Joined: July 2004
||Posted: 29 Oct. 2019,12:25
I wrote about this issue some time ago and it's not become any clearer since, sadly. FAQ
Most of the resin-based jointing mortars, both one-part and two-part, declare that a permeable bedding should be used beneath the paving, and this is perfectloy true, in an ideal world. The porblem we have in Britain and Ireland is that, by and large, we are still laying our paving on more-or-less impermeable bedding. So: should we not use resin-based jointing mortars?
The situation is that, while these mortars work far better when used with paving laid on a permeable bed, they *will* work well enough with paving laid on standard mortar or similar. It's less than ideal, but then we don't live in an ideal world.
TuffTop is an excellent product, there is no doubt, but is has exactly the same requirements: it works best with a permeable bedding mortar, but it's not the end of the world when it's used with paving laid in the more traditional manner.
The better two-parts and the TuffTop are not really affected by the near-permanent damp that arises within a pavement joint when an impermeable bedding mortar has been used. Some of the one-part polymnerics fare far less well, though, and a handful of the really crappy ones will, literally, fall apart after a season or two, The biggest issue with any permeable jointing mortars, 1-part, 2-part, or cementitious, when used over an impermeable bed, is the resulting 'reservoir' becomes an ideal home for mosses and other undesirable vegetation.....but that's easily shifted by weedkiller or pressure washing.
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