Is 6 inches of attic insulation enough?

Most joists are six to seven inches tall, and if they are completely filled with material, they are insulated at R-21. However, the DOE recommends that attics in Southern homes be insulated with 13 to 14 inches, or R-38, of insulation at minimum.

How many inches of insulation do I need in the attic?

According to the U.S. Department of Energy, it's recommended that attics have an R-38 to R-49, or about 12” to 15” of fiberglass or cellulose insulation. Use unfaced insulation when adding more insulation to an attic that already has some insulation, laying the rolls or batts at right angles to the floor joists.

What R-Value is 6 inches of insulation?

Fiberglass blankets or rolls provide an R-value of up to 3.2 per inch, so a 6-inch fiberglass batt may achieve an R-value of 19.2, and some high-performance products are rated at R-21.

What thickness is best for attic insulation?

Each type of insulation has a different insulation value or U-Value - the lower the U-Value, the better the insulating material. Typical insulation in an attic should be more than 20-30cm thick unless you are using more advanced thinner materials.

Can you put too much insulation in an attic?

It's possible to over-insulate an attic as too much will cause moisture buildup and eventually result in mold. Eventually, adding more insulation leads to diminishing returns in trapping heat as well.

How to Beef Up Attic Insulation | This Old House

Should I insulate between the rafters in my attic?

Insulating between rafters will do no good, because the attic should be ventilated, and the rafter insulation would be between two unheated spaces. You can add insulation to the floor; the more the merrier. Just don't put it in the eaves. Also, make sure the attic is well ventilated.

What happens if you over insulate?

It is possible to over-insulate your house so much that it can't breathe. The whole point of home insulation is to tightly seal your home's interior. But if it becomes too tightly sealed with too many layers of insulation, moisture can get trapped inside those layers. That's when mold starts to grow.

What is the minimum thickness for roof insulation?

The minimum recommended thickness of loft insulation has differed greatly over the years. In the 1980s, it was quite standard to install any thickness from 25 to 50 mm. Then, building regulations stated that homes should have as much as 100 mm of loft insulation.

What thickness of insulation do I need?

Achieving a U value of 0.20W/m² (meaning your roof will be better insulated than your walls) will need 120mm thickness of rigid foam or 200mm of mineral wool or natural insulation. Hitting amazing levels of 0.13W/m² will need 300mm of mineral wool or 180mm of rigid foam.

How much difference does attic insulation make?

One of the places in your home where a little bit of attention can make a big difference in your comfort — and heating bill — is the attic. According to the Department of Energy, properly insulating the attic can save 10 to 50 percent on a typical heating bill.

What insulation should I use for 6 inch walls?

Use R-19 or R-21 kraft-faced fiberglass insulation for two-by-six (2x6) walls. This combination ensures that the insulation is neither too loose nor too tightly packed within the walls.

What is the R-value of 6 inch Styrofoam?

One common use of extruded polystyrene foam board is for foundation insulation panels. Polyiso (Polyisocyanurate). This is an even more dense and more expensive foam board insulation. It provides an R-value of 6 per inch of thickness and often comes foil-faced to help reflect radiant heat.

Does doubling insulation Double R-value?

Doubling the thickness of insulation will double the insulation's R-value, cutting heat loss in half. Each time the insulation layer is doubled in thickness, this rule applies.

How do I know if I have enough insulation in my attic?

Looking across your attic, if the insulation is level with or below the attic floor joists, you probably need to add more insulation. Assumes R-3/inch. If you cannot see any of the floor joists because the insulation is well above them, you probably have enough, and adding more insulation may not be cost-effective.

How do you tell if attic is well insulated?

Do you need an air gap for insulation?

Insulation is technically a solid with a lot of air in it therefore, it is NOT an air gap. You literally must have a VOID, nothing in the air gap except air itself. So if you are installing under a roof or in a wall, you must create an air gap.

How thick should insulation be between rafters?

Common rafter depths range from 100mm to 200mm. This limits the maximum thickness of the insulation between the rafters to between 50mm and 175mm. This generally would not be a sufficient thickness to achieve the U-values required to meet Building Regulations and more insulation would need to be added.

Should you insulate the underside of your roof?

In order to avoid damage to the roof deck, you should insulate ceilings to create an air barrier between the living space and an unfinished attic or airspace underneath the roof deck.

How thick should insulation be on a warm flat roof?

An uninsulated flat roof has a U-Value of around 1.5 W/m2K. When insulating one, you're aiming for a value of 0.25 W/m2K or less. To achieve this, you should insulate your flat roof with insulation boards totalling around 150mm thickness.

Is it worth adding extra loft insulation?

Financial saving

The most obvious difference offered by an insulated loft is the saving in energy bills, and it's very simple here. It's estimated that a quarter of all the escaping heat from a building goes through the roof. If that could be stopped, your bills should be reduced by a quarter.

Is it better to insulate ceiling or roof?

If you are deciding between insulating the roof deck or the ceiling, Insulating your ceiling should be the priority. Not only is it easier but ceiling insulation is beneficial in a number of ways: Keeps the temperature in the building regulated. Saves on energy costs.

Is R60 attic insulation worth it?

Recommended R-Value Varies by State

You need exactly as much as the area you live in determines. Here, where temps get pretty hot for much of the year, attics should have from R30 to R60 (average is R38). Those living up north want anything from R49 to R60. This helps insulate against the extreme cold weather.

Should you insulate the attic ceiling?

Proper attic insulation can also keep your roof in better condition by helping to prevent ice dams and condensation. Your building codes may require you to have a certain quality of insulation. However, installing even better insulation is to your advantage and your roof's advantage.

What is too much insulation?

How Much Insulation is Too Much? In Southern California, you'll want to shoot for an R-Value of around 30 for an optimum experience. The California Department of Energy's 2019 Building Envelope requirements state the minimum R-Value for wood-construction ventilated attic spaces in California is R-22.