Cladding staining render

[daunker]

I have untreated Siberian larch cladding and just had the renderboard below rendered a couple of weeks ago. The larch was put on in April.

 

Anyway just had some rain and seems like the water running down the cladding is staining the new render below. This is only after two rainy days... Really worried how this will look by end of winter?

 

 

The rendering is thin coat system. Is there anything I can do to stop this happening, and secondly to clean if presumably I can stop it.

Edited September 29, 2021 by daunker

[nod]

It is a common problem 

Only sealing the cladding will stop this 

[daunker]

Thanks very nuch. Any drawbacks to sealing it, is there a good product? As it's in situ I'll only be able to do the front face.

 

Will it stop leaching on its own accord, or is that a very slow process.

 

Any advice on cleaning will rain and sun bleach and wash it or is there a recommended cleaning agent. 

 

Sorry for all questions thanks @nod. I'd not heard of it before or I'd have not put up untreated, I thought all the coatings were to colour preserve from sun bleaching (which doesn't overly concern me)

Edited September 29, 2021 by daunker

[ukmgranger]

Hi there @daunker

 

Did you ever resolve this issue?

We have exactly the same problem.  When it rains, the cladding is leaching onto the white render below.  It also drips onto the windowsills and stains the render around these, and also stains around the boiler flue, and outdoor lighting on the render too.

 

Looks pretty awful at the moment to be honest.

 

We wanted the cladding (Siberian Larch) to weather naturally to a grey, but are worried it is ruining the render in the process.

[daunker]

Hi fella, yep same as mine. Maybe a bit worse not sure of your design, if you have extra water running down it. Or if your cladding and render were done similar ish times.

 

Good news anyway, wasn't really happy with the suggestion of the renderer to paint it, so I did nothing and the sun and weather washed/bleached it. Now it's all good!

 

Don't know if that wall is shaded so may take longer, how long has it been up?

Edited July 28, 2022 by daunker

[Strawberry]

Hi @daunker and @ukmgranger

 

I have the same thing happening on my newly renovated house - it looks terrible! I have VPI thin coat render below Douglas fir cladding with staining as per your photos. I am wondering if you found anything to clean the stains from the render? Or to stop the staining? 
 
@daunker I see that sunlight may have improved things for you - is the staining completely gone now? 
 

many thanks all 😃

[Russdl]

1 hour ago, Strawberry said:

I have the same thing happening on my newly renovated house - it looks terrible!

That’s bad news. It needs a proper drip flashing to stop what’s happening in the pictures above, which I guess you don’t have. I suspect one could be retrofitted, but at a cost.

 

Can you go back to whoever installed it all in the first place and get them to rectify it and then fix the render?

 

Is the work guaranteed?

 

Got a photo?

 

[Strawberry]

Thanks for your reply @Russdl

 

I have attached a photo which shows the problem we face. The staining is mostly contained to the band detail we have which runs below the cladding. 
 

Getting the builder back who did the work won’t be possible - to be honest he followed the architect drawings/spec and nothing else was indicated on it. 
 

I had thought of having a drip tray retrofitted which we can do. I briefly mentioned my idea to a renderer and it wasn’t well received as they indicated we would still get staining from wind blown rain. Has anyone who has a drip tray able to advise here? Also what sort of spec should I be looking for? 
 

I think the alternative might be stain blocking the cladding which will be more expensive as it will require scaffolding all round the house 😏 

 

Thanks so much for your time.

[Russdl]

1 hour ago, Strawberry said:

they indicated we would still get staining from wind blown rain.

That sounds like a load of tosh. No one would render anything if wind blown rain stained it. 
 

We have Wood Plastic Composite cladding above our render. The WPC doesn’t leach tannins to the same extent that natural wood does but I’m sure it would stain the render if it weren’t for the zinc drip we have between the two. (I’ll try and find a photo). 
 

If it were me I’d get a drip between the timber and the render, restore the stained render and then sit back and relax. 
 

 

[scottishjohn]

6 hours ago, Russdl said:

That sounds like a load of tosh. No one would render anything if wind blown rain stained it. 
 

We have Wood Plastic Composite cladding above our render. The WPC doesn’t leach tannins to the same extent that natural wood does but I’m sure it would stain the render if it weren’t for the zinc drip we have between the two. (I’ll try and find a photo). 
 

If it were me I’d get a drip between the timber and the render, restore the stained render and then sit back and relax. 
 

 

which is why mine will the cement board type of product 

[Andehh]

Seeing as render doesn't absorb water, any stain would surely eventually wash off?

 

Just a game of patience to let it all leach out the wood, then wash awahm

[Strawberry]

Thanks for your reply @Russdl

 

56 minutes ago, Andehh said:

Seeing as render doesn't absorb water, any stain would surely eventually wash off?

 

Just a game of patience to let it all leach out the wood, then wash awahm

hmmmm - only thing is, these stains don’t wash off. Have tried pressure washing on the fan setting and also used brick acid which removes tannin drip stains on the render caused by our oak frame porch, but not these stains from the cladding.  

 

I would be happy (delighted in fact!) to just sit back and wait if I felt confident the situation will resolve itself, but am not feeling confident about that approach at the moment. 
 

@Russdl - if you have photos or spec for your drip flashing that would be great. 

 

Thanks so much for your time.

[Russdl]

@Strawberry I’m away from home at the moment and I don’t have any photos with me. I’ll post some when I get home tomorrow. 
 

Ours are zinc made on site by the bloke who did the rest of the zinc work on site but if you’ve got a metal fabricator nearby they’ll be able to make whatever you want (probably out of aluminium) and powder coat it to whatever colour you want. 

 

[scottishjohn]

2 hours ago, Russdl said:

@Strawberry I’m away from home at the moment and I don’t have any photos with me. I’ll post some when I get home tomorrow. 
 

Ours are zinc made on site by the bloke who did the rest of the zinc work on site but if you’ve got a metal fabricator nearby they’ll be able to make whatever you want (probably out of aluminium) and powder coat it to whatever colour you want. 

 

or maybe use grp shaped flashing?

[Russdl]

Yeah, I reckon pretty much anything would do provided it kept the drips that will be running down the cladding off the render. 

[Bonner]

20 hours ago, Russdl said:

That sounds like a load of tosh. No one would render anything if wind blown rain stained it. 

I think there is some sense in what he said. If you install a drip say 30mm off the wall, there will be quite a bit of the run off gets blown back on the wall. Will reduce the staining, not eliminate it.

[Dave Jones]

another + for render and timber as outside skin .........

[Russdl]

@Strawberry still not made it home yet but I’ve found one of my drawings detailing the cladding/render join and the zinc drip.
 

It obviously doesn’t have to be zinc, or metal. Just anything to stop the water going directly from cladding to render. It’s not that clear but our zinc drip is a stretched out ‘Z’ shape. It may be possible for you to do something similar to the drawing below and slide something up behind your cladding so that it can be firmly fixed in place and then project out over the render. 
 

[Strawberry]

Thanks very much for this, @Russdl 

 

I have reviewed the construction drawings prepared by our architect and there is no mention of a flashing detail here. It seems your work is of a higher quality! Thanks very much for this - it is very helpful. I am reluctant to spend (more) money unless I feel confident it will improve/resolve the situation and it has been difficult to get to this point.
 

I also noticed you are just up the road from us - albeit with a nicer looking house I imagine 🤣

[Russdl]

24 minutes ago, Strawberry said:

albeit with a nicer looking house I imagine 🤣

Beauty is in the eye of the beholder. Not everyone beholds the beauty we see hence we call it Marmite House. 

[Mike]

On 21/05/2024 at 20:15, Strawberry said:

I would be happy (delighted in fact!) to just sit back and wait if I felt confident the situation will resolve itself, but am not feeling confident about that approach at the moment. 

It should mostly resolve itself. The tannins will leach out over a couple of years or so, subject to the weather. And likely from the render too some time after that.

 

However, there is likely to be some ongoing staining from the rain - it's a potential problem whenever whenever rain drips off one surface on to another absorbent one. A drip bead similar to @Russdl's can significantly reduce that.

 

 

 

 

[Russdl]

@Strawberry here’s a couple of pictures.