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Posted: Thu Jun 23, 2005 8:02 pm
by JR
What are the pro's and con's regarding a mortar joint or a butt joint when laying kerb units. I prefer a nice crisp mortar joint as it makes a nice contrast. What is the best way of doing the joints, as you lay them( like a brick) or after they have set.
Best regards,
JR
Posted: Tue Jun 28, 2005 6:54 pm
by Tony McC
I prefer mortared joints as I believe they just look better, more professional. However, it's labour-intensive work and it requires a degree of skill in working with mortar that not every paving layer will possess.
If the kerb units are laid to straight lines, then butt-jointing is acceptable (to me) because the joints are tight and regular. Where I have a problem is when curves and arcs become involved and you end up with gaping joints at the front or back of each unit, which I feel detracts from the finished appearance.
Worst of all are those small-unit kerb lines where just the very widest of joints have been stuffed with a dollop of mortar, while other 'open' joints are left with 6-12mm gaps. The fact that just one or two joints that have been pointred (if you can call it that!) actually draws attention to the anomaly, rather than making the kerb line look like a well-constructed, uniform item.
Everyone will have their own preferred method for laying these small unit kerbs. I prefer to butter the new kerb with the mortar and push it into place, in much the same manner as is used when bricklaying. Excess mortar is squeezed up and out, and can be trimmed off with no staining of the kerb face itself. Other contractors prefer to butter the receiving kerb, which is basically six of one and half-a-doxen of t'other. However, some use no butter mortar at all: they simply lay each unit with a 'guessed' gap' between itself and its neighbours, and then fall back when the line is laid to point each joint individually - I find this to be a terrible bore and the messiest method of the lot.
There is no "right" way. You have to find the method that best suits you. As long as the joints are well-filled, neatly struck and tooled, and there's no mortar smeared all over the kerb tops and faces, it's right.
Posted: Tue Jun 28, 2005 9:13 pm
by JR
Thanks Tony. So I should lay the kerb units on a bed of concrete haunched at the sides and butter the new kerb unit with mortar as in bricklaying. Should the mortar mix be a stiff 4:1 mix with plastisizer?
Best Regards,
JR
Posted: Wed Jun 29, 2005 12:05 pm
by Tony McC
Yep - 4:1, stiffish with plasticiser.
If I get a chance this summer, I'll photograph a typical installation. I have some photoes from last summer of a step being built using KL kerbs units laid in this way, but they are 'stage' shots, showing each stage of the work, rather than 'working' shots, showing how the individual kerbs are placed and laid.