Would there ever be a situation for brick sealer?

[ben81]

Hypothetically, if someone was to clean salts and efflorescence off brickwork with acid then seal it with a "breathable" substance to allegedly prevent droplets of water enter the brickwork and more salts from exiting whilst supposedly staying permeable to water vapour, is there ever a situation where this is a reasonable idea?

My thoughts are
1) Water on bricks is fine and normal and if the house hasnt fallen down after 120 years its probably ok

2) If the salts want to come out shoulnt we let that happen rather than trapping them in and potentially having them try to exit internally

3) Is it more acceptable on the top of a chimney stack which has plenty of ventilation as opposed to the wall under a kitchen window?

 

[Stevers]

The salts appearing on my basement chimney breast (see projects) do just brush off the old lime mortar, which makes me question whether I should re-tank it. Since removing the old tanking, perished cement render and damp pink gypsum plaster, the room smells nice and fresh for the very first time, and that's with the rest of the room still being largely tanked. I'll be putting a couple of coats of NHL render on before I decide either way.

 

[malcolm]

Salts coming out of bricks is normally a sign that water is trying to get out. If it's on the bricks themselves it might suggest the lime mortar normally responsible for letting the water out has been replaced with something more impermeable like cement.

Water does come up from the ground but it's really not much. It's best to let that evaporate to the outside to keep the wall dry. Same with chimneys. I had a tree growing out of mine and it died after I vented the chimney to get rid of the water.

I would not use a brick sealer on an outside wall.

 

[ben81]

Its mainly on bits of the new lime mortar. The entire back and gable end of the house had the cement previous owners had put in scraped out and was redone with lime. Some failed so they sent their new brickie over to redo it. The chimney is a bit of a state because I suspect as you say Malcolm that water is now exiting via the new mortar and to a lesser extent from some bricks. There was no cap on one of the pots when we moved in which I guess wont have helped.

I've told them no sealant. I've heard there may be a specific brand of breathable sealant (which sounds like a bit of an oxymoron) but considering this work is being done as part of the guarantee theres no saying what brand they would use