Thermowood

[RickH]

Looking to purchase some cladding for an external building (approx 50 sq m) ... Western Red Cedar would cost close to £6.5 per linear m .... which is very expensive to clad.

After looking at other options ... been suggested I use Finnish Thermowood
http://www.thermowood.fi/data.php/200312/795460200312311156_tw_handbook.pdf

Not cheap, but better than WRC.

It should perform much better than plain softwood cladding.
What i want to avoid is a cheap shiplap that splits badly as it ages (i.e' like that on a B&Q shed)

Anybody any experience of Thermowood

 

[ratman123]

Pretty much does what it says on the tin.

 

[RickH]

So it should be a lot better than plain softwood cladding.

Have you used it ? .... does it take a stain OK ?

 

[ratman123]

It basicly is a softwood/pine, so paints & stains the same, looks the same (though brown due to the heat treatment and a little smelly).

The treatment makes it durable, and makes it stable, and the process means that it will be very unlikely to arrive on site "wet", and so excess shrinking after fitting wont be an issue.

 

[RickH]

just went along to my local Jewson's and picked up a sample .... looks good.
The Thermal treatment gives it as you say a brown colour .... which would ceratinly be OK initially, then I would need to stain once it weathers to grey in a few years.
It feels harder than typical softwood .. maybe that is a side effect of treatment.

 

[ratman123]

The treatment actually makes it softer and lighter, but i have seen beech and oak samples of thermowood recently, and that may be what you looked at.

The greying affect you see when timber weathers are bleached surface fibres, and if you apply a finish to weathered timber, it will fail prematurely, so i wouldnt recomend waiting for it to weather to apply a finish.

Try looking for accoya if you want a lighter colour, it uses acetalization rather than thermal treatment, but the end result is the same (except it smells of vinigar instead of burnt timber)

 

[RickH]

what I have a sample of is Themo-treated "Radiata pine".

Following on from what you said, you think it advisable to satin when new ?
Just don't want to be staining annually.

 

[ratman123]

If you properly apply a pigmented (coloured) stain, you should reasonably expect 4 years or so between maintenence. Try a sikkens or ronseal cladding stain.

It's only clear finishes that need yearly maintenence.