How to specify cavity wall ties

Brick and block cavity wall ties are ontiese of the most common types of constructional elements used on site. However, it is relatively easy to select the incorrect type of cavity wall tie or specify an insufficient number along a given length of brick wall. Another area where careful consideration is needed is around openings and here any anomalies in the detailing can lead to issues further down the live.

Here are our top tips for choosing and using cavity wall ties:

  1. Make sure you are using the correct length of wall tie

Approved Document A, table 5, provides guidance on the length of wall tie that should be used:

 Table 6: maximum spacing of cavity wall ties


Width of cavity (mm)


Horizontal spacing (mm)


Vertical spacing (mm)



Other comment

50-75 900 450 See notes 1 and 2
76 – 100 750 450 See notes 1, 2 and 3

1.     The horizontal and vertical spacing of wall ties may be varied if necessary to suit the construction provided the number of ties per unit are maintained.

2.     Wall ties spaced not more than 300mm apart vertically should be provided within 225mm from the sides of all openings with unbonded jambs

3.     Vertical Twist Type ties, or ties of equivalent performance should be used in cavities wider than 75mm


  1. Use stainless steel

Cavity wall ties should be manufactured from stainless steel because of the materials superior strength and corrosion resistance.

  1. Use an insulation clamp

Avoid hooking wall ties together using masonry globs to keep insulation in place because it can lead to cold bridging and dampness. The remedial action for this can be extensive, including having to re-build the wall. It is often possible to detect where insulation has moved, which usually manifests itself with cold areas on the inner wall within the room, and this can lead to condensation and mould growth as well as excessive heat loss.

Fortunately, there are simple and inexpensive solutions to this problem, such as our Insulation clips. This is a universal retaining clip that holds insulation in position, where it should be, against the inner leaf of a cavity wall.

Use only insulation clips that are compatible with your wall tie, such as our SS/DTW Double Triangular Wall Tie.

  1. Prevent moisture travelling along the wall tie

When cavity walls first began to be constructed around 100 years ago builders used ‘through stones’ instead of wall ties to maintain the cavity. However, this often lead to moisture tracking along these stones, either from the outside, or penetrating poor mortar joins and weeping down the inside of the outer leaf and across to the inner leaf.  It also allowed cold bridging, with both resulting in damp areas on internal plastered walls exactly where the ‘through stone’ was located.

It is still possible for moisture to travel along cavity wall ties, although you can avoid this by setting them so that they ‘fall’ outwards.

It also worth choosing a wall tie with a double drip feature as this further prevents moisture travelling to the inner leaf, but always make sure that the ‘drip’ kink in the wall tie points downwards and is positioned near the centre of the cavity.

  1. Choose CE marked products

Cavity wall ties that have a CE mark is your reassurance that the range complies with a harmonised European Standards or have a European Technical Approval. All our wall ties have CE marking and have been independently tested by a Notified Body to:

  • Compressive load capacity
  • Tensile load capacity
  • Water shedding capacity Resistant
  • Durability
  • Dangerous substance

CE marking doesn’t replace Building Regulations and so you still need to make sure your wall ties meet relevant standards.

  1. Reduce wall tie spacing at openings

You should reduce the vertical spacing of wall ties around openings such as windows, doors, roof verges and movement joints to a maximum 300mm and placing them within 225mm of the opening. Effectively that means a wall tie every course of blocks within 225mm of the opening.

Cavity wall ties are an important element in ensuring the stability of your cavity walls. Our guidelines above will provide you with information on the correct selection, spacing and installation of wall ties.

The above are for guidance only. Before choosing wall ties always refer to Approved Document A for more detail.

For more information on our range of wall ties, visit: or call: 01924 364794.

Why is demand for fencing, decking and gardening ranges from holiday parks increasing?

According to figures from Visit England, a record breaking 4.3 million people visited this country in 2016. That represents a rise of around 7 percent on the previous year and looks set to continue as the pound falls against other currencies, making UK holidays for those travelling from abroad cheaper. Add to this the fact that a weaker pound makes it more expensive for UK citizens to go abroad (instead choosing a staycation) and you can see why holiday parks are becoming busier.

Many leisure and caravan park operators have already benefitted from this trend. Some have seized the opportunity and accelerated their improvement programmes in order to make their facilities even more attractive to holiday makers. Park Holidays, the largest provider of Caravan Holiday Parks in the South of England, has already reported a 40% increase in the sales of their holiday caravans and lodges to British families compared to last year’s figures at the start of July.

The rise in staycations and an increase in investments by holiday and leisure park home operators has resulted in an influx of orders for our fencing, decking and gardening ranges. These include essential items such as post anchors, galvanised mesh cubes, gates and planters. As part of our one-stop-shop we also offer a vast range of building refurbishment items such as angle brackets, corner brackets, plasterers’ angle beads, joist hangers, cavity wall ties and restraint straps amongst many others. All essential items if you are refurbishing an existing facility or building new on your park. Our wide range of constructional fixings and fencing, decking and gardening ranges are available from builders’ merchants and stockists throughout the UK.

A holiday park operator in West Yorkshire that is benefitting from this trend is Nostell Priory Holiday Park, which recently specified our Powapost® Bolt Down Shoes during construction of a new post and rail fence. These were ordered from Howarth Timber in Wakefield by the park’s operator, Blue Sky Resorts Ltd, and delivered direct to the customer in packs of six.

The bolt down post shoes were used to create new boundary fence at the park, which is located in a scenic part of West Yorkshire, close to the historic palladium house Nostell Priory. Our Powapost® Bolt Down Shoe range is designed for use when posts are required to be installed on an existing hard surface such as a concrete or timber base. That makes them ideally suited for use during construction of landscaping projects including fencing, gazebos, pergolas and other garden structures made from timber that require strong, stable ground anchors.

Howarth timber delivered the post shoes to the Holiday Park, with the contractor using them to install a timber post and rail fence alongside a new footpath. The post shoes were bolted to a concrete base, before inserting the posts and using the Twin Bolt arrangement to securely tighten the steel jacket around the timber posts. Alternatively, some customer prefer to choose our easyGrip version, which features a wedge type grip that enables quick and easy installation without the need for tightening bolts. Both versions of our post show are designed to be fixed to a solid substrate base such as concrete, timber or paving.

The great thing about our Powapost® Post Shoes is that they allow the shoes to be securely tightened around the timber post, whilst still allowing the post to be easily removed should it be damaged or become rotten.

The contractors who installed the Powapost® shoes at Nostell Priory specified our 90 x 90mm post shoe (PS1/90). Our range of Bolt Down Post Shoes are available in 50, 60, 75, 90 and 100mm versions. All sizes are available in standard Twin Bolt and easyGrip design.

The contractor chose BPC Fixings because they had used our products previously on a number of projects and therefore knew that they would receive excellent quality and service. There are other reasons why more landscaping contractors are choosing BPC fixings for their fencing, decking and gardening ranges. One of these is because we offers a range of complementary PowaPost ® Drive-In Post Spikes, Flush Fit Bolt Down Shoes, Concrete-In Post Shoes, repair spikes, post extenders and supports.

Nostell Priory BPC
Nostell Priory BPC

For more information on our fencing, decking and gardening ranges, visit: