Is R30 insulation good for an attic?

Author: Tia Schulist  |  Last update: Sunday, June 29, 2025

Attics are one of the most common areas for R30 insulation. Since heat rises, an uninsulated attic can become a major source of heat loss in winter and heat gain in summer. Installing R30 insulation helps create an effective thermal barrier, maintaining a stable indoor temperature.

Is R30 enough insulation for an attic?

Depending on where you live and the part of your home you're insulating (walls, crawlspace, attic, etc.), you'll need a different R-Value. Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38 and R-49 are common for ceilings and attic spaces.

Is R19 or R30 better for an attic?

Yes, you can use R19 insulation in an attic, but whether it's suitable depends on a few factors: Climate Zone: R19 insulation is typically appropriate for attics in moderate climates. In colder climates, higher R-values (like R30 or R38) may be recommended to effectively prevent heat loss.

What R-value should I use in my attic?

Insulation levels are specified by R-Value. R-Value is a measure of insulation's ability to resist heat flow. The higher the R-Value, the better the thermal performance of the insulation. The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.

Which is better insulation R30 or R38?

The higher the R value, the more insulation it provides and with the R38 being the least expensive, it is the way to.

How to Choose the Best Insulation for Your Home | DIY Home Renovation

What are the benefits of R30 insulation?

This insulation is particularly beneficial for homeowners in regions with extreme seasonal weather patterns. Additionally, R30 insulation is ideal for reducing heating and cooling costs. By creating a thermal barrier, it minimizes the workload on HVAC systems, leading to energy savings.

Can you have too high of an R-value insulation?

The optimal R-value for most homes is 30, but you can go as high as 38 if you live in a tropical climate. Anything higher than 38 indicates an over-insulated space.

Can you over insulate an attic?

While loft insulation is an effective way to improve energy efficiency and reduce heating costs, over-insulating can lead to several potential issues. Firstly, over-insulation can lead to poor ventilation in the attic, which can cause moisture buildup and increase the risk of mould growth.

Which insulation is best for a ceiling?

When it comes to insulating ceilings, attics, walls, and crawlspaces, homeowners and builders often choose fiberglass batts. Besides being cost-effective, they prevent heat from passing through walls, ceilings, and floors. Generally, fiberglass batts come in 2*4 or 2*6, but you can cut them down if necessary.

Is it OK to use R19 insulation in attics?

You will want to bring up your attic up to R-38:

If your attic has 5-6″ of existing insulation, you'll want to install an R-19 to achieve a total of R-38.

Is it worth upgrading attic insulation?

Heat naturally rises, and without proper insulation, it escapes through your attic, forcing your HVAC system to work harder. 💰 Upgrading insulation can reduce energy costs by up to 30%! ✅ Better insulation = less heat loss in winter and less heat gain in summer.

What is the recommended level of attic insulation?

Warm loft insulation (Professional)

For the full recommended depth of 270mm, insulation must be installed between and beneath the rafters. You'll also need Building Regulations approval before work can begin.

How thick is R30 roof insulation?

The owner's requirement for, say, R-30 insulation means 5.2” of polyiso, but that definitely does not mean a 5.2” thick board. At minimum, you want to provide two layers of 2.6” iso, with the top layer's joints offset at least 6” from the underlying layer.

What is the most common attic insulation?

The first and most common type of attic insulation is fiberglass batt insulation. It looks remarkably like cotton-candy and clouds, and it's likely the image you envision when someone says “attic insulation.” Its popularity has remained steady for decades, and it is a firm favorite amongst homeowners.

What is the minimum thickness for attic insulation?

According to the Ontario Building Code, the minimum recommended R-value for attic insulation in new construction homes is R-60. This translates to approximately 22 inches of loose-fill insulation or 16 inches of fiberglass batt insulation.

Should attic insulation be faced or unfaced?

You can use faced or unfaced batting when installing between the roof rafters of finished attic spaces. When using paper or plastic batting insulation, that moisture barrier should face outward toward the attic space. Even if the attic space is unheated, it's typically warmer than the outside air in winter.

Should I remove old attic insulation before adding new?

Do I Have To Remove Old Insulation? Unless your insulation is wet, moldy or infested with pests, you don't need to remove it before adding insulation on top of it. ENERGY STAR® recommends that you inspect your insulation for signs of mold, mildew, moisture and pest infiltration before making this determination.

Where should you not put insulation in the attic?

Also, when laying down additional insulation, work from the perimeter toward the attic opening. Never lay insulation over recessed light fixtures or soffit vents. Keep all insulation at least 3 inches away from recessed "can" lights, unless they are rated IC (Insulated Ceiling).

Should an attic be sealed or vented?

In hot, humid locations, it may also be advisable to construct unvented rather than vented attics to help reduce the entry of moisture-laden air into the attic. In hot, humid locations, the outside air is likely to be more humid than the inside air.

What is the best R-value for an attic?

The U.S. Department of Energy recommends attic insulation levels of R-49 to R-60 for most homes in colder climates, and R-30 to R-49 for homes in warmer climates.

What is considered a bad R-value?

If we wish to label the strength of the association, for absolute values of r, 0-0.19 is regarded as very weak, 0.2-0.39 as weak, 0.40-0.59 as moderate, 0.6-0.79 as strong and 0.8-1 as very strong correlation, but these are rather arbitrary limits, and the context of the results should be considered.

Does doubling up insulation increase the R-value?

The thermal barrier of a home should consist of a continuous layer of insulation on all sides—including the lowest floor, the exterior walls, and the ceiling or roof. Doubling the thickness of insulation will double the insulation's R-value, cutting heat loss in half.

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