Looking at cladding a garden office in a PVC shiplap/weatherboard but coloured variants seem quite costly.

I then came across silicone render.

I wondered if anyone had any experience of using this when applied to a wooden rather than a conventionally built  structure? (thinking clad in OSB board and then render that).

Can it be done DIY – seemed to be a very few options to buy bags of silicone render to mix yourself.

You can’t render onto OSB, or any other wood board for that matter.
Render carrier boards are usually fibre-cement or MgO boards. You could install these over the  existing shed with battens to form a cavity.

You could also board over the shed with an EPS or mineral wool insulation and render onto that (known as an EWIS or ETICS system)  – silicone renders are very commonly used for this purpose.

@import – thank you for the wisdom!

Is rendering the wool or EPS better than rendering the board and insulating between the battons?

I assume there needs to be a layer of something – OSB perhaps attached to the battons rather than just affixing the insulation to the batton and then rendering that?!

I know a lot about the systems through my occupation, but am quite hopeless with a trowel, so can’t comment on which substrate would be easier to render.
For a DIYer, I wouldn’t have thought there’s much difference between setting out battens and boards versus fixing up the EPS panels. Doing the insulation does require specific fixings with large heads. Insulating between battens does still leave a larger thermal bridge, which may or may matter in a shed…

I think it comes down to whether you want to insulate the shed or not – if yes go with the insulated system and if not, just fix up battens and boards.

Both types are multi-layer systems, with basecoat, mesh and finishing coat required.

I render professionally albeit with lime however I have used system renders that have been specd by architects

I have rendered on to osb boards but we are talking small areas that have also been covered in stainless expamet render mesh that is nailed tight to the structure. The osb construction was within a larger block building and was therefore a rigid section of the whole build. I wasn’t terribly convinced but that’s what architect and client wanted, and it has stayed intact for 8 years so far.

I’ve used render systems onto wood fibre boards, again these were covered with a nylon render mesh. A more convincing construction overall. As far as I am aware they are ok and client happy.

Would I render direct to timber or OSB? No.

Is it diyable?  Well yes but like a lot of jobs, getting something on the wall is easy. Getting it looking good and likely to last is another matter. There’s also the time needed to do it, decisions about how you apply it, tools and mixing apparatus. It can get expensive quite quickly, so always look beyond the headline price of the options you are considering. Your cladding option might not actually be the most expensive

Very helpful tips thank you. Does the eps/wool need a backer board or can it go straight to battens (i guess issue with no backer is having battens close enough together)

Are there any Downside of rendering the insulation – service life or durability for example?

Will be insulating (and having windows) to make a garden room type space for turbo or office.

You apply the insulation direct to the substrate wall, without additional backing boards. You can also apply it onto intermediate battens, which by forming a small cavity can be helpful in avoiding condensation risks in timber structures.

The systems I’m familiar with have a typical service life of 25 years when installed well, so durability shouldn’t be an issue. They’re all from mainstream suppliers and need to be specced up as a complete system though – don’t accept substituting of parts or a mix’n’match.

the failures that I’ve seen have all been a result of poor design, detailing or workmanship rather than material failures

My BIL does renovations and uses it a fair bit.

From a [non-technical] perspective of someone who’s looked into it and seen enough houses done with silicon render, my feeling is it looks great when first applied but 4 years later it’s turning green or pink and has to be jetwashed every year to stop it looking crap!

MrsSB used to love it but has gone very quiet on the subject.

* House next to me by the sea.

Thanks all.

I think it looks like the original coloured PVC or composite weather board is probably the best way to go then.

To give a very narrow answer, I had silicone render done on the gable end wall of my previous house and it was fantastic. 100% recommended.

SW facing, loads of driving rain (high up in Sheffield), it didn’t have a crack or a mark on it after three years. Then I moved.

It was an expensive pro install, I can’t imagine DIY would be very successful for anything but the smallest area given I think it has such a nice finish partly because it gets sprayed on.

I think it has such a nice finish partly because it gets sprayed on.

I’m fairly sure it isn’t!

I think it looks like the original coloured PVC or composite weather board is probably the best way to go then.

We did composite cladding at our other place about 8 years ago and we’re extremely happy with it (we used Marley Cedral)

I’m fairly sure it isn’t!

Fair – no doubt manual application is also appropriate, but my gable end wall was 90m2 so that would have been even more of a job. And the spray method did give a lovely finish.