Benefits to repointing brick and stone walls on your home
Repointing brick and stone might not be the first thing on your mind as we approach spring, but after the harsh winter where we seem to have been battered by 100 different storms here in Sheffield, your home may have taken a bit of a bashing from the elements. Here we try to cover everything we do when repointing your home.
The mortar used on your house is a large part of the total building. Although it may be something you may not notice so much, it is actually what binds everything together and makes the building structurally sound. It can make up a large percentage of the total area of the brick or stonework. Leaving the mortar to perish for a number of years let moisture in causing a number of structural and damp issues inside and outside your home. Left too long this can cause big problems.
A good pointing job can stop all these problems along with transforming the way your house looks. A poor pointing job can be as useless as leaving the mortar in the first place. Poorly mixed weak mortar, brickwork not raked out, rinsed out and brushed out all contribute to the pointing perishing in a couple of years. Read on for our tips on how we do a proper repointing job that will last for years.
Repointing stone masonry usually requires a softer mortar. We use a lime-based mortar mix. Most older stone or brick houses, cottages and listed buildings were built before the time cement was used in building. Lime mortar is a softer and more pliable mix that isn’t as strong as the stone it holds together. This allows for any moisture to escape through the joint rather than making its way through the stone and causing the stone to perish before the jointing. Cement-based mortars are usually harder and more brittle not allowing water to escape and making the masonry decay before the joint.
Raking out the old mortar on a stone job will be by masonry chisel for the harder top parts and a wire or stiff brush to finish and get all the loose debris out. Followed by a rinse with a hosepipe. Not too much here as the softer mortar that is exposed could allow damp to penetrate through into the home as there is no cavity wall on older buildings or properties.
Lime mortars are usually 1 part hydraulic lime to 3 parts sharp sand batched by filling a bucket so as to keep the same colour and consistency. Some brick jobs may require a quarter part of portland cement.
Brick pointing usually uses a cement-based mix. It all depends on the age of the house and masonry and type of bricks used. It would be up to the builder to decide what mix to work with. Generally, the older the bricks are in the buildings the softer the mortar should be. A stone pointing job and some softer bricks should be used with lime mortar. The bricks on show below were pointed with a 5-1 mix as they are quite a solid brick. This will be plenty strong enough to stand the weather but not too strong to damage the brick.
A grinder was used to rake out the old mortar to a depth of 20mm-25mm any further could cause the walls to become unsound. The brickwork or stonework is then rinsed with water. Usually at the end of the day to allow to dry overnight. Then before new pointing starts a quick run back over it with a stiff brush to make sure all debris has been removed before you repoint.
Brick-Repointing – How To DIY On Your Own Home.
If you follow all the steps repointing is quite an easy job theoretically. It is quite messy to start with the grinding out, but if you are not scared to get your hands dirty it is easy to do and can save a lot of money on labour costs. It can be actually quite relaxing once you are set up with the radio on.
First, make sure you have the correct PPE. A must when doing any grinding job are goggles and a dust mask. Especially when grinding out lime mortar from brick and stone walls. When using a grinder there is a lot of loose mortar being thrown about. We don’t want any getting in your eyes. Along with this is a lot of dust. A LOT OF DUST. Needless to say, you don’t want this getting on your lungs. There are good quality respirators on the market which make a good seal to your face, but even a cheap throwaway dust mask should be used at a minimum. A pair of work gloves is usually a good idea when working with power tools and mortar. Another good idea is a hoodie when grinding out to keep the dust out of your hair. Not essential but you will thank me when it comes to bath time.
Tools You Will Need.
You will need a few tools to carry out the job. Some of you will have some already in your garage, but if not a whole set can be less than £100.
First off you will need a grinder. I often opt for a cheaper version you can get from most large DIY centres. Simply because they come under a lot of use if grinding a 3-bed semi and are much cheaper to replace than an expensive brand when it inevitably burns out. If you are only going to use it once there is no point splashing out on an expensive version to then leave in the shed collecting dust. Amazingly you can pick up a grinder for around £25 -£30 these days. Ideal for our purposes.
First of all, you need to grind out.
Every pointing job starts with grinding or chasing out the old mortar joints. We need a solid and dust-free joint to apply the mortar. We always use a grinder for this. The old fashioned way, and on most stone jobs is chasing out with a hammer and chisel. On brickwork that could take forever. For this I a diamond-tipped grinding disc. These are thicker than the usual cutting or grinding discs and remove most if not all of the mortar in the joint. They are a bit dearer than normal discs but worth the investment in the time it saves. One disc lasts a day grinding so depending on the size of the job you may go through quite a few discs.
It is recommended that you grind out to a depth of 20mm – 25mm to make sure that you have got all the old perished mortar out of the masonry joints.
Grinding out the Masonry Joints
Let the grinder do the work. Don’t try to force it. It doesn’t go any faster and can cause the grinder to grab and kick back at you and cause damage to the wall or yourself. It can also lead to damage or burn the motor of the grinder out. Take care to take regular breaks. It can be quite bad on the wrists and with prolonged use cause vibration white finger. It may be wise to get some guidance on using vibrating tools if you are worried about vibration white finger. You can read more about it here. You may want to do a section of grinding and then start pointing that section and do it in stages or you can carry on and do the whole of the grinding and then start and do the new pointing in one hit. Just be sure to read the guidelines about vibrational tools and take care.
After Grinding out there will still be a lot of dust and small debris in the mortar joints. It is good practice to go along the joint with a hosepipe and rinse all of this out. Use a hose without a fitting on as any pressure may lead to damp penetrating on an older property. Starting at the top just run along the mortar joints with the hose and let the water work its way down the face of the building wall.
I often do this last thing before I leave so it has overnight to dry. If I start work while the brickwork is wet it tends to smear and will lead to a bigger cleaning job at the end.
Making the Mortar
Everybody has their own method of mixing mortar. This is how I do it. You can either use a mixer or do it by hand. Just make sure you batch each mix to make sure you get the same colour.
Batching is when you use a bucket and fill each quantity of mix to the same level or to the brim and scrape it off to make sure you are getting the exact same mix each time. To extra sure make sure you are buying the same brand as well.
As mentioned, the strength of the mix is down to the discretion of the builder to asses the existing wall to be pointed.
4 parts sand to 1 part cement is commonly used but if the masonry is more soft and porous use 5 to one.
When making a lime putty I mix 3 parts sharp sand to 1 part hydraulic lime. Some people put a quarter part of portland cement in to harden it. Again it is down to the discretion of the builder. I have done repointing on an older building and repointed their copings on the roof with the same lime putty only for it to fail quite quickly. In these cases, a harder mix should be used.
Starting the Brick and Stone repointing
Once you have the mortar mixed it is time to apply it to the brick or stone walls. When attempting repointing brick and stone walls I often start by rinsing all the old mortar joints out with a hosepipe and let dry overnight.
Applying the New Mortar
Now we are ready to apply the new mortar to brick or stone masonry Depending on the style of pointing you wish to use. Different types of jointing can be seen in this article here.
Using a hawk or trowel