Penetrating Damp

[veedee]

Gable wall on Victorian house has exposed brickwork from the ground up to about 30% of the wall.

The other 70% is rendered

I am getting patches of penetrating damp on the exposed brickwork

During rainfall, I noticed the following

1. Rain would run down the rendered wall

2. At the end of the render, rainwater water would run directly onto the exposed brickwork below causing damp.

To solve this issue.

Would placing a gutter (under the render) to catch the rain water be a decent solution? The water would run into a nearby drain

 

[^woody^]

A gutter wont work and will look crap.

The render should have a bell cast at the bottom of it to cast water off the wall below it.

Point up any defective pointing and apply a silane water repellent if need be

 

[veedee]

The render should have a bell cast at the bottom of it to cast water off the wall below it.

I will grab a close up of the bottom of the render.. If it doesn't have the bell cast finish is this easy for a competent DIY'er to do?

Point up any defective pointing

What't the best/most effective tool to use to rake out the mortar joints quickly?

I'm worried about cutting into the brick with my grinder/diamond blade

apply a silane water repellent if need be

Like this?
http://www.stormdry.com/products/masonry-protection-cream

 

[^woody^]

1 - Maybe. You can fit stainless steel beads, or fix a temporary lath. Do a bit of a search or YouTube.

2 - A mini- grinder and a thick disc 8mm or so is the best thing, not a thin diamond blade.

3 - Yes something like that. Just not the Thompson water seal type products - which are good but not long term as they degrade.

 

[veedee]

1 - Maybe. You can fit stainless steel beads, or fix a temporary lath. Do a bit of a search or YouTube.

2 - A mini- grinder and a thick disc 8mm or so is the best thing, not a thin diamond blade.

3 - Yes something like that. Just not the Thompson water seal type products - which are good but not long term as they degrade.

Cheers Woody

What size is a mini grinder? Do you have an example of the blade you recommended from say screwfix/toolstation?

Also what are your thoughts on a mortar raking bit for the perps, such as this?

They look quite effective in this video (0.27s)

Evo Rake Youtube

 

[^woody^]

A mini grinder is typically 4 1/2 " or 115mm, although there are less common 5" or 125mm. Just make sure you get the right size diameter discs for the grinder.

Those rakes need to be in a contraption on wheels IIRC, else they wonder all over the place like a router cutter would. And they are a lot slower going by that video - presumably he's only going slow to control it. I would avoid them, they are not easier than a disc.

Here's an example 8mm diamond disc 2X Mortar Raking Disc 115mm 41/2" Diamond Mortar Raking Angle Grinder Disc: Amazon.co.uk: DIY & Tools , but you probably wont need two for a relatively small area. Or just look for the old fashioned cabonundrum discs in 8mm or 10mm thickness, nothing thinner.

 

[veedee]

Doesn't look like I have that bell cast finish, so i will get that sorted

I have a 4 1/2 grinder which is good and thanks for the link to the mortar raking disc.

 

[Bullet-Proof_Biscuit]

The damp on the inside leaf is only evident at and below the render line??

 

[veedee]

The damp on the inside leaf is only evident at and below the render line??

That is correct. Damp only appears to be present below the render line

Is this surprising? Were you expecting potential damp to come from elsewhere?

 

[Bullet-Proof_Biscuit]

Yes I was expecting the evil that is cement render on period masonry to be the cause. Sounds like the lack of drip edge causing the rain water to 'pour' onto the brickwork is the cause as per above mentioned.