External Wall Insulation Thickness

Insulation is rated by its r value.

External wall insulation thickness.

Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. Eaves width can be a deal breaker in that if the eaves are not wide enough to accept the insulation the cost of extending the eaves can outweigh the benefit of the insulation. R value measures how resistant types of insulation are to heat flow. Standard fiberglass insulation batts or blankets provide an r value of 2 2 to 3 8 per inch of thickness.

When you are insulating two by four 2x4 and two by six 2x6 framed exterior walls and want to use fiberglass insulation what thickness is best the question becomes all more critical because of the permanent nature of wall assemblies and wall insulation. Once the insulation is in the wall and sealed up with drywall it is not easy to change out. If the dew point is too close to the internal surface of the existing wall moisture can be absorbed by the insulation and appear as damp patches on the plasterboard. Insulation decreases the amount of heat entering from outside when it s hot and traps warmth inside when it s cold.

Drill holes in the sheathing and blow insulation into the empty wall cavity before installing the new siding and. Before installing the external insulation all of the exterior units such as satellite dishes pipework or security lights have to be removed and then replaced adding to the cost. Internal wall insulation will tend to keep the wall at external ambient temperature and thereby draw the dew point towards the internal surface. An external wall insulation system or ewis is a thermally insulated protective decorative exterior cladding procedure involving the use of expanded polystyrene mineral wool polyurethane foam or phenolic foam topped off with a reinforced cement based mineral or synthetic finish and plaster.

R values vary based on the type thickness and density of the insulation material. The total footprint of the external walls of a house can easily be around 15 20 of the ground floor area and this becomes significant. 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. Add r5 to r6 insulative wall sheathing beneath the new.

External insulation will add thickness to the wall most evident at the reveals and eaves. With increasing levels of insulation the total thickness of a wall becomes an issue in relation to land values especially in densely built urban areas where space is restricted. Most manufacturers produce an r 13 batt that fits into a 2 by 4 wall cavity which is. The roof eaves and window sills will have to be extended so that they fit the thickness of the exterior wall.