Mortar Between Bricks

[wallaceoc]

Hi,

Rlughly 6 months ago I had a new section of wall on my house built with red brick. I noticed during the week that the mortar around some of the bricks is not "sealed" as the rest of them. I've included a photo of one of the bricks.

Should I be somehow sealing around these bricks in case water is travelling in towards the cavity?

Thanks for your suggestions.
Wallace

Untitled

• wallaceoc
• 20 Feb 2015
• 1

 

[theprinceofdarkness]

That's called "movement". Its not a mortar problem, though you are right that water will get in. Its more likely to be bad foundations or some thing wrong with a lower course of bricks.
Traditionally one would cement a piece of flat glass across the crack, then you can see how much movement there is. If after a couple of years, if there is no further movement, rake the mortar out to a depth of 20mm and repoint.
Frank

 

[wallaceoc]

Hi the princeofdarkness,

thanks for your reply. In the mean time is there any way I should seal up the hairline even with clear silicone or something?

I'd be surprised if there is movement thought as the foundataions are 1m deep and only a few bricks are affected. Also, it's a single storey bay window so all the wall is supporting is a PVC window with a flat roof?

 

[theprinceofdarkness]

PVC has a rotten temperature coefficient, that is it expands and contracts a lot with change in temperature. Could be that your frame has contracted in the cold and lifted some bricks with it being firmly tethered at the top. Or some residual strains being worked out by the PVC bowing and lifting the centre.
I work tap the bricks with the handle of a hammer to see how loose they are. If they seem to be moderately tight, Wait till spring, then dig out the pointing and repoint.
Frank

 

[KenGMac]

wallaceoc, HI.

Possible that the mortar was over cemented, that can at times give rise to the mortar cracking?

Also possible that the brick is very susceptible to temperature differentials, that is in winter with the air temperature dropping the bricks are contracting

I would wait until Spring and have another look at the same joints the mix of both above may be combining to cause the separation cracks.

As for the possibility of Subsidence, No, subsidence cracking takes a very different form, and in general emanates from ground level travelling at times vertically, but generally horizontally as a section of Foundation fails

Ken

 

[tony1851]

It's just surface shrinkage of the mortar - nothing unusal or serious. Possibly caused by a slightly too-strong mortar.

Don't bother about it. Water will get into a cavity wall, but then that's what cavity walls are for.