Damp patches on silicone render

[Orchard60]

I have a two year old timber frame house with the Whetherby Silicone render system applied to Rendaboard which is battened off on 2x3inch timber battens. There's ventilation top and bottom. The render has damp patches all over and in places water runs down the front of the render from the damp patches!

Whetherby say the render is waterproof and should not let water in although it is breathable and should let moisture out. When it rains, the render seems to get saturated and the Rendaboard is now saturated too along with the battens (I sent a camera up behind the boards to have a look). In the summer the sunny side of the house seems to dry out OK, but on the north side the damp patches are there year round.

Now we're back into winter the render looks a mess with all the damp patches.

Has anyone else had a problem like this?

 

[User___removed]

Is there anywhere else the water can be getting in?would be very surprised if it is getting in through a silicone finish.



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[scogs]

I would think it more likely the water is getting in from behind and leaching out if anything. I would be looking at the abutment to the roof/soffit narrowing it down to the areas where it appears on the render then investigate further. Difficult so have an idea without seeing it. Any photos? Or put the area your in surely some one will try advise????

 

[CTPlastering]

Best to get some one out who does these systems , you could be on for hours looking for something they would spot straight away , that you might never of even considered

 

[plasterjfe]

We fit loads of frame systems over board. I would guess at ingress around a detail or two and then bleeding forward..

It should not be getting through from the finished surface to a degree you mention. Unless the product was watered down significantly. Some applicators do water this product down.

Another issue sometimes found on a boarded facade is condensation. Sometimes pins or battens van be seen through the render where a little dew has formed rule this out if poss first.

I dont use wetherby system for different reasons and heve never seen such a problem without actual obvious water ingress.

Is your vented head covered with the appropriate capping or soffit ?

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[Orchard60]

Thanks to everyone who has replied. I appreciate all your thoughts. As you might expect we have made several investigations to make sure there is no water ingress behind the render board and I can confirm that this is the case. I have actually just checked again this afternoon after last nights very windy monsoon conditions and once again it's bone dry behind the facia.

The render was applied in October 2011. It was cool and damp at the time and there was a partial wash off due to it raining the night it was applied. A top coat was then re-applied over what was left. Is it possible that this has compromised the render in some way?

 

[Orchard60]

Just to confirm the head of the render is under the soffit with a bug screen about 30mm deep.

 

[scogs]

Whereabouts are you?

 

[plasterjfe]

Have wby entertained your problem as in have they visited in wet conditions etc ?

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[plasterjfe]

The finish coats do not dry out properly in moist or cold conditions. It will take moisture from the air and keep itself soft. It is also possible to trap moisture underneath if previous coats ate not fully dry but this usually results in blebbing and delaminating top coat which you would have noticed.

Without seeing it I can only say it sounds like it is taking moisture on and slowly releasing it as it dries out

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[plasterjfe]

If it is as wet as you say then the battens will surely be under threat and with the weight of render board etc it is not good.

It goes without saying that the render made and specified for these systems certainly the products I use would never let that amount of moisture through the surface unless something was wrong with it.

Was it installed by an approved applicator and if so did wby do a specification for you and did they do site visits and did they also sign it off after completion and pass you a certificate of warranty ?

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[S a plastering]

Give Steve a ring from wetherby mate he's the tech guy just ring em up an ask for his mobs num or if your struggling I can get it for ya pal

 

[Orchard60]

Thanks everyone. I have had Wetherby out and they don't seem interested. Have now had a surveyor out who seems to think the render has failed. They are planing to take core samples and test it which will give a definitive answer! Will let you know results when I get them.

 

[Olican]

A complete thread staying on topic :RpS_thumbsup:

 

[plasterjfe]

Thanks everyone. I have had Wetherby out and they don't seem interested. Have now had a surveyor out who seems to think the render has failed. They are planing to take core samples and test it which will give a definitive answer! Will let you know results when I get them.

Please do let us know the outcome. I am very interested to hear the outcome from any concerned.

Make sure the surveyors are specialised in their field and not guys from say a selling or estate agent they don't know jack all and normally have a tick off list to go by that's as far as their knowledge goes.

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[PFTwales]

Can you confirm the correct board have been used i.e calcium silicate, aquapanel or similar. These type of boards are waterproof and should not get saturated. A cement particle board may be used in error and this will look the same as the previous boards but will not be waterproof