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Mortar bonding after brick movement

Posted: Mon Jul 17, 2023 9:17 am
by silvershadelynx
Dear all,

I am a beginning bricklayer and I want to do some small masonry jobs on my house.

For example, I have successfully filled some holes in a wall with new bricks. Our house dates from 1926 and has stone walls.

Yesterday I built a window sill. The bricks were at an angle (pointing downwards) and before I placed mortar I test-laid all the bricks in dry condition to make sure everything fits and looks ok. That all went well.

Then I placed mortar and laid the first brick. This one slid off the wall. The stone also compressed the mortar too much. So I quickly placed a wooden lath on the wall and placed the bricks on this lath. After that it went well and, in my opinion, I built a neat window sill.

Unfortunately, I then made a mistake: after 3 hours, I began to worry about whether I could still remove the wooden batten and carefully pulled it forward. This took a lot of strength, because there were 13 bricks resting on it. When I pulled the lath forward a few millimeters, a number of stones began to slide with it, forward.

I had hoped that the lath would come off without sliding stones, but I was thus too quick to remove it. In retrospect, I should have done this after the mortar had hardened. I carefully pushed the bricks back and carefully pressed on the mortar with a tuck pointer.

The mortar was on the damp (wet) side and beforehand I wet the bricks as well as the wall. I also misted the mortar with water every hour. I'm wondering if this had any positive effect in this situation?

On the face of it, everything seems fine and neat. But I now doubt whether the adhesion is good enough because, as I learned after this mistake from a neighbour, you have to work within 30 minutes and not move stones after that. Do you guys have any idea if this can still be good and how I can test it? My plan is to let the mortar harden and then press on it to test if it seems to adhere well.

Re: Mortar bonding after brick movement

Posted: Tue Jul 18, 2023 10:02 pm
by stoneyboy
Hi silvershadelynx,
Sounds like you have done all the right things especially damping all parts. You could try lifting one of the bricks to see how good the adhesion is - if it lifts easily you’re back to square one.
Regards S

Re: Mortar bonding after brick movement

Posted: Wed Jul 19, 2023 8:31 am
by silvershadelynx
Hi stoneboy, thanks a lot for your response!

I will check it after 2 weeks - (I'm on holiday first) - and then pull it up with some force. If it doesn't come loose I'll accept it - it just looks very neat - which makes it a bit frustrating for me as a first time brikclayer and perfectionist.

I'll try to put a picture online of the window sill after I'm back from holiday.