Rigid Insulation For Slab On Grade

R 7 7 rigid foam insulation model 310891 18 35 18 35.

Rigid insulation for slab on grade.

Continuous insulation is defined in 90 1 as insulation that is continuous across all structural members without thermal bridges other than fasteners and service. When building a slab on grade eps rigid foam insulation is the most common choice of insulation for performance and cost. Materials suitable for below grade insulation are limited to rigid foam high density spray foam and rockwool boards. In climate zones 4 and 5 the code requires certain slabs below grade slabs that are less than 12 in.

Two common rigid foam insulations specified for below grade applications are expanded polystyrene eps and extruded polystyrene xps. The f factors for slab on grade floors are defined in standard 90 1. These f factors are acceptable for all slab on grade floors but you need to make sure. If the slab has hydronic tubing the minimum r value of this insulation increases to r 15.

Insulating a slab on grade can be expensive. Rigid insulation is placed vertically on the exterior face of the foundation wall. Figure 4 11 illustrates a slab on grade foundation with a masonry foundation wall. It also discusses installation procedures for below grade and under slab insulation.

Spray foam for sure has uses where it is the best choice by a long shot but under a slab is not the place. An easy way to recognize eps on the jobsite is that it is commonly white. Slab is one foot or less below grade r 10 insulation required extending 2 feet below grade for climate zones 4 and 5 4 feet below grade for climate zone 6 insulation should extend downward from the top of the slab with two options to reduce slab edge insulation r value exterior slab insulation must be protected 46. Below grade under slab with foamular xps insulation.

Consult appendix a table a6 3 1 in the 2016 edition for a tabulation of assembly f factors for slab on grade floors based on the arrangement and rated r value of the applied insulation. While standard building codes typically require insulating value ranging from r 10 to r 15 detailing around the perimeter is generally weak. Set your store to see local availability add to cart. Water resistant rigid board for under concrete slab insulation and slab support in traffic bearing applications.

This insulation aligns with rigid foam sheathing that covers the framed walls above grade. I wouldn t go as far as saying you couldn t use spray foam below a slab but i m not sure why you d want to. This may leave a significant thermal. Below grade to have r 10 vertical insulation at the slab perimeter extending downward from the top of the slab to a depth of at least 2 ft.

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