QA

Question: How To Insulate Roof Rafters

Is it OK to insulate roof rafters?

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. Good ventilation, from soffit vents and a ridge vent, will stop that.

Should I insulate between 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).

What insulation do you use for roof rafters?

Consider using high-density R-30 batts, which are as thick as R-25 batts, but fit into 2×10 framing. You can also add rigid foam insulation under the rafters, which adds R-value and eliminates thermal bridging through wood rafters.

Should you insulate the underside of your roof?

Preserve The Attic’s Airflow The airflow from the soffits to the ridge vent keeps the roof cool and prevents ice dams, and the material will block that flow. For the same reason, insulation shouldn’t touch the roof’s underside.

How do you insulate underside of roof?

Open-cell spray polyurethane foam or closed-cell spray polyurethane foam (ccSPF) insulation can be sprayed along the underside of the roof sheathing to provide a conditioned and insulated attic space that can be durable and efficient in all climate zones (see Figure 1).

How much space do you need between roof and insulation?

A minimum 2-inch air space is then provided as an “over-roof” to carry away any moisture that escapes up through joints in the insulation. The ventilation space also helps keep the underside of the over-roof surface cold, thus avoiding snow melting and forming ice dams.

What is the best insulation to use in your attic?

Many people consider fiberglass batt to be the best attic insulation. It consists of plastic reinforced by small glass fibers. The batt version comes in blanket form — i.e., small, pre-cut sections that you can lay down wherever you need to.

Does kingspan need an air gap?

The timbers must be deep enough to allow the desired thickness of Kingspan Kooltherm K112 Framing Board to be fitted between them along with a 25 mm (min.) air gap between the insulation layer and the brick wall. Once the boards are installed, Kingspan Kooltherm K118 Insulated Plasterboard can be fixed to the battens.

Is adding insulation to attic worth it?

According to the Department of Energy, properly insulating the attic can save 10 to 50 percent on a typical heating bill. For many homeowners, insulating the attic is the most effective method to save on energy costs.

How do you insulate a 2×4 rafter?

Put insulation meant for 2×4 framed walls between the joists (which will be the same height as the joists), then lay a perpendicular layer of attic insulation (maybe R-30) on top of them.

Should you spray foam your roof?

It really should be called spray foam insulation and air barrier. A properly done spray foam job not only insulates but also greatly reduces the air leakage of a home. If you leave the existing insulation in the attic, it interferes with the foam installation.

Can you spray foam your roof?

Apply spray foam at the underside of the roof sheathing and at the wall perimeter to create an air barrier connecting the wall to the roof, and to provide adequate thermal resistance to prevent condensation.

Can you insulate against a roof?

Experts usually advise builders that you can’t install fiberglass insulation directly against the underside of roof sheathing. (This system works because concrete tiles and clay tiles are well ventilated and vapor-permeable, so any moisture that accumulates in the roof sheathing can dry toward the exterior.)Aug 21, 2015.

Is it better to insulate attic ceiling or floor?

roof insulation is no-contest. The floor wins every time. Insulating the floor is standard practice for an unfinished attic space. The exception to this rule takes place when families opt to convert an unfinished attic space into something usable or livable.

Do you put insulation in the eaves?

Insulation should be continued right to the edge of the ceilings but it shouldn’t block the eaves’ ventilation. Ventilation is vital to ensure the necessary air movement to prevent condensation from water vapour, as this can lead to decay of the structural timbers.

Can I put insulation on attic ceiling?

To maximize headroom, properly insulate your attic and ventilate the roof, use a combination of dense batt insulation, rigid foam sheeting and air chutes. This means you can have a combined R-value ranging from R-23 to R-31 with only 5-1/2 inches of combined fiberglass and foam insulation.

Do I need an air gap in my roof?

An air gap in the rafters is not required as long as there is a channel for water drainage to run down the roof, this can be achieved with counter battens that run vertically down the roof.