The problem with cedar cladding

Cedar is a durable softwood timber usually sourced in North America. Its colour is brownish red and because of its durable properties it has been used in recent years as a cladding for buildings. In my opinion it has been used excessively and usually has not been protected against the elements. It therefore usually looks terrible after wet weather. It is worth considering whether this cladding is more suitable for buildings with a dryer climate than Ireland or the UK.

Even a durable timber like cedar needs to be sealed against water ingress to protect it. All timber will absorb moisture in damp conditions and release it again in dry weather. The recent craze for using cedar cladding hasn’t extended to understanding that the timber must be sealed. As a result, buildings clad thus, can have a really miserable look after wet weather, having a dark, wet and blotchy appearance.  It is hard to think of a cladding that would seem shoddier after wet weather. See photographs below, it is worth noting that both of the buildings below have been completed within the last three years. See also a suppliers viewpoint in comments section below.

 

Cedar Cladding in Kildare

 

 

Cedar Cladding in Dublin

Algae on untreated timber cladding

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11 Responses to The problem with cedar cladding

  1. Western Red Cedar (thuja plicata) is actually mostly sourced from West coat Canada (Vancouver area BC). Like all timber, it darkens when it gets wet and bleaches to a grey colour if left natural due to UV degradation. It requires no treatment whatsoever, unless a low grade of WR Cedar is used and contains sapwood which requires preservative treament).
    The only reason anyone should coat Western Red Cedar is to help prolong the natural colour of the timber, this is usually the start of the problem on building sites. Coatings require maintenance and the proper coating must be specified in the first instance. The second picture you have shown is a project in Crumlin, Dublin if I am correct. This project was originally varnished which is clear example of what NOT to do. Firstly Varnish should never be used and secondly, the coating must be maintained.
    Cedar can be used without any treatment and can look very well. Architects and should also share in the responsibility as the design of any building can have a dramatic effect on how any wood element (cedar or otherwise) behaves. Consideration should be made regarding any timber elements partly sheltered by balconies / soffits / overhangs. South facing elements weather much faster that other elements. If coating is required, a natural wood cladding oil such as Osmo UV Cladding Oil which contains anti fungal inhibitors should be specified along with a regular maintenance programme.
    The dark / wet / blotchy appearance of weathered cedar is as a result of Tannin / extractive bleeding from the timber. This eventually weathers to a uniform grey colour is exposed but sheltered areas wont weather as fast or as uniform as clear open panels.
    Cedar ticks all the boxes in terms of affordability, durability and stability. No one should be afraid of using Cedar for Cladding. Just get the right advice from the right people unlike in the past few celtic tiger years where the material was just thrown up on the side of a building without any thought on grade, performance or maintainence.

    • admin says:

      Thanks for the input. Some good points and getting the right advice is always important. Regarding your point about untreated cedar, I have added another picture of untreated cedar cladding, this time with algae growing on it.

      • gary says:

        Just as an added point any timber and numerous materials are suseptible to fungil growth dependent on uv % available over time. Most people are unaware of the importance of good circulation and natural light when choosing products/materials.

  2. Thanks for the additional picture with Algae growth. This is a prime example of poor detailing by an Architect. It is always recommended to stop any wood cladding 200mm – 250mm above ground level to prevent indirect wetting (splashing off ground). Indirect wetting as a result of splashing off the ground or other horizontal surfaces such as roofs or balconies, below the cladding, can lead to a deterioration of surface finishes and possible algal growth.

  3. frank says:

    Hi guys
    I am a building designer and always strive to getting it right. so, can you please advise on what treatment cedar cladding should receive to maintain its new appearance when first installed rather than having the grey appearance when it has weathered.
    the situation where the cladding would be specified is on gable ends of roofs, dormer windows and cheeks and to the faces of a single storey home office clad mainly in cedar and glass built off a masonry plinth say 200-250mm high from ground level to avoid any splashing staining the boards. I have read that Alkyd resin based stain should be used, so i am trying to accumalte as much info as I can to advise my Client accordingly.
    Any comments will be greatly appreciated.
    Yours
    frank

    • admin says:

      Will e-mail you directly.

      • Nick says:

        can you let me know what treatment cedar cladding should receive to maintain its new appearance when first installed rather than having the grey appearance when it has weathered?

  4. Mark says:

    Hi
    We sell cedar all over the country north and south. http://www.corell.ie . If you are looking to retain the natural colour of cedar then I would suggest using an oil based stain like an OSMOS 410D. Also have a look at SIKKENS Cetol. Its a water based system which is best applied to the timber with a vacuum coater.
    Mark

  5. Karen Swingler says:

    Any advise – we have 2 cedar windows facing west in direct afternoon sun -Iwant to paint both windows not stain what preparation do you advise.

  6. Therese Ryan says:

    Our house is clad in cedar and all is weathering very well except for the north facing side of the house. There is a lot of green algae on it. I would like to know what I can do to remove the algae, also what product would you recommend to apply so as to prevent the algae coming back, but which will allow the cedar to age. Looking forward to your response

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