Lime pointing question

[Nick England]

I've got a couple of questions regarding the choice of lime pointing to use on a couple of renovations in the house.

Firstly, we've exposed the old fireplace in the kitchen, and will be putting a wood burning oven in to the left of it.

The stack and wall need repointing. It's fairly soft brick, but not bad.

Am unsure as to whether to make up a batch of lime putty mortar and use that, or point with NHL 2 or 3.5.

My only consideration is the heat from the burner. Which pointing would stand up to that best?


Secondly, is the back outside wall of the kitchen. It needs repointing, and I meant to to it this summer, but work got in the way.

It will need doing sooner rather than later. There's a lot of failing mortar and soft brick.

Ideally, I should use lime putty mortar, but I've left it too late in the year. How many weeks do you think we have left before it's too cold? 3?

I'm wondering if NHL 2 or 3.5 would be better, but as the bricks are old and soft, ideally it should be lime putty.



Any thoughts?

Cheers,

Nick

 

[Nicknuv]

I think an NHL would be too strong for those soft reds. A hot mix would be a better bet.

 

[a twig]

I’d NHL2 everything personally (avoiding St Astier as their “2” is suspiciously hard after a couple of years) but I am absolutely not an expert

 

[Nick England]

I've never worked with a hot mix Nick.. what advantages do they have over lime putty or NHL?

 

[malcolm]

I've never used hot mix either. I'm really lazy and have mostly decent bricks so keep on using the mix I'm used to. Can't go wrong with lime putty inside.

On the outside wall putty is going to be good for 100 years before it needs repointing. Hopefully people will have realised cement pointing will kill an ancient wall within 30 years, but by then but it's not going to be your problem.

I've used NHL a lot in my later building. Works fine and seems to breathe well. Not necessary though, and it goes rock hard after a couple of years.

 

[stuart45]

The bricks look a bit soft, so you need the right choice for your mortar. There're quite a few pigs in the wall. Was it built on top of an old garden wall?

 

[Nick England]

Thanks for the replies.

It was an outbuilding. A shoemakers back in the 1800's.

I've ordered some NHL 2 to put in there. Strong enough, but not too hard. I hope.

 

[Lacan07]

I always thought my bricks were soft red but when I sent a sample of my mortar to the lime centre for matching they recommended NHL 3.5. I guess I ought to check that before I repoint my house.

 

[malcolm]

I've used NHL 3.5 pointing mine. Mostly my bricks are from the last couple hundred years and aren't too soft. Apart from the garden wall bricks and I used NHL 3.5 on that too.

NHL2 will be fine. Lime putty would be fine too. We get carried away with what mix to use and have very little information to make our own judgements. For me NHL3.5 turned out very much harder than I expected after a few years. It's not a big bother. It still breathes perfectly well and can dry the bricks but my feeling is I didn't need to go for something so hard. Softer would have let the bricks move around more and would have made it easier for the next guy to preserve my work in 100 years. I think it doesn't matter which one you go for and softer is better.