Tying in Bowing Walls...

[jungle_jim01]

I've just had an engineer around to look at the victorian extension to the front of our house. Fortunately he didn't give any apocalyptic warnings about the state of the building! As expected however he mentioned that the front wall will need tying in. He mentioned using multiple rods going through about the joists (joists are parallel to the wall). I've seen something similar to what he described here: http://www.helifix.co.uk/products/remedial_products/bt.aspx It doesn't seem too hard to do, but i'm aware it could be the proverbial 'can of worms'! Does anyone out there have any experience with this? Advice...tips...warnings...all appreciated.

Thanks

 

[chapel]

Hi Jim,

No experience of using this, but i did see a couple of DIY'ers use this system on an episode of Help My House is Falling Down recently (maybe if you google it, or try on one of those 'watch again' players you'll be able to watch it

It looked really simple, they were far from experienced and it saved them a packet.

 

[Lime]

A modern method.
Not something I'd use but it may work for a while.

However the failure mode is what would worry me.............

I'd be worried about the glue to the brick hole being able to hold the brick to the tie because old bricks are often quite weak in any other form of stress other than compression for which they were designed. Bricks are weak in tension, old bricks particularly. The hole is also a point of weakness. The brick may burst.

I'd be worried about a single brick being able, via lime mortar, to hold and pull back the surrounding bricks.
Again lime mortar is designed for compression not tension. It is not like modern cement.

I'd be very concerned about the stress that would be applied to the old joists at a point at which they are weak. The shape of a joist gives strength in a vertical plane. The joists were not designed for lateral stress and will rely almost totally on the floorboards and ceilings to keep themselves upright and in place.

 

[Flyfisher]

I'd agree with all that in principle; bricks and mortar (of any kind) are certainly better in compression rather than tension. However, they obviously can perform in both ways, albeit to vastly different forces - and it's the forces involved that we don't know about. Why is the wall bowing? Is it leaning at a big angle (= more force acting upon it)? And probably other questions I can't think of.

Seems to me that this is (or certainly could be) a structural issue and should really be dealt with by a structural engineer, i.e. someone who can design a suitable solution based on some defined principles and calculations.

For example, trying to tie the entire wall with a single rod will transfer the entire bowing force (whatever it may be) to a single brick. If the force is small and the strength of the brick is known then this might work, although my guess is that it would be risky. Use two rods and the same force is shared across two bricks, which might bring the force within the tensile stress of the brick. Still a bit of a guess though. Use one rod for every brick in the wall and I'd guess that would do the job, but I'd also guess it would be overkill. So the practical answer will lie somewhere between, with a suitable safety factors for good measure.

This is the sort of thing that should be bread-and-butter for a structural engineer; ensuring an adequate job with a suitable safety factor. As the OP has already had the wall inspected by an engineer, I would ask for their formal written advice, effectively a specification that could be given to someone doing the work. I'd expect this specification to define how many rods to use, over what area, where to fix them and how to fix them.

I've watched builders use helifix bars and it looked pretty straightforward to me and well within the capability of a competent DIYer. However, it's their application rather than their installation that I would seek advice about.

 

[MatthewC]

Is it not possible to use the traditional method of a rod right through to the other side, with a big "X" at either end?

 

[Feltwell]

Is it not possible to use the traditional method of a rod right through to the other side, with a big "X" at either end?

That would be my thought as well. Not just X's, you can get a wide variety of pattresses to go on your tie rods.

http://www.redgwick.co.uk/ Some of these are overly ornate I think. Simple is good.

 

[Delta]

Wouldn't it be worth getting a detailed recommendation from a structural engineer? If the house is listed then I'd suggest that would be a must, and they would spec exactly what to do. We had a small report done for a consent application, ~£500, and I sleep safer too.

BTW I don’t think you will ever reverse the movement with any form of ties, if you do then I’d suggest the wall is dangerously unstable.


Unrelated to the consent application I mention above, but on this topic -

I like the traditional approach myself, a long bar through the house with plates at either end. We have one the width of our double fronted 1800 house. I recall seeing this “pipe” running along the bottom of the upstairs skirting when viewing our future purchase. I was prompty thinking to myself some sod has made a gash job of the plumbing, and swearing that will have to go. I have since met the Gent who welded the 1” steel rods together to make the tie bar for his Dad, circa 1955. Apparently it was a bugger to fit. That and a judicious quantity of concrete dumped into a hole at one end of the house has stopped the movement though. The crack was re-pointed with cement and hasn’t moved since, so it stays