I recently had a new patio, with Marshalls Heritage slabs, laid (by a professional landscape gardener). The work was finished about 3 weeks ago, and I now notice that some of the slabs have what looks like wet edges. The wet spots run along the sides of the slabs, and extend up to 4 or 5 centimetres into the affected slab. Some other slabs look completely dry, and the wet edges exist completely randomly (but always on the same slabs).
Are these wet edges something that will eventually disappear or do they point to a problem with the laying, or the pointing?
Hope I have described this so people can understand what I mean - but I could send a digital photo if required.
Thanks in advance for any replies
Rose
Wet edges on slabs?
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84-1093879891
The problem you describe is a common one, Rose. What's happening is that moisture is being held by the jointing material, like a thin strip of sponge, and is gradually leached out to the flagstone during the drier periods.
It's a totally natural process, and the only way to combat it is to use a waterproof grouting material. Often, if the flags are pointed with a decent mortar, this effect is less pronounced or even completely absent, but if a porous mortar, a dry grout, or a dry sand joint has been used, then the 'sponge effect' is exacerbated.
Their is no long term detriment to your flags, which are more than capable of coping with long-term damp, but I appreciate it can be less than attractive. It will disappear during the summer, and, if the jointing seals itself over the next season, you may find that come next winter, it's stopped altogether, or is more evenly spread throughout the flag, rather than just appearing at the edges.
If you can live with it, then give it until the end of next summer to see how it develops, and then,m if you still think it's a blight, you could consider re-pointing and/or sealing the paving, but to do so now, would probably be a waste of time and money.
It's a totally natural process, and the only way to combat it is to use a waterproof grouting material. Often, if the flags are pointed with a decent mortar, this effect is less pronounced or even completely absent, but if a porous mortar, a dry grout, or a dry sand joint has been used, then the 'sponge effect' is exacerbated.
Their is no long term detriment to your flags, which are more than capable of coping with long-term damp, but I appreciate it can be less than attractive. It will disappear during the summer, and, if the jointing seals itself over the next season, you may find that come next winter, it's stopped altogether, or is more evenly spread throughout the flag, rather than just appearing at the edges.
If you can live with it, then give it until the end of next summer to see how it develops, and then,m if you still think it's a blight, you could consider re-pointing and/or sealing the paving, but to do so now, would probably be a waste of time and money.