was wondering if you can re-wet screed when its already been put down, as sometimes it goes dry and sandy if left in the heat for to long?? and how should you do it??

also when the screed is set and your spreading the glue if the screed crumbles at the top is that a problem or will the tiles and glue still stick ok???

thanks in advance for any info.

Don't know if you're still around seeing as your post is 2 weeks old but.....

If it's hot I prefer to mist an area with a sprayer after it's been screeded, just to slow down the evaporation and ensure the screed properly hydrates. I like to pack the screed with a steel trowel because you end up with a harder surface when it's cured. Outside in the blazing sun?, I don't know never done that, maybe there are retarders you could add to your mix?, but I'd rather get at it first thing in the morning before it gets too hot.

As far as the screed crumbling when your setting the tiles, guess it depends on the severity, if the whole thing is disintegrating it's stuffed, but small portions here and there may not be a problem. Maybe you need to mix your screed a little bit wetter and pack it down with a trowel. I find I can walk on it the next day and it's very solid. Although my mix is a bit wetter than the norm it's not a problem to work with.

I agree if you know it is going to be a hot day get in and do it before sun comes up otherwise your base concrete will keep drying too quickly for a start and also the screed dries before it can acctualy cure properly. You can use a hose and mist the top a bit every so often but youll find that if it dries too fast it will crumble too much to be able to tile on it afterwards.