The right strap for lateral restraint of a bowing wall?

Hello. I would be really grateful if someone with more experience of these things could offer me some advice.

Our end of terrace house has developed a slight bow in the side wall which has caused cracking where the ceiling joins the wall.

A few months ago, our local builder said we need to tie the side wall to the joists to prevent any further movement. He then installed what he called "lateral restraint" straps between every second joist and the wall, like the one I've sketched below. It's basically a long metal strip with a 90 degree twist near one end.


I've now been told by another builder that this type of strap is not suitable because it will flex too easily (near where the twist is) - and to be honest that seems quite plausible to me.

I've searched the web but can't find any examples of this type of strap being used to stop lateral movement between a wall and the joists.

Does anyone know which builder is right?

Thanks,
Bob.

(Incidentally, the side wall is built of a double thickness of bricks, without a cavity between them. Don't know if that makes a difference.)

Why don't you get a few lengths of this...
http://www.sdg.ie/Construction-Technology/Formwork/Dywidag-System
Bore the gable wall, pass it through to the opposite wall and out through again and tighten up the wing nuts. Job done.
That dywidag bar in the image if good for about 80 tons.

Thanks Norcon. I appreciate the suggestion. Unfortunately external access is limited on both sides of my house by neighbouring properties so I can't bore through the walls. Otherwise I think it would be a perfect solution.

What I really need to know is whether the straps installed by the first builder are suitable for tying the wall to the joists.

Can anyone advise please?

The strap as shown in your sketch is not a horizontal lateral restraint strap, but a twisted holding down strap for fixing vertical loads such as holding down joists to a flat roof, or in some cases instead of strapping down the plate on pitched roofs, it can be used for strapping down the trusses or rafters. It is helping the situation but it is not a horizontal laterial support and it is not a cure. If the joists are going from flank to party wall then the joists should act, repeat should act as lateral restraint.
If this is not happening, it is still possible to add restraint to a 215mm thick external wall, but without a lot of further information, it is not possible to advise you which road to travel.
If the bulge is under 8mm from DPC to eaves level then we would suggest that you monitor the width of the crack every month over the next 12 months, as it is possible that it will not move any more.
oldun

You could get steel plate 6mm made to do the same job as the "strap" you have.

What has been used in the past to monitor the movement/crack is to glue a small strip of glass across the gap and watch that over a period of time. If it cracks its moved. ( think microscope slide).

Thanks very much for the info theoldun.

Yes, I feared they weren't the right sort of strap.

We were recommended to use some form of a lateral restraint by our insurance company's surveyor. (He was consulted in case the cracking was down to subsidence. He says it isn't, so the insurance co. have now washed their hands of it.)

Unfortunately, the surveyor didn't specify exactly what kind of restraint to use or how it should be fixed. For this we have to rely on our builder who, it seems, isn't very reliable. He swears that what he's installed is a lateral restraint. He says it's just a "vertical" type lateral restraint rather than a horizontal one.

Any chance you could suggest a suitable restraint mechanism based on the following info:

• 1. The bowing is at it's maximum at about first floor joist height and at about half-way along the wall.
  
  2. The bowing amounts to about 8mm at its maximum. It has been present and stable for over 20 years, but last winter seemed to increase by 1 or 2 mm. It's been stable again since February.
  
  3. The wall itself is 9 inches (230mm) thick, without a cavity. It is constructed of "old" size engineering bricks.
  
  4. The joists are 7 inches deep and 2.75 inches wide. They do, as you say, run from the flank to the party wall - a total run of about 18.5 feet. The joists themselves are sound with no sign of rotting.
  
  5. The joists penetrate half a brick length (4.5 inches) into the wall. There is an irregular gap between the joists and the surrounding brickwork as they enter the wall. The gaps each average about half an inch all round. The joists are not fixed in any way to the brickwork (other than with the straps recently installed) - they just rest on the brick course below.
  
  6. The flank wall sits on the boundary 3 feet from my neighbour's house, so access is limited physically. Just to make things more difficult, the neighbour won't allow access for any work from his path and he won't tolerate anything like plates or nuts projecting even an inch into his airspace. Nice sort of bloke really!

So I really need an internal mechanism for tying the wall to the joists if anything like that is possible.

Any suggestions would be very gratefully received.

Alarm, thanks for the suggestion. I suppose a custom job might be the answer if there's nothing ready made on the market. What would be the best way of fixing it to the wall? Anchor bolts or threaded rod and epoxy?

Quote. [For this we have to rely on our builder who, it seems, isn't very reliable. He swears that what he's installed is a lateral restraint. He says it's just a "vertical" type lateral restraint rather than a horizontal one].
You should not be to hard on your builder, as in good faith he has supplied and fitted exactly what is described in the brochure. Quote. [ H and L straps are designed to The Building Regulations, BS 5268 Part 3 and other building standards for vertical and horizontal restraint when connecting timber floor and roof systems to masonry walls.] The manufacturer should take most of the blame for not giving more detail of the use of restraint straps, for floors and restraint straps for roofs, but then again if you google Simpsons Strong Tie, H and L restraint straps they do show diagrams of the uses of both twisted and bent straps.
These diagrams are exactly the same as in Approved Document A, page 28, diagram 15, lateral support for floors, and page 29 diagram 16 lateral support roofs.
There are two or three ways that restraint can still be provided to your joists providing that your stairs do not run up the flank wall and the bulge is in the middle of the stairwell.
We will be only to pleased to explain them to you and provide some drawings, how ever as this will take up a few pages and we do not know how to post drawings we will need to post them to you by royal mail.
If this is okay with you, then PM us the information on the stairs and your postal address, give us 7 days and we will have them to you. In return, we would ask you to explain step by step how to post a drawing such as you did in your first post. Believe me this will not be an easy task, as I am an old thick as sh*te bricklayer, well past his sell by date whose knowledge of computors consists of being able to turn them on and off.
oldun

Yes perhaps I was being too hard on him. It's just a bit frustrating trying to get this sorted out in the right way.

It's very kind of you to offer to send the info by post theoldun - it's very much appreciated. The stairs don't run along the flank wall - in fact the stairwell is in a different part of the house well away from any of the joists that would be tied to the wall. I'll PM the address information to you shortly.

To post a sketch what you need to do is:

1. Scan the sketch into your PC. I used a scanning resolution of 150 dpi (dots per inch) and set the scanner to greyscale scanning, but it wouldn't really matter if you used 100 or 200 dpi or full colour scanning. It's best to save the image as a JPEG file with a .JPG extension. You can save it anywhere convenient on your PC (e.g. in a folder of your choice or on the Desktop). You could scan a photographic print in the same way as a sketch, but you might want to use 300dpi full colour (24-bit) scanning. (Obviously, if you want to upload a photo from a digital camera instead you would simply need to transfer is to your PC in whatever way is recommended for your particular camera.)

2. Next, log in to your account on the DIYNot web site. Select the Images link near the top of the page, and then click the [Create New Album] button.

3. On the next page enter an album name (anything you like) and check that the various viewing options are suitable (particularly make sure that Everyone is allowed to see the album). Then click the [Add Album] button at the bottom of the page.

4. On the next page click the [Browse] button. This brings up a window/box that allows you to look through the folders on your PC and select the image you saved in step 1. Select the image and click the [Open] button. This should copy (i.e. upload) the image file from your PC to your album on the DIYNot web site. The uploading process might take several seconds to complete, depending upon the size of your image and the speed of your internet connection.

5. Finally, you need to embed the image in your posting. You do this while typing in or editing your posting. First click the Show My Images link (just below the main text box). This will display a thumbnail of each image in your album. Then, just click on the thumbnail you want to insert and you'll see that a BB code something like "[n e t]167605/34992_89622960.jpg[/n e t]" gets embedded in the text of your posting. When your posting finally gets viewed, the image is displayed instead of the BBCode. You can move the image to a different place in your posting simply by cutting and pasting the BBCode (in its entirety) to wherever you want the image to appear.

Hope this helps theoldun, but let me know if you want me to clarify anything.

Hi

With 10mm of movement I wouldn't bother wasting your time doing anything with the wall, by all means monitor the wall maybe once or twice a year, but until the time arrives that you have around a 50mm (2")deflection it is all aesthectics and basically looks worse that it really is. Hence the possible reason that the insurance company are not bothered with it.

As a note the fixing strap in your drawing is holding down the joist and has absolutely nothing to do with restraining the wall.

If you feel you cannot sleep at night then go to redgwick.co.uk and view 'wall tie patress plates' as these are the items you would need to install, basically there would be a tie bar running one end to the other of the building line and the tie bar would be terminated on the outside wall either end with the patress plate.

With respect to your neighbour, he cannot refuse you access to carry out repairs to your property, but if you cannot come to an agreement over access you would need to obtain access by going to Court and obtaining and access order under the 'Access to Neighbouring Land Act'.

Regards