Damp Proof Course Protection...

[ben85]

Hi all,

On my terraced house (mid 80's) I can clearly see the damp proof course which is some kind of black sheeting after 2 layers of bricks from the bottom.

My neighbour pointed out they the bricks (2 bricks high) underneath the DPC are the same bricks as the rest of the house and they are. I was told that there should be engineering bricks which I believe are a more sturdy type of bricks usually reserved for underneath the DPC's and for frost and water resistance.

Some of the bricks underneath the DPC are a little white on the face of them but appear to be sturdy. I was thinking of scraping off any bits and painting the 2 layers of bricks underneath the DPC with brick paint or masonary paint just to add another layer of protection for the front of the bricks and prevent moisture/frost ingress.

Would I be able to use brick/masonary to seal the front of the bricks or what is best appropriate?

Secondly, is this situation quite common on mid 80's terraced houses or should it definitely have it?

Regards

BW

 

[RonnyRaygun]

The bricks below DPC don't have to be engineering bricks; they just have to have an F2 frost rating. Engineering bricks just have a higher compressive strength and are usually used where loads are high such as in piers or padstones although they have to have an F2 frost rating, so are always suitable below DPC.

There's no way of knowing if your bricks have the correct frost rating or not although if you can't see any spalling after around 25 years then I suspect they might be OK.

The white stuff is efflorescence and is the leaching of minerals from within the bricks. You'll get it below DPC due to the presence of water. It won't cause any problems itself, just looks a bit ugly, but can be easily cleaned with a wire brush and some elbow grease.

 

[theoldun]

Do not apply brick or masonry paint to brickwork below DPC.
At the moment the brickwork can breathe and the dampness is being drawn to the front surface and evaporating.
If you seal the brickwork the dampness can not evaporate and over a period of time will cause spalling of the bricks.
oldun

 

[ben85]

To the oldun- I didn't check this forum before I applied what I thought was right. I applied some Thompsons water-based water seal which i found readily availiable in diy stores. It states on the tin that it is meant to reduce efflorescence (white deposits on surface of bricks) so I bought a small tin and painted it on the two layers of bricks beneath the DPC. It came as a clear fluid and has almost dried as of today, it appears to have soaked into the bricks.

Will this have caused any lasting damage to the bricks beneath the DPC? I hope haven't caused them to degrade, they need to last at least another 75 years!

I'm hoping this thompsons fluid will be breathable and allow the bricks underneath the DPC to breath, will it being water-based means it will do this.

I managed to grab a quote of the product below and have included this so people can acetate whether it should be ok, the good thing is, it mentions it is breathable

Quote from official website:

Thompson's Water Seal utilises hydrophobic technology to deliver invisible protection against water damage. The deep penetrating formulation travels deep into exterior dry porous surfaces to form a breathable membrane that allows moisture vapour inside the substrate to evaporate whilst protecting against water penetration and damage. Thompson's Water Seal has a unique formulation which, unlike some waterproofers, penetrates the surface therefore waterproofing even after the initial beading is gone. It will not be destroyed by ultraviolet light and is long lasting even under heavy moisture conditions. Assuming application instructions and coverage guidelines are adhered to it provides effective water repellency for years.

Regards

BW