is comfortable, preserves the building materials, and separates the outside elements from the interior climate zone.

first, of course, you need correct waterproofing. in the case of the warm/cold zone between the ceiling and the attic, that should be between the roof base joists and the drywall. if it's not there, well, it's even more important to keep water out of the cold zone so it doesn't drip.

so first, seal up all the attic penetrations around pipes, wires, chimney, etc. with fireproof silicone and/or 5/8 fire-rated drywall.

now, what to insulate. where I come from, temp swings from 150 to 20 below in the attic, you do not want that to affect the house. insulating the ROOF extends the controlled zone into the attic area, and there is supposed to be ventilation in the attic to keep mold and moisture away. so this is a really bad idea, insulating the roof.

in fact, it's devastatingly bad.

so the proper place to insulate the house on top is over the bottom joists of the roof, insulation smack dab against the celing below and up to the recommended thickness above that, without gaps.

if you don't have a vapor barrier, using a base of spray foam will provide one. but it has to be boxed in by non-flammable materials, as all the foams burn like napalm if they catch fire. there is a gypsum spray they can topcoat it with. foam insulation is good, but pricey.

most folks will use blown cellulose or fiberglas, and that is the best value. you can rent (or at most centers, buy enough insulation, the blower is free for an afternoon, rent their truck to drive it across the lawn) a blower.

batt insulation is still used, but a proper installation requires butting the batts up tight against the joists, then criss-crossing a second layer over to get to the recommended insulation level. this is not routinely done, and thus you get heat leaks.

we did our insulation boosting ourselves for about $700 with blown fiberglass to R42 total, over about 4-6 ratty inches of cellulose. that includes the truck rental, the insulation, and all. you will have to snake a couple of big extention cords to two different circuits, and drag a big 6 inch flex hose and a control cable in a window, up the attic cut, and across the joists. long pants and shirt, cap, eye and breathing protection and gloves, please, or you will be a hurting critter.

to me, that's one of the easiest $2300 I ever earned.

sig: if this is a new economy, how come they still want my old-fashioned money?
Jun 08, 2013, 05:41 PM
I believe that with an open-beam ceiling that Melin is looking at insulated roof panels. These would be exterior panels of sandwiched foam.

Is it worth it? Probably. Most of your heat loss in the winter is through the roof. Much of your cooling load in the summer is making up for all the radiant heat coming from the roof. If you have to pick one place to insulate between ceilings, walls or floor, go for the ceilings or roof first.

Take a look at your utility bills. An insulated roof over a non-insulated roof will probably run in the neighborhood of 30% to 35% less. Plug that number into your annual utility cost and see how long it takes to save the $3,000 cost. If it's under five years than it's a great idea.

Jun 08, 2013, 11:56 PM
Thanks so much for the feedback. I have no attic, hence needing to insulate from the outside. It seems to make sense but the price tag has me a bit hesitant since we are already needing a roof ($6,500) and really want AC one of these days soon. Has anyone done a roof insulation like this? Or maybe a cool roof coating? I love and hate my open beam ceilings! Thank you again....
Jun 09, 2013, 09:31 AM
My sister and her ex built a log home years ago with the roof decking exposed. They installed two layers of 2" inch poly-iso panels over the decking, and then plywood on that for the nailing surface for the shingles Poly-iso has an R factor of 8 per inch giving them an R-32 roof deck.

As I recall, they used special long screws to hold everything down. It was 30 years ago now, and I didn't help put the roof on some I could be a little fuzzy on the exact details. I did install some poly-iso panels this way on a flat commercial roof at my kids private school about 8 years ago. We used long screws with a 1.5-2" washer on it, we didn't do OSB on this roof because we were doing a membrane roof, not a shingle roof, which would be impossible or useless, on a flat roof.

General Disclaimer

Any advice given here is general in nature and is not necessarily valid for your given area. If in doubt check with your local codes enforcement department for what is required when doing electrical, plumbing or structural work on your house. Permits may or may not be required in your area and home owners may not be able to DIY some tasks. I have no way of knowing if you have the skills needed to complete the tasks you are asking about, when in doubt seek professional assistance.

My advice may be worth exactly what you pay me for it. :-) For the record I did not stay in a Holiday Inn Express last night.
Jun 09, 2013, 10:48 AM
There are insulated roof panels made just for this - a foam core with a thin skin on each side. They are designed so that they can be used just as insulation panels or can have a hot tar roof installed on top. There are also insulated panels that have an OSB top layer for the install of conventional shingles.

You will not find this at any homeowner big box store, look for a commercial roofing supply house or just talk to a qualified roofer.

I still think it will be worth your money. You lose so much heat through the roof and in the summer get a lot of radiant heat inside. Between the actual dollar savings on your energy bill and the extra comfort, if you are going to live in this house for at least 3 to 5 years it should pay off.

For money, check with your local utility provider. Many have low or no interest programs for improvements that give your house greater energy efficiency.

Jun 09, 2013, 04:16 PM
My personal opinion, and admittedly, not having any expertise in the subject, is If you reroof without insulating , you're going to have the same conditions you have now, and when you can't stand it any longer, you will have to install the insulation anyway, who knows how much of your new roof will have to be modified and at what cost.
I think following Jaybee's advice is right for you
Jun 09, 2013, 11:35 PM
Thank you for your honest feedback. I really appreciate it. I guess my issue is money. I need a new roof and want AC. We had been planning for the AC but found out a few weeks ago that we need a new roof. OUCH. Then I heard about exterior roof insulation and how it can bring interior temps down 12-15 degrees. Of course that got me interested and I wondered if we could just get the roof + this amazing sounding insulation and no AC (since the combo of two would cost us around $20k -- yikes). One of the roof quotes I got said I could do a "cool roof" for an extra $300 in lieu of, or in addition to the insulation. Anyone have thoughts on that? Boy, am I rambling. Sorry. First time buyer with an old house and lots of issues here!
Jun 09, 2013, 11:40 PM
By the way, great advice Jaybee. I just checked with my utility and you're right; there appears to be some financing options I can look into. Never even thought of that. Thank you.