call us 020 7998 1690  |  ire +353 (0)1 8409 286

Insulating Walls with Pavatex wood fibre insulation – Externally and Internally

Insulating Walls

External Wall Insulation EWI

To be Rendered Directly

External Wall Insulation EWI

To be Cladded with a Ventilated Façade

Before External Wall Insulation After External Wall Insulation Ventilated Facade

This house was extended and externally insulated with wood fibre and lime render to greatly enhance its appearance and indoor warmth and comfort.

 

External Wall Insulation (EWI)

External Wall Insulation which is Rendered Directly

Diffutherm External Insulation Softboard
Diffutherm
A thicker water resistant external insulation softboard made of a combination of boards of varying densities which can be rendered directly with a breathable render.
(Similar to Hofatex SysTem)
PDF IconData Sheet
Diffuboard External Insulation Board
Diffuboard
Very similar to Diffutherm except that it is denser and is only available in 40mm thickness. Suitable for masonry and timber frame walls.
(Similar to Hofatex SysTem)
PDF IconData Sheet

External Wall Insulation which has a Ventilated Façade or Cladding

Isolair Sarking Board
Isolair
A thinner water resistant sarking board for externally insulating roofs as well as masonry or timber frame walls which are cladded with a ventilated façade.
(Similar to Hofatex UD)
PDF IconMore Details
Pavatherm Plus Sarking Board
Pavatherm-Plus
A thicker water resistant sarking board which is a combination of Pavatherm and Isolair for externally insulating roofs and masonry or timber frame walls behind a ventilated façade.
(Similar to Hofatex Kombi)
PDF IconMore Details

 

The Benefits of Insulating Walls Externally

External Wall Insulation (EWI) is an excellent way of insulating the external walls of a new or existing property because the complete building envelope is wrapped in insulation, and so cold bridges through junctions are avoided e.g. where internal walls meet the external wall. Pavatex wood fibre insulation boards are installed directly onto the outside of external walls, irrespective of whether the walls are constructed of solid or cavity masonry or timber frame. The walls must be smooth and level before insulating so they may need to be first rendered with a breathable render basecoat e.g. lime or clay. If insulating solid masonry walls please see the section on Insulating Old or Historic Buildings. The water resistant wood fibre insulation boards, Diffutherm and Diffuboard, can be rendered with a breathable render or a ventilated façade can be fitted over Isolair and Pavatherm-Plus, so as well as improving the energy efficiency of the building it also enhances the building’s appearance, if required. Pavatex wood fibre boards are a totally natural and renewable product, which allow water vapour to pass through the structure and so ensure a healthier and warmer indoor atmosphere.

 

Other advantages of externally insulating a property are that the internal footprint of the property will not be affected and there will be no upheaval indoors as a result of moving furniture and re-decorating. The sound insulation of the entire building structure will also be enhanced due to the high density of the wood fibre and the building will be wind-tight. Wood fibre insulation also helps to regulate indoor temperatures all year round due to its unique thermal mass properties which is particularly critical on timber framed and metal framed buildings. Because the wood fibre boards are water resistant they can be left exposed on the building for up to three months while construction is taking place.

 

Examples of Low U-value Applications on Masonry Walls – External

Brick or Block – Diffutherm EWI – Render

  • 15 mm lime plaster or plasterboard
  • 215 mm aircrete blocks (0.15 W/mK)

OR

  • 215 mm brickwork (0.75 W/mK)OR 215 mm dense aggregate block (1.42 W/mK)
  • 200 mm rigid Diffutherm wood fibre EWI (0.043 W/mK)
  • 15 mm lime or vapour permeable render

U-value: 0.16 – Aircrete blocks (subject to specification)
0.19 – Brickwork (subject to specification)
0.20 – Dense Blocks (subject to specification)

Brick – Timber Studs – Diffutherm EWI – Render OR Ventilated Cladding

  • 15 mm lime plaster or plasterboard
  • 215 mm brickwork (0.75 W/mK)
  • 160 mm Pavaflex flexible wood fibre between studs (0.038
    W/mK)
  • 140 mm rigid Diffutherm wood fibre EWI (0.043 W/mK)
  • 15 mm lime or vapour permeable render OR a ventilated cavity
    with cladding

U-value: 0.13 (subject to specification)

Examples of Low U-value Applications on Timber Frame Walls – External

OSB – Timber Frame – Pavatherm-Plus Sarking Board – Ventilated Cladding

  • 12.5 mm plasterboard and skim
  • 38 mm service void
  • 15 mm OSB racking / air tightness / vapour control (0.13 W/mK)
  • 220 mm Pavaflex flexible wood fibre between studs (0.038 W/mK)
  • 80 mm rigid Pavatherm-Plus wood fibre sarking boards (0.043 W/mK)
  • Ventilated cavity
  • Timber board cladding or similar

U-value:0.11 (subject to specification)

OSB – Timber Frame – Diffutherm EWI – Render

  • 12.5 mm plasterboard and skim
  • 38 mm service void
  • 15 mm OSB racking / air tightness / vapour control (0.13 W/mK)
  • 140 mm Pavaflex flexible wood fibre between studs (0.038 W/mK)
  • 140 mm rigid Diffutherm wood fibre sarking boards (0.043 W/mK)
  • Lime or vapour permeable render

U-value:0.12 (subject to specification)

Internal Wall Insulation (IWI)

Internal Wall Insulation with Plasterboard or Other Wall Covering

Pavatherm Wood Fibre Board
Pavatherm
A universal rigid wood fibre board for insulating internally above floor sub-decks, below roof rafters or flush with walls to reduce thermal bridging.
(Similar to Hofatex Therm)
PDF IconMore Details
Softboard Standard Natural Board
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)
PDF IconMore Details

Internal Wall Insulation which is Plastered Directly

Pavadentro Insulation Board
Pavadentro
An internal insulation board that can be plastered directly with a breathable plaster. Excellent hygroscopic properties due to unique mineral layer that controls moisture transfer.

(Similar to Hofatex SysTem IA)

PDF IconMore Details

Flexible Insulation between Studs

Pavaflex Wood Fibre
Pavaflex
A flexible and breathable wood fibre batt for snugly insulating between joists, rafters and studs to provide excellent thermal insulation results.
PDF IconMore Details

 

The Benefits of Insulating Walls Internally

Internal Wall Insulation (IWI) is another option for thermally insulating the inside of external walls especially when the exterior of the building cannot be altered e.g. on listed or older buildings and on properties with a unique external appearance. The Pavatex wood fibre insulation is fixed directly to either masonry or timber framed walls. The Pavadentro board can be plastered directly with a breathable plaster for optimum results or the Pavatherm and Softboard Standard Natural boards can be covered with plasterboard or other suitable wall board. These breathable, hygroscopic, natural insulation boards can absorb moisture from inside the room and then release it either back into the room or out through the walls as the humidity level lowers, without any detrimental effects to the integrity of the insulation boards. This avoids condensation, mould growth and humidity in buildings and creates a very pleasant, comfortable interior climate. Interstitial condensation should not get trapped in the structure which can cause untold damage. Pavadentro has a unique green layer within the board which ensures that moisture transfer occurs at a controlled rate so is the optimum choice to use. Another advantage of internally insulating walls is that the building can be upgraded on a room by room basis if budgetary constrictions apply.

 

If the external wall is a timber frame stud wall it is best to insulate between the studs with the flexible and hygroscopic Pavaflex insulation material. For optimum results also insulate in front of the studs with any of the Pavatex rigid wood fibre boards as described above.

 

The main disadvantage of insulating walls internally rather than externally is that the junctions (e.g. the floor area between upstairs and downstairs) will not be insulated and so heat will escape from these un-insulated areas. Also the internal floor area will be reduced. However the unique characteristics of wood fibre thermal insulation will remain the same whether the boards are installed internally or externally.

 

Example of Low U-value Applications on Masonry Walls – Internal
Brick – Plaster – Pavadentro IWI – Plaster

Masonry Walls

  • 215 mm existing brickwork (0.75 W/mK)
  • 8 mm min. parge coat of lime / clay plaster
  • 100 mm rigid Pavadentro wood fibre insulation (0.047 W/mK)
  • Lime / clay plaster

U-value:0.38 (subject to specification)

U-value Calculator

To calculate your own U-value figures on various structures try the Free U-Value Calculator.

 

Pavatex Wood Fibre Stockists