Monday, July 16, 2012

adjusting the pitch

I am turning into a palapa aficionado.

And you all know why.  Mexico has given me a post-graduate extension course in construction with our church's new palapa.  Most of you know the details from all aboard.

One of my readers commented that the lateral bracing appeared to be inadequate due to the wind load that would be created by the pitch of the palapa.  I am not an engineer (and I have never played one on television).  So, I cannot offer an intelligent assessment on the warning.

But I thought of his comment as I was driving back to Melaque from Puerto Vallarta.  The highway runs along the edge of the Pacific until the highway meets the mouth of the Tomatlán River.  Perched high on the cliff above the Pacific is Le Kliff -- a bar and restaurant.  (I took the photograph in just move it from the restaurant's parking lot.)

A major portion of the restaurant is a giant palapa.  Currently in the process of getting a new roof.  You can see it at the top of this post.

I do not know how long the palapa has been there.  But it has been years.

What struck me about it was the pitch of its roof.  That palapa is buffeted by far higher winds than the church's palapa in Melaque.

If the Le Kliff palapa can survive, I suspect ours will do just fine.


Rick said...

The palapas in the Yucatan (although very light construction) tend to survive the hurricanes since the palm fronds simply blow off the branches forming the frame. The slight frame structure doesnt pose enough resistance to blow away.  I have watched as workers gather the fronds off the beach after a storm and re-tie to the 'rafters'.  It was amazing to see the beach palapas returned to service a few days later.

Steve Cotton said...

 It is a very practical construction technique.  That may be why it is ubiquitous in the tropics.

John Calypso said...

Little grass shacks are so charming until they get huffed and puffed down.  Then one gathers his fronds and regroups (them). The advantages of having a palapa are many save the hurricanes.

Steve Cotton said...

The tropical value of versatility.

Dubious said...

I am the engineer about whom you speak.  I have a couple of points to make.  The designers of the Le Kliff palapa were clever, they reduced the lateral wind loading by smoothing the gable ends with a semi-circular design.  Rather than wind loads hitting a nearly vertical wall causing the trusses to fall like dominoes, those forces will gently move aloft.

Secondly, your photos did not show the "bones" of the Le Kliff palapa which, may or may not, have more sophisticated roof trussing.

Conventional wood frame roofs rely heavily on the sheathing (rigid plywood or horizontal planks) to prevent racking.  Simple vertically oriented sticks with lots of weight on them have little chance of survival.  Just ask the three little pigs.

Steve Cotton said...

We may be setting sail on the Kon-Tiki.

I realize engineering principles are universal.  But I have been amazed at what works down here.  If you looked at the power lines on the street outside my gate, you would be amazed that anything electrical would actually work inside my house.  Of course, there are the random shocks.