Wet cavity in new blockwork wall - is this normal??

Multiplex · 2 Jan 2013

Hi,

We've just had the first phase of a garage conversion completed by a local builder. After a few weeks we've noticed that the cavity of the new wall constructed is damp on the inside and the cavity insulation is basically soaked through with water.

Before I go back to the builder is this expected from blockwork? We're planning to render the house in the summer but I was not aware that blockwork leaked water like this and required render to make it weatherproof!

Attached are two photos. One is of the outside of the garage conversion and the other is taken from the inside showing the wet blockwork (the water droplets on the window frame came off the insulation as I was pulling it out).

Untitled

Multiplex
2 Jan 2013
1

Untitled

Multiplex
2 Jan 2013
1

Thanks,
Simon

JohnD · 2 Jan 2013

Rain will have got into the cavity until the roof was put on. It will slowly dry out now, unless there is a leak allowing more water in.

It can take a year for a new wall to dry out.

^woody^ · 2 Jan 2013

During construction, insulation and the cavity should be kept dry. That amount of dampness does not look typical of it coming through the blockwork - more like down the top of the cavity?

Now that it has got soaked, the insulation's performance could be affected, but it will be difficult to do anything about it now. Take what you can out, let the cavity dry and then put some new insulation back in

JohnD · 2 Jan 2013

looking again at the picture, was the new wall to block the former doorway of an existing garage? If so, the roof was already in place, so the rain must have got in through the window aperture. At least that reduces the amount of wet. I would be inclined to drill a small hole through a joint outside just above DPC in case there is a pool of water to run out. But it will probably all have soaked into the blocks.

joinerjohn · 3 Jan 2013

Unrendered blockwork will allow water through, and the amount of rain we've had this past 3 or so months, I'm not surprised that the cavity is damp.

joe-90 · 3 Jan 2013

But as JohnD says - it should get very little rain under that roof.

jeds · 3 Jan 2013

Blockwork wouldn't absorb that much dampness post construction - especially being directly under the roof eaves like that. Must have been left exposed during some heavy rain. Not good but also not uncommon to be honest. It will dry out eventually. Some prolonged dry warm weather would be ideal. But don't hold your breath on that!

Multiplex · 3 Jan 2013

The windows were fitted just one day after the blockwork was finished on a dry day. I think with the recent bad weather the rain has battered the blockwork and water is penetrating much more than I expected.

There's a doorway around the side of the garage that the builder bricked up and fitted a window. Water is literally dripping down the cavity when it rains and is also visible inside as we haven't decorated inside the garage yet.

I'm honestly confused how this is normal. Is my builder supposed to have left the blockwork exposed knowing that I'm not going to be rendered for several months?

Thanks,
Simon

limerockconstruction · 3 Jan 2013

we always try to get our blockwork covered with render as soon as possible - if all you have engaged him to do is the blockwork, then its your call if you choose to hang off rendering, not his.

They do look damper than you'd hope though! I assume nothing is penetrating to the inner skin, which at least means the cav is working. Can't you at least get it scratch coated, looks like about 90mins work from start to finish....

JohnD · 4 Jan 2013

there is so much I think it must be penetrating round the windowframe.

stuart45 · 4 Jan 2013

AAC blocks do soak up the moisture more than concs. The inner skin should be OK, unless the wrong type of insulation was used.

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Wet cavity in new blockwork wall - is this normal??

joinerjohn

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