Wall Tie Replacement

[WaveyDave]

Hi Guys

I've been told that the house I'm buying is showing signs of wall tie failure. I've spoken to a guy that can do the wall ties, but I'm concerned about the effects on the external render. The house is smooth rendered (stucco?) and painted. I know that wall tie replacement is going to mean lots of holes, that will be filled. Am I likely to need the whole house re-rendered? Its a 1930s semi, original render I think, painted white.

Cheers

Dave

 

[joe-90]

What problems is the house showing? Wall tie replacement is the new DPC rip-off.

 

[WaveyDave]

Thanks for the reply.

Two separate surveyors have said that it is starting to display symptoms. Some horizontal cracking appearing every few courses of bricks. Not urgent at the moment, but we're trying to get a handle on what needs doing!

Cheers

Dave

 

[joe-90]

The cracking that you refer to is caused by the old ties rusting and expanding thus creating a running crack. Adding new ties won't stop that from happening. If all that is happening is that the odd mortar course is cracking - just patch it up. The real problem with wall tie failure is when the two leaves of brickwork fall apart. This probably won't happen ever.

 

[WaveyDave]

Ok

So are you saying that I don't need to have the wall ties replaced, or that it's unlikely? Obviously, I don't want to leave it until the outer skin falls away, and if it did, I doubt I'd be able to claim on insurance because I've had 2 surveys that say it needs doing!

Just a bit wary!

Thanks

Dave

 

[freddiemercurystwin]

You could phone up your local building control, they're usually a helpful bunch and probably won't mind giving you some impartial advice, you don't have to give your details, of course officially they may have to agree with your surveys but if you're friendly about it you should be able to get an 'off the record' opinion ie is your outer skin going to fall down in the wind or not. If the renders cracking its safe to assume the bricks are no longer bonded where the cracks occur. We've all seen the (occasional) horror in the news of single skin walls collapsing after all. I certainly wouldn't go by the advice taken off a forum (No offence joe-90).

/appreciates you may of course want to ignore every thing I've just said.

 

[anobium]

The cracking that you refer to is caused by the old ties rusting and expanding thus creating a running crack. Adding new ties won't stop that from happening. If all that is happening is that the odd mortar course is cracking - just patch it up. The real problem with wall tie failure is when the two leaves of brickwork fall apart. This probably won't happen ever.

Once again Joe-90 gives advice when he clearly does not know what the hell he is talking about.
The facts ,if some ties have started to rust ,then it is logical to assume that the rest of the ties will corrode in due course.
Why are ties installed in the first place, to provide support to the cavity wall.
Therefore whilst a few cracks are nothing to worry about, they are the warning signs that something should be done before it gets worse.
Adding new ties will obviously not stop the corrosion to the other ties but it will secure the inner leaf to the outer leaf.
Waveydave you be guided by the people who have actually seen the problem and if you are in any doubt get an independent surveyor in.

 

[^woody^]

To answer the original question, yes you will need to re-render -or else you will see lots of patches of different render surface texture

The defective ties will need to be removed - or else they will continue to expand and spoil the render. And new ones will need to be fitted.

If a cavity wall did not need ties, then I'm sure none would be fitted in the first place.

 

[WaveyDave]

Thanks for the replies guys.

I've had 2 surveys carried out (one homebuyers and one mortgage valuation), both have commented on the wall ties.

I think I'll go ahead and get a proper wall tie survey on the property.

Cheers

Dave

 

[joe-90]

The cracking that you refer to is caused by the old ties rusting and expanding thus creating a running crack. Adding new ties won't stop that from happening. If all that is happening is that the odd mortar course is cracking - just patch it up. The real problem with wall tie failure is when the two leaves of brickwork fall apart. This probably won't happen ever.

Once again Joe-90 gives advice when he clearly does not know what the hell he is talking about.
The facts ,if some ties have started to rust ,then it is logical to assume that the rest of the ties will corrode in due course.
Why are ties installed in the first place, to provide support to the cavity wall.
Therefore whilst a few cracks are nothing to worry about, they are the warning signs that something should be done before it gets worse.
Adding new ties will obviously not stop the corrosion to the other ties but it will secure the inner leaf to the outer leaf.
Waveydave you be guided by the people who have actually seen the problem and if you are in any doubt get an independent surveyor in.

Which means every house in the area - if not the country - will need wall tie renewal. It's the new 'Damp course' debacle. Thought you might have guessed that much

 

[anobium]

Joe-90, don't take my word for it , just read what the BRE has to say about it.

Cavity Wall Tie Renewal/Insertion Document >


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History and Background | Corrosion

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HISTORY AND BACKGROUND


Cavity walls incorporating metal ties have been in use since the beginning of the nineteenth century but it was the 1930’s building boom that produced large numbers of cavity construction dwellings. From 1945 cavity wall construction became the normal for houses and many other buildings.



The early metal ties produced mainly from wrought or cast iron performed satisfactorily but in more recent years mild steel ties have been used and despite galvanising or bitumastic treatments have been found to suffer from corrosion. A British Standard was produced in 1945.



The estimated life of these mild steel ties is appreciably less than the 60 year life expected. The 1945 standard was relaxed in 1964 and 1978 but in 1981, when the extent of the problem was registered, the British Standard was amended to triple the zinc coating thickness on a wire tie.



A number of cases of distress of cavity walls, attributable to wall tie failure, have occurred in the United Kingdom and it is now clear that the problem could eventually affect all the cavity wall structures built before 1981, some 10 million dwellings, and will not in future be confined only to cases or poorly made ties.



Wall tie failures reported to the Building Research Establishment (BRE) include inferior coatings of bitumen, insufficient zinc galvanising on mild steel, aggressive mortars (particularly black ash), exposure to marine climates and permeable mortars such as lime that permits rapid carbonation.



It is estimated that over 3 million houses of cavity wall construction were built before the introduction of the 1945 standard. Between 1945 and 1964 an additional 3 million houses were built to the British Standard BS 1243-1945 with a wire tie life expectancy of 15 to 31 years and a strip tie life expectancy of 31 to 61 years. From 1964 to 1986 over 4 million houses were built to the lower British Standard with a tie life expectancy of 23 to 46 years.



It was estimated in the 1986 Survey of English Houses that around 12 million properties exist with cavity walls of which the number requiring some repairs to wall structures is approaching one million

 

[joe-90]

Yes and every house with loose slates/tiles on the roof needs re-roofing.

Stick to the particular poster's problem.

If he has the ties re-done and has the house re-rendered - will that cure the problem? Or will his render simply crack once more? Will they remove the old ties? Under what scenario is the wall tie corrosion likely to become a problem? How much will it cost him to cure a problem that at present isn't a problem?

Let's live in the real world for a bit eh? Or shall we re-roof every house with slipping slates?

 

[anobium]

Yes and every house with loose slates/tiles on the roof needs re-roofing

Is that what you think!

Stick to the particular poster's problem

Look who's talking.

If he has the ties re-done and has the house re-rendered - will that cure the problem? Or will his render simply crack once more? Will they remove the old ties? Under what scenario is the wall tie corrosion likely to become a problem? How much will it cost him to cure a problem that at present isn't a problem?

If you read my post you will have noticed that I recommended that Wavey Dave called in a independent surveyor. He will be able to give specific answers to the questions you raise.
Unfortunately if you knew what you were talking about you would have realised that as a rule it is impossible to give specific recommendations to problems with a building whilst sat at a keyboard.
Ah, I have just realised you are the exception to this rule.
Just one final question Joe, why do you condemn the whole of the building maintenance establishment, did you have a bad experience once.?

 

[joe-90]

I restore and renovate properties for a living - and have done for the past 30 years. What do you do? I also live in the real world whereby important things get fixed and 'fads' like wall tie renewal don't. Walls don't just 'fall down' because a few ties have rusted. It's the latest 'bandwagon' being used to fleece the unwary.

 

[anobium]

I restore and renovate properties for a living - and have done for the past 30 years. What do you do?

Ditto, but for over 40 years.
Wall tie replacement is not new, it's been around for as long as I can remember.
Yes walls do and have collapsed because of the failure of wall ties.
It's certainly not a recent "bandwagon" as you indicate.
Surely Joe if you are going to renovate a building, should'nt you ensure that the fabric is sound before you install fancy overpriced kitchens and bathrooms.
PS, have you heard the most scare , "radon" in buildings, now theres some money to be made in that.