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Historic Brick Pointing

One of the most frustrating parts of our job is having to view endless houses that have been 'repointed' in the most horrible way with cement.  Usually, bodgit builder takes an agle grinder to the brickwork, cuts away at the joints making them wider than they were, destroying the top and bottom edges of the bricks (arrises).  He then smears cement all over the place, turning beautiful brickwork into a smeary mess - which results in the bricks self destructing as moisture now has to exit the wall via the brick.  It's lungs, the mortar joints, have been plugged.

Historic brick pointing is not difficult to do right, you just need to know how to do it - and in many cases you need time and patience.  A 6mm mortar joint is a hard thing to rake out by hand.  The thing is, most mortar joints DON'T NEED repointing.  People just think they do.  If the mortar hasn't disappeared from the joints, just leave it - a little bit of a recess is fine.  If it's more than 10 or 15mm, then ok, it may be needed.  

The photos on this page are from a project Pete did a couple of years ago. It's a farmhouse that was heavily cement rendered. Underneath the render, to our amazement was a jettied timber frame which you see in the later photos.  Soft brick had started to disintegrate. Pete organised a team of expert labour to rake out the joints by hand, and re-point using a sharp, gritty local sand and a 2.5 hydraulic lime.  The result is a beautiful blend of glowing, soft orange brickwork, set within a tracery of joints.  It's jobs like this which make the conservation game so worthwhile.  You come across a job like this once every so many years - and even then, you need a willing client that will go on the journey with you.  From a technical viewpoint - the brickwork is 17th Century - it is infill, and replaces the 16th Century timber frame at the bottom half of the building under the jetty.  At the rear, the frame was found - although very rotten.  We replaced and repaired, and elsewhere on this site you'll see the timber frame in all of its glory.  So - historic brick pointing need not be a scarey thing - but it needs to be done with care and love.

Repointing stonework is similarly a fun and rewarding job if its done right.  To repoint stone, you often need stone skills too.  Most stone walls are built with two skins - an inner, and an outer skin, with a rubble filling in the middle. The stone blocks are laid with very little mortar between them - if they cant slightly, they are held with little stone wedges called pinnings.  If there are wider joints or gaps where stones meet, they are also filled with pinnings and pointed around.  When stone walls are repointed, it is common for us to find that 'bodgit and scarper' builder removed both mortar and pinnings, and repoints the stone with thick gobs of cement.  Not only do you end up with very wide joints, but the thick gobs of cement stop the wall from breathing. This is a particular problem in North Wales.  Pete frequently encounters old cottages built with slate which are sopping wet.  Slate.. yes - it's impervious - it was used for damp courses - and no, damp doesnt get into the wall by rising.. So why are these cottages sopping wet?  It's because most of the moisture comes from within - via the plaster internally - and can't get out again.  Trapped, by cement.  The moment you take the cement out, the wall starts to dry out.  So - repointing a stone wall is not hard - but remember - mortar MUST always be softer than the stone.  So if it's a Shropshire limestone for example, which isn't that hard, mortar must be as soft as you can get - preferably made with putty and a gritty sharp sand.  If you are dealing with slate or granite walls, you could use NHL2.5 or even a 3.5 hydraulic mortar - which would still be a lot more porous and breathable than the stone.

We see some dreadful examples of 'strap' pointing - especially on those lovely old gritstone houses of the north - up around Barnsley, Leeds, Huddersfield - thousands of gorgeous properties totally ruined by bodgit builder and his cement.  The stone up there is quite a soft gritstone, which easily spalls - and is badly damaged by any amount of cement.  Luckily, the strap pointing that bodgit uses, is usually not very deep - he can't be bothered to rake out the joints deeply enough.  You should aim to rake out about 2.5 times the joint width - so a 10mm joint should be raked out 25mm.

 

 

 

What happens when you use cement...

Here's a couple of photos to show what that beautiful brickwork above, will look like if wally builder points it with cement.  These photos are from a beautiful barn, totally ruined by a builder / developer who re-pointed soft brick with cement.  Within 10 years, the barn needed major restoration work to the brickwork.  These are just a couple of shots to show how the bricks try to lose moisture, and explode - the mortar joints can no longer act as the lungs of the building, and the bricks take over - and die.

In this example, the only way to save the wall was a very expensive program of raking out to remove the cement. Disintegrating bricks then had to be individually removed, using small chisels and hammer, although we did speed the process with an arbortech brick saw (approved for this sort of job by Historic England).  Bricks were turned if they were in good enough condition, and replaced if they were not.  The job cost around £15,000 - money that was completely uneccessary if the idiot of a builder had done the job properly in the first place.  

This highlights the need for 'builders' or 'contractors' to be assessed as an intelligent, qualified, conservation educated person / company before you dive into work on your building.  Just 'engaging a contractor' doesn't work - most of them have NOT got the knowledge or skills to work on an old building.

It wasn't until I loaded these pictures that I saw angle grinder marks. These are the kiss of death for this wall.  If you look at the bottom picture, you'll see an angle grinder mark on the top of the middle brick at right.  If you look at the top of the bottom brick, you'll see it is cut straight with the grinder.  All the glaze has now been cut off the edges of these bricks, and they have little or no chance of long term survival.  The builder has effectively destroyed the building.

 

 

 

 

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