ROOF AND CEILING INSULATION

Ceiling (and roof) insulation - typically associated with attics - is an interesting investment, even if the insulation demands lifting the roof. The benefits can be huge.

Climate & Type of Roof Insulation

In colder climates, the insulation of the top of the building means almost always attic-ceiling insulation. In hotter climates it is based on reflective insulation(radiant barriers). In other climates, attic insulation can be combined with reflective insulation.

Types of roofs & Insulation

If your home has a pitched roof and an open attic, you should insulate the attic. Inspect the attic insulation to determine its insulation needs.

Building codes recommend attic insulation levels of at least R-45 (R-60 is often more advantageous). If your attic has less than the recommended levels, add enough insulation to get the recommended amounts. The payback will be short.

If your roof is tall enough, installing extra insulation isn't a big problem. The most common solution is to to blow enough loose-fill insulation (e.g. fiberglass) into attics and roof cavities. But if you have a flat roof, or a vaulted or cathedral ceiling, than the solution isn't so simple.

Flat roofs and cathedral - vaulted ceilings

Flat roofs and cathedral and vaulted ceilings have often a small attic cavity. The new insulation should fill some or all of that cavity, even if it is only one feet deep or so.

Bit this isn't an easy task, and it is better done by an insulation contractor. The small attic cavity limits the amount of insulation you can install (a high-density insulation material is a way of overcoming it) and can pose problems of ventilation, hard to solve and, in some cases, controversial.

Structural approaches in bad designed ceilings and roofs

If you have a flat or vaulted cathedral ceilings, structural approaches should be considered to overcome their poor designs.

Here are two of such approaches:

1) Building a pitched roof over the top of the flat (or nearly-flat) roof, creating a new attic in order to get space to install the required insulation;

2) Adding a very high-density foam insulation on the top surface, above the roofing of the vaulting ceiling.

Insulation Materials and R-values

Ceiling insulation materials and their R-values are those listed for Attic Insulation.

The reflective materials used under the roofs (in hot climates) are a typical layer of RFL sarking or foil batts. When installing a reflective material, make sure there is a small gap (about 1 inch/2,5cm) between the roof and the RFL. If using sarking, install it between the battens and the rafters, with the shiny side facing down.

See:
Reflective roofs
Reflective roof materials
Cooling & Insulation