After talking about underfloor cavity and physical wall cutting among the rising damp solutions (or supposed ones), we explain what chemical barrier (or chemical wall cutting) is and how it works.

Chemical barrier: what it is

Chemical barrier consists of drilling wall holes, in which "injectors" are inserted; injecting a chemical material (usually liquid); the latter penetrates wall cavities and creates an impermeable barrier, thus preventing rising humidity above the application level.

Different types of chemical barriers

In their history chemical barriers evolved into two main types, which differ in application methodology and chemical compounds. A widespread chemical barrier model (mainly as it is often applied autonomously) is composed of pre-dosed pockets of a liquid material, mainly silicon based, which is slowly released into the wall introduced into the slow diffusion wall so as to impregnate target intervention section. Another type of chemical barrier involves gel cups. It is a more complex application requiring the intervention of skilled labor (although in the last few years DIY kits have become popular on the market), since material injection must be carried out under pressure and often repeated many times.

How to apply chemical barriers to masonry

Chemical barrier application is an invasive work that should be performed in all the walls in contact with the ground to have a satisfying effect, and it involves the following phases:
  • wall drilling every 20-60 cm and a variable depth (depending on the method used)
  • injectors insertion inside the holes
  • deteriorated plasters elimination
  • pressure resins injection (or application of slow release bags)
  • masonry restoration and finishing

Pros of chemical barrier

  1. possible DIY application
  2. relatively cheap method

Cons of chemical barrier

  1. impossible to verify barrier effectiveness on all masonry parts
  2. humidity continues to deteriorate the materials below the barrier
  3. unsightly application often prolonged (or repeated) over time

Costs of chemical barriers

Chemical barrier costs around € 200/250 per linear meter, labor excluded (unless you opt for the DIY solution)