Problems with my thin coat render system

[Thedreamer]

I am sorry to hear that they are not going to do the right thing. 

 

Just thinking outside the box, are the big issues with the render system the bits closest to the ground?  What about stripping off the lower part and having a split between the render and timber cladding?

 

Perhaps a little bit of tidying up around the windows etc?

 

[CC45]

hope it gets sorted OK @ProDave  I liked the system & would have used it next time but not too keen now....

 

Fingers crossed you get it resolved.

[SimonD]

On 06/04/2021 at 17:39, nod said:

From the photo it doesn’t look to close to the ground 

I normally advise 150 minimum

 

All the woodfibre manufacturers specify min 300mm from ground level although some will provide detailing at below that. This usually involves a gravel splash area and the use of either xps or eps insulation up to the 300mm, including the use of various membranes. What's really unfortunate is that it gives them an excuse to try an wriggle out of it!

 

On 06/04/2021 at 17:46, ProDave said:

I have replied making it clear to the supplier (and hopefully more likely to get a resolution) that we have scaffolding and the plasterer is offering to rework for free, so it is only materials we need, and importantly technical input to ensure we have not genuinely done anything wrong.

 

That's eminently reasonable on your part. Hope they come back with a decent response and the technical support you need.

 

BTW I know you're up in Scotland, but do you suffer particularly from wind-driven rain? Here's a paper from Norway looking at EWI failures and moisture damage. May not solve your problem, but may give you some more info about what might be going on for you? Durability of ETICS with Rendering in Norway—Experimental and Field Investigations

 

I'm keeping an eye on this thread as I have 96sqm of woodfibre ewi about to go on my walls. And after receiving what appears to be incorrect advice already about which render system to use, it looks like I'm down to using the Baumit system! ? Although Weber.Therm is also suitable according to the woodfibre manufacturer.

 

The only other option is to find an independent surveyor with the knowledge to do an assesment and provide a report. If the supplier doesn't come back to you with an offer to assess it themselves, this is perhaps something you could suggest they work with you on getting done?

[nod]

7 minutes ago, SimonD said:

 

All the woodfibre manufacturers specify min 300mm from ground level although some will provide detailing at below that. This usually involves a gravel splash area and the use of either xps or eps insulation up to the 300mm, including the use of various membranes. What's really unfortunate is that it gives them an excuse to try an wriggle out of it!

 

 

That's eminently reasonable on your part. Hope they come back with a decent response and the technical support you need.

 

BTW I know you're up in Scotland, but do you suffer particularly from wind-driven rain? Here's a paper from Norway looking at EWI failures and moisture damage. May not solve your problem, but may give you some more info about what might be going on for you? Durability of ETICS with Rendering in Norway—Experimental and Field Investigations

 

I'm keeping an eye on this thread as I have 96sqm of woodfibre ewi about to go on my walls. And after receiving what appears to be incorrect advice already about which render system to use, it looks like I'm down to using the Baumit system! ? Although Weber.Therm is also suitable according to the woodfibre manufacturer.

 

The only other option is to find an independent surveyor with the knowledge to do an assesment and provide a report. If the supplier doesn't come back to you with an offer to assess it themselves, this is perhaps something you could suggest they work with you on getting done?

On most of the jobs I do paving is run right against the wall with very little clearance Sometimes we are asked to render below dpc 
I’ve using through coloured renders for over 40 years I’ve never known splash back be an issue 

 

It’s worth considering K Rend for your build You don’t get this kind only nonsense from there reps 

[SimonD]

7 minutes ago, nod said:

It’s worth considering K Rend for your build You don’t get this kind only nonsense from there reps 

 

Thanks, but unfortunately K Rend doesn't do a render for woodfibre insulation, just EPS, mineral wool, or phenolic.

[ProDave]

2 hours ago, SimonD said:

 

All the woodfibre manufacturers specify min 300mm from ground level although some will provide detailing at below that. This usually involves a gravel splash area and the use of either xps or eps insulation up to the 300mm, including the use of various membranes. What's really unfortunate is that it gives them an excuse to try an wriggle out of it!

 

 

That's eminently reasonable on your part. Hope they come back with a decent response and the technical support you need.

 

BTW I know you're up in Scotland, but do you suffer particularly from wind-driven rain? Here's a paper from Norway looking at EWI failures and moisture damage. May not solve your problem, but may give you some more info about what might be going on for you? Durability of ETICS with Rendering in Norway—Experimental and Field Investigations

 

 

Thanks that paper is an interesting read. Though it does not deal with render on wood fibre directly.

 

Re wind driven rain.  The wall that has suffered worst here is the east facing wall. that gets very little direct rain.  The West facing wall that gets lots of wind driven rain has not suffered anywhere as bad.

 

I don't buy the too close to the ground argument.  If that were the cause I would expect all the problems to be along the bottoms of the walls.  but in many placec the delamination and blistering is higher up the wall, sometimes a lot higher up.  If it were water getting in at the bottom and wicking up, then why has it only failed higher up and not all the way up to the point this supposed moisture has wicked up to?

 

At some point I need to strip off the failed top coat in places to see what is going on underneath.  That should tell us a lot about what is wet and what is not.  I don't want to do that yet, I wanted to wait until the manufacturers rep was here to look at what is going on.  That is what I am trying to get, someone to come and have a proper look rather than give me a remote diagnosis.

 

Re the EPS detail at the bottom.  That seems to be a treatment of a wall below DPC level or of a timber wall that goes all the way down.  We have blockwork below DPC level and that is exposed and painted with masonry paint.  I am not a fan of rendering a wall below DPC as it will obviously be damp and with frost is a likely candidate to fail.  I really cannot see how not cladding our below DPC blockwork with EPS and then rendering it has caused our problems.

 

At the moment the supplier does seem to be hiding behind the "you got that tiny detail wrong" excuse and not wanting to help.  If you are considering an external render system, ask yourself the question, do you want to buy from a supplier that will do all they can to wriggle out of any responsibility and not even offer any constructive help if they can find an excuse to do so?  If you want a supplier that takes an interest in their product and wants to help solve a problem, at the moment I suggest you look at a different render system.

 

At the back of my mind I am concerned that the root of the issue might be our cold climate.  Is it just too cold here for such a system?  That suspicion is partly because it is the east wall that has suffered the most, and that is the garage wall so it is an unheated space so there is not even a tiny but if heat escaping from the building to limit how cold the wall gets.

 

 

 

 

 

[SimonD]

5 hours ago, ProDave said:

I don't buy the too close to the ground argument.  If that were the cause I would expect all the problems to be along the bottoms of the walls.  but in many placec the delamination and blistering is higher up the wall, sometimes a lot higher up.  If it were water getting in at the bottom and wicking up, then why has it only failed higher up and not all the way up to the point this supposed moisture has wicked up to?

 

At the moment the supplier does seem to be hiding behind the "you got that tiny detail wrong" excuse and not wanting to help.  If you are considering an external render system, ask yourself the question, do you want to buy from a supplier that will do all they can to wriggle out of any responsibility and not even offer any constructive help if they can find an excuse to do so?  If you want a supplier that takes an interest in their product and wants to help solve a problem, at the moment I suggest you look at a different render system.

 

At the back of my mind I am concerned that the root of the issue might be our cold climate.  Is it just too cold here for such a system?  That suspicion is partly because it is the east wall that has suffered the most, and that is the garage wall so it is an unheated space so there is not even a tiny but if heat escaping from the building to limit how cold the wall gets.

 

Please don't get me wrong. I wasn't suggesting for a minute that the too close to the ground argument was okay, more implying that it sounds to me like something a two-bit insurance company might use to refuse a claim! So far I think the response is disappointing and must be infuriating for you. I am looking at alternatives.

 

I do wonder whether the Scottish climate plays into it. I don't think it's too cold per se but that is has damp-cold-frost cycles so it's not unusual to have a soaking wet wall and then severe frost. This has been found to be a problem in Finland with these EWI systems and as a result they developed their own test and certification system beyond the normal European Technical Assessment. In the Finnish case they found some systems fine, others failed - I haven't be able to find specific results to know which ones were okay and which weren't.