Cavity wall ties

[AndrewR]

I've recently opened up an existing external door way into a side extension (its gone from approx 800 to 1200mm wide). Having looked into the cavity I can see very few wall ties and have noted a slight bowing in the external leaf, which also exists within the wall away from new opening.

This slight bowing (up to 5mm) does appear to be longstanding so I don't have any immediate concerns but do feel I should at least address the issue locally to the new wider opening.

My initial thoughts are to install remedial resin fixed ties around the opening and within the general vacinity. Does anyone have any thoughts or experience of using these ties?

 

[r896neo]

how old is the house? and what are the ties made of?

 

[AndrewR]

The house was built around 1959 so it isn't that old. The existing ties look like stainless steel to me but certainly haven't corroded away; the exposed are in good condition.

They just haven't put many in!

 

[freddiemercurystwin]

This slight bowing (up to 5mm)

Slight Bowing 5mm!!!! That's well within normal building tolerances! Ties in standard cavity walls are really there to support the skins during construction they offer little support afterwards.

 

[AndrewR]

If they're only there for during construction then why is so much enphasize put on them, particularly with regards to wind loading etc etc etc?

I know I've said I feel the bowing is longstanding but something is just niggling at me saying it may be progressive! I'm no builder but do have a lot of experience within structures and it just doesn't feel right.

I was thinking along the lines of new resin ties should holt any active movement, if is accuring. Obviously the other option could be to rebuild the section of wall but I'd rather avoid that if possible.

 

[^woody^]

I think you are creating a whole lot of work for yourself over nothing

Why would you think it is progressive movement?

Is the wall 50mm out of plumb? Are there horizontal cracks the length of the elevation, Has all the mastic split at the window reveals? Has the soffit board been pushed out?

A cavity wall is not going to fail locally, and not going to fail at ground floor level, so not only is there no reason for any repair, but a repair will not achieve anything either

 

[stuart45]

Are they every 6 courses?

 

[^woody^]

Are these ties supposed to keep the walls together or apart?

 

[AndrewR]

Thanks Woody,

The full story is I've replaced the original wooden lintel with a new longer steel item then removed the extra 400 mm of brickwork, which I've now left it for a couple of months. Looking at it now the bow appears greater than I originally recall (though your memory can play tricks), though I know the wall wasn't plumb originally. When cutting back the wall I disturbed a few half bricks in the process, which I reinstated. A couple of these now a loose which is making me suspect there has been movement.

In taking the wall down I removed one tie and having looked within the cavity there is only another one or two within the 1500mm (and looking vertically) to the corner of the house; its not very well built at all, but then it's been up 50years without any other real sign of movement.

 

[Deluks]

it's been up 50years without any other real sign of movement.

This is a nail head/hammer interface type situation.