Johnstones Water Seal - anyone ever used over painted masnry

[DudleySquires]

Greetings all, new here

I'm having issues getting the single skin block walls on my new garage water tight. The blocks seemed to soak up the rain until it runs down the inside and puddles - not good.

I shielded the wall and managed to get it dry. Then I painted the outside with dulux trade weathershield masonry paint. 1 watered down coat and then 2 full coats. It has been raining the last couple of days and while there looks to be an improvement inside, there are still small patches of wet that have appeared. These patches are not just a slight darkening of the block, they are full on glistening damp patches. I'm worried that when it rains properly it will just be the same as before - puddly.

I'd rather not go to the expense of render just yet, or cladding for that matter. I've heard good things about Johnstones Water Seal but the datasheet doesnt mention whether it can be used over previously painted masonry. Does anyone know if it can?

Thanks
Jon

 

[joe-90]

You've got a leaky roof.

 

[DudleySquires]

You've got a leaky roof.

The roof probably lets in air. However, I have not tested it so cannot say for sure. Chances are it does though. I certainly didn't intend to get an air-tight roof. So for me to argue with you and say that it is not leaky, strictly speaking I guess I would be wrong.

However I can say for sure that I have never seen any evidence of water getting through the roof. There are no drips on the floor or anything in the garage. The trusses are dry. The membrane under the tiles is dry. the tops of the wall plates are dry. The small areas of the insides of the fascias that I can see are dry.

I hope that is clear.

Thanks for your help.

 

[joe-90]

You can't get water to pass through a concrete wall and run down the inside - capillary action won't allow it to. Neither will you get enough water in the UK to wet a wall right through or every old terraced house would be wet inside. Try hosing your wall and see how much runs down the inside - and that stream of water is about a thousand times greater than a bit of rain.

 

[DudleySquires]

That was the only way I could explain the damp patches on the wall that I mentioned. The proper glisteners. Of course there is mortar between the blocks, that goes without saying. Perhaps that is the ingress point? Blocks are fibolites - maybe these aren't suitable?

Or perhaps the water is dripping of the underside off the leaky roof and the gale that is getting in through the leaky roof is blowing the drips onto the wall to give the appearance of water ingress through the wall itself?? And not a single drop from this leaky roof is landing on the floor?? Nor are any landing on anything else in the garage.

Shall we assume it's not a leaky roof: my original Q still stands. Has anyone ever successfully used Johnstones Water Seal over water-based masonry paint?

 

[joe-90]

No it ISN'T going through your wall. You've given it 3 coats of masonry paint.

Old Victorian toilets/sheds are all VERY absorbent single brick - and they NEVER get wet.

Your problem is roof/gutter related. Why can't you see that?

 

[DudleySquires]

Can you see these pics?

These are the inside of my garage. It has been ~24 hours since it has rained. I didn't get a shot of the roof because there is nothing to see, drip-wise.

I understand what you are saying, Joe. I look at bare block walls on other buildings and wonder why they are obviously not suffering the same way as I am. Very frustrating, but this is where I am and I am trying to deal with it. Everything to me looks like the water is coming through the blocks. Before I had put anything on the outside of the walls, when it rained the inside was horrific. Totally sodden, glistening, and puddles at the bottom of the walls. btw DPS is installed.

I can assure everyone that the water on the inside of these walls is not coming from a leaky roof.

Will Johnstones Water Seal work if applied over masonry paint?

Thanks

 

[joe-90]

No it won't. If three coats of masonry paint don't sort it then nothing will.

 

[Pigeon85]

What is the garage used for? Any tumble drying used in there

 

[DudleySquires]

bashing bits of wood together is about all its used for until I get these problems sorted. No services in there yet.

 

[Pigeon85]

Well there's one of my theory's out the window lol. It is a strange one and I think something you have to live with to find the actual cause of. Have you inspected the mortar from the outside closely to make sure that is in good condition also try a few experiments like stated above giving it a hose, hope you do find the answer and solution soon because it can be a pain and could be a waste of time and money.

 

[joe-90]

Thanks for the piccies. What I think is happening is this.

You've painted the outside wall and checked the mortar joints - and they are fine and waterproof.

What is happening is water is getting in right at the top where the roof joins. It is then tricking through the very aerated Fibolite blocks and is running right through from top to bottom and pooling on the concrete below.

In certain sections, the mortar is more water resistant and allows the blocks to become waterlogged. That is why the damp shows up just above the mortar joint.

Test this theory by putting an old towel or whatever on TOP of the block near the roof.

This is the only solution that agrees with the science. Otherwise we'll have to call it magic.