There are many reasons why you may be considering re pointing your wall. Please ensure that you have read all of this page if you are not 100% sure if re pointing is what you need to do in order to deal with the root cause of problem that you have.
This may seem an obvious statement, but it is always good to remember that the pointing on a building is a finish and by their very nature finishes should look good and be done at the end of any job sequence, otherwise the finish may be disturbed. Although pointing performs other tasks, it is always good to recognise your motivation for enquiring about a re pointing quote. It may just save you a lot of time and money !
I believe that it is good to ask yourself the following questions when planning to commission re pointing works.
Please read through the section below and see if it helps! I have compiled showing common problems I have found when answering potential customers' request for a re pointing quote.
Roof failure above cavity.
If the sarking underneath the roof tiles has decayed, it is possible for moisture to enter the cavity at roof level. Often, the cavity wall will cope with this but sometimes the inner wall will become waterlogged and track dampness inside the building. This can be aggravated by waterlogged cavity wall insulation. If moisture is entering around windows and doors, you may have a failed cavity tray system or if a “type e” modular cavity tray has been installed, the moisture may find its way behind and cause the problem.
Cavity tray failure.
Please refer to the cavity tray section link for a detailed explanation. In brief, as a cavity tray should prevent moisture ingress around reveals (windows doors etc.) moisture around these areas may be caused by tray failure. This should also be considered, investigated and eliminated prior to re pointing.
Wall tie failure.
Please refer to the wall ties section link for a detailed explanation. In brief, as wall ties corrode, they can often disturb the pointing immediately surrounding the failing tie. This is often mistaken re pointed without finding the root cause of the problem.
Unsuitable pointing.
Another common complaint is when a hard cement mortar has been specified in the past and the brick work often takes some time to dry out. Often you will find that brick faces are failing. This is often due to frost damage when the bricks are soaked.
If your wall has a soft lime mortar a common mistake by both previous householders and contractors is to choose “ a good hard mortar” with “plenty of cement in it” to “sort it out”! A lime mortar will naturally accommodate the building's natural movement (any brick built building will expand and contract slightly under seasonal weather conditions) A lime mortar will also breath, so any moisture taken on by the wall will also be able to be expelled through the mortar beds.
If a hard cement mortar is used on a lime mortar wall, a number of things will happen. The important things to note will be that it will not breath, so any moisture in the wall will have to find it's way out through the brick faces rather than the mortar beds. The mortar will also not accommodate movement but, it will not stop the naturally occurring movement in the wall behind. Hairline cracks will start to form as the cement mortar will break rather than flex with the wall naturally. Once you have hairline cracks forming, they will take on moisture but the moisture will not be able to be readily expelled as the mortar does not breathe! The net effect is to see the wall reject the mortar.
Weak or shallow pointing
There are many houses that simply have a mortar mix that is too weak. In these cases, it is often just badly mixed mortar when building so localised areas fail only. Sometime an appropriate mortar mix has been used to re point but, it has not been ground out properly first before application and the bond is weak between the existing wall and the new pointing. It therefore fails in time! This is often long after the contractor has any obligation to service the complaint but long before any replacement works were due.
Unsightly pointing.
Re pointing can often be seen as an unpleasant job and sometimes bad workmanship manifests itself in a poor finish. This is often just smearing of mortar over the brickwork. Many people think this is permanent and in some cases it is but the good news is that not all cases are terminal. Most can be cleaned! Please see the Re pointing – the solution.
A lesson for us all is to get to the root cause of the problem and then plan the works!
This section has been written assuming that Re pointing – the problem (above) has already been read.
If you need to re point your wall, the solution is to re point it, but properly!
Preparation
All the mortar beds should be raked out. Normally this means approx. 15- 25 mm depth with a diamond mortar rake and dust extraction unit. Dust extraction should always be used where possible (see photos) although some very tricky areas of a wall may mean that the extraction guard will not fit into the tight space.
After this rake out has been completed, the wall should be washed down. It is important to remove all the dust and debris that has not been removed fusing the dust extraction from the joints. It is also important to enure that the wall is miostened prior to pointing in order to ensure a good bond between the new pointing and existing substrate.
Decide on your mix.
Many mixes can be used. Some common mixes are 6:1:1 / 9:2:1 and 12:3:1 (Sand : Hydrated lime : Portland cement) and 3:1 (Sand / lime putty). The choice of mix is determined by the wall to be repointed. The BRE (building research establishment) document GRG24 is a good reference point for both customers and contractors to use as thier basis for planing works. In my opinion it ensures an objective view from a reputable source.
It is important to ensure that the mix is right and properly guaged to provide a consistant finish.
The most common is the half round (bucket handle) finish followed by weather struck, It is important to note that weather struck is much more labour intensive than half round and therefore more expensive. Normally best saved for the front of buildings!
Decide on your finish.
Many finishes are available - the most common is the “half round” (bucket handle) finish. It can look good and is a cost effective option because it is not particularly labour intensive. Mortar is carefully added to the bed joints and then (at the appropriate time in the setting process) compressed in with a “rubbing iron”. Later, after a short period of setting, the joints are brushed clean. It is important not to do this too early otherwise the finish will be damaged and brickwork smeared.
Weather struck, It is important to note that weather struck is much more labour intensive than half round and therefore more expensive. Normally best saved for the front of buildings! As you can see from the finish, it can look very attractive and neat if done well.