Celotex Isover

Insulation for Timber Joist Internal Floors

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The primary purpose of an internal floor is to provide acoustic separation for airborne sound between two adjacent rooms within a dwelling, thereby improving the acoustic comfort of those within the dwelling.

These floors are typically constructed using solid timber joists or timber I-beams with a minimum 18mm thick timber floor deck laid above the joists and a plasterboard finish applied below the joists.

The insulation of choice for internal floors is typically a glass mineral wool (GMW) roll or slab. ISOVER products can be installed as part of the internal floor construction between the joists/I-beams to provide the level of sound reduction required according to Approved Document E (England & Wales) and Section 5 (Scotland).

The building detail is for illustrative purposes only. It does not constitute advice and should not be relied upon.


Insulation products to consider
Product Name Thickness Range Sizes Lambda BBA
ISOVER Acoustic Partition Roll (Apr 1200) 25-100mm Width 2x600mm, Length 9170mm-20000mm NA Tick Icon
ISOVER Acoustic Slab 50-100mm Width 600mm, Length 1200mm NA Tick Icon
ISOVER Unislab 50-140mm Width 400mm or 600mm, Length 1200mm 0.036 W/m.K Tick Icon