Exterior brick wall re-pointing mortar joints the easy way

painted bricks with wall coatings

Many houses around the UK are constructed from brick and they have been used for building houses, bridges, churches, schools, and more or less most other buildings, since the Roman times.

Bricks come in different shapes and sizes, different densities, and each type is manufactured for different and specific uses.

Buildings can be erected quick easily and quickly using common bricks, laid by trained bricklayers or builders.

Brick wall surfaces usually can repel the weather and remain relatively water tight and damp free, but over time bricks without an exterior coating such as render, paint or pebbledash, can get damaged by the weather, and/or the mortar joints that bind the bricks together, commonly called pointing, can deteriorate and fall away.

Exterior brick wall re-pointing

Replacing pointing or loose mortar joints can be a very time consuming job and can be costly for this sole reason.

In addition, the face of the brick, the square edge that you see when you look at the wall, can be damaged by the weather over time which can make the bricks porous, which when doing a spot of DIY exterior painting, can be very troublesome.

Before starting a repainting project on a brick exterior house wall, perhaps to apply a wall coating or a paint finish, or damp proofing treatment, correct preparation of the brick wall is the key.

Experienced builder Guy Alexander Bell explains how we can do this quickly and relative easily

Tools and equipment required :

Correct quantities of sand and cement for the job

  •  OPTIONAL: hydrated lime.
  •  Access to a water supply.
  •  Protective gloves.
  •  Small trowel.
  • Small paint brush.
  •  Plasterers hawk and trowel.
  • Bricklayer trowel.
  •  Overalls or old work clothes.
  •  Dust-sheets or equivalent.
  • Plastic buckets (pails)
  • A lump hammer and cold chisel.
  • Large masonry paint brush or broom brush head.
  • Access equipment such as tower, scaffolding or ladders. (Do not attempt large areas of re-pointing from a ladder)
  • PVA mortar additive admix or febmix, such as Unibond or similar.
Packing away our tools and cleaning the site once finished

Packing away our tools and cleaning the site once finished

The problem with porous bricks is that if moisture enters into the brick itself, it can freeze during colder weather, and the water in the brick expands, which cracks the brick and then eventually pushes the face or outside edge of the brick, away from the wall which usually means that the face of the brick falls off.

“This is the start of serious deterioration in a brick exterior wall and repair and remedial works are necessary as a point of urgency, to stop further deterioration and to repair the face of the brick.”

Sometimes, the bricks can be carefully chiselled out and replaced, although an exact colour and texture match, even with recycled bricks, is rare, and do this (rather expensive) process too many times and your brick exterior wall will end up looking like a patchwork quilt in the end.

Of course if you plan to have the wall coated with a secondary external wall finish, something like pebbledash, render, cladding, spardash or tyrolean, then this article is perhaps not that relevant, but if you are looking to keep at least the character of the house with a painted brick wall finish then read on!

Painting brick walls

A brick house in Wiltshire we painted

Before you start to work on the wall

So to start the job, you need to fully appraise what exactly needs to be done.

A professional will make notes as he (or she) examines the wall, making specific reference to how good or bad the existing exterior wall surface is, and its an advisable thing to do if the area to be treated is large.

As a guide, and honest advice here, if you haven’t done wall re-pointing before dont presume it is easy as it is not! If you’re not confident (and this is only a rough guide, not a definitive text), then call in a specialist company.

Questions that need to be considered would commonly include:

How big is the wall to be repaired? Is it too big to manage?

If so, call a builder or someone like an exterior wall coating company to come and take a look. Yes its going to cost more than doing it yourself, but you should ever attempt something if it is beyond your experience.

Always work safely!

What is happening to the wall?

Are there gaps where mortar joints should be? (check the floor also to see if anything has fallen off recently). Are there are stains on the wall such as green mould or algae?

This would be a strong indicator that your wall is porous and letting water in.

If you’re getting damp inside the house, that’s a good indicator treatment is needed to the external walls.

poor condition bricks eroded

An example of how, over time, moisture collected in these porous bricks, which then froze, creating cracks, which eventually made the whole corner fall off. Imagine if that corner was holding a roof up…….and you were stood under it!

Look at the surface of a small area of bricks and take an average as to what condition the bricks are in.

  • Are there small holes or pits in the face of the bricks?
  • When you rub your finger on the face of the brick, do you get a stain or a mark come off on your hand?
  • Is the brick powdery to touch? This would indicate the fabric of each brick, the way it is held together is deteriorating.
  • Are there any bricks that are loose or are there any bricks that have lost their face or square edge?
  • Do I have a tight budget?
  • Am I trying to do it on the cheap, or do I have enough money to pay someone to do it for me?

If the answer is yes to any of the above, remedial work is required to the exterior brick wall surface.

How to repair the face edge of a common house brick.

There are 2 ways to do this.

METHOD ONE, Replacement:

The brick must be replaced and therefore the first thing to do is to take the old brick out, which can be easy or difficult depending on how bad the old brick is.

If the brick is still fairly solid, the mortar joints around the brick must be taken away. If the mortar is loose, this should be easy, but if the mortar is fairly sound, then you must use a heavy hammer and chisel to hack away at the mortar joints.

EYE PROTECTION IS ADVISED FOR THIS TASK, AS ARE GLOVES.

cleaning wall coatings

Protect your eyes!

Don’t use a disc cutter to remove the mortar as this will damage the bricks as well.

Once the old brick has been taken out, you must clean any loose material from the hole, match up the new brick to ensure it is going to fit comfortably, and then with a sand and cement mortar mix, put small amounts around the edge and base of the hole, a small amount on top of the new brick, and then carefully insert the new brick.

If it is a cavity wall, dont push the brick in too hard or it will disappear into the cavity and could then form a bridge between the inner leaf and outer leaf of the wall and will then start to cause damp. Also it can knock wall ties out of place too, so please pay special attention to the above and be careful.

I must stress again if you dont know what you’re doing, DON’T DO IT and call a builder or wall specialist contractor instead.

Yes I’m somewhat biased as I work for one (!), but in my defence, I have lost count of how many times our teams have turned up to half finished projects where the once optimistic and well-meaning owner tried to save a bit of cash, and it eventually turned into a disaster!

Brickwork that needs repair

Brickwork that needs repair

Once the brick is in place, and again, especially if it a cavity wall, remove any excess mortar around the brick, satisfy yourself it is in straight and true, not sticking out from the wall, and leave the mortar a while or so to start to set.

Then return to the brick once you know it is not moving around in its new home, and then apply mortar around the edges of the brick.

This can be smoothed over with either a small trowel, or a damp narrow paintbrush, depending on the finish required.

TIP: If you are planning to leave the brickwork unpainted, it is often more advisable to use hydrated lime instead of cement as this will provide better brickwork waterproofing.

METHOD TWO, Renewal of the brick face

This method is applicable if the brick is still be located in the same place and the spalling face (the edge of the brick that has come away) has left a hole or indentation no deeper than about 1 and half inches, and this applies only when the surface is to be covered over with either paint or an exterior wall coating product.

A recently pointed and repaired brick wall

A recently pointed and repaired brick wall

OK, how about salvaging bad brickwork by rendering over the bricks?

Sometimes the brickwork is far too gone and the only option you may have now is to have a render exterior wall covering applied over the top, which will change the appearance dramatically, although if your brick house really is that bad, then surely that’s a good thing?

Starting with the brick wall, identify the worst areas, sometimes where there is virtually no brick left, just a square and rather sad hole, and scrape out the remains, the “ex-brick”, the deceased one, and then clean the aperture. Paint the edges with water and unibond PVA mix, get the correct size replacement brick, apply some mortar around 2 or 3 sides and shove it in there!

Then re-point the joints around the brick, making sure it is flush with the rest of the wall.

Then you need to render on a scratch coat, covering but consolidating the poor bricks beneath.

Lightly brush away any loose material from the area to be repaired, and paint the brick face several times with a mix of PVA and water which will stabilise the surface and give the new mortar a good key, i.e. a surface that the mortar or render will adhere to.

Once this has been done, mix up (in a bucket) a small amount of sand and cement (usually 3 parts sand to one part cement in this case), add water and mix to a smooth and malleable consistency.

Using the trowel, load a small amount onto the plasterers hawk, and using confident but firm hand direction, skim the surface of the brick to smooth finish. If the hole is deep, you may want to do a SCRATCH COAT first, allow to dry and then a top coat of render.

This is what the first “primer” render coating (or scratch coat) will look like.

Exterior rendering scratch coat

This is what a scratch coat of render looks like

Scrape any excess render away and try and recreate the straight edges of a brick to your new piece of mortar or render.

Once the mortar starts Hydrating or curing, i.e. drying, the new surface may be smoothed over to achieve a flat finish. For extra precision, a damp household sponge lightly brushed over the surface can also be used to get it looking really good.

So, once your loose and missing bricks are sorted, then comes the re-pointing, but hey …..wait a minute,  …….this is going to take ages isn’t it?!!

“NOT NECESSARILY!”

If you are painting or applying an exterior protective wall coating to the house, re-pointing in the traditional fashion is not required as there is a much easier and quicker way and this is what I’m now going to explain so pay attention!!!!

same house in Wiltshire after a treatment with exterior wall coatings

How to use a bagging render wash to quickly repair and prepare the wall prior to painting

Re-pointing a brick wall is a very time consuming job and unless the wall is to be retained as a feature with exposed brickwork, re pointing a wall is often best left to the experts, especially if it is a whole house.

(There are some companies who can do machine re-pointing, check your yellow pages to see if there is anyone in your area if that is what you wish to have done)

Pebble-dash cleaning

A method commonly used in the textured wall coatings industry is to use a sand and cement wash, with a febmix or Unibond added to it.

This is mixed up by the bucket load instead of mixing large amounts with a spot board or cement mixer. In my experience I always use half cement and half sand, add the unibond to the water 1st and mix in so it looks like milk, and then slowly add, and stir, add and stir, until a light creamy mix is achieved.

GLOVES MUST BE WORN AS IF THE MIX GETS ON YOUR HANDS, THE CEMENT WILL LITERALLY EAT AWAY AT THE TOP LAYER OF YOUR SKIN

This method is commonly, but not officially, known as “bagging” and it can also be used to smooth out and prepare pebbledash and spar dashed walls before painting too.

As this can be quite messy, protect the floor with dust sheets and then commence masking up.

This commonly involves wrapping brown paper around the pipes and fixing them with tape, and covering over doors, windows and porch roofs with paper.

If the bagging cement wash mix gets onto these surfaces and dries, it can be sometimes impossible to remove. Also if you try and clean wet bagging off UPVC, the sand in the mixture may scratch plastic doors and windows so be warned!

Masked up house and applying primer.

The house masked up and primer being applied

Then get your brush and start applying the bagging, from the top of the wall, downwards, but if you are inexperienced, try it on a small part at ground level first, however once it dries, dont go over it again or you will flatten out the wall surface and the brick profile you are trying to achieve will disappear.

Remember to regularly check the consistency of the mix as over time it will thicken, so from time to add, add a but more water and stir it before continuing. If you let the mixture thicken, not only is it harder to apply, but it will start making brush lines on the bricks, which when hardened, will be extremely difficult to cover up.

As the mixture is applied to the wall, it will fill in any gaps in the pointing, and also any pits or small holes in the brick itself. Once the whole wall is finished, it should look a cement colour, but you can still see the bricks underneath.

After the wall is painted, or after it has an application of a spray applied exterior coating, it will have a nice and clean finish across the whole elevation.

Remember again, this is to be done after all missing bricks have been repaired, and it is not suitable to fill large pointing gaps, they may have to be done using the method we talked about earlier, with mortar and a trowel, although this can sometimes be done after the bagging process as the mixture itself would have made a good key for the mortar repairs to be carried out to the exterior wall surface.

Once the bagging cement wash has dried, step back .. (NOT ON A LADDER, I MEAN STEP BACK ON THE GROUND!) ..and look up at the wall. Does anything catch your eye?

If you are a contractor, anything you spot may also be spotted by the customer, the person paying you, so make sure you are totally happy with how the wall has ended up after this treatment as once the paint or wall coating system goes onto the wall and ON TOP of your new surface, you wont be able to correct any mistakes, missed bits or random lumps or splodges you missed when you were doing the job!

Its often good practice once the bagging has dried, to GENTLY brush it over with a soft, clean broom head or brush to remove any dust or cement splodges from the wall, but I must stress, do it LIGHTLY, and dont brush off all your hard work so far.

Once you are happy with the wall, it needs a primer to be applied, and then a top coat of either masonry paint or an application of a weather resistant wall coating, depending on if you are doing DIY exterior painting, or if you are a painting a contractor and depending on the external house finish required.

If the above is carried out according to these instructions, you should be left with a nice painted wall, still showing the outlines of the brickwork, but your wall is now protected, all bricks should be consistent in surface, no loose or missing pointing, and the whole things should look great!

Remember if you are not sure and do not have experience in DIY exterior pointing, rendering, or anything else in this line of work, you would be advised to contact us today as we can carry out these works at a competitive price.

Phone us free today and get a quote for brick wall repointing and rendering

Phone us free today and get a quote for brick wall re-pointing and rendering

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