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.

you need an energy audit!

BTW - choose light colored shingles next time you re-roof

to obviate the entire problem, cover your roof with PV cells and gar some free kilowatts -- during the winter you can burn dollar bills in your fireplace too

eventually, there will be PV cells cheap enuff to do this with...

Had my shingles replaced a few years ago after major hurricane season, yep replaced them with light colored architectural. I do agree an energy audit is in order. Thanks

I definitely think that I may need more ventilation. I've got a ridge vent, but my roof is sloped front to back and side to side, so I think my ridge vent is too short. I've got plenty of soffit vent for intake of cooler air, but not enough for escaping hot air. (is my non expert opinion).

We have a newish roof (5-7 years, I think) and yes, we had it done in light colored tiles. I'd paint the damn thing with gloss white epoxy if I could.

A builder told me most ridge vents aren't tall enough and/or built right. End to end would let the heat out faster.

You can also buy small solar panels which power a fan. I don't know if these are made for only the eave(are these called gable?) venting systems though.

I have a energy audit scheduled for this Saturday from one of the vendors that were at the home show. I will post the results.

Yeah, my problem is that instead of having a gable roof with ridgevents.
http://i.ehow.com/images/GlobalPhoto...-main_Full.jpg

I've got a hip roof with ridge vents.
http://www.precraftedhomes.com/pix/64/comraf-hip.jpg
So I don't have 36' of ridge vent, I've got 6' of ridge vent.

We had a new roof put on a few years back. They came out with an estimate. Our ins co was willing to pay for some of the roof because of hail. We told them, "We can only afford to cover $___, above what the insurance company is covering." They said "OK, we'll do it." Because of the county that we live in (coastal), there are stringent specs that must be followed and inspections that must be performed. They didn't get any of that done. Fortunately when we found out and got the engineer out for an inspection, he passed us. When the company came out, they had the old turbine vents, we asked for ridge, but I didn't know enough to also ask for hip vents or to realize that ridge would be inadequate.

Now I'm wondering about adding either turbine vents or hip vents after the fact. I also think we need to get the more insulation put in.

At least now I'll know this crap for next time. sigh...

I would agree you do not have enough ventilation. I have gable and the ridge vent runs almost the entire length of the ridge. I'm surprised your 6 foot of ridge passes code ?

It doesn't. You need to add ridge vent to the hips (looks ugly), a power vent (block off your current ridge vent or it will suck the air fom there instead of the soffit), turtle backs, turbines, etc.

UPDATE- energy audit # 1 done
 

Well yesterday energy audit dude # 1 shows up and does a decent job of inspecting the house and using a IR handheld to make his case. I was surprised when he said my 15 year old attic insulation still meets current code, he even said he was surprised. He said I have plenty of soffit/ridge vent. Then went to windows no surprise my 15 year old single pane should be replaced with double pane. My AC system was replaced in 2006 and is 14 Seer and no suggestion was made to replace even though up to 30 Seer is now available. Finally we discussed solar water heating. Bottom line was $5500.00 for system installed. So I did learn a few things but still don't know what my path will be. I'm still leaning towards having the foam insulation under the roof deck. I have a second energy audit scheduled for Monday so we'll see what comes from that. While the solar water heater sounded good and with various incentives only costs about half of the 5500.00 for some reason I'm still not convinced it's the way to go.

You should try to have an attic ventilation and put more windows. It depends on your budget for the construction. Sometimes if your lot is wide enough then you might have to plant some kind of tress to lessen the heat the surrounds your house.

UPDATE- Well right or wrong I decided to have all the windows in my house replaced with vinyl windows. Going double hung white with low-E and argon gas filled. For 11 windows including 5 " eye brows " and one of them being tempered to meet code over the tub the job will be $5800.00. I can write off about $1400.00 on my taxes and I'll get some money back from the electric company. I expect my electric bill to go down but not sure how much. Also hope it adds resale value for the future. Also took advantage of their no interest no payments for one year :D so I'm happy. When the bill comes due I'll write the check and incur zero interest. I think next year I'll add more conventional insulation to the attic and possibly a solar fan or two for additional heat extraction.

In a year you will be able to compare how much you saved by replacing the windows (comparing same electrical useage to same month data) and I've read new windows add about 80% of their cost to the value of your home (about $4600 in your case).

is it a flat roof?
we got something here where they put insulation plates (you can walk on em)on top of the asphalt layer, and then put pebbles on top of the insulation... supposed to be really efficient...
Rockwhool Rhynox is the brand name.

Insulation on the outside is more effective then insulation on the inside

No it is a conventional roof. Currently has a combination of conventional fiberglass insulation over half the house that has vaulted ceilings and blown fiberglass over the other half that has conventional flat ceilings. I'm thinking maybe doubling up the insulation and adding one or two solar fans might not be too bad of a hit on the wallet.

how thick is it now, and does it have a moisture barrier?

Not sure on the moisture barrier but I believe it is 6 inches thick for both types of insulation.

6 inches is not really unreasonable, the moisture barrier is important though, as it serves to keep the insulation dry, and effective... you need to make sure of the moisture barrier.. else them 6 inches won't work they way they should.

Very important in colder enviroments, not sure how important it is in warm environment.
But i can imagine it still matters at night, when warm , moist air passes the insulation, and then with the colder evening temps, the moisture condenses once it migrates through the insulation... Maybe somebody else can comment on this?