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Energy efficient timber windows 

NatureLine 90 window with flashing groove profile

NatureLine 90 window with hardwood sill and external reveals

90mm thick window sash and frame


Double- or triple glazing possible


Durable 3 tenon corner joints instead of mitres


Factory finished product


Very high security standard


2 seals are a standard feature


Made of dry multilayer laminated timber

Thermal properties

U-value window:           0.772

R-value window:            1.29 thickness:    52 mm

*values based on Siberian Larch and 0.5 W/m2K triple glazing




At ThermaDura we have developed a smart and efficient system which enables the builder to install our wooden windows and doors economically and to a high quality standard. On the inside of the timber window/door frame we machine a 10.5mm wide groove (4 sided). This multigroove can accommodate reveals, interior sills and even gibbboard.




Key advantages

  • Allows for differences in wall thickness

  • Conceils the window/door fasteners (no visible fixings)

  • Allows the builder to measure the reveal width after installation (reveals are supplied separately)

  • Allows an economic and safe way of transporting the timber windows and doors all around New Zealand

  • Flexibility - reveals, internal sills and gibboard can be fitted into the groove

NatureLine window with multigroove

NatureLine window with attached reveals

NatureLine window with external reveal (option)

NatureLine window with fitted external sill and reveals


In New Zealand it is still common practice to install windows flush with the external cladding of the building. In this case your window is fully exposed to the elements, but more importantly it creates a cold bridge between the outside and the inside.

In most cases only a thin 20mm piece of timber (reveal) is all the insulation around the windows which creates considerable heat loss. This installation situation also makes WANZ support bars necessary as the window is not supported by the house framing anymore.


At ThermaDura we offer external reveals to move the window back into the insulation layer of your home to ensure maximum energy efficiency.



Key advantages

  • Windows will sit in the insulation line of the wall framing and increase thermal efficiency

  • Timber windows are better protected against environmental conditions

  • Tongue and groove connection (structural joint) between reveal and window frame ensure a high quality finish and weathertighness

  • Possibility to machine a rebate into the erxternal reveal to accommodate weatherboards without the need for facingboards

  • Recessed windows give the home a quality look

Wooden window timber


Wooden Windows, Double glazing


Conservatory heating


Window handles


Wooden window finishes


European window blinds


Conservatory prices
Conservatory installation



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