Can you put batt insulation between rafters?

Author: Isai Daugherty  |  Last update: Tuesday, March 24, 2026

Placing Insulation: Place the insulation between the rafters. For fiberglass batts, ensure the paper side faces down if you mainly heat your home. If you mainly cool your home, the paper side should face up. Pressing Firmly: Press the insulation firmly into place but avoid compressing it.

Is it okay to put insulation between roof rafters?

The general advice we give is that you should always insulate between and above the rafters (warm roof) or between and under the rafters (cold roof).

Is it better to insulate between rafters or joists?

Here's the deal with insulating your ceiling: for most situations, placing insulation between the ceiling joists is the way to go! Think of the joists like the ribs of your ceiling - insulation in between acts like filling spaces in a cozy sweater for maximum warmth (or coolness).

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).

Can I insulate the underside of my roof?

Yes, you can insulate the underside of your roof. This approach helps improve energy efficiency and comfort by reducing heat transfer. Common methods include spray foam or fiberglass batts. Zavza Seal LLC can guide you on the best insulation options for your specific needs.

Insulating Attic Ceilings & Cathedral Ceilings (Phillips Vision: Episode - 63)

Does roof insulation need air gap?

Yes, an air gap between the roof and insulation is needed, especially for traditional materials like fibreglass, mineral wool, and foil insulation.

What is the best insulation for rafters?

The best attic insulation between rafters is mineral wool insulation. It's an affordable, easy-to-install, and effective material at retaining heat. However, an even more sustainable and effective alternative is treated sheep's wool, found at a slightly higher price.

Can you put too much insulation in 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.

Is it okay to put plywood over insulation in an attic?

Can I put plywood over insulation in the attic? Yes you can install plywood subflooring directly over the floor joists and insulation on your floor. You need to install rigid insulation boards on top of the attic flooring joists and then install plywood over the top.

How much insulation do I need between rafters?

The thickness of insulation material between rafters is a crucial factor in achieving an optimal level of thermal performance. That's why the UK regulations state that the recommended thickness range should be between 170mm and 350mm.

Can insulation touch the roof?

Yes it can touch. As long as there is nothing obstructing flow from the soffits - which sounds like the baffles are.

What goes between rafters?

Outrigger. An outrigger is sometimes called a "lookout". These are pieces of wood installed perpendicularly across rafters, from the common rafters in past one roof rafter and secured into the next.

Can you put insulation between joists?

Make sure that insulation boards are fitted tightly between joists and any gaps are filled with expanding urethane sealant. Any narrow gaps between a joist and perimeter wall should be insulated by specially cut pieces of board which in turn should be supported on blocks nailed to the underside of the joists.

Can you put rockwool in between rafters?

ROCKWOOL offers a range of products for installation both between and over the rafters. Offering more than warmth, ROCKWOOL pitched roof insulation also delivers additional peace of mind through its additional advantages of sound protection and exceptional fire resistance.

Is it better to insulate rafters or ceiling?

Since insulation is not water-resistant, insulating your ceiling will give you better protection for your money. The insulation in your ceiling is less likely to suffer damage from unidentified leaks. When a roof leak develops, you'll find it more easily, which means you can have it repaired sooner.

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.

Which is better, attic insulation blown or rolled?

Blown fiberglass insulation scores an R-value of 3.2 to 3.8, making it slightly less likely than rolled fiberglass to prevent the flow of heat into and out of your house. That being said, though, blown fiberglass insulation isn't meant to cover huge areas like rolled fiberglass 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.

Where should you not put insulation?

Never place insulation close to water heaters, oil burners or anything hot. The backing is especially flammable and will be a major fire hazard for your home.

Can your R-value be too high?

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. While you might think that too much insulation can't be bad, there are some significant consequences to consider.

Should I use r30 or r38 for attic?

If your attic has little or no existing insulation, you'll want to install an R-38 rated material. If your attic has 2-3″ of existing insulation, you'll want to install an R-30 to achieve a total of 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 OK to put insulation between roof rafters?

Insulating between roof rafters is not only okay, but it is often recommended as a way to minimise the use of headspace while maintaining comfortable indoor temperatures.

What is the best insulation for the underside of the roof?

Our Conclusion. We recommend spray foam insulation because of its relatively simple installation process, high R-value, and applicability to different climate regions.

Do I need insulation baffles in every rafter?

Homes with both traditional and vaulted ceilings need attic baffles if they utilize vented roofs, which feature: Closed (or box) eaves, where the rafters are enclosed and vented via soffits. Ridge vents at the apex of the roof, and/or. Gable vents on the flat area between the roofline and the exterior walls.

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