Mike Paulsen wrote:
Waltrrr wrote:
(snip)


(1) Are 787 cubic feet of mulch (the play area surrounding the
playhouse, filled to a depth of 9" – 12") truly necessary?

(snip)

especially in the absence of evidence that such a
quantity of “soft” ground is any better at mitigating injuries over
time than ground mulched to a lesser depth.)


The manufacturer's guidelines are almost certainly based upon
recommendations published by the CPSC. The CPSC did impact testing with
the various materials (sand, pea gravel, mulch, etc.) and came up with
depths which would protect against "life threatening" head injury, not
"big owie", or even "serious injury" so I think it's OK to view it as a
reasonable minimum standard.


(2) Assuming a deep mulch to be desirable, our initial response would
be to construct a 38’ L x 23’ W x 20" D area, level the ground within,
and border this with pressure treated 2 x 6s. After constructing and
“planting” the playhouse, we would fill the bottom of the play area
with pea gravel to a depth of 6” (to expedite drainage), cover this
with 12" of “rubber” mulch under a porous matting material, and top the
whole off with 2" of natural mulch, to be replenished seasonally as
required. The 64K questions: (a) Does this make sense, and (b) do y’all
have any better ideas?


I think the 2" of wood mulch would quickly get displaced, exposing the
matting. I'd skip the rubber mulch and go with 9" - 12" of wood mulch.

CPSC information he
http://www.cpsc.gov/CPSCPUB/PUBS/playpubs.html

I like # 2, BUT: I'd go 6 " of the rubber under the mat and go 8 - 10 " of
the wood mulch.