Does insulation go face up or face down?

Author: Keanu Gutmann MD  |  Last update: Saturday, December 6, 2025

(The general rule for insulation is that the facing always goes toward the conditioned space.) The second layer of insulation should be unfaced so that moisture doesn't collect between the layers.

Should insulation face up or down?

The insulation barrier should face down towards the house to prevent heat and moisture from entering the insulation.

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.

Does it matter which way an insulation board faces?

Therefore, when installing foil faced insulation always fit the foil side where the temperature difference is greatest. So, any time you use a single side foil insulation, the foil needs to be facing toward the living space.

What is the proper placement of insulation?

In finished attic rooms with or without dormers, insulate (2A) between the studs of "knee" walls, (2B) between the studs and rafters of the exterior walls and the roof, (2C) and ceilings with unconditioned spaces above. (2D) Extend insulation into joist space to reduce air flows.

Which way does Faced Batt Insulation go?

Which way do you install insulation board?

Installing Insulation Boards Using Mechanical Fixings
  1. Step 1: Clean and prepare surfaces. ...
  2. Step 2: Remove render. ...
  3. Step 3: Measure and cut boards. ...
  4. Step 4: Apply flexible sealant to the wall. ...
  5. Step 5: Install the timber battens. ...
  6. Step 6: Fit insulation boards onto battens. ...
  7. Step 7: Seal gaps between the boards, floors, and ceiling.

Do you need to put plastic over faced insulation?

You should always install a vapor barrier to protect exposed ceiling insulation even if it's temporary. Consult with a building or safety expert to confirm where else in the structure a vapor barrier may be required.

Should you leave a small gap between the insulation and the boards?

It is important to leave a small air gap between boards and the mineral wool in order to stop damp forming. Remember that insulating between the joists will create a cold roof space as the heat is kept underneath the insulation like a blanket.

Does insulation go foil side up or down?

No air space means no thermal value. The reflective side must be facing downwards when in roofs, upwards when installed underneath a floor and inwards when installed in walls.

Does faced insulation need to be stapled?

If you're using faced insulation, install it with the vapor retarder positioned down toward the room. Hold the insulation up with one hand, while stapling the flange on both sides every 6" - 8" with the other hand. Leave a little extra on each end to cover the top plate of the outside wall.

Should wires go in front or behind insulation?

Wires should be going through studs near the center of each stud to prevent screws from hitting them when drywall is installed. If you put the insulation in front of or behind the wire, it squeezes the insulation, making it lose R-Value.

Does order of insulation matter?

One of the most important rules of insulation installation order is to install the thickest layer of insulation first, and then add thinner layers on top of it. This is because the thicker the insulation, the higher the R-value, and the more effective it is at preventing heat transfer.

What should you not do when installing insulation?

Leaving Too Many Gaps

One of the biggest problems DIY homeowners face is leaving too many gaps in their insulation. Gaps or insulation that isn't secured correctly can leave the building structure open to air and moisture leaks. Spray foam insulation is best for reaching into small cracks and any areas left open.

Does pink insulation have asbestos?

What is the pink fluffy stuff on the walls? The pink fluffy material is usually fiberglass insulation, commonly used for its safety and efficiency. It does not contain asbestos.

What is the correct way to install insulation?

You should install two layers of insulation in your attic; wood joists must be covered to allow the air to move. The first layer will sit between the joists, and the second layer will run perpendicular over the joists. The first layer should have the facing against the drywall to act as a vapor barrier.

What side should insulation face?

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.

What happens if you install insulation without a mask?

If you do not like the sensation of dirt or dust on your skin, you will want to wear gloves and cover exposed skin. The dust of cellulose can still be hazardous for your eyes and lungs. If you are near cellulose being installed and do not wear a mask, you will inhale dust and irritate your lungs.

What goes on first insulation board or house wrap?

Yes, House Wrap Does Come First!

Often, those installing foam insulation ask, “Do I put house wrap on first or second?” Whether you're installing James Hardie siding or not, house wrap is always applied first. The experts place the material in the proper orientation to achieve maximum insulation.

Can you glue insulation board to a wall?

Answer: Insulated plasterboards can be bonded over existing plaster using acrylic sealant adhesive or low expanding PU foam adhesive, so long as the plaster is sound, solid and dry.

Can foil-faced insulation be left exposed?

Kraft or foil facedFaced insulation is a batt or roll of fiberglass insulation with an attached kraft paper or foil facing. Kraft and standard foil facings can burn and must not be left exposed.

Should paper go up or down for crawl space insulation?

A: The paper should always be placed towards the living space according to the manufacturers we are familiar with. Make sure the wood is dry before installing.

Should attic insulation face up or down?

When installing fiberglass insulation in your home, be sure to put the paper or foil vapor barrier facing toward the heated and cooled living area of the home (down in attics, up under floors, in on walls) to prevent condensation from occurring.

Is R19 insulation good for crawl space?

A Common Place to Use R19 Insulation

The most common application of R19 Insulation is in a vertical wall framed by 2×6 studs. As mentioned above this is a common code requirement in some parts of the United States. R19 Insulation can also be used in other areas around the home, including floors and crawl spaces.

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