Radiant Barrier directly under vinyl siding

[skeer]

Whether it's the single layer foil, or the double-sided bubble-wrap or foam core... What is the current consensus of putting a barrier underneath vinyl siding?

Utterly useless?
Are the horizontal pockets of air gap enough?

 

[jack stand]

I'd check with the siding manufacturer. I would listen to any manufacturer that you can get an answer from. Excessive heat and vinyl siding can be a problem.
I had one unit (with one window) in a condominium project that had one little area on an inside corner where the sunshine would reflect off one windows and distort a little area on the adjacent wall. As the original contractor I replaced it for several years out of sympathy for the (also) innocent bystander.
By the way the double bubble stuff is a gimmick.

 

[skeer]

Egad! I forgot all about all the heat being reflected back out.

 

[CraigStu]

I know this is a way different situation but a friend was involved in the electronics wiring part of a county gov. building that was being rehabbed. he was there initially and then called back once in a while when a change was needed in the computer wiring. Apparently there were a lot of glass windows on the inside of the 'U' shaped building. There had always been problems w/ those offices being hot from sun so part of the rehab was to coat the glass w/ something to reduce the heat. Worked great inside. But outside nearly every shrub that was planted would end up dead. He was on an upgrade 2 yrs later and asked about the sorry look outside. Someone finally realized that the heat now being reflected off the grass made 'U' into a desert. I can only imagine what a house wall w/ covered w/ foil would be like.

 

[skeer]

Ugh.. the east and south sides of my house cook in the summer. Been thinking up ways to combat that.. grass I'm not too concerned about as the soil here is more sand and moss than anything. Planting thick bushes perhaps but I'd rather not wait a few years for them to be useful. We are going to film the windows with some ceramic window film but the walls themselves. I guess the easiest and most cost effective path forward would be to place some 5mm encapsulated foam (non-reflective) under the siding instead.

 

[paulsomlo]

Radiant barriers need an air space on at least one side to be effective, about 3/4". If you can't provide that, it may not be worth it. The people who sell those barriers make all kinds of claims regarding R value, most of which are rubbish.

 

[ycgoat]

I would expect that vinyl siding would have air gaps for at least 1/2 of the surface area and so the foil would reflect %50 of the radiant heat back out which could still be good value when comparing A/C cost to install cost over a period of time. For heating of the vinyl I have no clue, you could set up a test sample.

 

[CraigStu]

It would be worth some internet searching to see if there are any vinyl (or other) siding that help deal w/ sun. This has to be a common problem. Beyond light colors I don't know but there may be something.