REMOVING CEMENT BASED RENDER FROM PERIOD BRICKWORK:
This is one of the most common requests that come in and a problem that if not dealt with can lead to some very serious issues.
All too often we see a period property with solid brick walls covered in a cement based render. The thinking used to be that the render would keep the water out and hence the inside dry, but far from it!
A cement based render unlike a lime mortar ,is not a breathable material and if you think about it, we produce a lot of moisture INSIDE the home-cooking showers,etc, even our breath creates moisture that has to go somewhere. If the home has sealed unit double glazing, draught proofing and all the good ,sensible elements of energy efficiency, then where does that moisture go to?-you can install trickle vents etc- good ventilation is essential, but some of that moisture will attempt to escape through the walls and if there is a cement render on the inside and or out side, that’s as far as it will go-just sit there as a damp patch either as condensation on the inside or in the brickwork.
As soon as most materials become damp they loose their energy efficiency and the problems begin.
Moving to the outside, a cement render is a strong, but suprisingly brittle substance- it does not like being moved!
Period brickwork ,especially with timber framing will move a good deal- enough to crack the cement render-you will often see this in a cement render of a few years old.Take a moment to view our ‘case study’ on one such timber framed building on the web site, it shows the damage that cement renders do to period homes!
These cracks become the enemy as they do the reverse of the intended purpose- they will let moisture in the form of rain INTO the wall through the cracks, the softer brick will then soak this up and the moisture then finds it difficult to escape out through the render barrier efficiently- wet walls and worse than this if you have timber framing, wet timber, with the risk then if wet or ‘dry’ rot setting in.
Even 19th Century homes can have timbers in the form of wall plates and window lintels built into the brickwork- these are then at great risk of undermining the structural integrity of the property.
Cement render was often the 20th Century ‘answer’ to all of the problems,fortunately most builders are more aware of the longer term issues these days.( though by no means all!)
Our approach is always to try to restore the brickwork if we can- we can carefully removed the cement render and once revealed we can assess the cost efficiency of restoration. In most cases the client will want the brickwork restored, after all it has done a good job for many years and with the damaged bricks replaced and the wall re pointed using an appropriate lime mortar there is no reason why it should not continue to do so.
The wall can then breathe as it should ,with no barriers the wind and sun can evaporate the moisture efficiently, the replaced bricks and the new lime mortar keep the inside of the walls dry.
A restored period brick wall is a joy to see and brings some of the original glory and that all important character back to the home.
There are times when restoration of the brickwork is beyond economic reaso, at this stage a LIME render might be the better option, check our web site for more detail on that issue, www.thegreenmanbuildingcompany.com