Floor Slab Insulation Thickness

Ground bearing floors can include insulation either below or above the concrete slab the choice the designer makes will have an impact on the temperatures inside the building as follows.

Floor slab insulation thickness.

2x4 wall 2 2x6 wall 2 attic 2 basement 3 crawlspace 2 exterior sheathing 3 exterior wall foundation 4 floor 1 garage 3 under slab. Insulation requirements for slab on grade floors can be found in section r402 2 9 of the 2012 iecc and section n1102 2 9 of the 2012 irc. Insulation is laid on the concrete and covered with a screed. If the insulation is installed below the slab the thermal capacity of the building is increased helping to maintain steady internal temperatures.

Insulation sheets should be laid tightly together with the joints staggered to avoid movement. 2015 iecc irc section r402 2 10 n1102 2 10 slab on grade floors. Lightweight rigid polyisocyanurate pir foam insulation boards such. In this scenario a rigid foam insulation is usual and as you d want the same u value in the roof we need the same thickness of insulation 180mm.

Get free shipping on qualified under slab foam board insulation or buy online pick up in store today in the. Insulation is placed below the concrete floor slab. A 50mm thick layer of proprietary floor slab insulation is usually enough to reach and maintain the target u value but this should be checked with an architect first. 4 10 2012 3 climate zones e301 1 6 5 8 4 slab r value table 402 1 1 insulation and fenestration requirements by component e402 1 1 climatezone slab r valued 4 10 2 ft 5 10 2 ft 6 10 4 ft 9.

The edge insulation should be at least 25mm thick and height should extend from the top of the concrete slab to the top of the finished floor screed. Slab on grade floors with a floor surface less than 12 inches below grade should be insulated in accordance with information provided in the insulation and fenestration requirements by component table which is reproduced following this paragraph. Protect the exposed top of the perimeter insulation from any damage until covered by skirting or wall finish. Product thickness in 2 in 2 1 5 in 1 2 375 in 1 3 in 1 insulation location.

The insulation is then laid followed by a polythene separating layer and either a concrete screed or tongue and groove chipboard ready to receive the specified floor finish. Insulation below the floor slab. There will be a damp proof membrane under the insulation and possibly a second membrane on top depending on the type of screed.