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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorRex
    • CommentTimeJan 17th 2020
     
    What ho one and all,

    One part of my house (nine year old now) has Western Red Cedar cladding on the first floor with a silicone based, white render below. This is the front, which more or less, faces south.

    With the recent storm, the front does get somewhat wet; but the water running off (or dripping from the bottom) of the cladding contains sufficient 'red' stain to stain the render.

    I have cleaned the discolouration off with a patio brush on the jet washer, and will probably give a fresh coat of paint in the near future.

    But that does not stop the problem. Does the stain from WRC ever wash out? Is there anything I can do to prevent it?

    Thanks and toodle pip
    •  
      CommentAuthordjh
    • CommentTimeJan 17th 2020
     
    Why is the cedar stained? It doesn't need staining. Exactly what is it stained with? The only hope you have I think is to discover exactly what ingredients are in the stain and then hope to find some 'fixative' that will make it less liable to run.
    • CommentAuthorRex
    • CommentTimeJan 17th 2020
     
    No, it is not actually stained, more like natural red / brown dye fro the wood.

    I don't think it is coming off the surface but as it is slightly absorbed, it is what filters down.

    The two corners, where I have a vertical section with the end grain at the bottom are particularly bad. What is interesting, it has never reduced; seems like an endless supply of 'resin' or whatever.
    •  
      CommentAuthordjh
    • CommentTimeJan 17th 2020
     
    Posted By: RexNo, it is not actually stained, more like natural red / brown dye fro the wood.

    Hmm, we've got a fair amount of WRC and I haven't seen any sign of staining below it. It just turns silver-grey in the sun. It's dark now but I'll try to have a proper look tomorrow.
    • CommentAuthorrevor
    • CommentTimeJan 19th 2020
     
    I am puzzled in that you are experiencing "leaching" from the cedar. I would not have thought cedar would do this. Given that it is 9 years old if it was to exhibit this phenomenon I would have expected it to have leached out by now. What is behind the cedar is there anything there that could be contributing?. I have a silicon based render and it repels anything so am equally puzzled that you paint yours. What is the brand of render?
    Where I live there is an air borne algae and buildings here are badly stained by it. It seems to only affect a particular brand of render.
    • CommentAuthorRex
    • CommentTimeJan 27th 2020
     
    Thanks for the replies.

    There is nothing behind the WRC cladding, just 6" of air (to provide the insects with somewhere to live!)

    This side of the house is south(ish) facing so the WRC gets quite a lot of sunshine.

    I always have difficulty in up-loading a photos to this forum, but we have a 1m roof overhang. The WRC immediately under the overhang is still kinda weathered red, but the cladding furthest from the overhang, and at its base, is more towards black.

    When I had the patio washer on the jet cleaner out, to try and wash the staining off the render (about 90% successful) I used the jet washer to blast a small section of the WRC. Not only did that result in very red water flowing down the render, but it also restore the WRC to red by washing away most of whatever seem to be on the surface.

    As for the render, it is a silicone bases (Alumasc thin render) but because it is the min. size (1mm) stained water does tend to dry on it.

    Also have a bit of WRC on the back of the house, and that has gone towards grey. However, it is rather 'gritty' and a good scrub with water and a brush cleans it off, almost back to reddy/grey. I have used the pation washer on this and the difference between before and after is very noticeable. Only problem is, I am unable to wash the higher sections as the balcony is not deep enough to use a ladder safely.
    •  
      CommentAuthordjh
    • CommentTimeJan 27th 2020
     
    Posted By: RexI always have difficulty in up-loading a photos to this forum

    The photos are probably too large (too high a resolution). You'll need to reduce the resolution if so. I think photos would be really helpful in this case. :)

    This side of the house is south(ish) facing so the WRC gets quite a lot of sunshine.

    WRC just goes silver-grey quite quickly in sunlight.

    The WRC immediately under the overhang is still kinda weathered red, but the cladding furthest from the overhang, and at its base, is more towards black.

    When I had the patio washer on the jet cleaner out, to try and wash the staining off the render (about 90% successful) I used the jet washer to blast a small section of the WRC. Not only did that result in very red water flowing down the render, but it also restore the WRC to red by washing away most of whatever seem to be on the surface.

    Hmm, I can't think of why timber would go black with southern exposure. Maybe if it faced north?

    There's a reasonable photo of fresh WRC at https://www.woodshopdirect.co.uk/planed-all-round/western-red-cedar-timber/ Does yours look like that? From there it just goes silver-grey as it ages. It sounds like yours might have been stained/treated/whatever. Where did you buy it and how is it described on the invoice?
    • CommentAuthorJeff B
    • CommentTimeJan 27th 2020
     
    Could it be red algae on the cladding?
    • CommentAuthorbogal2
    • CommentTimeJan 28th 2020
     
    My architect specified an aluminium drip profile below the cladding that reduces drip onto the render. Could you retrofit this?
    • CommentAuthorRex
    • CommentTimeJan 28th 2020
     
    It would be possible to retro-fit a better drip edge but when the problem occurs, usually when there is a windy / rainy weather, the prevailing wind direction will just blow the drips onto the render.

    With regular, vertical falling rain, the roof over-hang prevents the wall getting wet. Wind is the problem!
    • CommentAuthorRex
    • CommentTimeJan 28th 2020 edited
     
    Ok, I have found how to insert a photo.

    Have to log-in first before going to the appropriative thread. If I reply to a thread and use the thread log-in, no chance of posting a photo.

    Sorry for the confusion.

    Cladding been in place for around ten years. Is lighter under the roof but not a reflection; it is certainly darker red than the original out-of-the-box. i believe the cladding was N.American grown, but honestly do not recall.

    Wind direction when it blows (I live in leafy Surrey) is from my camera position. This wall virtually faces south
      WRC (Medium)2.JPG
    •  
      CommentAuthordjh
    • CommentTimeJan 28th 2020
     
    To ask again: has it been stained? I don't believe that is ten-year old natural WRC facing south.

    If so, what has it been stained with?
    • CommentAuthorRex
    • CommentTimeJan 28th 2020 edited
     
    I certainly did not stain it. And I was the one, with my builder, who installed it, so he didn't either.

    Came from Bennetts Timber; listed as USA and Canada and they say "Colouring of Western Red Cedar cladding can vary from almost pink to very light ‘sandy’ brown right through to extremely dark, rich, red tones. This is a highly important factor to consider, as colour can vary in uniformity within this timber and even in and between individual boards."

    "Western Red Cedar has a high tannin content which can be corrosive to iron and can itself stain badly as a result of any corrosion. Stainless steel nails, screws or fixings are therefore strongly recommended."

    Certainly my cladding seems to have an endless tannin content!
    •  
      CommentAuthordjh
    • CommentTimeJan 28th 2020
     
    After ten years, untreated WRC would be completely grey; no trace of a red colour. Ours is grey after five years and has been for a while.
    • CommentAuthorowlman
    • CommentTimeJan 28th 2020
     
    Rex, this isn't the first time I've read of Cedar turning black. The lower darkening, at a guess is tannin bleed from the upper boards, onto absorbent/relatively spongy lower ones. I guess there isn't much you can do about it apart from stain, paint, or some chemical bleaching solution, there are several, but they may result in an even more blotchy effect, plus very difficult to apply evenly in a vertical plane. If you can't live with it them replacement may be the only solution.
    Wood is often strange stuff, I've worked with it for years and every now and then you get a rogue tree, personally I think the growing soil conditions have a lot to do with it, maybe iron deposits, as can drying. I once had a batch of English Ash that was quite ginger in colour, and another, still in my timber store where the grain is extremely wavy on both the face and edge.
    • CommentAuthorrevor
    • CommentTimeJan 29th 2020
     
    I alo have Alumasc render 1 mm topcoat and stuff does not stain it. The run off the ends of my slate cills does dirty the render a bit but soapy water washes it off. Whilst I did the chimney stacks with Weber as specified by architect, before long, realised that they were staining badly so by time it came to do the walls had moved to Alumasc. Even though one elevation (N) is close to trees and the fascia boards and gutters get badly stained the wall remains clean. Bird droppings eventually get washed off in the rain. Your run off staining from the cedar suggests it is particularly "sticky". Perhaps at the end of the day you may need to paint it. I have cedar cladding but painted mine using Owatrol paint and is guaranteed for 15 years on horizontal cladding. Owatrol do a range of priming and sealing coatings I would get in touch with them as they may have a solution to your issue. I have found them extremely helpful and knowledgeable.

    https://www.owatroldirect.co.uk/?gclid=EAIaIQobChMI0eXYzMOo5wIVB7DtCh0pvAGxEAAYASAAEgKHzfD_BwE
    • CommentAuthorRex
    • CommentTimeJan 29th 2020
     
    Revor,

    Don't think my render is 'sticky', more likely that the texture holds enough stained water so that when dried, the stain remains. Next heavy, wind blown rain, same happens ans so the discolouration gradually builds.

    Certainly the roof overhang does keep rain off most of the walls on three sides, but the garage which does not have an overhang and does get wet, is still clean.

    Repainting will certainly give a clean wall, but will not solved the stain running from / out of the WRC.

    The plan was not to paint the WRC as doing so implies that it needs recoating every X years and that was something I did not intend to do.
    • CommentAuthorRex
    • CommentTimeJan 31st 2020
     
    Contacted the supplier and this was their response:

    Having looked at your concerns I would advise as follows :
    It was October 2009 when the goods were supplied so it is surprising that the tannins have not ran out. However, the tannins are released by movement of water running through the boards so if this elevation does get particularly wet then I am afraid this problem may persist. Also looking at where the goods are situated it could be because they have some protection from the overhead canopy and to where the boards are situated.
    The cladding itself should clean fairly easily as you demonstrated – I thinks it is merely surface dirt / build up over the years
    Would suggest application of end grain sealer to the edges of the cladding where it meets the render. Have attached a link below a product which can be used (we can supply direct from teknos but this would incur delivery charges) so it may be worth visiting a local crown / dulux decorating centre to source something alike direct to the store (they may carry in stock). These products are designed for situations as these and should dramatically reduce the issue you are having with the boards.

    https://www.teknos.com/website/uk/uk-industrial/uk-iw-2feec9a7/teknoseal-4000-00/


    I think when the weather is warmer, I will get a plastic sheet of something that I can form an extended temp' drip edge, and get the patio washer onto the cladding. Hopefully, the extended temp drip edge will lead most of the dirty water away from the render.

    May have to get a twoer to access the higher areas. Yet another job for the summer!
  1.  
    From the picture above it looks like the cladding stands off the wall a bit. could you put a small gutter at the bottom of the cladding to lead the water to the side to avoid it going on the render. The catchment area of the vertical cladding is small so the gutter would not need to be very big.
    • CommentAuthorRex
    • CommentTimeFeb 1st 2020
     
    PiH

    That is a very good idea; definitely blue sky thinking.
    • CommentAuthorRex
    • CommentTimeFeb 10th 2020
     
    Having washed the staining off by the time I posted this thread, yesterday, following the 'storm' this is the staining.
      WRC Stain (Medium).jpg
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