Pointing old brick arch kiln entrance - Now with Photos

[wytco0]

I have an old underground brick kiln in my garden and it has a arched tunnel entrance, the arch is in poor condition and I am doing some work to repair it.

The arch is made from soft red brick and lime mortar, on the outsides the outer layer of the 2 layers of bricks that make up the arch was missing in some areas. I have just spent a day cutting out rotten bricks and pointing some of the big gaps in the remaining single layer, I am planning to put a new second layer on in the next couple of weeks.

I have uses 5:1:1 mortar with lime for colour and I hope that it will be OK. (I cant afford lime mortar) When the second layer is on I plan to cover it with some sort of render as it had originally.

I have two questions:

1) Can you recommend an affordable render that I could use, preferably white. One option is to use a cement render and whitewash it. If I use a cement render what mix would be best? Would 3:1:1 be too hard and cause cracking?

2) Inside the arch there are a couple of areas where I need to re-point, however the affected bricks are up in the ceiling. How do I re-point them? I will be standing underneath, has anyone done re-pointing in a ceiling? if so how?


Thanks

[stuart45]

Use 4/1/1 for the scratch coat and 5/1/1 for the top coat. You can get white cement.
Pointing a ceiling is basically the same as the walls, you need to push it well into the joints. Getting the mix right helps, so it will be a case of trial and error.
If you are confident enough to replace some of the arch bricks then the pointing should be no problem.

[wytco0]

Hi Stuart, thanks for the advice on the render. If I understand correctly the scratch coat is the first coat and this is then followed by the top coat?

I had another look at the pointing needed in the ceiling this morning and as you suggest I think I can do it by pushing the mortar in at an angle.


I will post some pictures later to show the kiln setup as its a bit unusual.

I had a bit of a fright this morning when I went out to check my pointing from yesterday, it was not hard, its definitely going off but its still very soft and I could easily pick it out if I tried.

I haven't used lime in a mortar before, I know it makes it creamy but does it also affect the time it takes to set? I am pretty sure I got the ratio 5:1:1 correct.

Also I have now discovered that the bricks that the kiln is made from are 9 x 4.5 x 2.5 inch, I had a load of soft reds that I had salvaged from an old building but they are 9.5 x 4 x 2.75 inch so no good. Not sure where I can get the size I want !!

[stuart45]

Top coat is last. Dont worry about the soft mortar. Ordinary Portand cement takes about 2 weeks to reach 99% of its hardness, and then about 99 years to get the other 1%. Lime hardens by absorbing CO2 from the air so it takes a bit longer. Finding the bricks may involve looking on the net.

[wytco0]

Hi as promised here are some photos showing the kiln that I am trying to repair.

View of top of kiln entrance

Roof of kiln entrance

Area where rotten bricks cut away

Close up showing where rotten bricks removed

Top

Side

Other Side

Other Side

Entrance to kiln

Looking down kiln entrace

Inside roof showing crack and where pointing needed, I am hoping that the crack will be stabilized when the outer bricks are back and the re-pointing is complete.

Roof Showing Crack and where pointing is needed

[stuart45]

Quite an unusual garden feature! As you are going to render the top you could use the bricks that you have, and make up the difference with the render. A pointing gun would be useful for getting plenty of mortar into the top inside. The more weight that you put on top of the arch the stronger it gets. That's why arches will little over the top often fail.
Once it's up and running you will be able to make any sized bricks you require.

[wytco0]

Well its taken me a long while to get it done but I have finally finished the top layer of bricks on the kiln. I will try and post some picture soon.

Its not a great work of art and it was much harder than I thought due to the angles and curves.

I ended up using a mixture of old bricks that I had laying about as the whole thing is going to be covered with cement render and wont be seen.

Now I have to rebuild some of the sides and top that's going to be seen. My bricklaying isn't great so I will be looking for basic tips

[JohnD]

are you sure it is a kiln? does it have a chimney? I think it might be an Ice Cellar or even an air-raid shelter. What are the dimensions? Is the interior whitewashed? Are there signs of door fixings or shelves.hooks inside?

when you look at the bricks, do they appear to be hand made (irregular shapes with soft round or crinkled corners? Or machine made (regular, sharp square arrises, possibly with a makers name embossed in the top)?

[wytco0]

Hi John, well apparently its a lime kiln and was build in the 19th century. I understand that there were a lot of them about, it seems to be a very industrial build with lots of rough work and infill. I think its been used as a store as there were some rotten wooden shelves in it but the have now rotted away completely. The garden that it is in was worked for lime and had a large amount taken out.

The bricks are fairly regular but very very soft. The mortar is lime mortar and the kiln used to have some sort of chimney exit in the middle but this was filled in at least 50 years ago. There are no marks on the bricks, they are soft and powdery and often seem to contains stones.

Its certainly not an air raid shelter. I cant measure it at the moment but the stairs are about 1.5M wide, underground its a donut shape with 3 round 'windows' of which 2 are blocked off. I would guess that the width underground is about 6-8M max.