home ?- insulation vs. new windows
 

Went to the Orlando home show yesterday and saw some nice displays of energy conserving products. My home is 15 years old and block construction. A few years ago I had foam insulation blown into the block walls and saw a nice return via lower electric bills. I also had a new AC system installed that is a 14 seer in 2006 so I'm covered there. I want to do the next improvement and I believe it should either be new windows or insulation in the attic. The same company that did the foam insulation in the walls now does foam on the bottom side of the roof. Looks like between the closed cell foam base and the top coat of open cell you can get a R24 insulation value. An added plus is the base coat of closed cell is also waterproof which is a plus in our hurricane region. For the size of my house ( 1880 sf ) it will cost aprox. $2500.00 - 3000.00 I just talked rough numbers with the guy at the show. Now lets talk windows, my home has 11 windows with 3 of them being arch top so multiply by a cost of aprox. $200.00 for each and the added cost of custom arch top the cost of replacing all the windows is about the same as the roof insulation. So which is the better bang for the buck ? And what rebates/incentives are available for each ? You guys should know my current windows are builders quality single pane and the roof insulation is blown fiberglass over half the house aprox. 4-5 inches thick and rolled fiberglass over the other half ( vaulted ceiling ) aprox. 5 1/2 inches thick. Obviously I would keep the exisiting insulation if I go with the foam. OK guys fire away with comments.

Hmm, interesting. Is your house a 1 story or 2? If it's a 1story, and you're in central FL (lots of sun), my guess would be Attic. Do you have ridge vents or the old fashioned kind? My attic gets REALLY hot, and I know causes a big part of my cooling bill in the summer.

How big are your windows, that would make a difference. 11 huge windows vs a few big and a few small, would change the assessment.

My house has also got 11 windows. 6 are probably around 2.5' x 5', and the other 5 are small bathroom/kitchen style windows. I know that they are VERY inefficient. I'm sure they are the windows that the house was built with in '67. We'd like to replace the windows and get insulation. I'd like to do the foam, but we don't plan to be in the house long enough to spend that much. I think we're going to get the attic insulation beefed up. I'm going to buy/build some sort of insulation for the attic door too.

I'm far from an expert, so take what I've said with several grains of salt.

My main client is the country's largest manufacturer of residential windows and glass doors. In terms of bang for your buck, conventional wisdom is that attic insulation will pay back its cost many times before new windows will repay their cost. It's a little different in Florida where heat is the big issue instead of cold; up here all our heat escapes through the roof, making attic insulation the best bang for the buck.

If your house is 15 years old, you're probably about due for new windows. The mid 1990s weren't a good time for window technology. The stuff that's available now is much improved, but I can't say you'll see a big energy savings. The fit, finish, glass quality, and overall performance and lifespan have improved since then. I know Low E windows qualify for the $1,500 tax credit.

Unless your windows have seal failures, are rotting out of their sills, or are obviously leaking air, you're not likely to see an energy savings with new windows that exceeds simply getting heavy blinds and closing them when you want to block the sun and opening them when you need the solar gain.

But nothing dresses up a house better than nice windows with good interior trim. Think of them as your newly polished Fuchs.

I would take that into consideration if you might be planning to sell in the next few years.

good advice - esp. if you ever resell it

it will also depend on where the window is located -- a south facing window will collect a lot OF THERMAL LOAD from radiation coming in. Awnings, roof extensions, or TREES will help tremendously with that and are cheap. "stuff on the outside" is better than drapes for heat gain issues

there was an energy act last year to give you tax breaks - IRS has info on their site - don't forget state tax breaks either -- I dunno how long the breaks last but they ARE good in 2010.

also call you utility co. and ask for an energy mgmt. specialist - around here, they are free and thicker than cockroaches

so do N. facing windows last or not at all

The house is a single story. The wife and I plan on being in this house about another 10 years before we retire. I am leaning towards the insulation mainly because I can replace the windows myself if I want to. Home Depot and Lowes both sell decent vinyl thermal windows that I can replace one by one. The arch top I may have to have a pro do. But I'm still open to suggestions.

Good info. I only have one window facing south and it is shaded by a large oak tree. The majority of windows are facing east and west. A few to the north and that is the side of the house that never sees sun. I think I'm slowly convincing myself that roof/attic insulation is the way to go. My home does have full ridge vent with full soffit vents on both edges of the house so ventilation is not an issue.

+1 on the insulation.

Insulation, hands down.

Don't forget, down there, the vapor barrier faces OUT.

Is your roof shaded on the S.?

You have existing insulation of 4"-5" (between R13 and R18) the only way I know to add to the insulation value is to add to the insulation itself.

If you foam the underside of the roof you might keep the attic space cooler, but what you want to do is to insulate the house to keep it cooler/warmer so add to the existing insulation and let your exaust vents take care of the heated air.

Another option for a DIUer is cellulose insulation. It gets blown in on top of your existing insulation and fills any cracks or spaces in the fiberglass.

According to this chart you should have between R50 & R60 Step One - Calculate Your Need | GreenFiber.com

If you use the chart on the same page to factor raising your insulation value to R60 it would take 160 bags (for a 2000 sq ft building) and last time I bought the cellulose it was $5.15 a bag (2 yrs ago to insulate my son's attic) it would cost you under $1000 ...and that is factoring in the rental of the blower machine (if they don't offer it's use for free), coveralls, gloves and dust masks.

Not sure of this, but I've heard spray-foam insulating of the underside of the roof(assuming an unheated attic/dark shingles/warm zone) will lead to premature failure of the asphalt shingles due to overheating.

Insulating the underside of your roof will do nothing for you; you need to insulate on top of your existing insulation. Air flow is ment to assist in the heating/cooling of your house and the attic is a free airflow zone.

I've heard and read in several places that it's always cheaper to pay someone to insulate your attic than it is to DIY. I think I've heard that the total cost to have someone else do it is cheaper than the cost of the materials.

I haven't confirmed this myself.

Locally, I've seen a couple recent insulation jobs where it was going to be $900 and $2200 to DIY, and the quotes from a pro were $1100 and $2600. Hard to justify the work for a couple hundred bucks difference. YMMV

If your planning on reselling in 10 years, I'd hold off on the windows until a couple years before you sell.

close to true in Canada, where you are, but he is in Florida

his problem is heat coming from outside and trying to stop it

your problem is heat leaving from inside and trying to stop that

I live in Houston, roughly the same climate as South Florida. My attic gets hotter than hell in the summer, and brings the temp of the house up. If I could insulate my roof so that the attic doesn't get as hot, that would help. That means that the foam would be useful.

I'd heard that the reflective insulation under the roof can overheat the asphalt, but not the spray on foam, but it could be.

You may need more attic ventilation.

Plant more trees on the South. and West.

Depends on where you by the material. If you buy from Home Cheapo or bLowe's, you'll pay more for the insulation. Find a local supply house to purchase the cellulose at a better rate. I will concede the insulation business is very competitive. On the other hand, the labor from some insulation contractors is pure crap. It's amazing the stupid tricks they will engage to save money. I need to pack up the truck with my commercial insulation blower, tour the country, and add insulation to Pelicanite homes. :)

I've also heard spray foam will reject additional heat to the roof, but the studies (with spray foam and/or radiant barriers) have shown the temperature of the roofing goes up by only a few degrees. That small change hardly offsets the tremendous gains from radiant barriers. Besides, if the roof "overheats," that implies the roof is a radiant barrier. If the roof is a radiant barrier, then how does the radiant heat reach the radiant barrier in the attic? Quite simply, most of the radiant heat reflected by the radiant barrier will be reflected back into the atmosphere. I predict Al Gore will lobby against radiant barriers, because they contribute to global warming. :rolleyes:

I urged my cousin to install radiant sheathing on his house (new construction). The framer used radiant-backed sheathing over the house, but used regularly sheathing over the adjacent garage. The framer said working over the garage in the middle of summer was bearable, but over the house, it was much, much worse.

I agree the idea is to keep the attic space cooler. Both vendors at the show stated the attic generally will get no hotter than 85 degrees at the height of summer. If true that is a drastic change from normal 100-110 plus. I don't think the foam is reflective it just insulates but I'm sure some heat goes back into the shingles. But in Florida a good roof shingle probably lives about 15 years so I don't think the addition of foam insulation is going to make a drastic change on longevity. I'm going to call my power company to see what they have to say and to find out what rebates are available from them.

I believe my ventilation is adequate but I'm no expert. I have eave vents the full length of the roof. Also have a full length ridge vent. I guess like anything else you could have more. I've got plenty of trees they just can't grow fast enough :D.