Water seal (Thomsons etc) for red brick

ravendude

Have a problem with water penetrating red brick (probably traversing wall ties in the cavity etc) in an older extension that became visible in the bad weather over the last few weeks, during building works when the slab etc was stripped back.

The joints have some fair cracks/gaps which we will repoint.

Also, we are planning on coating with some water seal, probably Thomsons.
Just wondering what is the best regarded product on the market? Anything "better" than Thomsons water seal available?

Lumen

Cement or lime mortar?

At the risk of irritatingly not answering your question (sorry!), are you sure you're approaching this from the right direction? It seems a bit of a stretch for driving rain to penetrate the mortar and then cross the wall ties in any kind of volume. The whole point of the cavity is to prevent that.

Is it not more likely to be coming from a roof/guttering defect?

And maybe part of the problem is that the wall isn't drying out properly. Is it externally vented?

I have a balcony with a drain hole that gets clogged periodically, and when that happens I get water streaming down the inside pane of the window below (fortunately just a plastered block wall so never any damage). The water crosses the cavity where the balcony attaches.