I started building an extension to my garage out of medium density concrete blocks in the summer. It was done when I had time and so only completed 2 weeks ago at which point the roof went on.
The major problem is that with the really heavy rain last week, the rain penetrated and the blockwork is wet on the inside. I don't mean damp - I mean has water on it, which if dried off with a cloth, appears to come through again in a minute or so.
It seems that the blocks are really porous but what I don't know, is how I can do anything about it now considering how bad the weather is. Temporarily I have covered the building with tarps to stop direct rain getting on it, but it isn't drying that quickly at all.
Is there any sealant I can apply which won't matter if the blockwork isn't dry? I need to try to sort this out before the cold weather creeps in because I am concerned about freeze/thaw damage.
Being a fumbling amateur, any advice would be very appreciated!
Hi Mazzo,probably the only thing i can think of is rendering the extension.But if the rest of the garage isn't rendered then it would look bad unless you done the whole garage and that would probably be a really big job.I built a garage in the summer(with dense 100mm concrete block)and i'm sure water was penetrating through that in bad weather,but now that it's been rendered it's bone dry inside.I just used a sand/cement mix with a bonding admixture,but if you feel the block would still be porous with that,then you might be able to buy a special type of render which would be resistant to moisture.On the plus side if you do have to render the whole garage and ext then it will look good...if it's done right!!!
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