Insulating Attics and Lofts with Pavatex Wood Fibre Insulation
Attic Floor Insulation
Pavatherm
A universal rigid wood fibre board for insulating attics internally above floor sub-decks, below roof rafters or flush with walls to reduce thermal bridging.
(Similar to Hofatex Therm)
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Pavaflex
A flexible and breathable wood fibre batt for snugly insulating attics and lofts between joists, rafters and studs to provide excellent thermal insulation results.
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Pavaboard
A high compression resistant board suitable for use above and below wet and dry screeds and above timber floor sub-decks. It significantly reduces impact sound.
(Similar to Hofatex Strongboard)
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Softboard Standard Natural
A thin universal standard board for insulating internally above floor sub-decks, below roof rafters or flush with walls to reduce thermal bridging.
(Similar to Hofatex Standard Natur)
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Pavastep
A very thin underlay board to reduce impact sound through timber, concrete and screed floors. Very high compression strength.
(Similar to Hofatex Silent)
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The Benefits of Insulating the Attic Floor
If the attic is not going to be used for living accommodation it is recommended to adequately insulate the attic floor to prevent the heat rising into the unused attic space. It is estimated that 25% of internal heat escapes through un-insulated roofs or attic floors. When insulating attics it is easiest to place Pavaflex flexible insulation batts between the floor joists on a timber floor. This breathable, natural insulation should fit snugly between the joists so that no gaps remain at the edges. However do not cover up the ventilation areas of the attic space or condensation will become a major problem. Pavatherm wood fibre rigid boards could also be cut to size so that they fit tightly between the joists but this can be a difficult task to complete on-site.
There are several options for adding more insulation above the attic floor cavity insulation. If a floor decking is to be laid in the attic then this should be laid on top of the joists and then a wood fibre insulation layer can be laid floating on top of the sub-deck. There are various wood fibreboard options for insulating attics depending on the available space and the thermal and acoustic requirements. If a much lower U-value figure is required then a layer of square edged Pavatherm can be laid butted together on the floor. Pavatherm comes in various thicknesses from 40 to 160 mm so the thicker the layer, the lower the resultant U-value. Pavatherm is suitable for average compression loads as it has a Compression Strength of at least 20 kPa, but if heavy loading on the attic floor is expected it is strongly recommended to use Pavaboard which has a very high Compression Strength of 150kPa. The main advantage of totally covering the floor space is that thermal bridging through the floor joists will be eliminated. It will also reduce both airborne (e.g. talking, music) noise and impact (e.g. footstep, moving furniture) noise through the attic floor and will reduce the risk of the property overheating in the warmer summer months by the addition of thermal mass to the structure. If the attic will never be used and there is no requirement for laying a flooring deck then just place the Pavatherm butted together on top of the joists. However this cannot be walked on so put in some walking boards over the Pavatherm for safety, ensuring that the boards are sitting across the joists.
If the required U-value is met or nearly met with the attic floor cavity insulation, but impact or footstep noise is a problem then consider laying a layer of Softboard Standard Natural which offers good compression strength and very good impact sound reduction as well as some airborne sound reduction through floors. These boards come in various thicknesses up to 19 mm so will not take too much height out of the room. It is generally laid floating directly on top of the sub-deck. The other advantages of wood fibre will also be met such as reducing thermal bridging and adding thermal mass to the floor area.
Another option is to use the very thin Pavastep underlay board which is 8 mm thick and helps to reduce impact noise through floors. This can be laid floating or bonded to the timber or concrete sub-deck and most flooring finishes can be laid over it.
Attic Roof Insulation
Please see Insulating Roofs Internally section.
Attic Wall Insulation
Please see Insulating Internal Walls section.
U-value Calculator
To calculate your own U-value figures on various structures try the >Free U-Value Calculator.
