I recently bought a 1930's house and although it was not recommended in the survey, I decided to get a DPC installed seeing as I was completely refurbishing the property and I presumed it would be better to prevent now rather than have a problem in the future. This was carried out from inside the property after i knocked off the plaster.

I was relatively happy with the work the builder carried out, However I have a few small issues, I would like advice on if anybody knows the answers:

Firstly, in places where the DPC has been installed (dryzone) it has gone into the mortar and not the brick. I think with the traditional damp proofing it was neccessary to drill in to the brick. Is this still the case?

Secondly and more importantly, i questioned the builder as to why the was no visible DPC on the exterior walls and his reply was that he drilled through from the inside and injected it into both skins of brick. I wondered, how would the builder know he was hitting the mortar on the exterior wall? or whether he was at the right height? Is it possible to do this?

Please forgive me to my lack of knowledge in this subject, but im keen to learn. Ive looked around the internet but have been unable to find the answer to these issues!! Thanks!

The new damp proofing creams are designed to be injected into the mortar.

Drilling through from the inside is the common method of doing this.

He would know if he was drilling into the brick as it would be harder than the mortar and also the dust created would be a different colour.

Mortar lines are often pretty close to each other as the wall ties are bedded in the mortar, so in most cases the inner and outer leaf of the property's mortar lines will be almost level.

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DIY | Donnas dream house