Anyone ever use a radiant barrier in their attic? What kind was it. How much of a difference did it make?
Anyone use a radiant barrier?
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4WD
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Years back I put in a product they called AstroFoil. Basically double bubble wrap with near pure aluminum on each side. Stapled it to the rafters and left about a half foot short at ridge vent and soffits. Also added some soffit vents. The idea of the double foil is to always have at least one clean surface.
We estimated about 10% on cooling bills - easy for a DIY and you don't have to finish all in a day like the spray in companies do.
This allowed me to get around some of the things stored in the attic. (one or two can do this work).
We estimated about 10% on cooling bills - easy for a DIY and you don't have to finish all in a day like the spray in companies do.
This allowed me to get around some of the things stored in the attic. (one or two can do this work).
I did not tell much difference with mine
They only work when facing an air space and do a good job of reducing radiant heat coming from the air facing side.
So, if you are in a cooling dominated climate then you want an air space between the underside of the roof sheathing and the foil.
In a heating dominated climate you want the radiant barrier against the roof sheathing with the foil facing the interior of the attic.
So, if you are in a cooling dominated climate then you want an air space between the underside of the roof sheathing and the foil.
In a heating dominated climate you want the radiant barrier against the roof sheathing with the foil facing the interior of the attic.
I find this a fascinating subject. We have a 13 year old home with a HUGE attic. Well insulated with blown in cellulose. However our two Hvac units are up in the attic and wow, it gets hot up there.
When the AC kicks on, your greeted with a hot blast of air.
I always wondered if what the OP did would significantly reduce the temperatures in the attic during summer.
Im assuming the attic is around 130 degrees on a 90+ degree day and its above 90 degrees everyday for 4 months.
Anyway, always wondered, not even sure if I would be able to do it, attic ceiling is high and a lot of blown in insulation would end up getting messed up because it would have to be pushed around to find the joists to walk on.
Maybe I could wrap the AC/Heat ducts with the stuff? Sounds nuts, but wonder if adding to the insulated reflective flex duct would help.
As far as the reflective stuff on the rafters, I know some areas I could more easy get too, like above the master br and if the stuff works, its would help in that area of the home.
My posts are based on directly stapling to the rafters with airspace between the roof, from the soffit to the ridge vent
When the AC kicks on, your greeted with a hot blast of air.
I always wondered if what the OP did would significantly reduce the temperatures in the attic during summer.
Im assuming the attic is around 130 degrees on a 90+ degree day and its above 90 degrees everyday for 4 months.
Anyway, always wondered, not even sure if I would be able to do it, attic ceiling is high and a lot of blown in insulation would end up getting messed up because it would have to be pushed around to find the joists to walk on.
Maybe I could wrap the AC/Heat ducts with the stuff? Sounds nuts, but wonder if adding to the insulated reflective flex duct would help.
As far as the reflective stuff on the rafters, I know some areas I could more easy get too, like above the master br and if the stuff works, its would help in that area of the home.
My posts are based on directly stapling to the rafters with airspace between the roof, from the soffit to the ridge vent
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I had a house with an attic in the ends and the center was exposed beam. One end I laid the reflective foil on top of the insulation and the other stapled the reflective foil under the rafters. It seemed to make a difference . I put ridge vents on the house and doubled the square feet of the vents on the eves by using larger vents and adding a few extra. Lots of hot air comes out of the ridge vents
in real hot TX, I built my home with Cool Ply, the radiant backed roof decking. Did it help? Maybe, but my attic is still boiling hot in the 9 month long summer we have.
Originally Posted by PimTac
In my opinion, attic ventilation in hot climates will have more effect than radiant barriers.
+ 100.
In my opinion, attic ventilation in hot climates will have more effect than radiant barriers.
+ 100.
Originally Posted by alarmguy
I find this a fascinating subject. We have a 13 year old home with a HUGE attic. Well insulated with blown in cellulose. However our two Hvac units are up in the attic and wow, it gets hot up there.
When the AC kicks on, your greeted with a hot blast of air.
I always wondered if what the OP did would significantly reduce the temperatures in the attic during summer.
Im assuming the attic is around 130 degrees on a 90+ degree day and its above 90 degrees everyday for 4 months.
Anyway, always wondered, not even sure if I would be able to do it, attic ceiling is high and a lot of blown in insulation would end up getting messed up because it would have to be pushed around to find the joists to walk on.
Maybe I could wrap the AC/Heat ducts with the stuff? Sounds nuts, but wonder if adding to the insulated reflective flex duct would help.
As far as the reflective stuff on the rafters, I know some areas I could more easy get too, like above the master br and if the stuff works, its would help in that area of the home.
My posts are based on directly stapling to the rafters with airspace between the roof, from the soffit to the ridge vent
Unfortunately HVAC in vented attic is standard in the SE US. Basically the equipment is "outside". In this case the best solution is to bring the HVAC equipment inside the housing envelope. This means you move the insulation from the attic floor to the roof deck and create an unvented roof. The best way to do that is to sandwich a layer of rigid foam between the rook deck and the exterior roofing material (Asphalt Shingles, Metal, tile, etc). The second way is to insulate from the interior side of the roof deck with closed cell spray foam (ccSPF) or a combination of ccSPF and either open cell spray foam (ocSPF) or fluffy stuff. Then add a small takeoff supply/return to the attic space to control humidity which travels up from the floors below.
ccSPF at 2" essentially becomes a vapor barrier. ocSPF will allow water vapor to migrate through to the roof sheathing where after repeated daytime solar drive that moisture will de-absorb and reabsorb at high sections of the roof and eventually rot.
The side benefit is that with an air-sealed attic space, you will get much better performance out of your HVAC and might even be able to save more $$ by replacing it with a smaller unit.
HVAC systems should NEVER be in an vented attic. Builders do it because they want to save money on construction costs.
I find this a fascinating subject. We have a 13 year old home with a HUGE attic. Well insulated with blown in cellulose. However our two Hvac units are up in the attic and wow, it gets hot up there.
When the AC kicks on, your greeted with a hot blast of air.
I always wondered if what the OP did would significantly reduce the temperatures in the attic during summer.
Im assuming the attic is around 130 degrees on a 90+ degree day and its above 90 degrees everyday for 4 months.
Anyway, always wondered, not even sure if I would be able to do it, attic ceiling is high and a lot of blown in insulation would end up getting messed up because it would have to be pushed around to find the joists to walk on.
Maybe I could wrap the AC/Heat ducts with the stuff? Sounds nuts, but wonder if adding to the insulated reflective flex duct would help.
As far as the reflective stuff on the rafters, I know some areas I could more easy get too, like above the master br and if the stuff works, its would help in that area of the home.
My posts are based on directly stapling to the rafters with airspace between the roof, from the soffit to the ridge vent
Unfortunately HVAC in vented attic is standard in the SE US. Basically the equipment is "outside". In this case the best solution is to bring the HVAC equipment inside the housing envelope. This means you move the insulation from the attic floor to the roof deck and create an unvented roof. The best way to do that is to sandwich a layer of rigid foam between the rook deck and the exterior roofing material (Asphalt Shingles, Metal, tile, etc). The second way is to insulate from the interior side of the roof deck with closed cell spray foam (ccSPF) or a combination of ccSPF and either open cell spray foam (ocSPF) or fluffy stuff. Then add a small takeoff supply/return to the attic space to control humidity which travels up from the floors below.
ccSPF at 2" essentially becomes a vapor barrier. ocSPF will allow water vapor to migrate through to the roof sheathing where after repeated daytime solar drive that moisture will de-absorb and reabsorb at high sections of the roof and eventually rot.
The side benefit is that with an air-sealed attic space, you will get much better performance out of your HVAC and might even be able to save more $$ by replacing it with a smaller unit.
HVAC systems should NEVER be in an vented attic. Builders do it because they want to save money on construction costs.
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FWIW: When we built our new home in 2017, I had the builder use the foil backed roof sheathing (foil is inward facing into the vented attic space, GP brand). It dropped the summer temperature in the attic by 20-30°F compared to our older house in which my vented attic didn't have this better sheathing product. Additional cost was ~$1.4K (~2400 SF house). Well worth it in my book. I have plenty of items stored in that new attic space (even after a good downsizing) and I did it for this reason as well as for better energy efficiency as well. We used blown-in insulation of ~R-40+ or so. My HVAC system is in the attic space (dual fuel type) as well.
I do wish I had built the attic with the HVAC system in a somewhat air-sealed space but that was not feasible in my case (refer to Matt Risinger on Youtube for more info on the benefits).
I do wish I had built the attic with the HVAC system in a somewhat air-sealed space but that was not feasible in my case (refer to Matt Risinger on Youtube for more info on the benefits).
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4WD
$50 site donor 2024
Originally Posted by billt460
Originally Posted by PimTac
In my opinion, attic ventilation in hot climates will have more effect than radiant barriers.
+ 100.
Really needed both in my case - and mine work together.
Two things on RB alone.
1) some homes need them more than others - I have a ranch style house with a tight attic - and when we moved there in 1996 there were no trees on the southwest side
2) if one is considering the RB install - they need to study up on it and understand what mistakes can be made - like someone mentioned an air gap needs to be present and the surface has to stay clean and shiny (why I used the double foil that actually has four faces - two of them internal.
If I was building new - especially a two story and no trees like some developers throw down - I'd just use the tech shield as mentioned above.
Originally Posted by PimTac
In my opinion, attic ventilation in hot climates will have more effect than radiant barriers.
+ 100.
Really needed both in my case - and mine work together.
Two things on RB alone.
1) some homes need them more than others - I have a ranch style house with a tight attic - and when we moved there in 1996 there were no trees on the southwest side
2) if one is considering the RB install - they need to study up on it and understand what mistakes can be made - like someone mentioned an air gap needs to be present and the surface has to stay clean and shiny (why I used the double foil that actually has four faces - two of them internal.
If I was building new - especially a two story and no trees like some developers throw down - I'd just use the tech shield as mentioned above.
In my experience with a house overseas that was extremely hot in the attic, I hooked up a bathroom exhaust fan at the peak of the attic and ran the exhaust to the soffit since I didn't want to cut holes in the roof. Due to the size of the attic I wired up two of these setups. The difference was dramatic after about 10-15 minutes.
We set them up on a switch inside the house and since these were Panasonic fans we didn't hear any noise at all.
We set them up on a switch inside the house and since these were Panasonic fans we didn't hear any noise at all.
Originally Posted by WhizkidTN
FWIW: When we built our new home in 2017, I had the builder use the foil backed roof sheathing (foil is inward facing into the vented attic space, GP brand). It dropped the summer temperature in the attic by 20-30°F compared to our older house in which my vented attic didn't have this better sheathing product. Additional cost was ~$1.4K (~2400 SF house). Well worth it in my book. I have plenty of items stored in that new attic space (even after a good downsizing) and I did it for this reason as well as for better energy efficiency as well. We used blown-in insulation of ~R-40+ or so. My HVAC system is in the attic space (dual fuel type) as well.
I do wish I had built the attic with the HVAC system in a somewhat air-sealed space but that was not feasible in my case (refer to Matt Risinger on Youtube for more info on the benefits).
Well good news is that E. Tennessee is a heating dominated climate (Climate Zone 4) so you're better off with your current setup.
FWIW: When we built our new home in 2017, I had the builder use the foil backed roof sheathing (foil is inward facing into the vented attic space, GP brand). It dropped the summer temperature in the attic by 20-30°F compared to our older house in which my vented attic didn't have this better sheathing product. Additional cost was ~$1.4K (~2400 SF house). Well worth it in my book. I have plenty of items stored in that new attic space (even after a good downsizing) and I did it for this reason as well as for better energy efficiency as well. We used blown-in insulation of ~R-40+ or so. My HVAC system is in the attic space (dual fuel type) as well.
I do wish I had built the attic with the HVAC system in a somewhat air-sealed space but that was not feasible in my case (refer to Matt Risinger on Youtube for more info on the benefits).
Well good news is that E. Tennessee is a heating dominated climate (Climate Zone 4) so you're better off with your current setup.
Our attic is huge, well ventilated so nothing more can be done for that. Soffits are all open on every side of the house with proper foam "channels" in needed areas to make sure they stay open and insulation doesn't block them. Ridge vents are along the entire top of the roof in all directions.
Power ventilators would most likely use more power then they would be worth and I doubt except for some over sized series of them would ever be effective and the cost plus electric would kill any advantage.
Spray Foam on the roof sheathing scares me, more so if not done right and then even another reason.
1. Moisture Concerns
2. Roof life concerns. By insulating the sheathing that the roof is nailed into greatly increases the roof temperature as the heat is not allowed to escape. I know foam is done, been in many attics doing security cables and Cat5.
No doubt, if I want that something extra would be to Staple AstroFoil to the rafters, it will still allow air to flow under the roof but will help push it up to the ridge vents.
Its something I thought of a long time, whether or not I get to do it, I dont know but I do know, I will do it on one side of the home above our master BR and Bath as it is easy to get to.
Power ventilators would most likely use more power then they would be worth and I doubt except for some over sized series of them would ever be effective and the cost plus electric would kill any advantage.
Spray Foam on the roof sheathing scares me, more so if not done right and then even another reason.
1. Moisture Concerns
2. Roof life concerns. By insulating the sheathing that the roof is nailed into greatly increases the roof temperature as the heat is not allowed to escape. I know foam is done, been in many attics doing security cables and Cat5.
No doubt, if I want that something extra would be to Staple AstroFoil to the rafters, it will still allow air to flow under the roof but will help push it up to the ridge vents.
Its something I thought of a long time, whether or not I get to do it, I dont know but I do know, I will do it on one side of the home above our master BR and Bath as it is easy to get to.
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Originally Posted by alarmguy
Maybe I could wrap the AC/Heat ducts with the stuff? Sounds nuts, but wonder if adding to the insulated reflective flex duct would help.
Go to www.atticfoil.com . They have videos, one says to wrap attic ducting to block heat from heating up the ducts.
Maybe I could wrap the AC/Heat ducts with the stuff? Sounds nuts, but wonder if adding to the insulated reflective flex duct would help.
Go to www.atticfoil.com . They have videos, one says to wrap attic ducting to block heat from heating up the ducts.
4WD
$50 site donor 2024
Yep … that is the one I never got around to doing - maybe this winter
However, I will still use the double foil because if the surface gets all dusty - guess what ?
However, I will still use the double foil because if the surface gets all dusty - guess what ?
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