Cavity wall ties versus cavity wall insulation

[Kareno]

Do I need cavity wall ties if I have cavity wall insulation?

I don't have cavity wall insulation at the moment but I am considering it to make the house warmer. I have also tried to remortgage and the surveyor has said there's slight movement in the walls and I need to get it cehcked out by a cavity wall tie specialist. However I've been told that if I have cavity wall insulation then I don't neet wall ties and now I'm puzzled.

Any help gladly appreciated.

Karen

 

[Shytalkz]

Whoever told you that is an idiot and should stick to delivering milk.

The two are there for entirely different reasons.

 

[Kareno]

I thought that advice was at odds, but according to Wikipedia

A tie is a piece of metal which connects the external and internal wall of a cavity wall together. Its design helps the condensed water on the external wall to stay on the external wall and not get into contact with the internal wall.

The tie in a cavity wall is used to tie the internal and external walls together. It is placed in the cavity wall itself, though the presence of insulation requires specialized ties. If the cavity wall is fully filled with insulation no tie is needed, but the builder must make sure no water passes through the external wall from the internal walls (also applies without insulation). Membranes or plastic like material may be used with fully insulated cavity walls.

Improper installation may lead to water damage or fungus formation within the cavity, leading to structural and health hazards.

As these ties are expected to be exposed to water, they are often made of steel (which may be galvanized) or cast iron, in order to resist corrosion, and for strength. Ties are normally placed above wall openings such as doors and windows.

This is because, firstly, the foam is a poor conductor of heat and it must first be conducted through it onto the outer walls before being convected, as well as that the foam can hold heat for a longer time than the bricks, and therefore thermal energy does not move into the hotter environment (the cavity), but instead into colder regions.

http://en.wikipedia.org/wiki/Tie_(cavity_wall)

Anyone enlighten me further?

 

[Shytalkz]

And there you have a prime reason for not trusting Wiki entries. Although I'll be generous and suggest that whoever wrote that probably meant the clips to keep the insulation in place, rather than the ties themselves.

The ties are there to keep the leaves together, so that they can collectively resist lateral and vertical loading, which individually they can't. Its prime aim is not to prevent the passage of water. The insulation is there as....insulation. It is not a structural element.

Ties are stainless steel these days, galvanised ones went out with the Ark. They are not just found above openings either!

 

[^woody^]

Who was the surveyor working for (you or the mortgage company), and what type of survey was it?

Also why was the surveyor not able to comment on wall tie issues? Did he have a couple of eyes with him and at least two brain cells, or just the Labrador that day?

Does the "report" say what movement was evident, as tie failure has specific signs. You need this clarified before shelling out.

If the report is vague, and the comments unreasonable then complain, or if you paid for the "survey" get the bloke back out and ask him what he is on about.

Basically if you are paying for a survey from a professional surveyor, then you want him to survey, and not just turn up and then say that you need another 20 people to come and look at 20 other things. Even if it was just a valuation survey, then the surveyor must say with certainty if the walls have tie failure or not.

 

[Shytalkz]

Even if it was just a valuation survey, then the surveyor must say with certainty if the walls have tie failure or not.

Which he can't without doing a borescope survey and you ain't getting one of those on a standard survey.

 

[gregers]

ha ha this post is really funny,im pretty sure even if you paid a visit to your local cafe at around 10am there wont be anybody there who will not tell you you dont need wall ties,as shy has said you need a through survey done so they can determine the state of the orriginal ties within your wall,but bear in mind a lot of firms will say they need doing when they dont.

 

[^woody^]

Which he can't without doing a borescope survey and you ain't getting one of those on a standard survey.

I tend to rely on the Mk1 Eyeball

 

[Shytalkz]

Employ that man! Tis truly a freak of nature that he is blessed with xray vision!!!!

 

[^woody^]

It's not such a blessing. Its great for the wall ties, but it's hideous on the high street with all the big momas around - oh the nightmares