It’s perforated precisely for the purpose of venting, so you’ll likely have no moisture issues. But if the permeance is low (i.e. a good barrier) I wouldn’t create a moisture trap between the XPS and foil.

Is Reflectix a moisture barrier?

The product provides a vapor/moisture barrier, which is a strong contributor to the efficiency of the system. Reflectix® is available in convenient roll sizes which contributes to ease of handling and installation.

Is reflective insulation a vapor barrier?





Since radiant barriers and reflective insulations are typically made from a metal foil or metalized film, they also act as excellent moisture vapor barriers.

Is reflective insulation good for walls?

Reflective insulation can block 95% of radiant heat and provides superior thermal performance. Reflective insulation reflects escaping heat back in the direction of your home’s interior. By harnessing the loss it lowers your heating bills.

What kind of insulation is best for basement walls?

Rigid foam sheets are best for DIYers who are insulating basements prior to framing the walls. Rigid foam also works well when the concrete or block walls are smooth and flat. Rigid foam insulation is easy to use. In addition to scoring, it can be cut by an ordinary wood saw.

Does foil insulation cause condensation?

As well as reflecting and blocking radiant heat, radiant barriers and reflective foil insulation are also great at reducing condensation.

Does reflective insulation need an air gap?





Quote from the video:
Quote from Youtube video: So if you're going to do a wall assembly you've got to create an air gap doesn't matter on either side it's going to work either off of reflectivity or emissivity.

Will insulating basement reduce humidity?

Insulating your basement cannot reduce the humidity because it is designed to help control temperature. Insulation can help reduce humidity by keeping the air colder or reducing condensation by keeping the air warmer. However, it cannot change the moisture levels in the air.

Should you insulate your basement walls?

Walls. Basement walls should be insulated with non-water sensitive insulation that prevents interior air from contacting cold basement surfaces—the concrete structural elements and the rim joist framing.

Do you need a vapor barrier on basement concrete wall?

Building codes usually require a vapor barrier (4 mil plastic sheeting) on exterior basement walls if the framing is attached to masonry or concrete surfaces, or if the wood framing butts up against the outer basement walls.

Can too much insulation cause condensation?



Moisture and insulation



Improperly installed insulation is one of the leading causes of condensation in the attic, especially when too much insulation traps warm air up near the roof and forces condensation.

Does internal wall insulation cause condensation?

Internal wall insulation changes the fabric of your home, and can, if not employed properly, cause issues such as damp and condensation.

Does insulation make condensation worse?

Advances in housing insulation have meant a big increase in condensation problems. Homeowners are being warned to act to prevent damp talking hold. Ironically, condensation and dampness is getting worse as homes become better insulated.

How do you protect moisture from insulation?



Vapor Blockers



Vapor barriers—sheets of plastic or kraft paper—keep water vapor out of the wall cavity, so the insulation stays dry. Not every type of insulation needs a vapor barrier. But if it does, the barrier should face inside in northern, heating climates, and outside in humid southern climates.

Does insulation keep humidity out?

Yes, insulating your home can lessen moisture, especially if the insulation includes vapor diffusion retarders. Because insulation decreases heat transfer, it moderates temperatures throughout your home so humidity and moisture will be less likely to develop.

Can insulation trap moisture?

Although insulation helps to reduce moisture, it can also trap it, particularly in basements, leading to mold growth between insulation and walls. Warm air inside the basement condenses on cold concrete walls, producing ideal conditions.

Is XPS foam a vapor barrier?

XPS is manufactured in both an unfaced form or with different plastic facings. However, XPS is considered a vapor retarder, not a vapor barrier.

Is XPS foam vapor permeable?



Therefore, 1 inch of XPS is considered to be vapor semi-permeable, while 2 inches is considered to be vapor semi-impermeable.