Dean Carpenter

Problems with hotwood cladding

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At significant expense (£34k just for materials)  I have installed a product called Thermoash otherwise known as Hotwood; it's ash that has been treated under pressure to give it Class 1 durability. The product is sold as being virtually indestructible (maintenance free, resistant to rot, cracking, warping, etc).  It's basically a form of real wood rainscreen. It sits on plastic clips fixed to battens 25mm from the building wall surface (the building is wrapped in a special version of Tyvek) and it is supposed to add to the thermal efficiency, etc, of the building. After a year since installation I'm seeing mould appear on it and also a difference between the battens. The manufacturer (Carpentier from Belgium) blamed me saying the installation was incorrect but that's simply not the case and after I showed them the installation was good they since refused to accept any responsibility. Then they told me to clean it regularly; what happened to 'maintenance free' ? I'm now left with a horrible looking rain screen. Does anyone have any experience with this problem and how to fix it?

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Sorry to be of no help. How much meterage was this 34k?!

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Welcome, sorry to hear that you seem to have been mis-sold this product.

 

I've done some research on thermal treatment of timber that is normally classed as non-durable, like ash, and it's clear that although the timber may have it's durability and rot resistance improved by heat treatment, that does not mean that it will be either maintenance free or resistant to surface growth of lichens etc.  There's nothing intrinsic in the way any thermally treated timber is produced that gives it any surface protection; the process is one that just improves durability and rot resistance.

 

The surface of any thermally-treated timber will behave much the same as any other untreated timber, and will end up with surface colour changes, the growth of harmless lichens and surface moulds and may well need cleaning from time to time.  If you live in an area with good air quality than surface growth of lichens etc is more likely.

 

The good news is that these should clean off easily, leaving no damage to the underlying timber.

 

In my view, you may have been made promises as to the performance of this cladding that were unreasonable, and, depending on the evidence that your supplier gave you (not the manufacturer, as the liability rests with the supplier/installer in law) you may have a case for the product having been misrepresented to you, and hence mis-sold.  This may not be easy to prove, especially if any sales pitch given to you was verbal.  Technically, a verbal promise is every bit as binding as a written one; the problem is proving exactly what you were told.

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Oz07: 315m2

 

JS Harris: many thanks. I bought the product from the manufacturer. 

 

Onoff: The company in your link is the company/product I purchased.

 

I was told it would grey to a beautiful patina over time and not require painting, etc. In fact it's gone blotchy black in places, stayed brown in others and where the battens are it's lighter. First I was told I had not used the correct construction: I have - I sent them a cross-section of the wall design, which easily proves this.

 

Then I was told I have not left enough clearance at the bottom (300mm) but firstly their site shows images of cladding to the floor and secondly on the worst elevations I have a 400mm ground clearance. To clean 315m2 of this stuff would take a week or more and cost a small fortune.

 

This is one quote I have before I bought it : "we use it for all kind of projects where people would use either aluminium ,because they don’t dare to work with wood."

 

Here's another I had once I sent images of the problem "I  have never seen anything like the pictures you show me."

 

I seriously regret installing this product. 

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This is an image showing the problem. Doesn't look like the images on their web site, does it?

 

Also, in some areas there is growth but to specific strips of wood only, which logically tells me that some of the wood is resistant and some is not

Hotwood-problems.jpg

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That looks very bad to my amateur eye. But I do not know how it should look.

 

May there be mileage in contacting the media on this case?

 

Or a piccie on Twitter might go viral as the failure is eye catching. Or a petition. A brochure vs reality split photo might have a good impact.

 

The key point on Twitter is to embarrass them and circulate widely, while having a set of demands that (to quote Terry Waite) "leave a door through which you can both exit together with dignity". On a petition it is to have a critical mass of signers in place before you launch it so it doesn't bomb, with same exit route.

 

You either need to make them submit eg in a court claim or persuade them to help you, perhaps as an escape before you batter them down.

 

Set out your strategy for yourself, however, and your objectives, carefully, to be ones that they can deliver. Obviously you are likely to need a professional report, and proof of valid install.

 

Obvs once you start you can't stop ... The Grand Old Duke of York strategy does not work, except to embarrass the GODYK, unless they surrender early. And that cannot be relied on.

 

Best of luck, and I will sign your petition if you choose to do one.

Edited by Ferdinand

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+1 on the good advice from @Ferdinand above.  Cases like this can be challenging to resolve satisfactorily, more so when the supplier is in another country.

 

Cleary the finish is bloody awful, and nothing like that you were led to expect from the brochure, but the legal position is going to hinge on what you were reasonably expected to receive, and there is a certain leeway for brochure photos to be "touched up", sadly.  In this case It does look very much as if the product has behaved pretty much exactly as I'd have expected thermally treated non-durable wood to behave in the UK climate, but not at all as the manufacturers suggest it should behave.

 

All the talk about installation method is, I'm sure, a red herring, it's the manufacturer/supplier trying to shift the blame for your poor results from their misrepresentation of the product to your own installation.  I doubt the installation has any effect at all on the severe surface discolouration you are seeing, that is something that is pretty normal with thermally treated wood, or even non-thermally treated wood.  The only discolouration that could definitely be put down to the fixing method is if there was staining from the fixings, something common with some timber species, like oak, but that does not seem to be the case at all with your cladding.

 

It's important to note that thermal treatment only does one main thing to non-durable wood - it makes it more durable, that's all.  It does change the natural colour slightly, but it's primary purpose is to make a cheaper, non-durable, timber behave like a more expensive species that is naturally durable.  It does not make it "maintenance free", or guarantee an even colour at the surface at all.   Even naturally durable timber, like Western Red Cedar, will change colour unless surface treated regularly, and may well discolour unevenly, depending on slight differences between boards and the exposure of each face.  We have larch cladding, which is moderately durable, and have not treated it.  There are areas where the colour is very different around the building, but after three years it's gradually starting to even out.  I think it will probably take another three to five years before it's a fairly uniform silver grey, but we did know this before we fitted it.

Edited by JSHarris

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Will it not have weathered more consistently in a year or two?

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Just now, Oz07 said:

Will it not have weathered more consistently in a year or two?

 

 

My best guess is that yes, it will, but I think it will take more than a year or two.  We still have areas where our larch is quite a bright orange/red colour and others where it's almost completely grey, after three years.  I'm inclined to think it might take five to ten years to weather to an even colour all over.  A few years ago our local authority re-clad a number of local bus stops in larch (I suspect they got it from the same mill as we did) and similarly it seems to be taking several years for the colour to even out, with some of them looking very patchy at the moment.

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Thanks for all of your replies. I must have a type of wood cladding as a condition of the planning permission (this is a conversion from commercial to domestic). Originally they wanted black painted weatherboard (to make it look like a barn) but I managed to convince them to go for something more contemporary (bad move on my part as it turns out) so if I changed the cladding I would likely have to go back to the planners for another material amendment; not ideal. Then there is the cost/work involved to replace, which would be horrendous and circa £50k

 

The manufacturer rep is actually a really nice guy and I do believe him when he says they have many trouble free installations but this is a case where clearly it's going to be more challenging and he/they simply are not prepared to take any responsibility. To quote "I don’t know anymore what to say." and "For 100% sure it is not the product to blame"

 

I've built a few houses and it's par for the  course to encounter problems but most are resolvable; this one is a painfully large problem.

 

to Ferdinand: petitions/pseudo-blackmail or whatever else it is called can work but is not without consequence. On the same project I bought near £20k of Garafoli (Italy) internal doors and some of them were really poorly installed. Pressing the UK rep got me nowhere, Garafoli batted me back to the so I gave them the Internet reviews they deserved and since then all I get is threats to sue me. I say go ahead as you can't be punished for telling the truth. This case was a real shame as the doors were beautiful but the rep (Moore & Moore) was terrible to deal with 

 

One thing I have learned from both of these bad experiences: buy British.

 

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My wife works at a private hospital  that had a large extension built around ten years ago

They cladded the whole outside in what I thought was untreated Cedar 

When i enquirer I was told it was thermal ash and would never need touching  It also went patchy for quite a few years

Now it is all very dark in colour Pretty much like the darkest patches pitchired 

Not sure if it’s the same stuff

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Maybe not the best solution but when i decided i did not like the “natural”  weathering on my larch clad building i painted it with a brown wood preserver, l love the neat look that the one colour brings to the building, so.... you could paint it with an anti fungal /coloured wood preserver and save a lot of money and time. 

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@Dean Carpenter

Just a thought but have considered a treatment product called Sioo?: http://www.sioox.org.uk/

its not a stain so shouldn’t affect your Planning Permission but it turns wood cladding an even light grey.

The downside is that it isn’t cheap to buy. For the 100m2 of cedar cladding on my own new-build I costed it at about £500

Edited by Ian

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17 minutes ago, Russell griffiths said:

Could @nod take a pic of the hospital to see if the finish could be satisfactory.  

I should have said that

i can soon snap a picture when I drop my wife off at work 

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@Dean Carpenter, I've had a brief search on the carpentier site but couldn't find any maintenance instructions, nor from Googling. Did you get anything?

 

Looking at similar Scandinavian products and they quote 30 years without treatment!

 

Then some suggest treating to enhance/prolong:

 

https://www.silvatimber.co.uk/thermowood-channel-cladding-21-119mm.html

 

 

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@Dean Carpenter How thick is the cladding? I do not understand how the vertical battens are having the effect of altering the colour of the cladding. I clad our house in Western Red Cedar 'no.2 clear and better' grade and had the profile I wanted, which was 15mm thick, machined for me. The cost of the cladding was under £40/m2. Nowhere are the battens visible. We haven't treated the cedar and it's been up over four years and the colour variation is significant over the whole house. The rain affects the cladding by washing out the colour and it turns grey quickly in those areas but where it's protected it's still brown.

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Where the battens treated with anything that could be leeching into the cladding.

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Would the battens be altering the appearance by trapping moisture against the back of the claddin ? 

Where as the spaces with no batten touching would be free to breath and dry. 

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The sioox product looks like it could be a solution: thanks for this advice. I will give that a try.

 

In my opinion the issue is product related because you can clearly see abutting sections where one is bad and the other is not so bad: I hesitate to say good 

 

The wall section is mostly concrete block-work of various types (I inherited most of the walls and the main construction was built over a 50 year period) . This was wrapped in Tyvek UV (black, doubly expensive) with all joints and openings tape sealed in a special Tyvek Uv tape (extra, extra expensive! and well over 1 week work just for the taping). The battens are fixed approx 600mm centres. the battens were supplied by Carpentier. I believe they are treated the same as the product itself but that shouldn't matter because the clips on the battens are plastic anyway: no moisture can transfer from batten to cladding. 

 

The cladding is a 29mm deep rhombus shape approx 50-60mm high with approx a 10mm air gap in between. I used the same material on my front gate but with less spacing. When installed the effect was stunning.

 

The claim they make about it not splitting, shrinking is also false but this was not a big problem for me. It's the blackening that's really peeved me

 

Carpentier really let themselves down as I had recommended the product to many people but since sent them all warnings for obvious reasons.

 

 

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A few places doing this heat treated wood seem to recommend jet washing it.

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22 hours ago, Dean Carpenter said:

This is an image showing the problem. Doesn't look like the images on their web site, does it?

 

Also, in some areas there is growth but to specific strips of wood only, which logically tells me that some of the wood is resistant and some is not

Hotwood-problems.jpg

What direction is the elevation facing?North?

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