Should foam board insulation be shiny side in or out?

Author: Kyler Senger  |  Last update: Saturday, April 25, 2026

If you are wondering how to install the foil backed insulation on your walls here you have few tips to consider. if it is hot outside, the reflective part of your foil insulation must face outside. if it is freezing outside, the best orientation of the reflective part is inside.

Should foam insulation be shiny side in or out?

If there is no dead air space, it doesn't matter which way the metallic side is facing. Placing the metallic facer towards an open-air space may allow the material to act as a radiant barrier.

Which side of foil board faces out?

Install the Foilboard® GREEN rigid insulation panel to the external face of the studwork, ensuring the anti-glare side is facing out, measure the area you require. Tape all penetrations, joints and gaps using the Foilboard® green PVC tape, ensuring the stop of cold / hot air transfer.

Which side goes up on insulation?

The rule is that the insulation should always face the warm-in-winter side of the space. This rule means that, in most cases, the vapor barrier should face the home's interior.

Which side faces out on foam board insulation?

if it is hot outside, the reflective part of your foil insulation must face outside. if it is freezing outside, the best orientation of the reflective part is inside. if you press the foil side of the insulation tight up against the wall (foil facing outward), the radiant barrier will not work.

Garage door insulation. Reflective foil side facing in or o

What is the warm side of insulation?

Vapor barrier materials are installed on the warm side of the insulation in a building assembly, as determined by climatic conditions. In warm climates, it will be on the exterior and in cold climates, it will be on the interior.

Should the shiny side of foil be in or out?

Foil has a shiny side and a dull side because of how it is manufactured. Unless you are using foil that's labeled non-stick, which does have a non-stick side, it does not matter what side you use. Both the shiny and dull sides can be used the same way to cook, freeze, and store food.

Do you need an air gap with foam board insulation?

Insulation boards are no exception to this rule, and it's important to leave an air gap between them and the surface they're installed on.

How to install foil faced foam board?

A Step-by-Step Guide How to Install Foil Faced Insulation Board
  1. Step 1: Measure the Area. ...
  2. Step 2: Cut the Insulation Board. ...
  3. Step 3: Apply Adhesive. ...
  4. Step 4: Install the Insulation Board. ...
  5. Step 5: Secure the Insulation Board. ...
  6. Step 6: Repeat for Additional Boards. ...
  7. Step 7: Clean Up. ...
  8. Step 8: Enjoy the Benefits.

What is the best way to fasten foam board insulation?

Ideally, you should use construction adhesive to install furring strips over foam boards. Alternatively, you can use nails. Make sure there is a gap of 3/4″ between the foam board and the block wall. Thus, even if moisture comes from the block, the foam will remain unaffected.

How is foam insulation installed?

How to Apply Spray Foam
  1. Start by doing a test spray. ...
  2. Spray evenly between the studs and on the backside of the exterior sheathing. ...
  3. Allow the foam to form and set.
  4. Shave away any foam that extends past the studs.

Does foam board insulation need to be covered?

That said, it's still advisable to cover any foam board insulation exposed to the Sun within 30-60 days at the most.

Which way to put insulation board?

To fix insulation boards to a wall using this method, start by ensuring the wall is clean and dry. Fix battens around the top and bottom of each wall. Be sure to apply a batten to each corner and around window and door frames. Then, fix the battens vertically around the room at a minimum of 600mm centres.

What is the difference between foil faced and unfaced foam board?

Foil faced insulation consists of a vapour retarder (the facing) that will block moisture movement from one space to another. While unfaced insulation such as fibreglass can be itchy to install, foil faced insulation is a way better material to work with.

Can you put drywall on foam board?

Assuming the foam was properly fastened, this would require fewer drywall screws and might minimize the possibility of dimpling. I'd also use extruded polystyrene instead of polyiso, because it seems denser and less likely to dimple. And I wouldn't use foam thicker than one inch.

What are the cons of foam board insulation?

Insulation Foam Boards Don't Work On Uneven Walls

This allows moisture to seep in. Excess moisture can cause mold, mildew, odors, decay, fungus growth and wood rot.

Should you leave an air gap between the insulation and the boards?

It's important to leave a ventilated air gap between the insulation and the boards to prevent condensation on the underside of the boards.

Do you need vapor barrier with foam board insulation?

In general, if the foam rigid insulation is installed correctly and sealed properly, a vapour barrier may not be necessary. However, there are certain situations where a vapour barrier is recommended, such as in areas with high humidity levels or where there is a risk of moisture infiltration.

What does "keep the shiny side up" mean?

Shiny side up. Your vehicle hasn't flipped over after a rollover or accident. “Keep the shiny side up” means to have a safe trip.

Which side of Reynolds aluminum foil to use?

With standard and heavy duty foil, it's perfectly fine to place your food on either side so you can decide if you prefer to have the shiny or dull side facing out. For Reynolds Wrap® Non-Stick Aluminum Foil, you'll want to have the dull side facing up.

Does it matter what side of insulation faces out?

When installing faced insulation, the facing should always point toward the interior, heated, or air-conditioned space. For example: On exterior walls, the facing should touch the drywall. In attics, the facing should point down toward the ceiling below.

Should you put a vapor barrier over insulation?

After the insulation is in place you will want to add a vapor retarder, sometimes called a vapor barrier, if you need one. Not every wall does. A vapor retarder is a material used to prevent water vapor from diffusing into the wall, ceiling or floor during the cold winter.

Should I put plastic over insulation before drywall?

Should I Put Vapor Barrier Plastic Over Insulation Before Drywall? Yes, covering your insulation with a vapor barrier plastic before installing drywall is crucial. It prevents moisture buildup that can lead to mold, rot, and even structural damage.

Previous article
Is there an alternative to washing clothes?
Next article
How much does a mechanic charge to recharge an AC?