How long for lime mortar to dry?

[vicky whitworth]

Hello, as some of you may recall we are having a brick skin built inside our faux (don't blame me I didn't start it!) 1980s inglenook in an endeavour to make it look better and to bring it down a little in size. The builder made a start on Friday and it does look better already. It's a fiddly job as he is working around the woodburner. The bricks are very wet as they have been stored outside, and he's using lime mortar - total height of bricks about 2m on all three sides of the inglenook. The woodburner is our only form of heating in the room, and the room is our sitting room with the only TV connection in the place. If we light the woodburner it's going to get very, very hot right next to the bricks and mortar but the longer we leave it the longer we have an out of use sitting room. Any thoughts on how long we should leave the woodburner unlit to allow the mortar to dry more slowly? And should we put an electric heater in the room to give it a bit of heat? I don't want to crack the mortar but I also don't want to wait months for it to dry. Thank you.

 

[CliffordPope]

WE had a lot of lime mortar pointing, stonework and brickwork recently, and the builder advised it takes up to 2 months for lime mortar to develop its full strength and hardness. I don't think it helps the process if it dries out too much, so heat certainly would not be a good idea.
But it does depend which kind of lime was used and wether it had any portland cement in the mix, which I understand accelerates setting.

 

[robgil]

why not just use cement?

 

[vicky whitworth]

We could have just used cement. But it tends to have a hard and harsh grey characteristic and lime is softer and creamier and more traditional. It looks really good what's been done so far.

 

[stuart45]

You can use white cement, or a mix of the 2 to get a colour closer to lime mortar.

 

[Gervase]

Because the job's already done, that's why not to use cement, numpties!
Seriously, light the stove and keep warm. Lime mortar/plaster will crack if applied to a surface, but when used as the bonding agent between bricks, it won't. It's under compression, so it doesn't matter that it will take months fully to carbonate. Just fire up the stove. You won't do any harm to the mortar. If you're really worried, give it a spray with water once a week.
Look, it's only lime mortar. It's been used and abused for 2000 years. It works. Don't get anal about it!

 

[Gervase]

For what it's worth, I did a fireplace for someone last month. Within a week they had the woodburner going like a blast furnace (glowing dark cherry red, in fact). Fireplace (which goes up 2.4 metres to the old hearth above) still intact; no settlement, no cracks, no worries.

 

[Tom]

....Within a week they had the woodburner going like a blast furnace (glowing dark cherry red, in fact)....

How did they do this? I got a roaring fire going earlier today, with flames leaping up the flue. All of a sudden I could hear 'popping' noises from the flue (both the black and silver parts). It sounded like really heavy, large raindrops on a greenhouse roof....I was soooo scared!! I thought the flue was going to burst into flames :shock: I shut the doors really quickly and closed all the vents. The noise got less and less over about a minute and then I could hear the stove itself 'clicking' as it cooled down a bit. Can you explain what was happening? And, if this happens so quickly, how on earth could I heat the stove until it was glowing? Was I just being a pansy? Was my stove actually behaving ok? Or was I risking a serious fire? It's never done anything like that before, even though I've had large, hot fires in there.

 

[robgil]

dont try and heat your stove up until it glows, that just madness.

 

[philpjuk100]

I know it is obvious but the setting time is dependant on its surroundings.Did some brickwork a few weeks ago the lime mortar is now hard but I had some left over and used it to secure some loose stones in a path and I can still leave fingerprints in it.

 

[skier-hughes]

The colder the stove at ligting time the more it will expand when heated, the quicker the heating the more noise it makes. Same goes if you have a metal flue.

 

[Tom]

Would a fast heat up make the flue sound like that, though? I mean it was a really constant, fast 'popping' like noise; quite scary

 

[skier-hughes]

yes ours does if you burn it very hot very quickly.

 

[Lime]

dont try and heat your stove up until it glows, that just madness.

Yes it is and very, very dangerous if the stove is made of cast iron.
Dull red cast iron allows carbon monoxide to pass through it as if it wasn't there.
You won't smell anything (because cast iron will only allow the carbon monoxide through) but it will kill you.
The first thing you may notice is a headache.... and then you may discover that your legs are paralyzed so you and everyone else are trapped.

 

[Lime]

..
And what's all this nonsense about using cement?

Cement is a hard unpleasant-looking material that has little or no place in old house interiors.
The fantasy that maintains that cement is better than lime mortar seems to totally overlook that interior brickwork built with cement looks awful almost without exception.
Cement mortar may harden quicker but it will crack like glass if heated.
Lime mortar behaves in a completely different fashion.

 

[robgil]

i dunno Lime , ive used cement in places where lime has failed through the years, plinths under doors for instance, foundations under plinths for timber framed walls etc etc. granted its nowhere where it can be seen. cement can be a useful material sometimes, especially if it give the house another 500 years of life.

 

[Lime]

i dunno Lime , ive used cement in places where lime has failed through the years, plinths under doors for instance, foundations under plinths for timber framed walls etc etc. granted its nowhere where it can be seen. cement can be a useful material sometimes, especially if it give the house another 500 years of life.

But cement won't give an old house another 500 years of life, that is the point.
It will remain a hard lump of cement amongst softer material (the rest of the old house) and will stand out like a sore thumb in years to come.
Old house materials move and cement is incapable of following such movements.

 

[Jill]

Would a fast heat up make the flue sound like that, though? I mean it was a really constant, fast 'popping' like noise; quite scary

Now who's being a girlie? :wink:

Sorry - I just couldn't resist that one after the how much wood do you burn thread.

Fires can be scary things, its ok making and lighting them, its how to handle them when the unexpected happens that is a concern.

 

[vicky whitworth]

Thank you Lime for your comments about using lime. That's exactly how I feel. This poor house has been so messed about with modern materials over the years that I want to do the best I can for it. And I know that the lime mortar will look so much more attractive. One thing I've learnt with this place is that attention to detail makes such a difference. It's often not the big things that people notice but the small things like door knobs, skirting boards, window latches.

It sounds like the consensus is that I can't do too much damage if I light the wood burner once the bricks are laid. I hope the builder will finish it tomorrow, then I think I will leave it unlit til later in the week and then fire up. Brick work so far laid in Flemish bond looks good.

 

[Tom]

Would a fast heat up make the flue sound like that, though? I mean it was a really constant, fast 'popping' like noise; quite scary

Now who's being a girlie? :wink:

:lol: :lol: Touche!!