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apples12

How to seal a concrete block building?

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Hi all

 

We recently bought a new home where the previous owners had very recently built a single skin concrete block building, quite large at 3.6m x 5.8m but only single skin concrete blocks with a felt flat roof.

 

It is water tight on the whole but I've noticed that one of the walls is soaking water through the mortar joints and I've little idea of how best to protect it.

 

It seems to be from driving rain and/or possibly run off from the neighbours shed. 

 

What are my options to waterproof this side of the building? It is not 'visible' so don't really care how 'pretty' it is, it needs to be functional. The other 3 sides will be clad in anthracite plastic cladding.

 

The 2 options I can see at the moment are as follows

 

1. Paint the wall with a few coats of a bitumen based/liquid rubber paint and leave it at that

 

2. Put up a physical barrier between the two buildings (I was thinking large sheets of cladding at an angle from under my guttering to the ground just past the edge of my concrete pad. 

 

Internally, once it's fully dry it will be celotex in the ceiling, board and plaster. Walls will be batten/Insulation/board/plaster.

 

Purpose of the room will be storage, gym. 

 

I've attached 3 images, one of the inside wall showing the water seepage in the affected wall, another showing the outside and lastly the external of the affected wall. 

 

The window was DIY fitted by myself and does need finishing off! 

 

 

Many thanks

 

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Edited by apples12
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We've very recently had a single skinned garage built; but it's been rendered with K-Rend on the outside and I've sealed the inside with 50/50 PVA & water and then painted it a number of times with masonry paint (white) on the inside

 

IMO if you can, get it rendered; it'll look much better and also give you the water-tightness you need. But deffo seal the inside with PVA too; but ideally you want it as dry as you can so you're not sealing in too much moisture

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Basically the block it is built out of a porous, the building has not been finished. It needs to be rendered with cement then you can paint it.

 

If you want to use it as a shed that will be all you need.

 

If you want to use it as a garden room you will need to insulate the roof if it's not done and I would baton the walls and then use 50mm insulated plaster board. 

 

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Render is my preferred/ideal option however with the gap between our shed and the neighbors being about a foot and a half, narrowing to a foot, I can't see how this could be done?

 

I'd gladly attempt a DIY render, indeed quite keen to! Can't be that difficult and not worried about aesthetic on that side!

 

I'll look into k rend

 

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Probably the simplest thing would be masonary paint but as above the block is not intended to be an external finish and will be porus.

 

Rendering in the gap might be tricky (and its harder than you think) so you could consider a breather membrane over the block with counter battens (to vent the boarding)over then a T&G board over that though you would need to do something at the roof as there isn't much of an overhang to cover the void. Plenty of info on line to explain what i mean.

 

Its cheap and cheerfully built i'm afraid!

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37 minutes ago, apples12 said:

Render is my preferred/ideal option however with the gap between our shed and the neighbors being about a foot and a half, narrowing to a foot, I can't see how this could be done?

 

I'd gladly attempt a DIY render, indeed quite keen to! Can't be that difficult and not worried about aesthetic on that side!

 

I'll look into k rend

 

 

Ours is similar, 9" between our garage and the neighbours. The guys that did the rendering just applied the k-rend there but didn't 'finish' it like the rest of the garage as they couldn't get the tool in. 

 

Other than that, you can't tell

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The moisture is too high to be run off from the neighbours shed, which makes me wonder about the guttering. It’s not clear from the photos, but it almost looks like the flat roof isn’t overhanging the guttering at the back, which would mean the run off is going straight down the wall.

 

Do you have a side shot of the back of the roof, so we can see how the gutter works with the roof?

 

<edit> Just some more thoughts on this. Although the advice on rendering is good, you need to find the root cause of the water first - there's no point slapping render on to protect the blocks if you don't fix the source of the water. The fact that the moisture is only on that back wall is a good sign that it's not caused by driving rain (it would affect all the walls to some extent, and that back wall appears to be one of the more sheltered walls so should be affected less, not more). As mentioned above, the fact that the moisture is high up the wall points to it not being due to run-off from the neighbouring shed. This only really leaves the run-off from your own roof as the source. Job one is to investigate the guttering. If the issue isn't obvious, pour a bucket of water onto the roof and watch where it ends up.

Edited by Spandex

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