Attic Knee Wall Insulation R Value

According to a report by the washing state university extension energy program blown in fiberglass insulation provides an r value of between 2 2 and 2 7 per inch.

Attic knee wall insulation r value. Most computer programs allow the user to calculate gross wall areas and subtract window and door areas. This knee wall has been encapsulated with 2 part closed cell spray foam. A 1 5 wide strip of 3 4 polyiso held in place with a 1 5 wide strip of 3 4 cdx or 1x furring doubles the r value of 2x4 framing and 5 deep cavity can fit a compressed r20 which would deliver a true r18 3 slightly better than an r19 stuffed in a 5 5 deep 2x6 cavity. Georgia recognized this problem about a decade ago and started requiring all attic kneewalls to have sheathing on the attic side and to be insulated to at least r 18.

Don t forget to verify that the r value of the roof insulation meets minimum code. A 2 x 4 wall cavity with blown in fiberglass insulation will provide on average an r 13 to r 15 insulation value. Now that the kneewall is located within the home s thermal enclosure it s no longer necessary to air seal electrical boxes or access doors in the kneewall. Bring the attic inside insulating between the rafters simplifies the air sealing details.

By adding an r19 to the existing r13 cavity insulation the knee wall assembly total r value is near r30 and is air tight. 1 use an r value map to determine the amount of insulation you need. 0 19 btu hft f loft ladder hatch u value 1 1 8 insulation thickness 5 2 attic ladder r value the knee wall access door dwk is intended to be built into l shaped walls. The best way to provide that sheathing is to use a rigid material.

All r values are insulation only tested labeled per ftc rule16 cfr 460. At an r6 per inch it provides an air barrier and outstanding thermal break. Superb thermo insulating parameters r value 5 2 along with high air tightness keep heat loss to a minimum. Walls are entered by the type of assembly and the r value of insulation.