Larch Cladding- treatment options

[Crofter]

Unlike seemingly every architect, TV presenter, etc, I'm not much of a fan of the 'leave it to weather' school of timber cladding.

I think you can get away with it in certain circumstances- very uniform wood which weathers evenly, no overhangs on the eaves, nothing that will allow different parts of the same wall to see different levels of exposure.

There are many examples of timber cladding up here on Skye where the weathering is very uneven and frankly I think it looks awful, like an old pallet left out to rot. Probably a case of architects designing for high quality Siberian larch and then the builder sticking cheaper native stuff up, or something like that.

 

Anyway- I'm wanting to treat my larch, it will be Scottish so not as dense as Siberian, and in a high exposure coastal site on a building with quite deep eaves overhangs, I don't think I would get away with leaving it unreated. Fortunately the building is small and all of the cladding will remain accessible by ladder after installation.

 

I've come across stuff called 'Sioo' which, according to the blurb, is very good stuff but it's incredibly expensive.

Any other suggestions out there?

[jack]

How expensive is "incredibly"?  

 

Our (Siberian, Russwood-supplied) larch has been up about a year and is so far weathering pretty unevenly in places.  As you say, underneath overhangs has hardly weathered at all, plus we have places where there's uneven staining from water movement.  It'll mostly even out in the end I suppose/hope.  In the meantime, I just tell myself that wood is a natural product and this is how natural products behave.

 

Sioo wasn't available when we needed our larch, although even with what we're experiencing now I'm not sure whether I'd have used it.  The uniformity is very nice, but I do wonder whether there's a loss of longer term character compared to letting it weather naturally (with all the flaws that that might bring).

 

 

[Crofter]

About 60% of the cost of the timber itself, and that's me not accounting for any wastage and only treating the exposed face of the timber, not the back.

It's supposed to have a 15yr service life so it would work out at about £30/yr which makes it a bit easier to swallow! If it really is as good as they say I could probably find the money, but it's not in the budget and I am wondering what alternatives there are.

[DavidFrancis]

Not used it myself, but Osmo oil gets a very good rating on Amazon.  Don't know how it compares in price.

[iSelfBuild]

We have treated the larch fascia boards with Sioo and so far we are very impressed. Impressed enough to get our Siberian Larch pre-treated by Russ Wood.

 

I'll take some photos next time I'm up on site, it really does seem to work to be fair.

 

 

[Auchlossen]

FYI here is a 2015 image of [very] rough sawn untreated Scottish larch in 3 generations:

• gable end erected in 2005
• logstore erected in 2008
• patio pergola erected in 2015

The timber has blended into a uniform pattern.

It has lasted well, and none has required replacing after more than ten years.

If I were repeating that particular approach of using local larch, I would probably choose a finer cut, rather than using my late neighbour's sawmill, since the very rough surface tends to hold the rain, with a presumed impact on endurance.

My view in 2005 was that the cladding had a life expectancy of 20+ years, and I have no reason to doubt that today.

[worldwidewebs]

Sioo is excellent stuff and Sansin isn't far behind. Have a word with Silva Timber - they'll be able to advise what would be best.

[Trw144]

I used osmo oil uv protection on my last house, it's two years old and has nt weathered grey at all, but it is a little patchy in places. I think this is probably to do with the wood and application of it rather than product though.

 

What I did find (unfortunately too late) was that if you sand the surface of the wood lightly, the oil seems to gets much better penetration and goes on more evenly.

 

Cost wise, I don't remember exactly what it was but don't remember it being extortionate.

 

[Tennentslager]

I think all the experts say treat before installation. 

More work but better results .

Means you can grade the boards too and put the best ones on top and the dodgy ones behind...

Best ones for your main elevation 

Seconds for the gables

Thirds for behind the top boards 

And forth ripped for battens or the fire 

[Crofter]

Yup I've read that it's best to treat the boards before installation, otherwise any shrinkage leads to exposed untreated wood.

I wonder if I should treat all sides though? Or maybe just three sides of the front boards, and one face of the back boards, as that is all that is conceivably going to see any UV exposure.

 

I was hoping not to have to buy so much larch that there would be much left over for the fire!

[Tennentslager]

Yep that's how I'd do it...

I got 10% extra and had nothing left, was just perfect amount.

[jack]

We still have some cladding to do (eaves) and I think we'll just scrape by with our 10% over estimate.

[Bitpipe]

Not done cladding but had a similar experience with tling, oak plank and karndean flooring  did the raw measurements, rounded up and then added 10% - just squeaked it in all cases and needed to buy another pack of floor tiles. Barely had a scrap of Karndean left in our 4 room 100m2 basement.

 

Have since been told that for larger format items (such as our 600mm square floor tiles) 20% is a safer option as wastage is higher.

 

Trade off seems to be whether you can balance under-ordering with getting additional material of the same batch (v important for tiles) at short notice (and extra delivery cost)!

 

edited to add - have already undershot a bit on architrave and waiting to see on skirting!

Edited August 2, 2016 by Bitpipe

[Crofter]

Yes I've used the 10% rule before on tiling and laminate flooring. The cladding is a bit different, though- I'm working it out to avoid any joints whatsoever (longest run is 16ft) so I've worked out a cutting list based on the actual lengths, not the areas. I hope to only need extras in case of mistakes or particularly bad bits of wood.

[Cpd]

Have used Scottish larch and like you i wanted to avoid joints, however even when i carefully worked out the requirements and quantities i was very short and ended up using another sort of wood cladding on the back of the caravan / cabin, this came about because i pre laid the wood out on the feild to see what worked best, large boards at the base smaller at the top, but also tried to work the wainy edge to look "right" to my eye, i had boards left over but was not happy with the quality of the last 10% or the ability to make them look as good as the other three sides, so decided to do something different on the back. In the end i was very happy but would recomend either veiwing your product or over order and use the dross for a wood shed or something. I also did not want the natural efect and uses a common brand wood preserver / stain / weather sheild, i expect i will have to repaint before the 5 year "guarantee"  but am ok with with that as i want to keep it looking fresh. I guess if your not using wainy edge it becomes a whole lot easier....... Will try and get a photo soon. 

[Crofter]

Thanks, I'm using board on board vertical (100x20mm square edge sawn)- so hopefully not the same issues as with waney edge.

 

I could be sold on the Sioo is it's really as good as advertised, but it's a hefty up front cost that I hadn't budgeted for, and I can't help wondering if it's really *that* much better than something more ordinary.

[divorcingjack]

I had a look at this as well, I'm not a fan of the weathered look either. From what I remember, whatever treatment you use must have an effective UV screen, otherwise it will grey, albeit more evenly. As mentioned above OSMO came out as a brand to look at. Thanks for the info about Sioo, I'll demo have a look - I'll buy any of your leftovers if you like, we've only got a relatively small amount of larch to do. 

[ProDave]

Another one here that can't answer the question but wold like to know the answer.

 

Quite a lot of houses are built up here with timber cladding, often only partly clad (and then usually partly rendered)

 

A common alternative to doing nothing is to "paint" them, with light green or light blue being popular colours.

 

I would be interested to know what "paint" they use for this, applied direct to rough sawn timber. The only product I can see that comes close to being suitable for this is paint intended for timber decking.  Otherwise all timber treatments seem to be "stain" rather than "paint" and mostly specified for sheds or fencing.
 

[Crofter]

Just by chance I bumped into a neighbour yesterday who is finishing up his build, and has partially clad in larch- he used Sioo and it does looks pretty good, but obviously only time will tell.

My larch cladding quote has come back about 70% higher than I was originally quoted, so I really don't have any budget to speak of in this area any more

[gravelld]

Do Osmo have a competitive product to Sioo?  The latter claim 15 years service, the former 4... Maybe I'm looking at the wrong product.

[Crofter]

22 minutes ago, gravelld said:

Do Osmo have a competitive product to Sioo?  The latter claim 15 years service, the former 4... Maybe I'm looking at the wrong product.

 

Not that I'm aware. And I think they work out about the same price so that points strongly towards Sioo.

[Crofter]

On 01/08/2016 at 16:29, iSelfBuild said:

We have treated the larch fascia boards with Sioo and so far we are very impressed. Impressed enough to get our Siberian Larch pre-treated by Russ Wood.

 

I'll take some photos next time I'm up on site, it really does seem to work to be fair.

 

 

 

Hi Rich- what did you make of your larch fascias? Did you use rough sawn same as your cladding? I was going to just use WBP but now that I think about it, larch would make sense since I am buying a kilometre of it anyway for the cladding.

[iSelfBuild]

They look great, I'm not on site but I will get my Dad to take photos and send them over. I think the finish is dressed on the fascias not rough sawn - we joined a few together to make deeper boards.

 

 

This was taken  a week after SIOO (just the front boards are treated here not the gable) I'll get my Dad to take another photo from the same angle which will be one month on.

[Crofter]

Thanks, dressed makes more sense I guess, I may well copy you on this!

[iSelfBuild]

On 13/08/2016 at 13:59, Crofter said:

Thanks, dressed makes more sense I guess, I may well copy you on this!

As promised, more photos here -

 

My Mother took bury photos, this one shows the weathering one month on the best:

 

Edited August 17, 2016 by iSelfBuild