Pointing. Again!

[Cassie]

Hi folks, a simple question I’m sure! When raking out old lime mortar, if I come across a bit that’s good, solid, adherent to the bricks, not hollow and the bricks are stable all around, is it acceptable to leave alone and patch point around it? Or will that cause problems with adherence of new mortar/drying out issues? Or other things I don’t know about? Given some of the giant holes and number of bricks that appear to be suspended by nothing other than fresh air, I’m inclined to leave bits that are doing their job! Thank you

 

[Cubist]

Hey Carrie, the general guidance is to rake out any 'loose' old mortar to a depth of about 20mm but to leave any good stable mortar alone and point around it. Many people dont like that though as it can result in a patchy appearance and consequently will take that out too. For me its a horses and courses thing and just how sanctimonious/idle I may be feeling.

I'm assuming though that you're not planning to render or plaster over the brickwork afterwards.

 

[Cassie]

Hi cubist, yes it will be plastered over eventually, so I’m not too bothered about appearance (good job, I’m clearly not a pro!) Where there was crumbly mortar, I’ve raked out to a good depth, where there was no mortar, I’ve started to replace it (with the help of stones/bits of slate in the deep bits!) so, if it’s not going to cause anything other than a cosmetic issue, I’ll leave the good, solid joints in, Not being idle, just hopefully keeping structural integrity in the few places it exists

 

[stuart45]

At Tech we were taught that when doing new brickwork that was to be rendered, the joints should be raked out around 3/8 in to provide a key for the render.

 

[Cassie]

That’s interesting Stuart-so I shouldn’t be trying to fill the joints right to the face?

 

[stuart45]

It's better if render has something to grip on. That's why you scratch the first coat. Some bricks, like certain engineering bricks, have grooves in the back, so they can be reversed. The old terracotta blocks had dovetailed grooves for an even better grip, as terracotta doesn't give much.

 

[Cassie]

I suspect there’s plenty of grip available-many of the bricks are spalled and once I’ve churn brushed the new lime pointing, it’s nice and grippy The bricks are very far from modern-very soft and rough even where the face is still intact!

 

[stuart45]

The raking out of mortar joints on new brickwork on site was very rarely done, so it's not a common thing to do. I'm sure your wall will be fine.

 

[Cassie]

Must be very common on old brickwork though judging by the number of posts on it I’m keeping my finger crossed