Failed render and attaching cables to render...

[68martin68]

Hi all,

I have a couple of questions about render...

Firstly, how long should it last? Cut a long story short the render on our house appears to have failed as damp patches have appeared in the kitchen and lounge around the coving. Our house is less than 10 years old and so came with the 10 year NHBC insurance so we are trying to claim on that, which brings me onto my next question...

Is it normal/acceptable practice to pin cables to a rendered wall?
Seems to me that it would be, but it's the only way I can see NHBC trying to get out of paying out as there are cables on the wall which is letting most of the damp in.

Having said that you can also see the block work pattern through then render which I am led to believe is another sign of failed/damp render.

Kind regards

Martin

 

[roy c]

If the block/brick pattern is showing thru the render and there is water coming thru the clips that hold the cables on ,then the only reason I can think of is the render may have only been put on in one coat!!! But if it is cavity construction then the only way water can get from front to inside would be by bridging across (either by dirty wall ties or debris in the cavity or no cavity trays over the lintols or trays that have "muck" in them Or from pipes or conduits going thru the wall )....It sounds like the outside isn't painted. A good rendering job shouldn't give you those problems and should last a lot longer than 10 years!!

 

[Micilin]

My brother lives in a house that we rendered in 1979, ( I was a lad!) no problems with it ! Render done well lasts generations, regardless of painting.
That particular house was not painted for years as it was done in white sand render /some dry dash panels /black quions(colour in the mix)

Pins/nails should not matter per se, but they should be driven in at an angle so water drips down them , away from the wall.

I think Roy might have the answer on the bridging

 

[68martin68]

Forgot to mention, the house is built out of solid 9inch block it would appear, hence why it is so easy for the water to get to the inside wall, no cavity!

Also the areas you can see the block work pattern are away from the cables so it is definitely a widespread problem! Thanks for the replies, gives me more ammo to argue if they try and wriggle out of paying out.

Cheers

Martin

 

[Micilin]

Ahh......


Do you know if built with a Durox/Thermalite type block?

Do you have a spec for the render?

Do you have a pic of fascia/barges ?

Are there any possible roof issues?

 

[68martin68]

No idea what type of block, we didn't buy the house new unfortunately.

Again for spec of render, no idea.

I don't have pics currently as it seems to have been ****ing down whenever I e been home in day light hours for ages!

Only pic I could get would be from inside of the damp.

I don't think there are roof issues, have had a pretty good look in the loft and from outside as best I can, also there is no damp coming through upstairs it seems to be coming in just a ceiling level downstairs.

Cheers

Martin

 

[Micilin]

Have you ever drilled a hole in it for any reason? This would give a clue to type of block.

Many dwellings used one thick block to give thermal values, with render on outside.

In which case it should haver a scratch coat of water proof render.

Unfortunately, many plasterers use lime and/or plasticiser in the scratch coat against the waterproof manufacturer's instructions.

Or did not use the correct mix or additive. Or the right sand Or did in in one coat? Did it in frosty weather (check the date it was rendered by asking for site diaries?
Maybe it is not thick enough . If you have the spec it will probably say 15mm

There are other possible reasons eg cracking. Perhaps no damp course /weep holes over the lintols/

Whatever it is, you should not be getting water ingress and if covered by insurance then pursue it.

Demand the specs, application , QA certs on the products used. What standards was the work done to? Who signed it off? Where is the paper trail for the ceritification? Who inspected the footings/blockwork/roof plater/roof/ Get googling. They will wriggle out of it like any insurance so you need to be persistant. That long ago will be hard to sort out but if you aks these kind of questions you are less likely to be fobbed off.

If they blame the nails, then say this is nonsense Pull one out and see how deep it is and what angle it goes in at. As a last resort if they insisited this was the cause. You could argue that you will remove all nails and seal the holes and see if it makes any difference

Keep updating us

 

[68martin68]

Ok, thanks for the comprehensive reply, really appreciated!

I have drilled holes as I am fitting a new kitchen, also I have had a new boiler fitted so a hole was drilled for the exhaust which I saw, what would tell me which block was used?

The house was built as a one off addition to an existing end of Terrace, and so ours is now the end of terrace, in this case who is likely to have information such as that, the council or the original builder? I think the builder was a local one so can probably get in contact with him to see if he has any records.

Cheers

martin

 

[Micilin]

If you drilled holes and they were quite easy once you got into the block, then possibly a 'thermal' block rather than concrete.

A white/grey dust might be Durox, a blue/grey might be Thermalite.

If there is a NHBC guarantee then maybe that is where you start - ref no from that ? If they are guaranteeing work then they must have some traceability?

If you know the builder , great but I doubt if he wants to shed much light on it. But do try.

 

[68martin68]

Ahhh ok, pretty sure they will be thermalite the as they are very easy to drill, sometimes to easy! And they are very light (we knocked some rear wall out for patio doors).

Ok I'll try get in contact with NHBC, they are sending a claims assessor round on 11th feb, but I may start asking questions beforehand.

Cheers

Martin

 

[roy c]

Good advice from Micilin ,,,,

 

[68martin68]

Hello all,

Just thought if post a quick update as I hate when posts are not resulted in some way lol!

NHBC man came round today, he has agreed that the render has failed and even said it is not even attached to the wall anymore in some places. He will write out a full report to this effect and advise that the whole house is re-rendered. They should pay out in full as the claim is above their claim threshold thing so should hear in a couple of weeks or so! The just got to wait for Britain to dry out a bit!

Thanks again for the advice

Martin