Radiant Barriers. Do they really work? (Austin, Fort Worth: rent, appliances, new home)

[jcamber]

Ok so I just moved to the Fort Worth Area (Keller, to be more specific). My house is 3,500 sqft, no radiant barrier and lacks enough vents on the roof (according to my past experience). I come from the midwest so summer months and their associated cooling costs aren't that much of a concern. But I hear it gets pretty hot down here and I'll see it when the first power bill for those months arrives . I'm trying to be proactive and do one of two things:

1. Install a radiant barrier. Not decided yet if I should go with the spray-on vs. foil. I think the going price for a home the size of mine is about $2k.
2. Have a roofer install solar-powered roof vents.

For all of you who have lived here longer than me, what do you recommend? obviously, I will do the other little improvements like installing ceiling fans, leave the AC thermostat at 80 and maybe 78 during the night, etc.

What works, what doesn't according to YOU?

thanks!

[johnrex62]

I vote for the foil solar shield. I have no experience with the sprayon, but have heard unsubstantiated negatives about that type of barrier.

I built my house using the barrier laminated OSB decking material and I can vouch for a very significant temp difference in my attic. I live near Austin and the summer after I finished construction I measured a 130 degree attic on a 99 degree day and I have a shed with the same roof style without a radiant barrier that measured 165 degrees at that time.

Even on days over 105 outside was only uncomfortable in the attic as opposed to unbearable as I used to experience in prior homes.

[UREDDY79]

The spray-on does not work, but the foil is very effective. Roof ventilation is very essential, along with soffitt ventilation air can flow properly through your attic.

[Guingirl]

Yep...I would definately do it.

Okay...so case in point, we have radiant barrier, on ALL electric (3500 sq ft) and our bill in December was 310.00 and my neighbor a few blocks away who doesn't have it (she does keep her house a little warmer 78 vs my 72) and her bill for that same month was 920.00 or so. So it can be a BIG difference!!

I know for me the ROI would pay for itself in a matter of months, not years.

[padcrasher]

Whoa, hold on a second. If you suspect inadequate air flow. Do that first. Much cheaper and it's an essential part of the whole roof design to have proper airflow. I don't know about solar power...plenty of wind here to run the turbines that cost less. I had two turbines installed in a 1965 built duplex I rent out and it did wonders for the climate control.

Once that is resolved, and your bill is still out of line, or you will live there long term, then look at the radiant barrier...most new homes do not have them. They get by with proper insulation and air flow.

First and foremost have the roof properly ventilated.

[loves2read]

radiant barrier is great -- should be required for code in all new construction to help with utility costs--
proper venting is helpful but it will not make the difference that radiant barrier use will...

spray-on barrier is not that great no matter what hype you get--adding the foil PROPERLY does help but it is not as good as using the roofing radiant plywood--and because the % of benefit is less, there is longer pay-out time...

depending on the attic construction/framing--it can be very difficult to add the foil sheets correctly--it might be more effective cost-wise to just add more R-factor in insulation---most construction has only mininal code/spec insulation which usually is not enough to make appreciable difference in utility costs...

remember YOUR home's windows, its orientation to the sun and design have big influence on its HVAC useage--most homes in TX are not built with eaves that really shade windows effectively and most subdivision design does not take sun's orientation into account--just how many lots can I carve out of the land I bought...

check out how well-sealed any ceiling light fixtures, windows, exterior doors, and wall outlets are--air infiltration from those areas creates persistant problem that should be dealt with whether is it heating or cooling season...

and remember regarding electric bills that you have other factors that influence your overall costs--major appliances, types of computers/tvs/light bulbs--they all add to KWH costs to run household--garage door opener is VERY expensive to run--so having it go up and down 4-5-6 times a day which is normal in most homes adds to KWH costs

in some homes the HVAC is only 1/3-1/2 of electric useage--are you doing 3-4 loads of clothes a day--leaving lights on during the day or in empty rooms--leaving computers turned on when not in use or turning it off at powerstrip?

what some (better) builders are doing now is to foam the floor of the attic to put heavy R factor insulation directly over the living space--1.5 to 2in of foam is like R-36 or more I think--and using the radiant backed sheathing for sides of homes--not just roofing...THAT makes big difference when there is effective seam sealing as well...

you also need to make sure that your HVAC ducting is tight and insulated--might even be worth seeing about foaming the tubes--have seen that done--to keep the air cool/hot vs attic temps...some people think that is not effective long term because the foam can dry out and crack--they should have mastic sealing instead of duct tape and foil backed batting for insulation at the least--most newer homes have the foil-backed insulation but not the mastic sealant which is more expensive and time consuming to install correctly---
it also makes sense to have different sized tubing depending on the HVAC run and the room sizes--

[Poltracker]

Yep! I vote for proper ventilation and insulation first. Ventilation can be done in a number of ways depending on the design of your home. There are some good websites concerning this. My house was improperly ventilated, no soffits worth mentioning. I got this corrected and paired up with a ridge vent (passive system) and saw a huge drop in the electric bill. For some designs, a turbine or gable might be more appropriate. The best type of radiant barrier is the roof decking like stated above. I plan to add this when I require a new roof not too long for now.

[jcamber]

Thanks everyone for your responses. I had no idea of the lack of vents until the inspector pointed it out to me. When I mentioned this to the superintendent at pre-closing walkthrough what do you think he said? "we build according to Texas code and you have enough vents ACCORDING to Texas code"... nice. Anyway, it doesn't take a scientist to know that if you have a roof shared by the garage, the kitchen and the breakfast area you can't possibly NOT have any vents on it.

A ridge vent would be awesome but I'm pretty sure these are expensive to install once your home is already built, right?

Thanks again!

[padcrasher]

"proper venting is helpful but it will not make the difference that radiant barrier use will..."


You've got to be kidding! Go put up your best radiant barrier and block your turbine and soffets up so no airflow takes place in 100 degre weather. You'd be able to cook a pot roast up there. Likely tempatures in excess of 200 degrees.

Do not listen to this guy. The roofing system basics must function properly before you do add ons like radiant barriers.

[Trainwreck20]

"we build according to Texas code and you have enough vents ACCORDING to Texas code"

Cities may have more restrictive codes than the state. Make sure that the correct codes are met, although your inspector should know this.

I did a quick check for Austin, and came up with the following codes:

2006 International Energy Conservation Code
2003 International Building Code - Commercial Construction
2006 International Residential Code - Residential Building and Mechanical Construction
2003 Uniform Plumbing Code - Residential and Commercial Construction
2003 Uniform Mechanical Code - Commercial
2005 National Electrical Code - All electrical installations

The Int'l Energy Cons. Code had some requirements for attic efficiency, although I did not try to dig through them all.