Proper Insulating Roof Ceiling

Insulation level are specified by r value.

Proper insulating roof ceiling.

Box out light fixtures. Foil faced batt insulation is recommended in cathedral ceilings because it offers the permeability rating required for use in ceilings without attics. The hot roof design allows more insulation to be installed in the roof cavity as the need for a vent space is eliminated. Water is insulation s enemy.

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. There s a difference between insulating the ceiling and the actual roof slope. Cathedral ceilings are a feature in many homes that add to value to the house because the high ceiling tends to make rooms look larger. 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.

Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be. The table below shows what levels of insulation are cost effective for different climates and locations in the home. The higher the r value the better the thermal performance of the insulation. Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation.

It provides an open airy look and feel to the room and they are often in demand among home buyers. When tom insulates a cathedral ceiling or a finished attic he also turns to foam. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow. If you have an attic there are quick ways to insulate the ceiling from above after drywalling it.

Illustration by ian worpole. How to put insulation in a ceiling before drywall. If you don t have an attic however there is. R value is a measure of insulation s ability to resist heat traveling through it.

For example cathedral ceilings built with 2x12 rafters have space for standard 10 inch batts r 30 and ventilation. It s easier to knock out in a weekend and it s more relevant to most people s goals when it comes to insulation. Find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces. When the ceiling is a cathedral type then you must provide a space between the roof decks and the ceiling in order to have room for insulation and ventilation.

The general consensus is if in doubt attic insulation takes priority over direct roof insulation. Sprayed against the underside of the roof deck it seals against air movement eliminating the need for a vapor barrier or ventilation.