mortar turning black and green

[dmcskippy]

Hello

Approx five months ago I had two single storey extensions built and a seperate small retaining wall in the garden, double skin.

I have noticed that there are a couple of patches of mortar that have turned almost black, I would say the patches are about 3 bricks by 3 bricks but only on one of the extensions, I can't see anything growing on the mortar, does anyone know what it could be? The patches are in full sun for half the day.

Also the mortar in the retaining wall is going very green in colour with a few patches of black. It all looks very unsightly.

The builder is coming back in a week or so to rectify one or two other issues, is it worth mentioning to him do you think?

Thank you in advance for any advice.

 

[noseall]

If ever a post needs a piccie this one does.

Any chance?

 

[dmcskippy]

If ever a post needs a piccie this one does.

Any chance?

Hi, I'll see what I can do, thanks.

 

[dmcskippy]

The first photo is of the wall of the extension that has no discolouration at all, black, green or white salt, to the mortar or brick, this is how it should be.

View media item 49080
The next photo is of the other extension, same brick/mortar, showing the mortar going black with some white what I believe to be salt deposits on the brickwork.

View media item 49078
This next one shows the salt deposits even more.

View media item 49083
The next three are of the small retaining wall in the garden..

View media item 49082 View media item 49079 View media item 49081
I think it's very odd as well that one extension isn't showing any of this discolouration.

Thanks for advice.

 

[JohnD]

you have a water leak. The bricks are wet. The green and black is algae and mildew. The white is efflorescence.

 

[dmcskippy]

Thanks, but there are a couple more black areas of mortar and none of them have any water pipes behind them so I can't think of where water would be coming from if it was a leak. Also when the wall is wet after rain the black areas are still much much darker than the rest of the mortar.

The black and green on the retaining wall is mildew and algae? Is mildew black?

I know other people that have had new builds at a similar time or longer ago than I have and the mortar on their walls is clean, no salt, black or green. Why could this happen do you think, is there anything the builder could have done or that I could do?

Thank you.

 

[JohnD]

I don't know why the wall is wet, but it is.

You will have to puzzle out where it's coming from, I can't do that.

Look for damp on the other side of the wall, or above, for example a leaking gutter, a garden tap, or just possibly a leak in the bathroom getting into the cavity.