Blown fiberglass installed in the attic has an R-value of 2.2 per inch, so 12 inches of it would give you an R-value of 26.4 in your attic installation project..
Table of Contents
Does blown in insulation need a vapor barrier?
Air / Vapor Barrier
A common misconception is that vapor barriers are required in all insulation installations. With Modern’s Cellulose insulation, a vapor barrier is not recommended except in very cold weather or high moisture areas such as spas or pool buildings.
What is the best R-value for 2×4 walls?
Insulation for 2×4 Walls
In most wall applications, you will use R-13 or R-15 kraft-faced fiberglass insulation rolls for these two-by-four stud walls. While rated differently, these two types of insulation are close enough in thickness that they can both fit into modern two-by-four wall systems.
What happens when blown in insulation gets wet?
The Effects of Wet Cellulose Insulation
Excessive moisture causes the cellulose to sag and settle, an effect that is especially detrimental in wall cavities. Settled insulation could leave the entire upper half of your walls uninsulated!
Where should a vapor barrier be installed when using blown in insulation?
The vapor barrier is always installed facing the heated side of the wall or ceiling, because that’s where the moisture is coming from. Now let’s look at your situation, which is a little different. You have loose-fill insulation in the attic, which doesn’t have a vapor barrier.
Can blown insulation grow mold?
Well, technically speaking, mold doesn’t grow directly on insulation, but settles there after falling from roof sheathing, or grows on dust on top of the insulation.
Is a little frost in the attic normal?
In fact, many homeowners don’t realize that frost buildup in your attic is even possible. However, in older homes, it is a fairly common problem and can cause serious damage to your home.
Can you dry blown in insulation?
After all, water is a conductor, so wet fiberglass insulation is about as effective as no insulation at all. To help fiberglass insulation dry out, place a dehumidifier or fan in the area. If possible, remove the affected batts and transfer them to a warm place to dry.
Does my attic need a vapor barrier? In hot-dry climates a vapor retarder should also not be installed, but attics can be vented. All attics — vented or unvented — should have an air barrier (a properly detailed airtight drywall ceiling, for example) regardless of climate.
How many inches of blown insulation is R30?
Fiberglass Chart
| R-Value | Thickness | Bags / 1000 Sq Ft |
|---|---|---|
| R49 | 16.25” | 22.6 |
| R44 | 14.75” | 20.1 |
| R38 | 12.75” | 16.8 |
| R30 | 10.25” | 13.0 |
How do you prepare insulation for blown in attic?
How Can You Prepare Your Attic for Blown Insulation?
- Begin the preparation process by scheduling a home energy assessment.
- Next, clean out your attic.
- After your attic is organized and ready for installation, verify there are no water leaks in the area.
- Protect any light fixtures in the attic.
What R-value should I use in my attic?
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.
What is a good R-value?
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.
Do I need a vapor barrier in my ceiling?
It is essential to have a vapor barrier installed with your ceiling insulation. It’s not uncommon for moisture and dew to form on a ceiling because of the temperature differences; moisture can cause mold and rot if left unchecked.
How can I make my attic air tighter? Seal small gaps.
- Form an insulation dam. Form an insulation dam to prevent insulation from contacting the flue pipe.
- Find attic bypasses. Check for gaps in your attic that facilitate air movement by checking for dirty insulation.
- Fill holes with caulk.
- Stuff gaps with insulation.
Do blown in insulation need rafter Vents? Installing attic rafter vents before blowing in 22 inches of insulation is extremely important! Proper attic ventilation is essential to both efficiency and shingle longevity.
How much does it cost to insulate a 1000 sq ft attic? Homeowners can expect to pay $600 to $1,200 to have 1,000 square feet of attic space insulated with blown-in insulation. The price rises from around $1,000 to $1,500 to insulate the same amount fo exterior wall space. Much of the higher price is due to the longer time it takes to install wall insulation.
How many inches of insulation is R60?
The average recommended level is 17 inches of R60. In Zone 3, the average minimum requirement for attic insulation is 9 inches of R30 fill.
Which is better R19 or R30 insulation?
The bigger the R value, the better the insulation is at slowing down the heat transfer. So R19 is better insulation than R13, and R30 is better than R19. The larger the R value, the better the insulation value.
How thick is R60 blown cellulose?
R60 Required Thickness of Insulation Materials
| Insulation Material | Thickness Required for R60 |
|---|---|
| Fiberglass (Loose-fill) | 16-20 inches |
| Spray foam (Closed-cell) | 6-10 inches |
| Spray foam (Open-cell) | 10-14 inches |
| Cellulose (Loose-fill) | 15-20 inches |
• Nov 20, 2021
How thick is R60 blown?
R 60: Thickness that oscillates between 19 and 22 inches. R 70: Thickness that oscillates between 22 and 25 inches.
How many inches of blown in cellulose insulation do I need?
Cellulose holds an R-value of 3.7 per inch. Insulating an attic will require 9-14 inches of thickness. Lastly, mineral wool will generally hold an R-value of 3.3 per inch. To insulate an attic, you’ll need 9-15 inches of thickness.
Can I put R19 in a 2×4 wall?
While you can stuff r19 insulation into a 2×4 wall, it is typically not the best way to go about boosting your home’s insulation rating. R19 insulation is meant to fit 2×6 walls. Cramming the insulation into a smaller area might seem like a good idea, but it ultimately won’t result in the r19 rating you would expect.
What is the R-value of 3 inches of spray foam?
Open cell spray foam insulation is R-3.6 to R-3.9 per inch. This R-Value is normal for open cell spray foam.
How thick of insulation can you put in a 2×4 wall? A 2×4 wall cavity can be insulated from R-13 to roughly R-25. A 2×6 wall can be insulated from R-19 to R-39. Material selection, density, and cavity depth all play a role in the “cavity” R-value of a wall. For the purpose of our discussion, we’ll use R-15 for a 2×4 wall, and R-21 for a 2×6 wall.
How many inches of insulation should be in an attic?
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.
