Posted: Mon Aug 20, 2018 3:25 pm
Hi,
First post!
A year ago a friend (ex bricklayer of some 20 years ago) helped me lay a new patio. We made sure to try and do everything the right way, a new retaining wall was built and all areas filled with MOT to raise the level overall. All compacted with a whacked plate and then the Indian sandstone slabs laid on a bed of mortar (slabs were also brushed with a proprietary cement mix on the back for better adhesion). Gaps were set to about 10mm between slabs. To point we used a modern resin compound (weatherpoint 365 by Marshall’s) which is brushed in to the joints after a thorough soaking all over. The finished job looked fantastic.
About 6 months ago I noticed a crack in the retaining wall along the cement mortar line in a zigzag pattern along one edge, which I put down to some ground settling (the walls were laid on foundations 6 inches deep). Since the hot weather we’ve had now I’m noticing some serious shrinkage in the mortar joints between the slabs, literally running the length or width of a slab (I’d add an image if I knew how). The majority of the shrinkage seems to be where the most MOT was used to backfill (we extended one section, only about 3 sq mts, but had quite a bit put in to fill it).
My question is this, is it likely that the shrinkage is just caused by the moisture being drawn out of the mortar below and the weathershield 365, or would it suggest a bigger problem?
Also, is it possible to just fill the gaps with more 365, I have half a tub left over still
Sorry for the long post and thanks in advance,
Scott
First post!
A year ago a friend (ex bricklayer of some 20 years ago) helped me lay a new patio. We made sure to try and do everything the right way, a new retaining wall was built and all areas filled with MOT to raise the level overall. All compacted with a whacked plate and then the Indian sandstone slabs laid on a bed of mortar (slabs were also brushed with a proprietary cement mix on the back for better adhesion). Gaps were set to about 10mm between slabs. To point we used a modern resin compound (weatherpoint 365 by Marshall’s) which is brushed in to the joints after a thorough soaking all over. The finished job looked fantastic.
About 6 months ago I noticed a crack in the retaining wall along the cement mortar line in a zigzag pattern along one edge, which I put down to some ground settling (the walls were laid on foundations 6 inches deep). Since the hot weather we’ve had now I’m noticing some serious shrinkage in the mortar joints between the slabs, literally running the length or width of a slab (I’d add an image if I knew how). The majority of the shrinkage seems to be where the most MOT was used to backfill (we extended one section, only about 3 sq mts, but had quite a bit put in to fill it).
My question is this, is it likely that the shrinkage is just caused by the moisture being drawn out of the mortar below and the weathershield 365, or would it suggest a bigger problem?
Also, is it possible to just fill the gaps with more 365, I have half a tub left over still
Sorry for the long post and thanks in advance,
Scott