Lime mortar

[Tiggerty]

Surveyor recommended about 20 or so bricks, near ground level, need to be repointed and stressed we must use lime mortar. Old property.

As it's a relatively small amount that's needed, what's the best way to purchase it? Also what tools do we need?

I’m just doing a load of repointing with lime mortar, there does seem to be an awful lot to be aware about compared to normal Portland mortar. After watching a ton of YouTube vids on the subject (🥱) it seems a lot of builders were using hydraulic lime (NOT hydrated) as this is faster to cure and somewhat akin to using normal cement.

Don’t rake out old mortar too deep, an inch or so is ok. Wet the brick before starting and make sure it’s dust free too.

-nhl 3.5 is available from Travis P, nearly £50 a bag though.
-mix with a combo of sharp/builders sand at 3 sand to 1 lime ratio. Some people are advising only using sharp, others not.
-it has to be really well mixed, ie 15-30 mins mixing. Mix dry before adding water and don’t mix too wet
-this is important: IT IS NASTY STUFF. wear a good mask when mixing, at least initially. You do not want this in your lungs.
On the first day of pointing, I got a small amount on the back of my hand and it came up in a burn the next day. Fully waterproof gloves needed.
-you need to keep it damp while curing (3 days or so) so drape fabric/hessian over the work afterwards and keep the fabric moist.
-don’t do external work if it’s dropping too cold.

If there’s any lime experts reading this and I’ve got any of this wrong I’m happy to be corrected, this is just what I’ve picked up from advice; I’m not a specialist or anything.

Just to add, as you haven’t got much to do, you may be better going for a pre mixed mortar rather than buying all the bits, you won’t have so much left over after you’ve finished and cheaper too. Eg:

www.lime-mortars.co.uk/b2c/lime-mortar/hydraulic/nhl-3.5/fox-cragg/25kg

I would very strongly advise buying Jane Schofield's little lime book:

https://www.celticsustainables.co.uk/lime-in-building-a-practical-guide-by-jane-schofield/

You need to avoid NHL limes as they set too hard for old masonry. You probably need to wait until spring now, so you have time to do some research/learning.

Carrington Lime, Cornish Lime and others do courses.

Join the FB group "Your old house UK - repair and conservation".

@Tiggerty what is the age of the property?

In an ideal world .. take a sample of the preexisting mortar (when you rake out a small section) and send off for analysis. That way you get a like for like chemical profiling and you will be unlikely to get any issues with the newest mortar.
A number of companies do that for you and will then sell you the size you need on the basis of what your original mortar is.

Lonelycrab
** what is the age of the property?

Approx 1870

You can buy it ready mixed in tubs…… much better than faffing around mixing yourself….especially if you don’t need much.

The Op has 20 bricks to repoint. This is hardly heritage renovation territory and I don’t think going on courses or reading books is going to be a massive help for the scale of this job. It’s a (slightly pre) Victorian property, not ancient or 400 years old.

Plenty of builders, including very experienced ones I know personally have advised that NHL is fine for pointing in these applications, NHL 2 can be used if there’s worry about brick integrity, but in the real world builders are using 3.5 with no problems re damaged masonry.

www.lime-mortars.co.uk/lime-mortar/guides/lime-hydraulic-or-non-hydraulic

Our surveyor said hydraulic lime mortar nhl 2.5 or 3.5 for our 1881 property. I bought some from Conserv but the sand and mortar need to be mixed (both are in the bag).

Wear goggles too to protect your eyes.

Our surveyor suggested a soft NHL, but the supplier asked for the brick type (Accrington NORIs, a VERY hard brick) and location (wet Pennines up on a windy ridge) and suggested a slightly harder mix, I'll check the exact one. I tried a bit 2 years ago (Lime Green was the brand, all in one) and it seems to be holding up fine. Just the rest of the house to do..... Wish some numpty hadn't raked the original lime out (wrecking the brick edges) and repointed with cement mortar.😡

We got together with neighbours and put a bulk order of premixed stuff from Mike Wye. They only do pallet delivery which is £50ish but the premises stuff does keep and is useful for patching stuff up with.