I got this email today…

Hi,
please advise me, I'd like to make a rock climbing huge boulder w/ climbing holds for children to practice and play climbing...will hypertufa be the answer? how do I do this?
thanks for any help u can offer

I thought it would make a good subject for an article.

Here is my reply…

Thanks for asking:
I don't think I would use Tufa for what you are doing.  It is a bit soft and crumbly if you get the mix wrong.  You don't want anyone to have a handhold break off.
Go with concrete.   It will be a big job.
I would go to a couple of places where they have them and ask how it was done.  I have never done anything like it and would not like to give advice that may be wrong.
Del

To elaborate on this a little I will add that I went to a local store where I had seen them setting up a climbing wall on the weekend.

I had been wondering how they made it.  The paint was still wet when I got there and I asked one of the guys what the wall was made of.

It was spray on foam over a plywood base.  The handholds where steel, they come pre-made and are screwed on.  They foam guy builds up around them and they use templates to show where to put the high and low spots.

These things are a work of art; they take 4 guys about 2 days to set up on average.  Once they are done they come back and do repairs and maintain them every day.   They last about 3-4 weeks and then are taken down and destroyed so that no one can get hurt playing on them.

They cost about $8 - 10000 including the daily maintenance.  Foam and plywood makes sense, it keeps the wall light and easy to move.  The foam is a special blend that gets a thick hard skin on it when it sets.  This makes it more realistic and of course durable. 

Now you know as much as me.   Should you start building?