Lime pointing in December

[Abi Cott]

From my reading of forum posts I think this is an issue. A local listed building is considering this as a possibility, and I'd like to sound you guys out before broaching the topic with them

 

[TheSpid]

insider or out?

If out - then yes, not a good idea at all - temperature have to stay above 5 degrees [I believe] ALL the time the lime is curing

 

[Abi Cott]

Exterior pointing whilst the scaffold is up to replace the roof. Oh and yes they are aware that is a bloody awful time to replace a roof too, but the grant money has time stipulations and acquiring the top up money has time stipulations and acquiring planning permission has time stipulations, it's not through choice, but they mentioned the pointing as a possibility tonight, and I wanted to check with you guys before broaching the topic of temperature with them.

How long does lime pointing take to cure?

 

[worms]

How long does lime pointing take to cure?

That’s going to depend on the mix. If they use a strongly hydraulic lime it will be much quicker than with non-hydraulic lime putty. It will also depend how deep the pointing goes, as the deeper layers take longer to carbonate.

I guess with the warmer winters we seem to be getting, they might get away with pointing in December and if it is a choice between taking the risk on lime in December versus cement, they are better to try it and hope for the best.

However, I believe that the stonemasons at Historic Environment Scotland don’t do any lime work after the first week in October...and since we still get frosts into May, it must make for a pretty short working season!

 

[livias]

Presumably they will have sheeted scaffold up? So they could add heat if necessary. I have done it myself. Not particularly ideal, but needs must ..

 

[Flyfisher]

If out - then yes, not a good idea at all - temperature have to stay above 5 degrees [I believe] ALL the time the lime is curing

I agree that outside lime work in December is not ideal but is that 5C figure a safety margin to prevent freeze/thaw problems or some sort of absolute figure to do with carbonation?

My amateur guesswork would be that it's the freeze/thaw issue that must be avoided and as long as that doesn't happen then then low temperatures would merely slow down the chemical reaction of carbonation. So it would take longer but otherwise would do no harm.

 

[livias]

The trouble is that once temperatures are getting down to 5 deg they are likely to stay low and the uncarbonated lime sits around setting vv slowly until Frost or Spring arrives

On the plus side, high up on a wall will not be affected by ground frost so unless there is a prolonged heavy frost they might get away with it

 

[Flyfisher]

That makes sense - so it's a safety margin guildeline really.

 

[88v8]

There was a thread on here which I can't now find, mentioning that full carbonation takes many months.
How long does the pointing remain vulnerable?

I presume that the protective scaffolding would need to remain in place until spring, perhaps more so to the north side and on areas of wall that are prone to wetting.
If it freezes, the pointing will crumble in varying degrees and either have to be redone or at least redone sooner.

It's a gamble. So, do they feel lucky?

Ivor

 

[MatthewC]

There was a thread on here which I can't now find, mentioning that full carbonation takes many months.
How long does the pointing remain vulnerable?

It depends on how deep it is but it is certainly months if not even years for "full" carbonation. However, I think there are two stages: first;y the evaporation stage then the carbonation stage, and it's during the first stage that you need to avoid frost - but I'd say that could still be a long time in winter.

It's a gamble. So, do they feel lucky?

I don't think it's a gamble at all as you are sure to lose if you use lime in December. In 2017 our contractors did some pointing on the church tower roof on about Nov 1st and it now needs replacing... :x

 

[JohnArmer]

We're having the back of our house (not far away from you in N. Lancs) pointed in September - but the builder says he doesn't do any external lime work after September. It's South facing and he wasn't too keen on doing it in the middle of Summer either (dries out too fast).

I remember when we had the front done a few years ago, we raked out in February ready for him but he didn't do it until May. Good job as there was a very sharp frost in mid April.