Xtra wide wall ties

[Anonymous]

Does anyone know where I can obtain wall ties for a 200 mm cavity masonry wall? I want to hopefully find a UK source which meet current building regs.

[David Olivier]

Ancon Clark, Sheffield make lots of different stainless steel ones suitable for 150 mm (and wider) cavities.

Helifix Ltd., London can possibly be used although I've no experience of those in cavity walls only in fixing slabs of insulation onto the outside of walls or roofs.

There are others which may be cheaper but unfortunately I've forgotten the manufacturers.

People used to use GRP ties made in Denmark but now that stainless steel are so widely available, the use of these seems to be dropping.

HTH.

[Peter Warm]

email me for details of how to get danish plastic wall ties. I am acting as an unofficial  agent for the manufacturers in UK and Ireland.
Beware they have no UK certification, so we offer structural calculations from a qualified engineer as part of the package.
You can look at the pdf order form on the “in construction” web site: http://www.warmhomes.co.ukwallties
peter warm  peter@peterwarm.co.uk

[David Olivier]

I cannot see how any strong rationale exists for use of plastic ties, now that stainless steel ones are available at about 1/4 the cost per m2 – although the price paid varies widely from one manufacturer to another. Also metal ties need fewer per m2 and this leads to a more buildable wall – there are many fewer of them, so they lead to fewer gaps in the insulation. The thermal bridging does not appear to me to be particularly severe as long as one uses structural calcs. and so ends up with the minimum cross-sectional area of ties, rather than a gross excess.

[David Olivier]

The amount of steel does not appear to be this great if the structural engineer does his/her calcs carefully. On a particular house I worked on where the SE did the calcs. there were approx. two 2 x 20 mm ties (from memory) per m2.

There is the vital issue of opportunity cost to consider. If you save money on wall ties – and it could be a few £ per m2 of wall – you have money to spend on other energy efficiency measures.

Also even in the case of a very well-built structure, the Elizabeth Fry building at UEA (1994), the clerk of works did comment that due to the number of ties (it was a concrete frame building but still had a wide cavity between that and the outer cladding of rendered blockwork) it was difficult to get the contractor's staff to do a perfect job. I believe that if a proper analysis was made, the adverse effect of the air gaps with 8 GRP ties per m2 would offset the thermal bridging with c 2 steel ties per m2.

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