Frost damage to render.

[ProDave]

To recap for those that don't know, my house is timber frame, clad in 100mm thick Pavatex wood fibre board and rendered with the Baumit.com render system, comprising a base coat of lime based render mixed from powder, and their silikon top final coat that comes ready mixed in tubs.

 

We were away for the xmas / new year period and came back on 3rd January to find a thick layer of ice all over the plot and the road, the neighburs told me nobody had been able to get their car up the road for 2 days. So it had obviously been very wet, then very cold.

 

I observed a small but of render has "blown" almost certainly frost damage.

 

This is the end wall of the garage.  No other parts of the house are affected.

 

Obviously it will need repair. But I am trying to understand why it happened, and what I can do to stop it happening again.

 

My random thoughts:

 

I believe it is only the thin silikon top layer that has blown, the base coat I believe is still solid.

 

This bit is closer to the ground than any other part. That together with the fact it's a concrete parking area, means it will get splashed with rainwater far more than any other part of the house.  That should not be an issue. The wood fibre board sits on plastic support trays at the bottom so splashing water should not make the wood fibre board wet. The fact it is only the top layer that appears to have blown suggests I am right and the wood fibre board is dry.

 

If excessive splashing rainwater is the problem, that will largely be solved eventually by the fact this concrete parking area will eventually be covered with a car port.

 

My other thoughts are at the moment, there is no garage door (garage door opening only just out of shot to the right) So the inside surface of this wall is at ambient temperature (i.e. damned cold during the period this happened) So this section of wall is cold right through, so much more likely to get frost than any other part of the house.  That situation will improve a lot when I can eventually afford to fit a door.

 

My last thought is a bit of an unknown.  With this render system, you apply the base coat, then paint on a primer then apply the top coat.  I was not present when this wall was rendered (the last one to be done) but I have a suspicion the primer may not have been applied, or if it was, the  primer was applied and then rendered the same day.  All other walls had the primer applied and top coat of render next day.  This wall has always been "odd" in that it appears a whiter colour than the rest of the house, in spite of being finished with the same colour render as the rest of the house.

 

Also worth noting, it is common to see frost on the walls, particularly the north facing wall and it has never created this problem before.

 

Anyone got any thoughts on this please or experienced similar?

 

 

[ToughButterCup]

42 minutes ago, ProDave said:

[...]

With this render system, you apply the base coat, then paint on a primer then apply the top coat.  I was not present when this wall was rendered (the last one to be done) but I have a suspicion the primer may not have been applied, or if it was, the  primer was applied and then rendered the same day.  All other walls had the primer applied and top coat of render next day. 

[...]

 

 

My Polish builder (Daniel) says he suspects the primer was not put on properly ... Or the wrong (AKA cheaper) primer was put on instead.....He has seen similar damage in England, but not Poland

 

Czejs  !

[ProDave]

Which might tie with the primer not put on at all?

[nod]

1 hour ago, ProDave said:

Which might tie with the primer not put on at all?

I think it’s unlikely that there is no primer on

The primer is designed to to help the top coat adhere But all to kill the suction from the base coat 

If there was no primer it would be very difficult to get a uniform finish

From the picture it looks like water has got between the two coats and frost has then done the damage 

It’s unlikely the base coat will be effected As it’s more durable than the top

 

in an ideal world we wouldn’t use these render systems if the tempriture  was likely to drop below 5 As recommended by the manufacturer 

But that wouldn’t be practical

This time of year we completely sheet the scaffold up to protect against As there no telling if it’s going to be frosty

I wouldn’t worry about the rest though